Articles
Keeping it simple
Referring to the article in Professional Engineering issue two of 2024, reflecting solar radiation back into space is one obvious way of reducing the gain of heat energy by the earth. Why are the methods of doing that, which are currently being discussed, so expensive and complicated?
Simple, cheap methods of achieving the reduction of energy gain are readily available for immediate use. There are around 25 million households in the UK. If each one of them erected a 1m2 mirror in an exposed place, up to 25,000,000,000 watts (25 billion watts) could be reflected back into space whenever the sun shines.
The reflectors need not be optically perfect. A board covered in kitchen foil would suffice. The sun moves around the sky, so the angle at which its rays are reflected would vary constantly. If retro-reflective paint was used instead of a plane mirror, the radiant energy would be reflected back towards its source. No mechanism would be needed and the angle of the reflector would not be critical. Existing surfaces, such as roofs and walls, would all then be suitable platforms for treatment. Painting house walls and roofs with reflective paint would greatly increase the available treatable area and have the added benefit of keeping the property cool. Sheds and garages are easily treatable and the paint would help to protect them from the weather.
Floating reflectors would keep the sea slightly cooler, assisting the North Atlantic meridional overturning current. Those could be tethered to – or close to – offshore wind farms so they would not present a great hazard to shipping.
I have bought a polished aluminium Venetian blind for a window at home. Hopefully that will keep one room cooler in summer and warmer in winter. Outside reflectors could be deployed to reflect the winter sun into a window to reduce the fuel requirement slightly.
Cheap, simple solutions are often the best overall, and the more people who adopt them, the greater the overall benefit, even if the efficiency of each individual application is relatively low. They can certainly put a brake on a runaway situation until better methods can be deployed. They can continue to contribute beneficially thereafter.
Alan Winter
Primary energy and other fallacies
In Professor Kalghatgi’s letter in issue one of 2024, he makes several alarming mistakes, which lead him to an even more alarming conclusion. Firstly, he takes the primary energy provided to the UK from fossil fuels and assumes we need to replace 60% of it with nuclear or wind generation. This is known as the ‘primary energy fallacy’. It implies we need to replace most, if not all, of the fossil fuel demand in today’s economy with clean power. But because fossil fuels waste so much energy and heat, and direct electrification of processes, heat pumps, EVs, etc. are so much more efficient at converting energy inputs to useful energy, that 60% can be as low as a third (see Lawrence Livermore National Laboratory flowcharts for the US as an example).
He then asserts that, because humans have adapted to 1.2ºC of warming, that we will be OK if it continues to warm. I can only point readers to the Intergovernmental Panel on Climate Change’s 2022 impact report, which makes clear the hazards of unchecked warming, particularly on the most vulnerable, not to mention on nature itself.
I presume Professor Kalghatgi’s arguments are made in good faith, but as someone still in their 20s who will have to live through a warming world if emissions are not reduced, I cannot accept his conclusion that we have to give up on mitigation and just adapt. Quite aside from being built on poor analysis, defeatism like this shows a lack of faith in the ingenuity and determination of humanity, and cannot prevail if young people today are to have a chance at living on a thriving planet in the future.
Ed Wilson
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