On renewable energy

There ain’t no such thing as a free lunch.

Robert A. Heinlein, The Moon is a Harsh Mistress

I originally wrote this essay a few weeks ago, but it’s now something of a companion piece to last week’s post on false hope, particularly as that relates to nuclear fusion. Because a lot of the false hope that people attach to fusion power is often attached to renewables, and many of the same issues apply.

People have been using the power of the wind and of running water to do useful stuff for a very long time. Sails have been in use for millennia, windmills go back at least as far as 9th-century Iran, Afghanistan and Pakistan, while the water-wheel may have been known to the ancient Greeks as well as to the Chinese of the same era. Now that people are finally noticing that we can’t go on relying on fossil fuels, renewable energy is all the rage.

This is perfectly sensible, as far as it goes. It will not, however, go as far as we tend to think. Due to the catastrophic failure of our collective imagination, which I’ve already discussed in a previous post, the only kind of future we can envisage is one that is just like the present, only with all the fossil-fuel energy replaced by renewables. This future is easy to imagine. It is also not going to happen.

Electric cars are of course a thing. Indeed they have been a thing for a surprisingly long time, predating the internal combustion engine. What we don’t have, though, is a practicable electric truck, and as far as I know nobody is even working on an electric tractor (apparently John Deere have actually denied it) or an electric cargo-ship. There have been heroic efforts to develop electric aircraft, but you are never going to have batteries offering the same energy density as aviation fuel.

Even if we knew how to build all these things, we probably don’t have the raw materials to manufacture them in the quantities needed, not to mention the enormous infrastructure of charging points. And charging-points aren’t much use unless you can generate the actual electricity for them, and that’s going to be a big issue if your power-grid is based on renewables.

The fundamental reason for this is that renewable energy sources, unlike fossil fuels, are intermittent. That is to say, you can’t rely on solar or wind-generated electricity being available at the time you need to use it. This is an issue, because demand for electricity fluctuates quite dramatically.

Moreover, wind and water power derive from the climate, which is to say they are affected by the weather. There are simply times when the wind doesn’t blow and the sun doesn’t shine. Even hydro-electric power can be disrupted by drought, as the Chinese and Americans are discovering at the moment. This isn’t an issue so long as renewables are merely supplementing the fossil-fuelled grid, because a gas-fired power station can merrily run 24/7 so long as it has gas. When renewables are it, though, you have a problem.

The existing power grids across the industrialised world were not designed to cope with intermittency. This is hardly surprising. But it turns out that building such a grid is extremely difficult, because we have no good way of efficiently storing large amounts of electricity, which is what you need to be able to do.

This is not to say that renewables are useless. They don’t solve the problem of powering a nationwide power grid, but we used to get along well enough without having such a thing. They can work well for small-scale local power generation, which also avoids the loss of electricity in transmission (around 6% for the US national grid). Back in the 1970s, when at least some people were prepared to assign some value to small-scale local solutions, a lot of useful work was done in this area. We could do worse than to revisit some of that.

Renewables can work even better to provide direct mechanical energy to do useful stuff, as they always used to do. This is far more energy-efficient, because the process of turning that raw mechanical energy into electricity and then back into useful energy again itself uses energy.

Imagine a cargo-ship that is powered by renewables. You could half-fill the thing with electric motors and batteries, cover the deck in solar panels, and have masts with wind-turbines on them. Alternatively, you could just put sails on the darn thing. That’s how global trade was powered through most of human history. It’s well-understood technology, although of course attempts to revive it have to involve computer-controlled sails, because it’s a well-known fact that nothing can be any good unless computers are involved.

Again, imagine a factory powered entirely by renewables. You could do what was done on the early days of the Industrial Revolution, and use water-power directly to drive the machinery. Indeed, steam-engines were quite a hard sell in those days, because coal costs money and the flow of a river doesn’t. This does mean you can’t just build a factory wherever you want, and it does put a hard limit on the number you can have, but where it works, it works pretty well.

All of this talk of limits and restrictions is of course rank heresy. We’re still committed to infinite growth on a finite planet, and we’re still going to face-plant until we finally grasp that it can’t be done. (It would still be a terrible idea even if it could be done, but that’s another conversation.) But we shouldn’t discard renewables just because they won’t fulfill our impossible fantasies. A hammer is still a useful tool, even if you can’t darn your socks with it.

In any case, soon enough we won’t need to imagine a world in which electricity supplies are intermittent: that will we be the world we inhabit. Thinking about alternatives now strikes me as a sensible use of time; certainly more sensible than trying to make a battery-powered aeroplane.

Comments are welcome, but I do pre-moderate them to make sure they comply with the house rules.