A new life-cycle analysis of potential low-GHG options for hydrogen production in Europe finds that hydrogen produced only using renewable electricity can be efficient without emissions, and that hydrogen pathways that include fossil fuels, even with carbon capture and storage, have a greenhouse gas density (GHG) high enough to be unlikely to contribute to the achievement of EU climate targets. The study, conducted by the International Council on Clean Transport (ICCT), found that waste-based biomethane production pathways generally have negative greenhouse gas density, but are subject to significant uncertainties.
The analysis appears as the European Union revises the Renewable Energy Directive (REDII), which govern the development of renewable energy in all sectors of the economy in Europe. The review is part of the EU’s “fit 55” package of measures to implement the European Green Deal, a broad EU proposal to cut net greenhouse gas emissions by 55% by 2030 and reach carbon neutrality by 2050.
“Hydrogen made from electrolysis powered by renewable electricity is essentially ‘clean for the climate’ from production to use,” ICCT researcher Yuanrong Zhou noted. “And it is the only viable carbon-free hydrogen option that can be scaled up in Europe.”
The analysis found wide variation in greenhouse gas densities for eight hydrogen production methods in the European Union, each using different feedstocks or processes. Some of the hydrogen pathways involve first producing bio-methane and then converting it to hydrogen. Typical pathways, from lowest to highest in greenhouse gas intensity, are wastewater sludge biomethane, renewable electricity, biomass gasification, natural gas combined with carbon capture and storage (CCS), LFG biomethane, compost biomethane, and the electricity grid in EU 2030, coal using CCS. Greenhouse gas density is measured as the greenhouse gases emitted per unit of energy produced.
Only three of these pathways meet the 70% (compared to petroleum) greenhouse gas reduction threshold required for hydrogen in REDII: wastewater sludge, renewable electricity, and forest biomass residuals (see figure). The highest GHG intensity among the eight modeled pathways was hydrogen produced from coal plus carbon dioxide capture and storage and hydrogen from the 2030 EU power grid. These do not meet the 70% greenhouse gas reduction requirement.
The impact of production processes on greenhouse gas density is evident in the study: hydrogen produced from electrolysis powered by solar and wind energy has a much lower greenhouse gas density than when electricity for electrolysis comes from the EU’s projected energy mix for 2030.
The study found that production based on wastewater sludge scored lower in greenhouse gas intensity. But sludge is not a reliable low greenhouse gas option for hydrogen production due to the risk of methane leakage during its life cycle. Because methane is a potent greenhouse gas with a significant climate impact, small leaks in the production phase could offset the potential climate benefits of hydrogen use. Indeed, the study highlights the high climate risk of any methane-based hydrogen production option (natural gas and bio-methane pathways), due to the risk of leakage.
In addition to hydrogen production, the study examined bio-methane produced from four feedstocks: sewage sludge, landfill gas, manure, and forage corn. Bio-methane can lead to significant emissions reductions, but like hydrogen derived from methane, the various options for producing it also carry methane leak risks.
“Policy makers should carefully consider the greenhouse gas profiles of hydrogen production and use options,” Chu said. “Some of the options that seem promising may actually harm the climate unless processes across their life cycle are working perfectly – which rarely happens.”
The study urges EU policy makers not to add fossil hydrogen as a qualifying pathway in the RED II review or incentivize it in any other policies. Instead, EU policymakers should adopt rules for RED II that require electrolysis hydrogen production from truly additional renewable electricity. It also recommends that policymakers use accurate and transparent life-cycle analysis to assess hydrogen production pathways. These recommendations will help ensure that European Commission policy supports only gas pathways compatible with the Deep Decarbonization Vision.
“Hydrogen from renewable electricity hits the ideal point for policy making,” Zhou notes. “It provides serious climate benefits with little risk of unintended climate damage.”
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The study entitled “Greenhouse gas emissions bio-methane life cycle and hydrogen pathways in the European Union” is available at theicct.org/publications/lca-b … ne-hydrogen-eu-oct21
Presented by the International Council on Clean Transportation
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