Climate Change Part 3: Energy Solutions

Hi all,

It's been a while--a couple busy months for me. I'm going to try to get back in the habit of posting stuff at least somewhat regularly now. I'll start by finishing up the climate change series I was working on before.

In part 1 and 2, I discussed the threats posed to humanity by global warming, and some policy tools being implemented to stop it. In this part, which I think is the coolest, and most encouraging, part, I'll discuss technologies that will enable us to pollute less while maintaining our energy-intensive lifestyles.

The arena where the biggest changes are happening is the electricity sector. Currently, fossil fuels produce most of our energy, with hydroelectric and nuclear making up the balance, and small contributions from “true” clean energy. (I put “true” in quotes because although neither hydro nor nuclear emits greenhouse gases, both are connected to major environmental problems and, I think, should eventually be phased out.)

So why is clean energy such a small part of the total? It's not inherently more expensive—whether you get it from solar, wind, geothermal, or waves, the energy source is free, unlike coal, natural gas, or uranium. One reason is startup costs—these things are wickedly expensive per kilowatt to start up. However, technology is progressing so much that these costs are coming down. Probably a more important reason, though, is that coal plants are able to externalize much of their costs. They don't have to pay the societal costs of destroying mountains, poisoning rivers and groundwater, and melting the ice caps. (Socialism for the rich, capitalism for the poor yet again.) Cap and trade will help with that, but still won't make them pay the full cost of it, and of course doesn't even touch non-climate pollution.

A third reason is that utilities don't really encourage it. The electric grid isn't designed to accommodate energy from areas with sun and wind resources (its technology hasn't really changed much since Edison's time), and many utilities won't even buy power produced on smaller scales. This problem has actually already been addressed by the stimulus bill last year, which is funding massive changes in the grid's connectivity, capacity, and sophistication.

Given this, it is quite likely that coal and natural gas will not be used for power generation 100 years from now—it'll just be too expensive, not to mention environmentally destructive. So what takes its place?

Solar is probably the real long term answer. It comes in two forms: photoelectric (PV) and solar thermal. PV is what most people think of when they think of solar power—glistening arrays of dark blue panels silently turning light into electricity via the photoelectric effect. The thing holding these panels back is that they take a lot of energy to make, and they aren't particularly efficient. However, the engineers making them keep finding ways to improve their efficiency, so they're constantly increasing in quality, and of course, decreasing in price per kilowatt. Another limitation is that they can only generate power when the sun is shining, so they need batteries to store power at night. Batteries of the type they need are not economical now, but great advances are being made and they should be available soon. Despite these setbacks, solar is an excellent energy source. The sun shines everywhere at least sometimes, so anyone can buy some panels, put them on their roof, and sell power to the grid in sunny weather. It doesn't require large concentrated arrays to be worthwhile, which opens up the market to ordinary people as well as big utilities.

Solar thermal is currently more efficient than PV. It works on the same principle as coal plants: water is boiled into steam, which drives a turbine, except that it's sunlight focused by mirrors heating it instead of 300 million year-old coal. Unlike PV, solar thermal can really only work in concentrated power plants—it's just too much infrastructure.

Wind is another big energy source that's starting to take off now. The image of slim, graceful windmills dotting the horizon is commonly used to represent our transition to clean energy, largely because it's the most promising immediately-available technology. Wind energy is quite simple, and the main thing holding it back is the lack of high capacity transmission lines in places with big wind resources. Wind does have fairly high startup costs, though currently not as high as PV.

A common complaint about wind energy is that windmill blades kill birds and bats. (Strangely, similar complaints are rarely voiced so loudly about fossil fuel activity when it proves destructive to wildlife. I wonder why.) This obviously is not good. However, research is being done (and appears to be succeeding) to find ways to mitigate this problem. Also, for most bird/bat species, the effects of global warming are likely to be far worse on them than windmills. If this continues to be a problem over the long term, wind could be phased out, similar to how hydroelectric plants are slowly starting to be phased out due to their effects on fish.

Geothermal is my favorite, and not just because I do Earth Science. Geothermal plants draw hot groundwater, which flashes to steam as it rises and depressurizes, and subsequently drives a turbine. It has been in use in some places for about a century. Traditionally, it has been limited to areas with hot, permeable aquifers, which are not exactly common. California has a lot of geothermal fields, for example, but the US east of about Colorado has essentially none. However, a new technology called Enhanced Geothermal Systems (EGS) looks like it could expand geothermal's range to more sites. This method involves drilling deep into hot, dry, impermeable rock formations, applying just enough water pressure to create networks of microfractures, and pumping water through them. As the water flows through the cracks, it heats up, and can be withdrawn by a geothermal well. This type of setup could be used in far more areas than traditional geothermal. Google.org has a nice summary of it.

Wave energy is the newest of these clean energy technologies. To my knowledge, it's not ready for commercial development. However, it shows some promise. Ocean waves carry loads of energy across entire oceans toward beaches, where it generally dissipates. Wave energy systems take advantage of the vertical oscillation of the water surface due to these waves, and use it to generate electricity. In theory, it's a great source of useful energy. However, it's difficult to implement. In the future, it may well play a role, but it's not ready yet.

Automotive fuels are another type of energy we're going to have to tackle. Several alternative car fuels have been developed, but it's questionable whether they can be implemented on a large scale and still make economic and environmental sense. Means of converting waste kitchen grease from restaurants into biodiesel have been wildly successful, but there just isn't enough waste grease out there to make biodiesel on a large scale. Making it from certain plants could be better for large scale production, but a lot of people (including me) are unconvinced that it'll actually prevent pollution to do so. Making it from algae looks promising, but the logistics of growing algae in such quantities have proven challenging. Ethanol appears to be a disaster no matter how it's made—it emits more carbon to make ethanol than to simply burn its equivalent amount of gasoline instead. Ethanol made from sugar cane might be energy positive, but growing sugar cane to make fuel would probably require destruction of rainforests for plantations. The best long term solution for cars and trucks is probably to do away with the horribly inefficient internal combustion engine and switch to electric vehicles, which are more efficient and can use electricity generated by clean power plants.

Switching to clean energy sources is critical to reducing carbon dioxide emissions. To do this, we need to continue investing heavily in solar and wave technology research and work harder to develop existing wind and geothermal resources. Reducing the number of coal plants, either by closing them or switching them to natural gas fuel, would further help reduce our emissions. All of this will be facilitated by the smart energy grid, currently in development, and a cap and trade system, which will hopefully be implemented soon.