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Small Scale Wind Turbines

masters electricite plusIn this final part of my series of articles on generating electricity by using the power of the wind, I'm going to consider small scale wind turbines, as would be used by independent households rather than large scale commercial developments.

The first point to make is that small scale wind turbines are more expensive per kilowatt than the medium scale wind turbines. They certainly can’t produce electricity at a price lower than that which is mains-supplied, if the capital costs are taken into account. And if the household wants to be completely independent from mains-supplied electricity, it would be necessary to have batteries to store electricity produced on windy days for use when the weather is calm.

It is possible to use a small-scale turbine to feed electricity back into the grid and receive a premium price for the electricity produced by this means, in the same way as that produced by photo-voltaic panels. Alternatively, the small-scale turbine might be used to supplement mains supplied electricity for those people who wish to contribute in a small way towards pollution-free energy production. Unfortunately, ill-conceived micro and small-scale wind turbine installations and exaggerated claims by installers have damaged the reputation of these systems. However, if care is taken with the siting and proper wind speed measurements and site surveys are undertaken, it is possible to use micro/small-scale turbines in independent residential settings.

Small-scale wind turbines and buildings do not mix. The turbine should not be closer to a building than ten times its equivalent height and supported on a mast where the hub of the turbine is at least twice the height of the building. Thus if an average two storey house is 7.5m high to the ridge of the roof, then the small-scale wind turbine should be at least 75m from the building and the mast 15 metres high. This is fine if the property is in a remote location, but in semi-rural locations it would be difficult to achieve and the construction would need planning consent. In 2009, the UK Energy Saving Trust carried out a field trial study at a number of sites around the UK. The trial found that in urban and suburban locations, building mounted wind turbines had inadequate wind speed values, resulting in very poor performance.

However, in exposed locations, particularly in Scotland, good performance figures were returned and in some cases load factors of 30% were achieved. As such, a properly sited and positioned 6kW rated free-standing, pole-mounted turbine would be expected to generate 18,000 kWh per annum.

Building mounted turbines exhibited generally poor output due to the inadequate wind speeds. Even those in exposed rural locations only achieved load factors just better than 5%; the best one was in Scotland with a load factor of 7.4%. In a survey of customers, who had installed a small-scale wind turbine, the feedback was that 85% were looking to reduce their electricity bills followed by a desire to help the environment and then to reduce carbon emissions. Some 49% said they had seen a small reduction in their electricity bills, whilst 35% had not seen any reduction.

However, this method of measurement is imprecise unless the price per kWh of electricity remains the same throughout the period of analysis. Moreover, it does not take into account the purchase cost of the turbine, the cost of site preparation, the installation and connection of the turbine and any maintenance fees, nor does it allow for interest on loans or loss of interest if savings are used to pay for it.

Economics of Wind Energy

In this article, the fifth in the series on using the wind as a source of energy, I consider the economics of the resource.

One of the ways that we describe wind turbines is by the rating of the generator in Mega-Watts (MW), e.g. 2 MW. If the turbine was turned by the wind at its full rated speed throughout the year, then the generator would produce 17520 MWh of electricity, i.e. 2 x 24 x 365. Of course the wind does not blow constantly, even in very windy regions, so in practice the wind turbine will have a much lower capacity.

Renewable UK, the voice of wind energy in the UK, tell us that the average load factor (load factor is the actual output of a turbine benchmarked against its theoretical maximum output in a year averaged over a five year period) for onshore turbines is 26%, whilst offshore turbines do better at 35%. In addition, the operating and maintenance costs have to be taken into account when assessing the viability of a turbine project. For a landbased turbine, this is approximately £40 - £50 per KW/year, so the running cost for our example above would be up to £100 000 per year.

The estimates for an offshore wind turbine would be 3 – 5 times this amount. The reason for the increased costs for offshore turbines varies with a range of factors, such as location, distance offshore, water depth, turbine redundancy and reliability, uncertain weather conditions for getting onto the turbine, material supply chains, currency exchange rates and vessel availability. The average capital investment costs for our example turbine calculated by the European Wind Energy Association would be 2,5 million euros, of which 75% would be the purchase cost of the turbine and the remainder is made up of grid connections, foundations, land rent, electricity, roads and other financial costs. As the cost of wind energy does not include the cost for fuel (wind is free), unlike the cost of energy from fuel-fired power stations, it is a relatively straightforward calculation to determine the cost of the resultant energy in advance.

Fuel-fired power stations have to estimate the future cost of the fuel, whether it is coal, oil or gas. Therefore power supplied from sources where the fuel cost is negligible or even zero are favourable during periods of high or escalating fuel prices. Obviously, the opposite is true when fuel prices are stable or falling.

When considering the payback times on capital investment, onshore wind turbines are very quick to install, in contrast to fossil-fuelled or nuclear power stations, or other renewable-energy options, such as tidal barrages or hydro-electric plants. Therefore, the wind turbine starts to give a return on the investment much more quickly and certainly before heavy interest charges are incurred on loans for the capital.

So does it make financial sense to invest in wind energy?

The problem is that the use of cost per KWh calculations are too simple for use as a direct comparison of energy supply options. The prudent energy utility company has to consider low cost against reliability and fuel cost against long term price uncertainty. Thus, wind energy has a place in the overall portfolio of energy supply but it is not the panacea to escalating electricity prices.

offshore windfarm
An offshore windfarm - reported to be more effective than onshore windfarms

Wind Energy and the Environment

In this series of articles on wind as an energy source, I have looked at its origins and development, the wind itself and how it is created and the types of wind turbines for harnessing that energy. In this article, I want to consider the environmental aspects of wind energy.

The proponents of wind energy express the benefits to be that it does not release carbon dioxide into the atmosphere, nor does it produce pollutants, such as nitrous oxide, that cause acid rain and smog.

There is no radioactive emission and there are no outputs that can pollute the land, water courses, rivers or the sea. And, it has been calculated, that a wind turbine, over its lifetime, can generate 40 to 80 times the amount of energy that it took to produce it.

On the negative side, however, we should consider the noise, electromagnetic interference, aviation issues, wildlife and public attitudes. The noise comes from two sources, mechanical noise from the gear train and generator and aerodynamic noise from the blades passing through the air. The designers of modern turbines have done much to reduce the noise, but a wind turbine still has an audible output of around 35-45 decibels at a distance of 350 metres, which is slightly more than a rural night-time background. The electromagnetic radiation from TV, radio and microwave transmitters can be affected by the blades of a wind turbine, such that the signal becomes distorted before it reaches the receiver.

Changes in the design of blades and towers and additional TV relay transmitters have helped to reduce this impact. The affect on aviation is to do with the potential disturbance of radar signals and the risk to low flying aircraft. The main potential impact on wild life is the risk to birds and bats that could be killed by flying into the rotating blades.

wind turbinesThe worst locations for bird strikes have been at the Altamont Pass in California and at Tarifa and Navarra in Spain where a number of raptor species have been affected. However, a study by Natural England in 2010, concluded that there is little evidence that wind farms in England have had a significant impact on birds. In a 1998 study, the Danish National Environmental Research Institute found that eiders keep a safe distance from the turbines but are not scared off their habitual foraging sites and that the offshore wind turbines had no significant impact on water birds.

The final category of environmental impact of wind turbines is that of the attitude of the public to them. Although large wind turbines can cause a flickering effect this is not harmful to health. I find that it is usually the visual impact that most people dislike. They object to the change in appearance of the rural landscape, although changes to any visual appearance from any new building or structure are often met with resistance.

