This is the third in a series of articles exploring the potential of green energy sources. The first two are here and here. I wrote how I consider it a moral imperative to provide everybody on this planet with as much energy as we Americans use today. That amount, needed by the end of the century, comes to 3,000 quads (quadrillion BTUs, one quad being equivalent to the amount of energy we can squeeze from 36 million tons of coal).
Because that’s a lot of coal, I wrote the previous two articles looking at the feasibility of solar and wind energy to provide for our energy. Summing up, there’s more than enough sunlight, but depending on how exponential the growth rate for solar power is, it might only give us 20% of what we need. (It could do more, but it isn’t certain.) There’s apparently a lot of wind, but there’s something going on with the numbers that I clearly don’t understand as yet, so we’re going to come back to it.
In this article I want to look at hydroelectricity. It gets overlooked here in the developed world because we’ve, well, developed most of the potential sites for large dams. They’re already built, they’re dependable, and so we just don’t pay attention to them the way Chinese might be paying attention to Three Gorges Dam.
But hydroelectric power produces 20% of the world’s electricity from 40,000 large dams. Actually, of all the electricity currently produced by renewables, hydroelectricity accounts for 88%… So it’s worthwhile looking at prospects for growth here. It works. It makes money for operators. It’s continuous–not affected by night or calm days.
Because the rich world has built most of the big dams that are feasible, growth will take place in the developed world. Indeed, of the 25 proposed dams listed on Wikipedia, 24 are in the developing world (mostly China, which already leads the world in hydro), and the 25th is in Russia. A further 20 major dams are in the proposal evaluation stage and all are in the developing world (again, mostly China).
Hydroelectric power produces about 3 terawatt hours last year, and that is expected to grow to 5 terawatts by 2030. The International Hydropower Association says that only 33% of high potential sites have been developed.
Sadly, even if we can reach 9 terawatt hours by developing the rest of the sites that will Update: (I made the classic tired man’s error of thinking of energy when writing about power and really goofed on this. Ah, well, no sense in making small mistakes, right? Think big… and thanks all, for pointing it out.) only amount to 270 quads, or 10% of my personal goal.
Well, what about small, or even micro hydro? A lot of smaller dams can generate electricity, and there are at least 850,000 smaller dams. They also work and they are already producing 85 gigawatts of electricity (again, 70% in China). Here in the US, only 3% of the nation’s 80,000 dams are used to generate electricity.
Concerns about environmental impacts have held up development of small hydro. However, in highly regulated Europe, small hydro has doubled in each of the past two decades. So it can be done.
Sadly, the physics of water powering many small turbines make it extremely unlikely that hydroelectric power, large or small, will give us more than 10% in the way of the 3,000 quads that we need for our world’s future. We will have to look elsewhere.
Nonetheless, because of the efficiency, cleanliness and reliability of hydro, it makes perfect sense to squeeze every last watt out of this that we can. But because it is a minor player, it also makes sense to pay close attention to its environmental impacts, which are not negligible.
So far, solar seems like the clear winner. But we’re not through.