Houston Chronicle Sunday
Hydrogen is gaining as a way to store wind, solar energy
The race is on to find the perfect medium to store wind and solar energy, and one emerging option is hydrogen, a molecule that fossil fuel firms know well and that is taking center stage in the clean energy revolution.
When oil and natural gas executives were not begging investors for more money, many touted their plans to produce various colors of hydrogen at CERAWeek by S&P Global, the annual energy leadership summit in Houston.
Hydrogen is the lightest element, highly flammable, odorless and colorless. When energy executives talk about hydrogen’s color, ranging from gray to green, they are referring to how sustainably it’s derived.
Gray hydrogen is made from natural gas and produces large amounts of carbon dioxide. Producers can turn it blue if they capture the CO2 or turquoise if they use the carbon for something else. Pink hydrogen is made from water using nuclear power; green is made using renewable electricity and releases no greenhouse gases.
Mitsubishi Power is developing an Advanced Clean Energy Storage system in Delta, Utah, for making green hydrogen. The company plans to use surplus wind and solar power to make green hydrogen, then store it for times when wind and solar run short. Modified natural gas turbines can blend in hydrogen with minimal emissions.
“When we looked at the
market, what was very clear to us was that in certain geographies there was an imminent need for long-duration storage, in California, the western part of the United States in particular where renewable penetration is about 35 percent,” said Arun Mitra, executive vice president and chief financial officer at Mitsubishi Power Americas. “There’s a clear need for shifting generation capacity from the spring to the summer season.”
Pure hydrogen, though, releases highly polluting nitrous oxides when used in standard gas turbines. For now, generators can blend hydrogen with natural gas up to 30 percent without trouble, but Mitra said Mitsubishi hopes to deliver 100 percent hydrogen pollution-free turbines by 2030.
What makes sense for the western U.S. electric grid will not work everywhere. Mitra and other experts agree that in Texas, North Dakota and other places with cheap natural gas and old oil wells that can store CO2, blue and turquoise hydrogen make more sense.
Exxon Mobil and a dozen partners want to build a blue hydrogen hub in the Houston area. The proposal would expand existing facilities that use natural gas to make hydrogen, sequester the CO2 in old offshore wells and export hydrogen from the Houston Ship Channel.
Transporting and storing hydrogen is not easy. However, natural gas pipelines can carry hydrogen gas with some modifications, and companies can supercool it into a liquid, just like liquefied natural gas.
Producers also can blend hydrogen with other chemicals to make liquid ammonia, methanol or renewable gas captured from decomposing plants or garbage. The green ammonia, methanol or renewable gas will store the energy in tanks or caverns until needed.
Then customers can easily separate the hydrogen from the carrier chemicals for power generation.
Mitra said green hydrogen from Mitsubishi’s Utah facility is already profitable in the electricity markets in the Western Interconnection grid. Green hydrogen could also make money in Europe, where natural gas prices are currently 10 times higher than in the United States.
Hydrogen producers must substantially reduce production costs to gain market share elsewhere. Energy companies are experimenting with new types of electrolysis to separate hydrogen from water or perfecting pyrolysis to reduce the cost of making hydrogen from natural gas.
Bloom Energy, a California fuel cell manufacturer, has spent the last decade selling modules that turn natural gas and biogas into electricity. But the same cells operated in reverse become electrolyzers, converting electricity and water into hydrogen and oxygen.
“Our costs have come down almost every year, on a curve of 12 percent per year,” said Sharelynn Moore, executive vice president of strategy and business development. “We can take excess wind here in Texas, excess solar, and with our electrolyzer, we can produce hydrogen.”
Instead of relying on natural gas from frozen wellheads during the next arctic blast, Texas could instead rely on free-flowing green hydrogen stored in salt caverns.
Most people only think of batteries when imagining how to store renewable energy.
But there are many more ways to hold onto wind and solar power during those times when the wind blows too fast, and the sun shines too bright. Government regulations must allow entrepreneurs to innovate and compete.
The CEOs of Big Oil get the main stage at CERAWeek, but the real innovators are meeting in the small rooms plotting a revolution.