By contrast, to some people, the revolving blades of the wind turbine are considered graceful. In the UK, there have been over 60 independent surveys since the 1990s of public attitude to wind turbines (e.g. NOP, 2005 and YouGov, 2010). On average, they found that 70% to 80% of people support the development of wind farms, which of course means that 20% to 30% of people do not. Which camp are you in?

Wind Turbines

Wind has been used as a source of energy by man for over 4,000 years. Windmills have been used for milling grain, pumping water, sawing wood and numerous other functions. As the design and visual appearance of the sails and structure were often similar despite the myriad different functions, they were all generally known as windmills and this term has continued to the present day.

The early devices were often of the vertical axis type, that is, the sails rotated around a vertical shaft which is perpendicular to the ground, and they relied on the differential drag on either side of the vertical shaft to create the drive. The 'sails' would have taken a variety of forms, e.g. moveable clappers that were pushed against a stop by the wind and then folded flat when facing into the wind, screened windmills where the sails were partly obscured from the wind by fixed screens on the backward part of the cycle and 'cup' type designs where the blades were shaped to offer greater resistance to the wind on one face compared to the other. A modern example of a vertical axis, 'cup' type windmill is the wind anemometer, which is used to measure the velocity of wind for meterological purposes. A simpler design is the S-shaped rotor that is used on vehicle ventilators, or in a larger format, as rotating advertising boards on garage forecourts.

The familiar horizontal axis windmills are thought to date in Europe from around the 12th century. The horizontal axis shaft carried radial arms that supported sails that were set at an oblique angle to the wind. The plane of rotation faced towards the direction from which the wind was coming and the angle of the sails caused the rotor to be turned at 90° to the wind. The tower on which the rotor was mounted could be rotated by manual effort to maintain the plane of rotation facing towards the oncoming wind as it backed or veered. The sails were fitted with curtains or shutters that could be opened or closed to take account of differing wind velocities and to start and stop the windmill.

According to an estimate by E.W. Golding in his book, Generation of Electricity by Wind Power (1955), before the Industrial Revolution 10,000 such windmills could be seen across the British countryside.

wind turbinesOver the years, a large number of styles and configurations of turbine design has been tried in order to best harness the power of the wind. The horizontal varieties include one, two, three or multibladed rotors, rotors that faced towards the wind or away from the wind, multirotor towers or rotors with contrarotating blades. In the vertical axis format there have been the screened, clapper and cup type, as mentioned above, but also those shaped like the letters V and H, as well the S-shaped rotors mentioned above and the Darrieus, which has hooped, aerofoil section blades that are connected to the top and bottom of the central shaft. Modern wind turbines can be found in both horizontal and vertical configurations. The horizontal configuration is of axial flow, in that the axis of rotation is in line with the wind.

The vertical configuration is predominantly cross flow, and here the axis is perpendicular to the direction of the wind. The turbines are available in a range of sizes from small domestic units that produce a few hundred Watts to commercial wind turbines that are able to produce up to 7.5 Mega-Watts.

Wind Energy

In a previous article, I looked at the origins and development of wind energy from its early beginnings of pumping water and milling corn to its current exponential growth as a means of generating electricity. In this article, I will look at the raw material, i.e. the wind.

Wind energy is in fact solar energy. Why? Because one square metre of the Earth's surface at the equator receives more solar radiation per year than one square metre at higher latitudes. The curvature of the Earth means that a point on its surface is more obliquely angled towards the Sun's rays the further it is towards the poles and, in addition, the Sun's rays have further to travel through the atmosphere to reach the higher latitudes, so more energy is absorbed by the atmosphere to reach that point. As a result, the temperatures are lower the further a point is from the equator. This differential in solar heating of the Earth's surface causes variations in atmospheric pressure, which in turn gives rises to atmospheric air movements and that creates the various wind systems around the world.

Air, as typical of all gases, expands when heated and contracts when cooled, so warm air will rise to high altitudes when warmed by the Sun's radiation striking the Earth's surface. At the equator, the warmed air rises until it reaches the troposphere, where it then moves northwards in the northern hemisphere and southwards in the southern hemisphere. The air gradually cools until it reaches laltitudes of around 30° where it sinks back to the surface. Some, but not all, of the air is then circulated back towards the equator to complete the circle. The remaining air travels northwards and southwards respectively until it reaches the 60° latitudes where it collides with the cold air moving from the poles. The warmer air then rises above the cold polar air and most of it circles back to the 30° latitude, the remaining air moves polewards and sinks at the poles before returning back to the 60° latitude to complete this circle.

However, these air movements are also subject to the rotation of the Earth in a phenomenon known as the Coriolis effect. This effect creates a drag on the air masses and as the Earth moves in an eastward rotation, winds in the northern hemisphere are caused to veer to the right and winds in the southern hemisphere and caused to veer left. So for example, in our belt between 30° and 60° N, the wind at or near the surface is moving northwards so it forced to veer to the east. By convention, a wind is described as where it is coming from, thus the predominant wind in our belt is westerly, i.e. from the west.

In addition to the main global wind systems, there are local wind patterns, for example, sea breezes and mountain-valley winds, which modify the global wind direction on a local scale. Sea breezes are generated in coastal areas as a result of different heat capacities of sea and land, which gives rise to different rates of heating and cooling. Mountain-valley winds are created when cool mountain air warms in the morning and rises as it becomes lighter, whereupon cool air from the valley moves up the slope to replace it.

During the night, the flow reverses and cool mountain air sinks into the valley. In a subsequent article, I will look at the power of the wind and how we harness it.

Wind Energy

The use of wind energy for pumping water goes back thousands of years to ancient Chinese and Babylonian civilizations. In the Middle Ages in Europe, wind was used to grind corn, which is where the term 'windmill' comes from. In the 21st century, there are still many thousands of 'windmills' in operation to grind corn and pump water, but a modern application of wind energy is as a pollution-free way to generate electricity. As a 'windmill' is intended for milling grain, we now use the more accurate description of 'wind turbine' to describe a unit whose function is to generate electricity.

The pioneering attempt to generate electricity by wind energy was made by Professor James Blyth of what is now Strathclyde University. In 1887, Blyth constructed a cloth-sailed windmill that he used to generate electricity to charge accumulators, which provided the power for lighting at his holiday cottage in Marykirk, Scotland. This device continued to generate electricity for over twenty years. The use of wind energy has been applied throughout the period since Blyth's invention to provide electricity for remote houses, farms and communities throughout the world. Small turbines have also been used to charge batteries on boats, caravans and mobile homes. In the years since the proliferation of the telephone, wind turbines have been developed for the purpose of providing electrical energy to remote telephone masts and telephone boxes.

However, in the last thirty years, the technology of wind turbines has matured and the wind energy sector has experienced a rapid growth, particularly as the real cost of wind turbines has reduced because of improvements in reliability and performance. By the end of 2010, there was a total of over 194 billion Watts (Giga-Watts or GW) of wind-generating capacity deployed around the world and nearly 36 GW was commissioned in that year alone. By 2014, the global installed wind turbine capacity had exceeded 369 GW, which shows that the construction of wind farms has continued at a prolific rate.

The world's largest producer of electricity from wind turbines is China and in 2014 of the 51 GW installed worldwide, half of this figure was in China alone. The UK has become the world's leader in the development of offshore wind farms. Since August 2013, the London Array, off Thanet in Kent, has been the largest offshore wind farm in the world with 175 turbines. It has a capacity of 630 Mega-Watts (MW), although the Greater Gabbard wind farm off the coast of Suffolk, which has a rated capacity of 504 MW (the third largest in the world) from 104 turbines produced the largest amount of electricity from a single wind farm in 2012 at 1195 Giga-Watt hours (Gwh).

