Wind turbines of the early 1980s operated at only one speed: the speed that would generate electricity to match the grid’s AC frequency of 60 Hz. This speed was controlled by automatically mechanically adjusting the pitch of the propellers. This meant that whether the wind blew at 10 km/hr or 100 km/hr, it generated the same electricity. “Why not,” I thought, “just have a DC generator, which would spin as fast as the wind would let it, then convert all available wind energy into hydrogen gas, storing the gas in times of high winds and burning the gas later to generate electricity when there is no wind.” In this way, the hydrogen would become the “stored electricity” in the AC grid, which really can’t store electricity.
Wind turbine technology evolved differently than what I had anticipated. Wind turbines now have all sorts of electronic and mechanical gizmos that harness much more of the energy from high speed winds while maintaining the AC Hz requirement of the electrical grid. But the fact that still remains is when the winds are not blowing, these advanced turbines are not generating much electricity.
Right now, the electrical grids use conventional electrical power (coal, gas, hydro, or nuclear) to pick up the slack when the winds are not blowing. But as more and more renewable energy resources come on stream, these sources of reliable electrical delivery will decrease. Hydrogen plants — facilities to create, store, and later convert hydrogen gas into electricity — will be the future source of reliable supply when the weather is not cooperating.
Operators of renewable energy sources would split their production into two streams. The first puts electricity directly into the grids. The second creates hydrogen when the weather has more energy to harness than the grid demands. Operators would convert their hydrogen in times of lower electricity supply, making their decision based electricity prices, how full their hydrogen tanks are, and their synopsis of weather and electricity supply. They should get a higher price for their hydrogen-based electricity when supplies are lower to justify the capital costs to build hydrogen plants. This higher price gives the renewable electrical grid its necessary stable long-term supply.
Hydrogen plants would be much more environmentally friendly than other electrical generating stations. There is no CO2, global warming, or nuclear wastes to deal with. And because hydrogen plants would still be made and operated by people, accidents will still happen. But when one such plant has a serious malfunction, hydrogen has very little polluting residue to clean up.
One interesting development I read about is that some scientists and engineers are thinking about running electricity co-axially with liquid hydrogen. The electricity would be carried in the middle of the pipeline, and the liquid hydrogen would super-cool the electrical conductor, thus reducing electrical resistance losses of electrical energy to almost zero (these losses consume about 7% of total electricity generated today). The hydrogen being pumped with the electrical line would also be converted to electricity at its destination. So I can see a hydrogen production and compression plant at the location of the renewable energy source and a big hydrogen fuel cell generator at the other.
When we finally reach this stage of technology and infrastructure, then we will be a true hydrogen economy. It’s too bad we don’t really have a social engineering plan to get there.
Published on davevolek.org 2012
