Saturday, 21 February 2009
A few notes on solar power
Say "solar power" and everyone thinks of photovoltaics, and investing in these would be a boon to the world -- we would live in a different planet now if most people did that back in the 1970s, when we had used up a sixth of the world's oil rather than half.
No matter how much we think we know the advantages of solar, it's useful to run through them again -- unlike oil, coal or peat, solar energy is not diminished by its harvesting; no matter how much we take today, there is still the same amount left tomorrow. Every day, enough energy falls on the Earth’s surface to supply all our energy needs for four to five years.
Unlike most sources of electricity, they use no fossil fuels and create no greenhouse gas emissions, beyond the panels’ initial manufacture, and an average home-sized solar panel will save 11 tonnes of carbon dioxide each year from adding to climate chaos.This does not even count the additional solar power we receive from wind, waves or rain into rivers, any of which can also generate electricity.
One potential problem with photovoltaics is that they require exotic metals that must be mined and shipped around the world, and whose supply might be limited. Even if we encounter supply problems with these, however, there are still Stirling engines, which really deserve their own article. Stirling engines focus the sun's rays with mirrors on a target, usually to boil water to power a turbine the way a nuclear plant does.
One of the simplest ways of using solar power requires no technology at all -- you merely face your doors and windows south (or north in the Southern Hemisphere), or build a conservatory, and let the sun warm your home. Some European villages were sometimes built this way, all facing the same direction, and while it looks strange at first to our eyes, the sense of it sinks in soon enough.
Creating hot water with the sun is almost as simple; glass or plastic boxes on your roof house darkly-coloured water pipes, and the water warms naturally.
A report last year from the German Federal Ministry for the Environment, Nature Conservation and Nuclear Safety found that Europe could cut its greenhouse gas emissions by 70 percent if everyone switched over to solar power -- and that includes countries like Ireland or Finland, where it is often said that solar power is not feasible. They also noted that the cost of collecting solar thermal energy equivalent to one barrel of oil is often less than the price of oil these days -- although that jumps around from week to week -- and is likely to go down further as demand increases and technology improves.
I don't want us to talk about "clean energy" as a blanket solution for everything; for example, they do not generate liquid fuels. But much of the world's electricity comes from fossil fuels, and clean energy could free up the remaining oil and gas for other things we might need -- driving for a little while longer, until we can make other arrangements. Buses and trains after the peak. Tractors for a while longer, until we can forge or breed alternatives. Manufacturing, including manufacturing solar panels, until someone finally creates a solar-powered solar-panel factory.
Photo: A Stirling Engine, via WikiCommons.