An important point to note is the installed capacity of a wind turbine is the theoretical maximum generating potential whereas the actual loading of the turbine gives the output figure. By loading, we mean the percentage of the time when the wind turbine is actually generating electricity. The estimated loading of Greater Gabbard from its design potential was 39,6%, yet in 2012, the year it generated the highest output, the loading works out at 27%. This point will be developed further as a subsequent article will look at the practicality of home-scale wind-generating possibilities.

Heating by Wood

At this time of year, as the leaves turn to gold and there is a chill in the air in the mornings and evenings, people start to think about the colder period to come and the need for heating. In South-west France, heating is often wholly or partially by wood-fired appliances. It is common to find at least one wood-burning stove in a home, be it an insert stove or a free-standing poêle. However, the process of preparing for winter for our french neighbours starts much earlier than October. For those that have their own wood supplies, the cutting and splitting of timber into logs begins immediately after the bad weather has receded. The wood is then stacked and allowed to dry throughout the spring and summer. It is vitally important that the moisture content of the wood is reduced to no more than 20% and ideally it should be even lower. Wood that has a high moisture content is a much less efficient fuel.

If wet wood is put on the fire, energy is wasted in drying out the wood before it can burn. To illustrate this, a kg of average log wood that had been completely dried out in a kiln, such that its moisture content was zero, would yield a net calorific value by mass of 5,3 kWh. In other words, the 1 kg of log wood would give out the same amount of heat as a 1 kW electric heater burning for 5 hours 18 minutes.

However, it is not practical or cost-effective to kiln-dry wood for heating. Air-dried wood of 20% moisture content has a net calorific value of 4,1 kWh/kg. Thus our 1 kg of wood has lost nearly 23% of its heat energy potential because of its moisture content. If the wood was poorly prepared, i.e. it was not left to season for long enough and the moisture content was as high as 30%, then the the calorific value would be around 3,5 kWh/kg.

If you are buying in wood, it makes sense to go to a reputable supplier, but put your order in early. Waiting until November to go looking for firewood means you’re likely to end up with wood that has been left out in the rain and it will have started to soak up moisture again.

Average prices for good quality oak and chestnut this year are around 50 – 55 euros a cubic meter (m3). With an average density of between 350 – 500 kg per m3, you should be getting between 1435 and 2050 kWh of heating from a m3. As a comparison, for those people who have had pellet stoves fitted, the energy density of wood pellets is greater than log wood. The average energy density is 3100 kWh/m3 and a net calorific value of 4,8 kWh/kg, therefore a 15 kg sack of wood pellets (costing 3,65 euros in Rochechouart) would give 72 kWh of heat energy.

Thunderstorm warning

The summer months are a delightful time to be in this region. Long, hot days and balmy evenings make life very comfortable. However, it is the time of year when the thunderstorms come in from the Bay of Biscay and move across our part of France in a north-eastward direction towards the mountains. The lightning occurs between two highly charged storm clouds, or between a cloud and the ground. The clap of thunder is the sound of the lightning striking and discharging its energy, which creates a shockwave similar in principle to the shockwave at the front of a supersonic aircraft. In the case of lightning, a current of several million amps flows between the cloud and the earth via the ionised channel that has been created. The effects of this are well known and for electrical, electronic and telecommunications equipment the outcome is usually disastrous.

Each year, the territory of France is struck by lightning around 2 million times. The thunderstorm intensity is calculated by the number of days that lightning is observed in a given department per year. This is called the niveau kéraunique, abbreviated as Nk. If the resultant Nk figure is greater than 25, a parafoudre, or surge protector, is obligatory on all domestic electrical installations unless the supply cabling is entirely underground, i.e. right back to the sub-station. In our region, the Dordogne (24) is the only department where the Nk figure is greater than 25. The Creuse (23) and the Haute Vienne (87) each have a value of 23 and the Charente (16) has 21. Although most of these strikes are harmless and cause no damage to either people or property, it is a different story for those that find their way into our electrical and telecommunications equipment.

There are two forms of protection against lightning damage. The first is by using a lightning conductor, or paratonnerre, to prevent the direct effects and these are used on exposed sites and high buildings. The other method is with a surge protection device (parafoudre). The indirect effects of the lightning are the consequences of a direct strike, on or close to the electrical or telecommunication distribution system, which is then carried by the network of lines to our apparatus. The effects of the voltage surge can also be created by lightning strikes in the vicinity of buildings, where the electrical surge can come up through the earthing system, or by the discharge of energy through a lightning conductor. The strength of the surge will depend on the intensity of the strike and the distance from the point where the electrical equipment is installed.

The parafoudres are categorised in three groups dependent on the level of risk, the expected strength of the surge and method of installation. A type 1 parafoudre is used where there is a high risk, such as where the building has a lightning conductor and where the strength of the strike would be consistent with a direct impact. They are fitted to buildings on exposed sites, or high buildings such as apartment blocks and churches. Type 2 parafoudres are installed at the head of the electrical panels, where the risk is only likely to be through an indirect effect. Type 3 parafoudres are used as a supplementary protection adjacent to a specific piece of equipment. It is not recommended to rely solely on a type 3 parafoudre, such as those purchased from a DIY store.

Air-conditioning

According to Météo-France, several monthly and all-time records for temperature in France were either tied or broken during the first weekend of July this year. In Paris, the temperature on 1st July reached 39,7°C, which is the second hottest reading there since 1873. Three other French locations had record highs, topping their records set during the last canicule of 2003. In our region, the highest temperature recorded at Limoges-Bellegarde was 35,3°C on 30th June and 3rd July.

Keeping cool in temperatures like these can be difficult. In older, traditional style houses with thick masonry walls, keeping the shutters and windows closed during the day and only opening them in the evening is the typical French way of managing with the high exterior temperatures. The masonry absorbs the heat of the direct sunlight and because of the wall's thickness the heat doesn't penetrate through before the cool evening. The wall then reradiates the heat and cools before the next day's onslaught. At least it does if the evening temperature descends low enough. Unfortunately, during a canicule, the night time temperature remains high, often over 20°C, and as a result the wall doesn't cool sufficiently, thus the wall temperature steadily increases and allows the heat to penetrate into the building.

The situation is worse in newer houses where the walls are constructed of concrete blocks. These blocks have a low thermal resistance and so heat passes through them with ease. In order to keep the house warm in winter and not let the warmth generated by the heating system be lost to the outside the walls are insulated to a depth of 100mm, in accordance with the building regulations. The problem is that during the summer, there is little protection against the sun heating the house from the outside. The heat striking the exterior penetrates into the interior and warms the house. The very effective wall and ceiling insulation prevents this heat from escaping. Hence the need for air-conditioning.

The heat energy is absorbed from the air by the refrigerant fluid contained in the unit’s evaporator. This is the coil of copper tubing and aluminium fins mounted above a fan enclosed in a wall-mounted unit in each room to be cooled. As the fan draws warm air into the unit past the tubing, the refrigerant in the tube absorbs the heat. In doing so it takes 8 – 10 °C from the temperature of the air, so the air returning to the room from the unit is significantly cooled. The heated refrigerant is carried to the external unit whereby it passes into the compressor. The compressed vapour continues on its journey through into the condensor which is another arrangement of tubing, fins and fan. This pressure of refrigerant is now allowed to reduce and in doing so it condenses and gives off the heat it absorbed from the earlier process, before returning to the interior unit (evaporator) to continue the cycle of cooling the room. The great advantage of the modern air-conditioning system is that it is completely reversible, i.e. it heats as well as cools, which means it is also a very effective and efficient heating system for the winter. Two systems for the price of one.

