In the quest for renewable energy sources, hydrogen is emerging as the energy carrier of the future. Today we make hydrogen cheaply from natural gas, rearranging the atoms in methane into a process that releases H2 and emits CO2. It's possible to clean this process up by capturing the CO2, but this is relatively inefficient, and will struggle to achieve complete emissions reduction. The major leading approach for 'green' hydrogen is electrolysis, which can be powered by renewables and reduce operating emissions truly to zero.
There is an alternative to deliver hydrogen with negative net emissions: Make the hydrogen from biomass feedstocks, and capture the carbon produced.
A recent analysis, Green hydrogen production from decarbonized biomass gasification: An integrated techno-economic and environmental analysis, took a look at the economics and found them surprisingly competitive. In this model, green hydrogen is created by first gasifying the biomass, then subjecting it to somewhat conventional chemical processing. With a biomass input cost of about $80/ton - a relatively conservative number - the cost of hydrogen produced though this gasification process falls to roughly $2.50/kg at scale. This is in the range of the costs of blue hydrogen (produced by capturing the carbon emitted by methane reforming), if higher than the long term costs estimated for hydrogen production from electrolysis.
On its own, this would probably not be interesting - electrolysis has better long term potential. The negative emissions of the biomass route also sequesters about 16 kg CO2 per kg H2 produced. which would create a credit for $1.33/kg H2 at the United States 45Q credit rate of $85/ton for point source emitters. If we took this value of carbon capture seriously, these negative would make biomass hydrogen competitive with electrolysis.
Really, though, the negative emissions should be considered equivalent to a DAC process - they pull CO2 from the air, after all. If we assign a value for the negative carbon of $185/ton, then the value of the negative emissions are $2.89/kg H2 produced - more than the cost of producing the hydrogen itself!
These numbers should be considered rough estimates, of course, but they certainly indicate that it's appropriate to take biomass routes to H2 seriously indeed, if we can use them as a path to negative emissions. If the rest of the hydrogen economy is inevitable - and this certainly appears to be the case - policymakers should take note of this path. A green, carbon-negative hydrogen process with competitive economics would change a lot of conversations..
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