OPINION Your views from across the built environment


SUBSIDISING WASTE


The current headlong rush into ‘green energy’ threatens to lead to more expensive, less efficient energy production, argues Colin McInnes


labour for the first time in human history. Energy became cheap while human labour became more expensive, and so our prosperity soared. Our entire modern economy is


Today’s policy goals on climate change ignore the lessons of


engineering history. We seem determined to replace historical transitions toward fuels of greater energy density with diffuse energy production. The move from wood to coal


in the Elizabethan era was such a transition, as was (much later) the use of oil, methane (natural gas) and then uranium. Each one of these had a lower carbon intensity than the last, with methane releasing about half as much carbon dioxide as coal per unit of energy produced, and nuclear being essentially carbon-free. That evolution has, so far, relied primarily on carbon-rich fuels. If we now want to displace carbon from energy production, we had better come up with something better and cheaper than coal – and, ultimately, oil. The answer is not, though, to abandon the pursuit of higher energy density. The current ‘green’ policy imperatives are taking us back to the


20 CIBSE Journal February 2012


use of diffuse energy sources that will require vast quantities of materials, land and subsidies, misallocating economic resources that we could use more productively elsewhere. Many forms of green energy are spatially diffuse and intermittent, making them inefficient and inherently expensive. Therein lies the need for feed-in tariffs and other support mechanisms. Green energy is set to grow, not because it is more productive, like Watt’s separate steam condenser, but because government mandates it and provides generous incentives. An energy transition that leads to more expensive, less efficient energy production is more of a regression than a revolution. In choosing to make energy more expensive we should remember that, with James Watt’s development of efficient steam power, hydrocarbon- fuelled machines replaced carbohydrate-fuelled human labour. In the late industrial revolution, this decoupled the costs of energy and


Energy can be delivered that is both cheaper and more abundant than at present


built on this remarkable decoupling. In contrast, our headlong rush into expensive green energy risks sacrificing jobs elsewhere in the economy: it also threatens large tracts of the British landscape and hits the pockets of those who can ill afford higher energy bills. As engineers, we should insist that energy policy sets out to deliver lower costs, security of supply, and now a transition to lower- carbon energy. This will require greater use of methane and uranium and less use of coal and, eventually, oil. A number of new technologies could


Green energy is set to grow, not because it is more productive but because government mandates it and provides generous incentives


help us to achieve these transitions. For example, while modern power stations have come a long way since Watt’s steam engine, we still generate much of the world’s electricity by heating water and then extracting useful work. A recent exciting innovation has been the demonstration of energy conversion using supercritical carbon dioxide as a working fluid, akin to a jet engine running on hot liquid. Not unlike Watt’s separate steam condenser, this offers a step-change in the efficiency of turning heat into useful work in future thermal plants. Other recent innovations include


China’s new national programme to develop next-generation molten- salt thorium nuclear reactors. This high-temperature, low-pressure fuel cycle fissions all of its fertile thorium fuel and leaves only short-lived waste products with a half life of around 30 years. Again, this development could


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