Halogen and Fluorescent Lamps

Some time ago, I wrote about the abolition of traditional tungsten filament incandescent lamps and the growth in popularity of light-emitting diode (LED) lamps as a replacement. The LED has the great advantage of a much longer life expectancy and the significant reduction in energy consumption for an equivalent light output. The disadvantage of the LED is the much higher purchase price, although on-line retailers are offering surprisingly low prices.

There are, however, alternatives to LED lamps. One is the halogen lamps and these are almost identical visually to the classic incandescent lamp. A closer look will reveal that instead of the wire filament suspended across the supports, there a small capsule inside the glass bulb.

The halogen lamp uses up to 30% less electricity for an equivalent light output, has a life expectancy of 2000 hours ( twice that of an incandescent lamp) and sells for about 2-3 times the price of an incandescent lamp. The halogen lamp works in much the same way to the incandescent lamp, as it still contains a tungsten filament. However, this time the filament is enclosed in a small quartz envelope, which is the visible capsule. It has to be quartz, as the filament is much closer to the capsule than in an incandescent lamp and if the capsule were made of glass it would melt. The capsule also contains a halogen gas. When this gas gets very hot it mixes with the tungsten vapour and as the tungsten atoms evaporate the halogen gas will combine with them and redeposit the tungsten material onto the filament. As a result, the filament lasts a lot longer and also the filament can be run at a higher temperature and thus be brighter, so there is more light per unit of energy. Thus a 42 Watt halogen lamp gives out the same amount of light as a 60 Watt incandescent lamp.

Another alternative to the incandescent lamp is the compact fluorescent lamp (CFL). These lamps are not a new invention; they have been around since 1974 and were developed in the response for the need to save energy in response to the oil crisis of the time. The idea was to replicate the technology used in fluorescent tubes to produce a low-energy light bulb. Although these were not particularly popular for domestic usage owing to their long warm-up to achieve full output and the unflattering colour of the light, improvements in design and and performance has made them into an acceptable alternative. Although they are more expensive to buy than a traditional light bulb, they have a life expectancy of 6000 to 12000 hours. A classic incandescent lamp gives off 10% of its energy as heat and 80% as infra-red radiation, thus only 10% of its electricity is converted to light energy, yet a CFL will emit 75% of its energy in the form of light. Therefore a 25 Watt CFL will give out the same amount of light as a 100 Watt incandescent lamp. The CFL is a fluorescent tube in miniature. The base of the lamp contains the electronic components that make the lamp appear to light continuously, although it as actually being extinguished and relit 100 times a second. A tungsten filament in the cathode tube produces electrons when heated, then an electric arc is propagated inside the tube, which cases the electrons to become agitated. The tungsten atoms collide with atoms of mercury, which is in the tube in a gaseous state, and in doing so produce ultra-violet (UV) light , which is invisible to the naked eye. The UV light reacts with the coating of fluorescent material on the inside of the tube. This coating is made up of phosphorous salts and when subjected to UV radiation they emit a visible white light.

Swimming Pool Heating

The weather over the last few weeks has been variable at best. We've had some very hot days in mid-May, but at the time of writing, the weather is on the cool side again; it’s not yet the long baking hot days of summer that we are normally used to in this part of France.

For most of you with swimming pools in the garden, the winter cover may still be on because it probably hasn’t been that inviting to go for a dip. If the air temperature is around 15°C, the water temperature is likely to be around the same level and it takes a hardy soul to jump into a pool of water at that temperature. However there is a solution and that is to heat the pool to a comfortable temperature. We normally consider that this should be between 26°C and 28°C.

An air-source heat pump such as the one shown does this in a very ecological manner. It uses refrigeration technology to extract heat from the surrounding air and transfers that heat to the pool water to raise the temperature to a comfortable level. The average swimming pool air source heat pump has a coefficient performance of around 1:5, when the air temperature is between 15°C and 26°C. This means that the heat pump generates five times as much energy to be used for heating, as it consumes in the work of generating that heat. In effect, around 80% of the energy required for the heating process is already stored in the air, so it is free. All that is required is to take this energy and turn it into a usuable form. The heat pump does this by allowing refrigerant fluid to absorb the heat and then the fluid is compressed, thus consolidating the heat energy. The electrical energy required to run the pump and the compressor is approximately 20% of the energy rating of the heat pump. So, for example, a pump of 5 kW rating would consume 1 kWh of electricity for each hour that it was running. As the typical household on the EDF base tarif would pay 0.144 euros per kWh, the cost of running a heat pump would be less than 15 cents an hour for the comfort of a heated swimming pool.

The actual size of the pump that would be required depends on the volume of water in the pool and the regional mean average air temperature. For this region, that would be 15°C or above from April to October inclusive. A 5kW heat pump would satisfy the heating requirement for a pool of up to 35 cubic metres. For pools of greater volume, a proportionately more powerful heat pump would be required.

The installation of the heat pump is quick and it generally requires only a small amount of modification to the pipework for the pool pump. The heat pumps are also very quiet in operation. A heat pump can extend the usable period of the pool for up to nine months of the year.

Three-phase Electricity

For people moving to France from the UK, it is often a puzzle why so many houses over here have three-phase electrical supplies whilst in Britain this is usually only supplied to industrial premises. The reason is largely linked to the size of the country and the distance between settlements.

When electricity is generated at the power station, the rotor in the generator revolves past three poles that are equally spaced around the circumference, i.e. the poles are 120° out of phase with each other. The output voltage from the generator is 25 000 volts (25 kV) per phase and this is stepped up to 400 kV in the transformers at the generating station for national transportation. The three phases are stepped down to 90 kV and 63 kV at regional substations and then stepped down again to 20 kV at district level. The local transformers, which can been seen on the poles in rural areas, step down the voltage to 400 V for consumption. 400 V is the voltage between any two of the three phases, whereas between one phase and neutral the voltage is 230 V and this is basis for which domestic apparatus is designed to function.

However, as electricity passes along a line it loses voltage owing to the resistance in the wire, this is known as voltage drop. In order to reduce the voltage drop, a larger wire could be used, but this is an expensive option. A cheaper and more efficient solution is to incorporate all three phases in the electrical installation and certain pieces of high-load of apparatus. Thus the use of all three phases in a property means that the load is spread over three cables and these can have a smaller cross-sectional area as they carry less current and are therefore less expensive.

The downside of a three-phase supply is that the tariff with EDF is based on a predicted maximum power requirement for the property. Power is the product of multiplying the voltage (V) by the current (A) and is expressed in Watts (W). In a house on single phase supply with a typical 12 kW tariff, the users can switch on as many lights and appliances as they like up to this amount However, in a three phase installation, for the same tariff the supply 3 x 4kW and if too many domestic appliances are used on the same phase at the same time the supply may trip off because the current has exceeded the tariff at the meter on one of the phases.

If this were a persistent problem, the solution would be to ask a qualified electrician to check that that the system was balanced out correctly. However, on an old installation, which had evolved in an unbalanced way over the years, it might be necessary to consider having your supply changed to single phase. This should be straight forward but again, consult a qualified electrician, who can advise you accordingly and make the arrangements with EDF.

Smoke Alarms

France has finally caught up with the rest of Europe and most other developed countries by making it mandatory to fit smoke alarms in residential properties. This obligation is not before time, as a smoke detector increases the chances of the occupants surviving a fire in a residential property by 90%. And, of course, it is during the night time when people are most at risk; 70% of fire-related deaths have been because the occupants were asleep when the fire broke out.

