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Embodied energy is the amount of energy required to produce, distribute, install and dispose of any manufactured item or energy itself and across the whole of the sustainability agenda, there is no technical issue more complex. Indeed, it is so complex that the custom and practice is to ignore it; no national government target or local planning condition requires embodied energy to be considered, never mind analysed. This is dangerously short-sighted as the embodied energy of some technologies in certain circumstances is greater than the energy they save. Ignoring embodied energy therefore means green technologies are being specified without knowing whether or not their deployment is genuinely to the net benefit of the environment.

This is particularly relevant when considering renewable technologies and especially solar panels, wind turbines and bio-mass boilers.

Solar panels

Solar panels 鈥� both thermal and photovoltaic 鈥� undoubtedly have a major contribution to make. But they cannot be universally applied 鈥� they only work when positioned on south east or south west facing roofs not overshadowed by buildings or trees. And while their manufacture and distribution is highly energy intensive, their main negative lies 20 to 30 years in the future when their working life is over. Solar panels are highly toxic and to date no serious work has been done on either their disposal or on how much energy this will require. Yes, on balance they are a good thing, but it would be better if we could prove it.

Wind turbines

Wind turbines are even more sensitive to local conditions and many of the UK鈥檚 major on- and off-shore wind farms are not producing the energy expected. The Renewable Energy Foundation have found that only a few Scottish wind farms are functioning efficiently enough to meet government expectations (an average of 600MW to the National Grid for every 2GW of installed capacity) and that south of the Scottish border some installations are operating at less than 10% of capacity and none at are hitting the critical 30%. It is no surprise, therefore, that the chances of a retro-fit, single dwelling wind turbine making either financial or ecological sense are slim.

Bio-mass boilers

Finally, bio-mass boilers. The issue here is not so much the boilers themselves 鈥� the manufacturing impact of all domestic boilers (gas, oil and wood chip) is broadly comparable 鈥� but the wood chips that fuel them. Unfortunately, as the UK supply chain isn鈥檛 yet up to speed, significant quantities have to be imported from China or Scandinavia and trucked around the country, which does little for their carbon footprint. Bio-mass boilers are increasingly favoured, primarily because they enable private and social housebuilders to meet energy targets laid down by planning requirements and the GLA London Toolkit which prescribe the use of renewable energy to meet those targets. The absence of embodied energy data therefore means we are again working blind on their overall environmental performance.

The embodied energy of some technologies is greater than the energy they save

Water wastage and energy

Embodied energy is also a major factor when considering macro-energy policy. For example, the collection, purification and redistribution of water for home and industry uses significant amounts of energy but campaigns to encourage less profligate use almost exclusively treat water as if it were a finite resource like oil. It would help the cause if people were also told how and why wasting water is also wasting energy.

Nuclear power

Then there is nuclear power, which is obviously the most controversial of all methods of energy generation. On the one hand, it is indisputable that once the plant has been built, the energy produced has that rare advantage of being zero carbon, but what of the vast amount of energy required to build the plant in the first place? This is not to argue either for or against nuclear, but to make the point that environmental impact must be taken into account if we are to make a decision based on the evidence rather than on preconceptions. Of course, for those instinctively pro-nuclear, issues such as energy security may trump any such facts. And those instinctively against nuclear may remain swayed by considerations of terrorist threat and/or the problems and cost of disposal and decommissioning. But at least if we know the facts, we will also know the true environmental consequences of any action taken.

Cynics may argue that it is not in the commercial interests of green technology manufacturers to research and then declare the embodied energy of their products, but given the multi-level and multi-national supply chains of these products, it is also a near impossible task. Also, how and where any given technology is applied has at least an equal effect on that technology鈥檚 total ecological impact as does its manufacture and distribution. A small wind turbine or solar panel accurately installed somewhere that is really windy or decidedly sunny has every chance of justifying its existence.

Therefore we can鈥檛 continue ignoring embodied energy, but it will require national, even international, action, legislation and co-operation to provide the data that will enable us to do the right thing for the right reason in the right place.