Electrolysis for hydrogen production
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Energy Sector Analysis
Pressure to decarbonize the global economy has nudged policymakers and companies to look at hydrogen as a way to tackle emissions.
Electrolysis for hydrogen production By Prachi Patel Feature Editor: Kathy Ayers
T
he lightest element has carried a heavy burden for half a century. Expectations for the hydrogen economy, first proposed in the 1970s, have been high. But hydrogen as a renewable, low-carbon fuel for vehicles, heating, and energy storage has remained evasive, held back by high costs, low efficiency, and a lack of infrastructure and storage technologies. Yet change is in the air. The International Energy Agency (IEA) calls this a year of “unprecedented momentum” for hydrogen in its June 2019 report, The Future of Hydrogen. Past initiatives focused on hydrogen fuel cells for vehicles. But this time, things are different, the report noted. Pressure to decarbonize the global economy has nudged policymakers and companies to look at hydrogen as a way to tackle emissions across a range of sectors beyond transportation. The cost to make and use hydrogen is falling. Renewables have become a key driver and beneficiary: as their share for power generation goes up, hydrogen could be the lowest-cost option for storing gigawatts of surplus solar and wind power for a long time, even compared to batteries. “It’s no longer a question of whether hydrogen will be part of an energy system, it’s what fraction it will comprise,” said Brian Pivovar, Fuel Cell Group Manager, Chemistry and Nanoscience Center, National Renewable Energy Laboratory (NREL). However, nearly all of the 70 million metric tons of hydrogen used every year—mainly for ammonia production and petroleum refining—is currently made by cracking natural gas via steam reforming, which is an energy-intensive, carbon-spewing method. For hydrogen to fulfill its promise as a clean fuel, there is a need to switch its production from gray to green. Age-old electrolysis, which splits water into pure hydrogen and oxygen by passing electricity through it, is one of the most promising technologies to enable that. Provided, of course, that electricity used for the systems comes from renewables. “If you have a surplus of electricity coming from renewables in the future, it makes sense to push those inexpensive electrons into an electrolyzer to make hydrogen,” said Marcelo Carmo, head of electrochemistry at Forschungszentrum Jülich GmbH in Germany. The problem is that hydrogen from electrolysis today is twice as expensive as that from steam reforming, which produces hydrogen for USD$2/kg. Electricity makes up 80% of the cost of electrolic hydrogen. But electrolyzer costs will come to the forefront as renewables provide cheap electricity in the future. Materials scientists and engineers are now working on better catalysts, membranes, and structural components, as well as manufacturing methods, that could chip away at capital and operating costs and help make hydrogen from water splitting a part of tomorrow’s low-carbon picture.
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