The new regulation states that from 8 March 2015, all residential properties must be fitted with at least one standardised smoke detector, that is to say one that conforms to the norme NF EN 14604 and is stamped with the CE mark. Those that have the highest standard carry the mark NF 292. In effect, the smoke detector must detect the fumes produced at the outset of a fire and then emit an audible signal of sufficient loudness to wake somebody sleeping in the building. In addition, the smoke detector may be either battery or mains-powered, but it must have a power on indicator and, if in the case that the batteries are designed to be replaced by the user they should have a minimum expected duration of one year. Moreover, there must be either a visual, mechanical or audible signal to show if the batteries have been removed. The smoke detector's alarm must have a noise level of at least 85dB(A) at 3 metres and a warning signal with a different tone to indicate if the power supply has failed or the battery is exhausted. The smoke detector should be indelibly marked with the maker's, or distributor's name and address, the number and date of the 'norme' to which it conforms, the fabrication date and batch number of the unit and the type of the replacement batteries.

The detector must be supplied with instructions for installation and method of use. The installation instructions should clearly show how and where in a domestic location the smoke detector should be fitted. In preference, this should be in the passageway or part of the dwelling which gives on to the bedrooms. The minimum level of protection should be one smoke alarm per floor, although it makes sense to fit them in bedrooms, living rooms and cellars, as the sooner that a fire is detected, the better. The smoke alarms should not be fitted in kitchens or bathrooms, as the steam could obscure the light-emitting diode's beam and set off the alarm. The smoke detector should be fixed securely to the upper part of the space, as close as possible to the highest point and away from walls. For those people living in buildings with communal areas, e.g. a stairwell serving two or more apartments, please note that it is forbidden to put smoke alarms in these areas. The reason for this is that if an alarm sounds in a communal passageway it will incite people to leave their dwelling and enter into the fumes. They would thus be put at risk of being killed by smoke inhalation and 75% of fire deaths are due to this effect.

Light Emitting Diodes

Those of us old enough to remember the 1960s, i.e. before the electronics revolution, will recall that the world was illuminated by incandescent light bulbs, televisions had valves (that failed regularly) and cathode ray tubes and if a switch was on, there was no tiny red dot of light to illustrate the fact. In that decade of 50 years ago, the amazing little device, the light emitting diode, or LED, was created.

Although experiments in Gallium Arsenide and other semiconductor alloys had been going on since 1927, it was in October 1962 that Nick Holonyak Jr developed the first practical visible spectrum LED, while working at General Electric Company. Holonyak, who is now known as the 'Father of the Light Emitting Diode published his discovery in the American Applied Physics Letters of December 1962 under the title COHERENT (VISIBLE) LIGHT EMISSION FROM ga(as1−xpx) JUNCTIONS Nick Holonyak and S. F. Bevacqua. The first LEDs were costly at 200 dollars each and therefore they had little practical use. It was not until 1968 that the first mass produced LEDs arrived courtesy of the Monsanto company. Hewlett Packard launched their hand-held calculators that year using the Monsanto supplied LEDs.

The first commercial LEDs were quite dim and difficult to see in daylight conditions and they produced red light, so they were perfect for digital displays in calculators and watches, which had plastic lenses over the display to magnify the digits, but it limited their application outside this area. Further development and technological advances improved both the brightness and the variety of available colours, so that the LED could be used to replace incandescent and neon indicators in a much greater range of applications. Nowadays the ubiquitous LED is to be found in aviation and vehicle lighting, street lights, traffic lights, bicycle lights, torches, strip lights, the list is almost endless. I cannot think of an application where the LED is not replacing more conventional lighting. As an electrician, I have been called upon to set up power supplies for stage shows. This used to mean that a lot of power was needed for the lighting set-up. Nowadays a group will arrive and all they need is one standard electrical socket to supply all of their requirements.

In the domestic and commercial lighting applications, the advantage of using the LED is a greatly reduced consumption of electricity and a much longer life expectancy. A typical halogen downlight bulb rated at 35 Watts would achieve a light output of around 10 lumens per Watt. In comparison, a 4,9 Watt LED bulb would produce 65 lm/W, thus using nearly seven times less electricity for the same amount of light. The average life expectancy of a halogen bulb is 2 000 hours against the 30 000 hours of an LED bulb.

From an electrician’s or architect’s perspective, another major advantage of LED lighting is the low heat output compared to halogen. Is there a disadvantage? The initial cost of an LED bulb is around 10 times that of a dichroic halogen downlight bulb, but the energy savings and longer life means that in the long term the LED bulb will more than pay for itself.

Wood for Heating

It's January, as I write this article and so far this year there has not been much of a winter. In fact, we only had the first frost just before Christmas, whereas other years have seen us in a blanket of crystalline white in the morning by early September. However, it appears things are set to turn colder by February.

A warm crackling fire can be a wonderful source of economical warmth as well as a comforting necessity in the winter months. Choosing the right kind of wood to burn, seasoning and storing it properly will help keep your house as well as your heart warm as the mercury drops.

It might seem like common sense, but dry wood burns much more effectively than wet wood. Freshly cut wood from recently felled trees must be allowed to 'season'. This is the process by which the sap is allowed to evaporate and thus reduce the moisture content in the wood. Some types of wood can contain up to 50% moisture when they are freshly cut, so various types of wood takedifferent lengths of time to season. In order to produce a satisfactory fire that is not too smoky, the wood must have a moisture content of less than 20%. When we get called to diagnose 'problem' stoves, where perhaps the glass is constantly blackened, one of the first things we check is the moisture content of the wood. It also makes sense to store your wood out of the wet weather. The best option is under a lean-to or in a well-ventilated shed. Do not be tempted to wrap it under a tarpaulin as this will trap the air and tend to increase the damp content in the wood.

If you get your wood from a merchant, you might be able to request the type of wood that you get. Hardwoods, particulary oak, ash and beech, are very good, hot-burning woods. Chestnut is very popular in this region and although very easy to split and burn, it is quite smoky. Most of the French people around us would not consider burning softwoods, such as pine, but that is not to say that it should not be used. I was discussing this with an experienced wood merchant last week. His view was that all types of wood may be used and, seasoned correctly, softwoods such as yellow pine and Douglas fir burn well and can be mixed with hardwoods to produce a good fire. Finally, the law in France is quite specific on the topic of chimney sweeping. A flue being used regularly and serving places of habitation should be swept twice a year, of which once is during the period of use. (Reglément Sanitaire. Art. 31,6 Conduits de fumées. Entretien, nettoyage et ramonage). Always make sure that the contractor who sweeps your chimney gives you a certificate of ramonage and, if you have more than one chimney, you should have one certificate for each. This is your proof if you suffer a house-fire and the insurance company asks if you have had your chimney swept. The certificates that we use have two parts, the tear-off second part is something that can be detached and given to your insurance company to put in your file.

Electrical Circuits

Lighting, heating, domestic appliances and entertainment apparatus, i.e. TVs, Hi-Fi, computers, all of these things need electricity, so it is everywhere in the home. However, one dwelling in four harbours a risk from that electricity and approximately 60% of the obligatory diagnostic checks carried out when a house is sold reveals at least one anomaly on the electrical installation, according to the director of Promotelec.

Moreover, every year, 23 000 fires originate from electrical faults and this leads to 200 fatalities. To this figure, we can add the number of fatal electrocutions and this brings the number of deaths to 400 per year as well as approximately 4000 serious electrocutions that do not result in a fatality.

Everyone knows about the dilapidated facilities that are common in older housing; about sockets that are not connected to earth and about wires and connections that are exposed and cables that are under-rated for the application to which they are put. However, the risk is not always visible. Quite often, people plug in apparatus without thinking about the rating of the circuit; the electrical load of washing machines, dishwashers and portable electric heaters is not anodine, especially when there are already other pieces of equipment that have been installed that weren't considered in the original construction, for example roller shutters and a plethora of electronic devices.

