Why I am sceptical about global warming and a convinced green-energy convert
MATTHEW PARRIS Last Sunday a group from Winster, a lovely nearby village in Derbyshire, had invited me to open their roadshow at 11 a.m. The group, Sustainable Winster, had organised a Climate Change Awareness Day. The area climate-change bus had arrived for the occasion, there were displays, posters, free linen bags containing packs of expandable chips to put in the cistern of your loo so it uses less water, a Morris Man, two rangers from the Peak District National Park, bright sunshine and an atmosphere of friendly evangelism.
The turnout was small but enthusiastic, and as I dipped my bared foot into a tub of charcoal-water to make a carbon footprint on paper and accepted my basket of homemade honey and damson gin from Winster's beautiful Carnival Queen, I felt ashamed of a momentary irritation, on awakening that morning, at having promised to come. Each of us needs a little seraph on our shoulder to whisper from time to time — and probably in our mother's voice — 'You'll enjoy it when you get there, darling.' We almost always do.
I did. Maybe it was not as much fun for my audience, because they were obliged to listen to a mini-science lecture from me, delivered in the middle of Winster Main Street. But they seemed receptive, and it's perhaps worth repeating part of it in case you, too, should agree — or be at least persuadable.
I described the new ground-source energy scheme I've been installing, and recently commissioned for use, in a dwelling on my rural property. 'Ground-source' energy has nothing to do with 'hot rocks' or 'geothermal' heat, which is obtained from deep beneath the ground. The term (and the accompanying concept, 'heat pump') causes much confusion, I know. Needlessly, because the theory is simple but involves clearing one minor intellectual hurdle. Once this is cleared, the idea is easily grasped.
The hurdle is that you do have to hold on to the basic Newtonian concept of 'energy' as opposed to 'heat'. A low level of heat in a large body may involve the same amount of energy as a high level of heat in a small body. Thus, if you plunge a slim red-hot poker into a big bucket of cold water, you will greatly cool the poker and slightly warm the water, the energy having been not 'created' or 'destroyed', but transferred.
But what if you could do the opposite — cool the water slightly and heat the poker? Again, you would have transferred, not created, energy. That is what a 'heat pump' does. Never mind how — it's all to do with pumping a gas around in a sealed circuit, compressing it where you want to deliver heat (think how hot the nozzle of a bicycle pump becomes when you pump the tyre), and decompressing it where you want to collect heat (think how cold the nozzle of an aerosol fly-spray gets, after continuous spraying). The technology is oldestablished. Your fridge is a heat pump, removing heat from a small, insulated space and disbursing it into the fresh air via the grille on the back. The technology does require an electric compressor-pump, but this uses only about a quarter as much energy as it gathers.
Because your house ends up hotter than the ground from which you've gathered the heat, energy from heat pumps may seem 'something for nothing'; but this is an illusion. They have not, in fact, 'made' energy (or heat) but moved it from a large mass to a small one, and in doing so raised the temperature. 'Ground source' moves energy out of a few thousand tons of soil in your field and into a few hundred pints of water in your domestic hot-water and central-heating system, slightly cooling your field and greatly warming your house.
Energy can be extracted from a range of sources (the air, for instance), but the soil is ideal because a couple of metres beneath the surface its temperature stays remarkably constant throughout the seasons, so you can design a heat pump to operate sensitively and efficiently, your input of heat being steady. Long loops of plastic piping are laid in sand in outdoor trenches, afterwards filled in, and a saline solution pumped continuously around the loops, warming as it passes beneath the field, then being cooled again by the heat pump.
My ground-source energy system has so far proved a complete success and should save me about £1,000 a year; but I had all-electric heating before, and the whole project plus machinery (efficiently supplied and installed by a Sheffield business called Eco Heat Pumps) cost me about £15,000, some of which went on adapting a property that had not been designed for it; so I would particularly recommend ground-source to those starting from scratch with a new building; those able to install under-floor central heating; and those who do not have gas. A few acres is all you need — or you can go down vertically with boreholes, which is more expensive.
The truth is, though, that this was not an economics-driven exercise. I'm a convinced green-energy convert. Yet, as I tried to explain at Winster, I'm still sceptical about global warning. The trend is clear — the world is heating up — but neither the causes nor the extrapolations have been proved. It seems probable to me that human activity has some part to play, but how great a part? Nor can we be sure whether this will prove the upswing of a cycle which may eventually curve down again (and, if so, when it will). Some scientists, and many media interpretations of science, seem to me to be overstating the certainties and glossing over the gaps in our knowledge.
But none of this dims my enthusiasm for mankind's efforts to minimise our impact on our environment. For the apocalyptic scenarios might be true, and there's surely a good chance that the more moderate consensus of scientific opinion, at least, is true. And even if they're all wrong, three things are beyond doubt. We are exhausting known reserves of fossil fuels and will one day run out. We are (in many parts of the globe) abstracting too much water for human use, and this accelerating consumption cannot continue. And we are running out of places to put all the rubbish we are generating.
You only need to be convinced of these three truths for it to follow that the search for sources of energy that do not involve combustion, and for ways of conserving and re-using water, and minimising and recycling waste, has to be prudent. More than prudent: a solemn obligation on our generation.
Or so I said in Winster. Then I washed my charcoaled foot in (oh dear) warm and (oh dear) soapy water; then (oh dear) I drove home. Ah well. However faltering, we have to make a start.
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