Making Natural Gas out of Thin Air

Mark's post about the people of Boulder challenging Xcel Energy's power generation monopoly and replacing coal with with renewables and natural gas finally prodded me into writing a post I'd had on the back burner for a while.

Here's the question: What if you could use wind power to literally generate natural gas out of thin air?

People in the energy industry invariably criticize "tree-huggers" as naive about the vagaries of power generation. Renewable energy sources are too unreliable, the old argument goes. What do you do when the wind doesn't blow and the sun doesn't shine? You have to keep power generation and consumption balanced or the grid collapses. Often, they claim, sun and wind generate too much electricity when you don't need it, and since you can't store it it just goes to waste.

First off, the excess power argument is flat wrong with solar. Solar generates the most power when we need it the most: at peak load times during the heat of the day. Solar is perfect for places like the American West, which get a lot of sun and use massive amounts of air conditioning.

Wind power -- and hydro for that matter -- do generate a lot of electricity during off-peak hours, and in places like the Dakotas that are distant from major population centers.

The question is how to store that energy for later use. If you could save it for later and use it for load balancing, the argument against wind completely falls apart.

Battery technology isn't up to snuff: too expensive and too small-scale. So there have been grand suggestions to use the excess electricity to compress air into vast underground caverns or pump water uphill into reservoirs, which could be used to turn turbines to generate electricity later. These solutions take a lot of space and have negative environmental and safety considerations.

But there's something else you can do with electricity: make hydrogen. A company in Germany is building a pilot plant to do exactly this. Their plan to pump hydrogen into natural gas pipelines seems a bit odd, but the basic idea is quite interesting.

Hydrogen can be produced by electrolysis, which uses electricity to separate the hydrogen and oxygen in water. This hydrogen could simply be burned against to make electricity (producing water), or to power fuel cells. These fuel cells can be used to generate electricity directly (which is what NASA did on the Space Shuttle Apollo moon missions), or they could be used to power cars that run on fuel cells (remember that song and dance from the George W. Bush days?). The International Space Station also uses electrolysis to generate oxygen (they vent the excess hydrogen into space).

One problem with hydrogen is that there isn't a lot of infrastructure for storing, transporting and distributing it. However, we do have a lot of infrastructure for natural gas (methane). So we could take this one step further, and produce methane.

Using what's called the Sabatier process hydrogen (H₂) and carbon dioxide (CO₂) can be combined to produce methane and water:

CO₂ + 4H₂ → CH₄ + 2H₂O

NASA is looking at using this reaction in the International Space Station to make a more closed life support system that recycles the CO₂ that astronauts exhale into water, and to make propellant for the return from a Mars mission.
Though NASA's space applications sound distant, these processes aren't fancy pie-in-the-sky physics pushing the boundaries of engineering like thermonuclear fusion. They're basic, centuries-old chemistry that mirror the natural processes of respiration, photosynthesis and bacterial decay. This kind of power generation would give us the ability to balance loads as well as produce fuels for cooking and transportation, all with zero carbon footprint.

There's a certain amount of inefficiency generating natural gas this way. But even so, it's still more efficient than blasting off mountaintops to expose coal seams, using millions of gallons of oil to mine the coal, then millions more gallons of oil to restore the mountaintops, then millions more gallons of oil to ship the coal across country to run power plants that belch out CO2, carcinogenic particulates, sulfur dioxide and mercury.

When their backs are against the wall, climate change skeptics always retreat with, "Well, if the climate really is warming, we'll just adapt. Humans are amazingly inventive when pressed."

I agree, we are inventive. But isn't it better to adapt before the emergency becomes dire, resources become scarce, floods and droughts become endemic, Miami and New York are inundated, famine becomes widespread, and wars over dwindling energy resources suck up our the time, energy and money?