Another factor that aggravates the situation is the use of ubiquitous multi-block sockets and particularly when they are connected one after another. I have seen these in older properties used like a chain with a variety of domestic appliances all plugged into a single two-pin (unearthed) socket.

Therefore, it is important that a professional should regularly verify that an installation is still adapted to its regular usage and if necessary updated to meet the demands that are being placed upon it. This was one of the reasons for the introduction of the diagnostic check that was introduced in 2009, but of course there are many houses that changed hands before this. In reality, an electrical installation should be checked over once every 10 years. This probably worries people into thinking that an electrical professional is going to come in and tell the home-owner that their house needs a rewire, but that is not necessarily the case.

Despite linking all of the sockets to earth and bonding apparatus in the bathroom to render the potential difference zero, it is also important to protect the people using the electrical installation from the risk of faulty appliances. To do this, all circuits must be protected by an earth leakage circuit breaker, more commonly known by the abbreviation RCD, for residual current device. These devices (there should be at least four in a house of more than 100m²) are very sensitive switches that rapidly cut the electrical supply to a group of circuits if the current leakage exceeds 30 milli-Amps. The rating is not arbitrary but has been set as this is the level at which the average human body will not suffer a cardiac arrest from an electric shock. RCDs, or in French Interrupteur Différentiel, have been obligatory on all French electrical installations since 2001 and they can be inserted in existing systems to provide protection to people using the electricity in a home.

Electric Showers

We have bought an electric shower in the UK, please could you install it in our house here in France?

A question that comes up every two or three years. On the face of it, it seems quite a reasonable thing to ask. My answer is that "Yes, I can, but you will need to have your electrical supply increased significantly and that the cost of your standing charge will be astronomical in comparison to your needs." This usually brings about a furrowed brow and a look of concern on my prospective client, before the inevitable. "Why?" The reason is quite straight forward and is to do with the different way in which that electricity is supplied in the two countries.

The electricity is basically the same whether we are here in France or back in Britain; it is 230 volts, give or take a margin, and 50Hz. However, in Britain the 'normal' supply current is 80 amps or even as much as 100 amps at the consumer unit in the house, which is 18.4 kW and 23 kW respectively. Therefore to put a 9 or 10 kW electric shower in is perfectly acceptable. The electrician simply runs a 10mm² twin and earth cable from the consumer unit to just outside the shower room, puts in a pull cord switch and, hey presto, instant hot showers (I'm ignoring the plumbing for the purposes of this article).

The difference is that in France, electricity is supplied in 3kW increments and for each increment the abonnement, or standing charge, is increased (apart from the 3kW rating the price of the electricity per kW hour is the same). For a house where the cooking is by gas, the heating by an oil fired boiler and the hot water by an electric ballon with a relay for running during the off peak electricity period, a 6kW supply is satisfactory. Use electricity for cooking and a 9kW supply would be needed. Now introduce the electric shower, which is usually rated at at least 9kW these days in order to get a half decent flow of hot water, and you start to see where we are going. The shower is going to take all, or even more than, the whole supply for the remaining appliances in the house. So here we are one morning, the man of the house is downstairs boiling the kettle (2.2kW) and madame jumps into the brand new shower in the en-suite bathroom for a lovely hot refreshing start to the day and ... clack, the electricity trips off.

Therefore, in order to have a 10 minute shower they have to have the single phase supply upgraded to the 18 kW tarif (although its not always available in rural areas) and the annual cost rises by 167€, and that's not counting the cost of the electricity actually consumed. If the house has (or needs to be connected via) a three phase supply, the available single phase power is divided by three, thus the tarif would necessarily be 30kW and the standing charge would cost 639.46€ per year. The simple solution: leave electric showers in the UK.

Smoke Alarms

It must be that most people think that having at least one smoke alarm in the house is a good thing. Despite many years of hesitation and debate, France will finally join most of Europe and many other developed countries by making it mandatory to fit smoke alarms in residential properties.

Originally proposed in 2005 after a series of fatal domestic fire incidents, two of the most notable being those in apartment blocks in Paris, the proposition has had to overcome a series of hurdles. The proposal was completely rejected by the Conseil Constitutionnel in 2009. One of the deputies complained that if these devices were installed, one would not be able to smoke in one's own home. However, the law was finally passed and on 8 March 2015, all home owners must ensure that the dwelling is fitted with at least one standardised smoke detector, that is to say one that conforms to the norme NF EN 14604 and is stamped with the CE mark. Note the use of the word 'owners', thus for rented properties, it the owner and not the tenant who is obliged to have the one or more smoke alarms fitted. However, once fitted, it is the occupier, whether that is the owner or the tenant, who is responsable for the maintenance and proper working order of the smoke alarm.

There are two main types of smoke alarm, the most common being the battery powered, stand-alone devices. These smoke alarms are known in France as Détecteurs Autonomes Avertisseurs de Fumée or DAAF. When a domestic fire starts often the first indication is a slow accumulation of smoke, which might be quite insignificant such as a lighted cigarette coming into contact with bedding. The DAAF is equipped with an optical sensor that uses a light beam from an LED emitter to illuminate a dark chamber. When smoke enters the chamber the light beam is deflected on to a photo-electric cell that generates a tiny electric current. This current starts the sequence to set off the highly audible alarm. The battery in DAAF may be either alcaline or lithium. The life of these batteries is specified by the manufacturer. Generally, for alcaline it would be for a period up to five years, whereas the lithium life expantancy would be from five to ten years.

The other type of smoke alarm is that which is connected to the household electrical system and operates from a 230 volt supply. These also have a battery, which is as a back-up in case the mains power is cut off. There is usually an additional wire that is used to link all the smoke alarms in the house into a chain. Thus if one alarm detects smokes and is set off, the others all sound their alarms as well. This a particularly useful function when the smoke alarms are fitted in a large house where the bedrooms may be some distance from the source of the fire. Nowadays, rather than interconnecting the smoke alarms by wiring, it is becoming common to find those that have a radiofrequency system to link between the units.

Wind Turbines

Whilst driving north through France recently, I was struck by the number of wind turbines that are to be seen clustered in groups of six or eight on the open plains thereabouts. Whilst here, in the western part of the Haute Vienne, we have a few wind turbines, most notably those just over the border in the Charente between Brigueil and Lesterps, this is nothing to numbers that I saw from the autoroute.

Wind turbines, I know, are the source of much controversy and debate. For some, they are an eyesore, a veritable blot on an otherwise unspoilt landscape, and they oppose their development. However, other people see the slender towers and slowly rotating blades as a graceful addition to the scenery and view the production of electrical energy from this renewable source in a positive light and consider them an asset in helping to protect the environment.

Whichever viewpoint, you have, I think its a fair assumption that wind turbines are here to stay. Wind as a resource has been harnessed by man for thousands of years for milling grain, pumping water and other mechanical power applications and there are still thousands of windmills around the world being used for water pumping. Wind energy as a pollution free means of generating electricity on a significant scale is a recent innovation. The first attempts took place in the late 19th century, when Professor James Blyth of the Royal College of Science and Technology, now Strathclyde University, built a range of wind energy devices to generate electricity, the first being in 1887. For many years, small scale wind turbines have been used to provide electricity for remote communities and farms and charging batteries on boats and for caravans. However, since the 1980s the technology has advanced to a point where the production and operation of large scale systems is sufficiently cost effective and this has given rise to the rapid growth of this sector.

