Californian startup Mote is establishing its first facility to convert wood waste into hydrogen fuel while capturing and sequestering the resulting CO₂ emissions.

The wood waste would come from citrus or nut trees, or even almond shells, sourced from orchards in California’s Central Valley, says co-founder and CEO Mac Kennedy. The state produces a vast amount of such biomass, he says.

The company expects to start producing carbon-negative hydrogen as soon as 2024. Volumes are expected to amount to c.7,000t/yr with 150,000t/yr of CO₂ removed from the air.

Kennedy says the process is the first to combine the creation of synthetic gas from biomass, hydrogen production from synthetic gas and CO₂ storage.

Biomass will be be heated in a limited-oxygen environment to above 1,500°F, converting it to a mixture of gases. In a series of operations, the mixture is reacted, separated and purified into hydrogen for sale as a transportation fuel and CO₂ for storage. Mote will recover the small amount of remaining ash and sell it as an additive for fertiliser, it says.

7,000t/yr – Expected hydrogen production

By selecting biomass that would otherwise decompose or burn, Mote will take carbon that trees and crops removed from the air and put it underground or into rocks, Kennedy says. The hydrogen produced will be carbon-negative with 180g/MJ being removed from the atmosphere compared with the 160g/MJ carbon intensity of today’s standard grey hydrogen made from fossil fuels.

Kennedy notes that a report by US federal research facility the Lawrence Livermore National Laboratory’s, Getting to Neutral: Options for Negative Carbon Emissions in California, found that gasifying waste biomass-to-hydrogen is the lowest cost and most scalable option for removing carbon from the air.

The engineering work for Mote’s first facility is under way in Kern County near Bakersfield. The exact site has not been announced. Mote has teamed up with US engineering company Fluor and biomass gasification firm Sungas Renewables to develop the plant.

Mote also says it is in discussions with carbon utilisation company Carboncure Technologies on the potential of permanently storing the CO₂ produced by the plant in concrete via Carboncure’s carbon-removal technologies, which are deployed in hundreds of CO₂ mineralisation systems at concrete plants worldwide.

Mote expects to announce several plants over the coming years, says Kennedy.

“The positive thing about this project in particular is that it will be capturing the CO₂, which gives it a good claim at being carbon-neutral, or possibly even carbon-negative, depending on your accounting methodology,” says Martin Tengler, lead hydrogen analyst at research firm BloombergNEF. “[It is] certainly worthwhile to use wood and agricultural waste, but this will always be a limited market.”

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Author: Ros Davidson