Reviving hydrogen as an energy carrier
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Energy Sector Analysis
Hydrogen sees its star rising again as a key solution to help the transition to a lower carbon economy.
Reviving hydrogen as an energy carrier By Eva Karatairi Feature Editor: Sabrina Sartori
H
ydrogen, the simplest of all molecules, made of the simplest of all atoms, is a material that has successfully accomplished many historic missions: it has powered the engines of space rockets and has served in the ammonia-based fertilizer revolution, the iron and steel sector, and electronics manufacturing. But the task of putting hydrogen in the center of the global energy scene has proven tantalizing, perpetually coming closer to materialization, but repeatedly being pushed to the future. Is it possible that the time has arrived for hydrogen to finally come into its own? A secondary energy source or energy carrier, for example electricity and heat, hydrogen is produced from primary energy sources. It must then be stored and distributed (e.g., as gas or liquid or as a part of an appropriate carrier, such as ammonia and other energy-intensive fuels) for end-use applications through the right infrastructure, and finally converted back to energy. By the time all matter and energy-conversion steps have been taken, the costs and energy invested in the process appear to far outweigh the benefits of hydrogen production. At least that has been the case until recently. With the Paris Agreement on climate accords in 2015, many countries have set the goal to limit global warming to 2°C or less by the end of the century. In the global collaboration projects and national roadmaps that have been published since, it is clear that hydrogen completes the toolset that is required in order for nations to reduce domestic greenhouse gas emissions and achieve deep decarbonization at a scale of 80% or more. Hydrogen production is expected to be a mixture of water electrolysis techniques, which are carbon-free if powered by renewables, and methane steam reforming or autothermal reforming with carbon capture and storage (CCS), which can reduce carbon emissions up to 90%. Despite the fact that hydrogen generation from splitting water with electricity is a technique that was discovered more than 220 years ago, today only 4% of the almost 70 million metric tons of hydrogen consumed every year for industrial purposes is produced through water electrolysis. The rest is generated from fossil sources: natural gas, oil, and coal. The low cost of renewable electricity, in combination with the successful scaling-up of electrolyzer manufacturing and a decrease of its capital expenditure, has heated up debates once more that electrolytic hydrogen can potentially match or even beat steam reforming costs. Unrealistic expectations have been raised before, resulting in much scepticism today. So what has changed? “It takes
a lot of electricity to make hydrogen. What’s different now is the revolution that made wind and solar power the cheapest sources of electric power in much of the world today,” said Ken Dragoon, executive director a
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