The present healthy state of the wind energy market is due largely to developments in Denmark and California in the 1970s and 1980s. In Denmark, largely because of the lack of fossil fuels, the use of wind mills never really ceased, as it did in other European countries. In the 1970s, events such as the 1973 oil crisis gave a new impetus and small Danish agricultural engineering firms took on the development of new generation wind turbines for farm-scale operation.

Wind power technology is one of the fastest growing renewable energy technologies worldwide. By the end of 2010, over 194 Giga-Watts (GW) of wind energy systems were in operation, with over 36 GW installed in that year alone. By 2012, the global installed capacity had exceeded 283 GW, of which France generated over 7.6 GW slightly behind the UK contribution of 8.6 GW and way behind Germany and Spain with 31.2 GW and 22.8 GW respectively. The countries that had the greatest installed capacity were China (75.3 GW) and the USA (60 GW). In 2013, the average annual growth rate was over 22% per annum.

Air-Source Heat Pumps

When the majority of people hear the term air-conditioning they think of a system that is used for cooling a hotel room or office, but this is not the case. A modern air-conditioning system is completely reversible, i.e. it heats as well as cools, which means it is a very effective and efficient heating system.

The modern air-conditioning unit is actually referred to as an air-source heat pump because of the way it works. The traditional reversible air-conditioner, is an air-air heat pump. It is called that because its heat source is the ambient air in the vicinity of the outside unit and the heat is emitted as a flow of warm air at around 46°C. The heat energy is absorbed from the air by the refrigerant fluid contained in the unit’s evaporator. This is the coil of copper tubing and aluminium fins that are visible to the side and rear of the external unit. The unit has a fan in order to draw in the ambient air. The refrigerant in the evaporator is in a gaseous state. It is drawn from the evaporator by the compressor, which as the name suggests compresses the gas and in doing so raises its temperature. This hot, high pressure gas is carried by the refrigerant piping to the unit inside the home where it is passed through another coil and fin arrangement, known as the condensor. A fan then blows a stream of air past the condensor coil and out of the unit. The heat contained in the refrigerant fluid is then emitted and it heats the room in which it is located. In losing its heat, the refrigerant changes from a gaseous to a liquid state, whereupon it passes through a regulator and re-enters the evaporator as a cool liquid and so the sequence continues.

The summer process is the exact reverse, so cooled air is blown into the room and the heat from inside the house is dispersed by the outside unit.

Air-air heat pumps are not limited to simply one outside unit and one inside unit. In a multi-split system, one outside unit can supply any number of inside units, depending on the capacity of the unit, which means the whole house can be heated/cooled in the same manner.

The reason for a heat pump’s economy is that it has a coefficient of performance of four or more. This means that that there is a four-fold increase in the amount of heat energy returned against the electrical energy consumed in its operation. In effect, for every one kilowatt of electricity used to run the unit, you get four kilowatts of heat out of it. It is a very economical way of heating your home, with the added bonus than in the summer it works the other way and thus cools it to a comfortable level. The system is particularly suited for installation in an existing building that does not already have a wet centralheating system, i.e. a network of pipework and radiators.

Refrigerant Fluids

Since July 2009, anyone who works with refrigerants has had to be licensed and any installation containing 2kg or more may only be commissioned, maintained, or dismantled by a holder of the attestation de capacité. Even to have a cylinder of refrigerant in a vehicle has been illegal. The reason for this legislation is the protection of the environment.

In 1929, the american scientist, Thomas Migdley, and his team produced the first molecules of Dichlorodifluorométhane or R12. This product and its close relative, Trichlorofluorométhane or R11 were found to be much less offensive to man than the earlier refrigerants, such as ammonia. However, what was not realised at the time was how damaging these Chlorofluorocarbons or CFCs were to the environment. When these gases were released into the air they rose into the upper atmosphere where the ozone layer is found. Under the effect of UV radiation from the sun, the ozone molecules are broken down into oxygen and a free oxygen atom. Normally this atom rapidly recombines with the oxygen, but with the presence of chlorine atoms the free oxygen is more attracted to the chlorine instead of reforming ozone. Hence the systematic destruction of the ozone layer and its ability to protect us from the harmful effects of UV radiation.

Since 1987, the Montreal Protocol has suppressed the use of CFCs and the similar Hydrochlorofluorocarbons (HCFC). The products have been either banned outright or are being phased out. Unfortunately, the replacement products, Hydrofluorocarbons (HFC) whilst harmless to ozone have a major impact on the greenhouse effect, otherwise known as global warming. Infrared radiation from the sun warms the Earth when clouds and carbon molecules in the atmosphere trap heat which would otherwise be reflected back out into space. Without this effect the Earth would have an average temperature of -18°C. The prescence of HFCs in the atmosphere, magnify this effect and the temperature rises. The Kyoto Protocol requires the emission of greenhouse gases to be returned to pre-1990 levels.

To bring about these changes, installations such as air-conditioning, refrigeration and heat pumps have to be prevented from leaking, the fluid from redundant or defective equipment has to be recovered and all engineers have to be tested and certified competent to perform their work. The professionals who carry out this work have had to pass written theory examinations to demonstrate their knowledge of the regulations, as well as the effects the refrigerant fluids would have on the environment. The written exam is followed by a practical assessment of at least four hours duration, whereby the candidates are required to successfully carry out a range of tasks, including leak testing, charging systems and recovering fluids. In order to attain the certification, the applicants must also prove they have the specialist tools and equipment for handling the fluids and testing equipment. The stringent tests and the costs of the specialist equipment has discouraged some operators from doing this work, but for those who are not licenced it is impossible to lawfully buy fluid or to handle refrigerants. The penalties for contravention are heavy. For each purchase by an operator or sale by a distributor the fine is 450€. For illegally working with refrigerant, the first offence is 1,500€ and 3,000€ for each subsequent offence. The most severe infractions, such as causing a leak of CFCs carries a 2 year prison sentence and a 75,000€ fine.

Geothermal Resource In The UK

Up until the early 1970s, the UK had a heavy dependence on imported oil, mainly from the Middle East, but the OPEC-engineered crisis of 1973 spurred the Department of Energy into examining other sources of energy. The surveys identified several areas of potential geothermal resources. These were the five sedimentary basins of East Yorkshire and Lincolnshire, Wessex, Worcester, Cheshire and Northern Ireland, as well as the three radio-thermal granite areas of the Eastern Highlands of Scotland, the Lake District and Cornwall.

In addition to sinking a number of shallow boreholes, four deep exploration wells were sunk, ranging from 1823 m to 2873 m in depth, at Marchwood, Larne, Southampton and Cleethorpes. At Cleethorpes and Larne, the band widths of the aquifer were between 300m and 400m deep but at less than 55°C the temperature was insufficient to justify exploitation without the additional use of heat pumps. The temperatures at Marchwood and Southampton were much higher (around 75°C), but the band widths were only 20m deep.

As a result, of the low geothermal potential, falling oil prices because of the development of the North Sea oil resource and the geographic position of the sites in areas of low population density, the potential projects were abandoned by the government. However, in 1986, Southampton City Council set up the Southampton District Energy scheme to exploit the resource situated below the city. This energy now provides 400 local homes plus hotels and businesses with heat from a district heating network and generates electricity to supply 26 million kWh a year to the Southampton Port.

Of the three granite zones mentioned above, the South-West has the highest heat-flow with areas of Devon and Cornwall having a projected temperatures over 200°C and it has estimated that the resource could match the energy content of the current UK coal reserves. There has been some development of the Cornish resource at Rosemanowes (the site of exploratory work between 1976 and 1992) and at the Eden Project where work has started on an Engineered Geothermal System (EGS) plant that should provide 4MWe.

