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.


sunny said...

True enough, solar power is a replaceable source. It is just there for us to consume in such a way that the enironment won't suffer.
Let's enjoy this God-given resources.

Robin said...

Totally spot-on. The difficult thing is how expensive Solar PV is for the average person. My neighbor and friend has a net-zero house, but their solar array cost $60k, not exactly in the range of most people's budgets these days. If governments could do some kind of helpful tax credit, it would go a long way toward getting more people up with Solar PV technology.

Passive solar and solar hot water are the most bang for your buck for sure. When we bought our house, south-facing windows were an absolute must, and we rarely use lights or heat in the daytime even in the winter. Then our deciduous trees keep us cool in the summer - so perfect and simple!

Anonymous said...

Great blog. Love the photos.

Regarding solar photovoltaics, you say:

"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...."

It seems to me, though, that the energy (and therefore carbon)cost of the initial manufacture must be quite significant, and the break even point - when energy produced is equal to the energy input - may be quite a few years. Do you have any data on how long it takes before photovoltaics begin to pay off?

I feel that the cost of production is often lacking in discussions of 'green' technology. We need to look at the total energy costs over the life of the technology. For example, I've read (though I can't say where)that because of the vastly higher cost of producing a hybrid vehicle, that the energy cost of driving a hybrid is equivalent to driving a hummer H3 if integrated over the total life span of the car.

My intuition tells me that often the simpler and lower tech solutions are the ones that will really pay off. Passive solar and solar hot water make a lot of sense to me, and I'll take a bicycle over a hybrid any day.


Brian Kaller said...

Thanks, Sunny.

Robin, I agree - I wish PVs and wind turbines were part of any government relief or stimulus package.

I love south-facing windows, and having deciduous trees to regulate sun -- it's brilliant, isn't it? Admittedly, most homes are already built without them now, and we might not have the energy to tear them down and build new ones, but more people could add conservatories on the south side.

Anonymous, I agree PV panels take a lot of energy to build, although I don't have figures with me. I will say, though, it's not just a calculation of energy vs. energy, but spending energy now vs. having energy when times get lean. It is also a matter of being independent if the grid goes down. Your point, though, is well taken.

Peak Oil Hausfrau said...

Don't forget Sun Ovens / solar cookers. In a sunny climate, you can cook in them 9 months of the year and use far less wood, natural gas, or electricity for cooking. AND the commercial ones only cost about $250.

Thesolar said...

Wow! Very informative and interesting blog you got here. Could have been better if you could add some videos and photos on how to make or to install solar panels. Anyway your blog still rocks,Keep Posting!!

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