October 08, 2006
|Micro-Generation Isn't The Answer||Energy Environment|
According to Britain's George Monbiot, author of Heat: How to Stop the Planet From Burning, micro-generation of electricity via small-scale wind turbines and solar panels is an over-hyped non-solution to global warming. Large-scale wind turbines, however, are a practical solution, especially for an island nation like the UK. Excerpt:
In seeking to work out how a 90% cut in carbon emissions could be achieved in the rich nations by 2030, I have made many surprising findings. But none has shocked me as much as the discovery that renewable micro generation has been grossly overhyped. Those who maintain that our own homes can produce all the renewable electricity and heat they need have harmed the campaign to stop climate chaos, by sowing complacency and misdirecting our efforts.
Last year, the environmental architect Bill Dunster, who designed the famous BedZed zero-carbon development outside London, published a brochure claiming that "up to half of your annual electric needs can be met by a near silent micro wind turbine". The turbine he specified has a diameter of 1.75 metres. A few months later Building for a Future magazine, which supports renewable energy, published an analysis of micro wind machines. At 4 metres per second — a high average wind speed for most parts of the UK — a 1.75 metre turbine produces about 5% of a household’s annual electricity. To provide the 50% Bill Dunster advertises, you would need a machine 4 metres in diameter. The lateral thrust it exerted would rip your house to bits.
Turbulence makes wind generators even less efficient. To avoid it, you must place them at least 11 metres above any obstacle within 100 metres. On most houses, this means constructing a minor hazard to aircraft. The higher the pole, the more likely you are to inflict serious damage to your house. In almost all circumstances, micro wind turbines are a waste of time and money. [...]
[S]eeking to generate all our electricity by [installing solar panels on residences] would be staggeringly and pointlessly expensive — there are far better ways of spending the same money. The International Energy Agency's MARKAL model gives a cost per tonne of carbon saved by solar electricity in 2020 of between £2200 and £3300. Onshore macro wind power, by contrast, varies between a saving of £40 and a cost of £130 a tonne.
[Another] problem is that the supply of solar electricity is poorly matched to demand. In the UK, demand peaks on winter evenings. Even if we could produce 407TWh a year from solar panels on our roofs, only some of it could be used. There would be a surge of production in the summer, during the middle of the day, and very little in the winter. While solar panels might reasonably supply 5-10% of our electricity, the size and inefficiency of the energy storage and standby power system required makes a purely solar network impossible.
Similar constraints affect all micro renewables: a report by a team at Imperial College shows that if 50% of our homes were fitted with solar water heaters, they would produce 0.056 exajoules of heat, or 2.3% of our total demand; while AEA Technology suggests that domestic heat pumps could supply only 0.022 eJ of the UK's current heat consumption, or under 1%. This doesn't mean they are not worth installing, just that they can't solve the problem by themselves.
Some campaigners accept that micro generators can make only a small contribution, but argue that they are still useful, as they wake people up to green issues. It seems more likely that these overhyped devices will have the opposite effect, as their owners discover how badly they have been ripped off and their neighbours are driven insane by the constant yawing and stalling of a windmill on a turbulent roof.
Far from shutting down the national grid,...we should be greatly expanding it, in order to produce electricity where renewable energy is most abundant. This means, above all, a massive investment in offshore windfarms. A recent government report suggests there is a potential offshore wind resource off the coast of England and Wales of 3,200TWh. High voltage direct current cables, which lose much less electricity in transmission than an AC network, would allow us to make use of a larger area of the continental shelf than before. This means we can generate more electricity more reliably, avoid any visual impact from the land and keep out of the routes taken by migratory birds. Much bigger turbines would realise economies of scale hitherto unavailable.
The electricity system cannot be run on wind alone. But surely it's clear that building giant offshore windmills is a far better use of our time and money than putting mini-turbines in places where they will generate more anger than power. [Emphasis added]
Driving along highway 18 in southwestern Wisconsin this weekend, Carie and I passed the Montfort windfarm — a string of 20 large turbines (30 Megawatt capacity) installed on a ridge running parallel to the road. The turbines are both stately and graceful — quite beautiful, in fact. The mere sight of them inspires hope. They are like visitors from a better future. They radiate peace. No carbon emitted, no oil wars required.
It should be a no-brainer.
I agree that most microgeneration (with the possible exception of micro hydro) options are an inefficient use of capital (with current technology) to deal with the problem of generating enough energy to meet our growing needs without carbon emissions, but individuals should not despair that there is nothing we can do... energy efficiency measures such as CFLs, Energy efficienct transport Passive Solar design, and extra insulation ARE extremely cost effective (most pay for themselves within a few years or even months,) and using energy more wisely will be an essential part of any carbon mitigation strategy.
Posted by: Tom Konrad at October 9, 2006 01:03 AM