A report from the Renewable Energy Association declares that from its deep geothermal resources the UK could provide 9.5GW of electricity, which could satisfy 20% of its current electrical consumption, and 100GW of heat. However, the unlocking of these geothermal resources would require the extensive application of the EGS technique and that is highly likely to come into conflict with public opinion. Attitudes in the UK towards renewable energy largely depend on the individual's proximity to the development, so whilst overall there is positive public support to renewable energy, it is lower in the context of local developments. In the UK, the geothermal energy zones are not in the most highly industrialized or heavily populated areas of the country. Nevertheless, the UK has a significant potential for satisfying much of its electricity and heating needs from its geothermal resources, but without a positive support from the public that will stiffen political will the development of this resource is likely struggle to become an acceptable alternative energy source.

Greenhouse Gas Emissions and the Environment

The recent extreme weather conditions that have been experienced around the world, and particularly the flooding in the UK, have brought climate change to the top of the agenda for many people, although energy efficiency and greenhouse gas emissions have been two very popular topics for some time here in France.

In 2007 the French Government, led by Nicolas Sarkozy, launched a cross-party multi-agency project called the Grenelle de l'Environment. Its mission is to bring together representatives from national and local government, nongovernmental organisations and trade bodies to debate, plan and initiate strategies for sustainable development and to combat climate change. The two topics go very much hand in hand, for example the more efficient and sustainable that we make our buildings the less energy that is used by the occupants and thus the emission of greenhouse gases from fossil fuel combustion is reduced.

Greenhouse gases are the gases in the atmosphere that absorb and emit radiation and they include water vapour, carbon dioxide, methane, nitrous oxide and ozone. All of these gases are naturally occurring and would be present in the atmosphere whether or not we were burning fossil fuels to produce energy. In fact, if there were no greenhouse gases then life on Earth could not be sustained as the surface temperature would be around -18°C. The gases act in a manner like the panes of glass in the typical garden greenhouse. As the incoming radiation from the Sun reaches the outer edge of our atmosphere about 30% is redirected back into space, the remaining solar radiation which lies in the spectrum from ultra-violet to short wave infra-red passes through into the atmosphere and warms the Earth's surface. The resulting long wave infra-red radiation is then retransmitted back into space, but a percentage of it is blocked by the clouds, which contain water vapour, and the other gases present in the atmosphere. As a result the Earth's surface temperature is maintained at a life-supporting 15°C. The problem is that the equilibrium is upset if there is an increase in the amount of greenhouse gases in the atmosphere and more infra-red radiation is prevented from escaping. The surface temperature then increases and our climatic conditions are altered, which leads to changes in weather patterns.

There are people who say that the changes in our climate have nothing to do with human activity. However, since the Industrial Revolution the level of carbon dioxide in the atmosphere has increased from the burning of fossil fuels and since 1950 the increase has been particularly dramatic. There has also been significant additional contributions from emissions of methane. Scientists from the International Panel on Climate Change (IPCC) have estimated that human induced emissions have caused the Earth's global mean surface temperature to rise by 0.7°C between 1950 and 2005. If emissions are not curbed, the Earth's surface temperature could rise by between .4°C and 5.8°C by the end of this century. Such rises would cause an increased frequency and severity of climatic extremes leading to serious disruptions to agriculture and the natural ecosystems.

Biomass For Heating

This has been a mild winter for our region of France, at least it has been so far and I hope that I'm not going to regret saying this. Nevertheless, it has not been so mild that we could do without heating and, if you have an oil or gas boiler, you have probably thought about how many euros are being burnt every time the boiler fires up.

Oil or gas fuels might be convenient, but they do not come cheap and the prices go up year on year. As these fossil fuels become ever more scarce and difficult to extract, the price rises will get increasing steep. So what are the alternatives?

Well, biomass systems are a cost-effective and environmentally neutral possibility. Using biomass as a fuel for heating and cooking is not new, as it's been around since the first humans created a spark to ignite a piece of dried grass, whereas we have only been using fossil fuels since the 1800s. Biomass systems use fuels derived from materials such as wood, straw, oilseeds and animal waste.

However, what I am principally referring to here is wood and wood pellets. The natural production of biomass is through the conversion of energy from the Sun into plant material by photosynthesis. This process takes carbon dioxide from the air to make carbon based living material and releases oxygen as a consequence. When the biomass is burned, the carbon attracts oxygen molecules and is released once more as carbon dioxide. However, as long as our consumption of biomass does not exceed its production, the combustion of biomass should not produce any more heat or release any more carbon dioxide than would have been formed by natural processes, thus it is environmentally neutral.

We tend to think of traditional stoves when it comes to burning wood, but these are messy and have an efficiency of only around 50%. Increasingly we are installing wood pellet burners. These have the advantage of being much cleaner in operation, as there is almost no ash residue, and the fuel is packaged in a convenient and easy to handle to manner, i.e. sacks rather than logs. As well as stoves it is increasingly common to have central heating boilers that burn biomass. These come in the form of those that burn logs and pellet burning boilers. In this region, wood in the form of logs is readily available and a modern high performance woodburning boiler has a yield of around 85%, which is comparable to typical oil-fired boilers. The advantage of the pellet version is again the convenience of fuel handling, the pellets may be loaded into the boiler manually or automatically from a hopper, and minimal residue. These have higher yield again of up to 95%. Is it possible to replace an oil fired boiler with a wood or pellet boiler? The answer is yes, although the flue must be checked by a qualified installer to ensure that it conforms to the correct specification for this type of fuel.

Electrical Safety

In 2013, there were 317 articles in the French press that related to fires in residential properties that had an electrical origin. The cause was often attributed to obsolete or damaged electrical installations, but it also included over-loaded multi-sockets and faulty appliances. So how much value do you put on your safety, or the safety of the people using the electrical system in your house, or for that matter, your house itself?

Well it seems that for a large proportion of the French population, the answer is not very much. A recent survey by Crédoc has found that, for the French, their electrical safety is not a priority. Questioned over their desire to improve the comfort of their residence, only 1% of the owners gave consideration to the electrical installation. In fact, over threequarters of those home-owners that were asked thought that the electrical installation was perfectly in accordance with the standards. However, in 60% of the homes that were 15 years old or more that were sold during 2012, the electrical system was found to be defective in some way or another and did not conform to the six minimum standards of safety.

The six key points are: the presence of a main isolator that is easily accessible; the presence at the origin of the installation of at least one device that provides differential protection appropriate to the earthing conditions; the presence on each circuit at least one circuit breaker for over-current protection that is adapted to the cross-sectional area of the conductors; the presence of equipotential bonding and the respect of the zones in each area that contains a bath or shower; the absence of all risks of direct contact with those elements that are under tension that could lead to electrocution and the absence of all obsolete or inappropriate materials and that all conductors are protected by conduits or trunking made of insulating material.

When a dwelling is constructed, it is obligatory that is inspected to ensure that the electrical installation conforms to the latest standard, that is NFC 15-100, if it doesn't the electrical supplier will not connect it. As the years pass, the regulations evolve whilst the electrical installation degrades. Obviously, the dwelling will be no longer 'a la norme', but it must be maintained in a safe condition for the residents and visitors. It is therefore essential that the house or apartment is routinely checked for its level of safety, at least every 10 years. Since 2009 this examination has been obligatory whenever the property changes ownership and the electrical inspection is included with the sellers package of checks. However, at this point, the inspector is not required to dismantle the house in order to check every detail, so whilst he or she may indicate whether or not the installation meets the six key points, it is not a 100% guarantee. This can only be done by a thorough inspection and test that must be carried out by an electrician with the appropriate test equipment, training and knowledge of the regulations.

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