Hydrogen is often viewed as an important energy carrier in a future decarbonized world. Currently, most hydrogen is produced by steam reforming of methane in natural gas (“gray hydrogen”), with high carbon dioxide emissions. Increasingly, many propose using carbon capture and storage to reduce these emissions, producing so-called “blue hydrogen,” frequently promoted as low emissions. We undertake the first effort in a peer-reviewed paper to examine the lifecycle greenhouse gas emissions of blue hydrogen accounting for emissions of both carbon dioxide and unburned fugitive methane. Far from being low carbon, greenhouse gas emissions from the production of blue hydrogen are quite high, particularly due to the release of fugitive methane. For our default assumptions (3.5% emission rate of methane from natural gas and a 20-year global warming potential), total carbon dioxide equivalent emissions for blue hydrogen are only 9%-12% less than for gray hydrogen. While carbon dioxide emissions are lower, fugitive methane emissions for blue hydrogen are higher than for gray hydrogen because of an increased use of natural gas to power the carbon capture. Perhaps surprisingly, the greenhouse gas footprint of blue hydrogen is more than 20% greater than burning natural gas or coal for heat and some 60% greater than burning diesel oil for heat, again with our default assumptions. In a sensitivity analysis in which the methane emission rate from natural gas is reduced to a low value of 1.54%, greenhouse gas emissions from blue hydrogen are still greater than from simply burning natural gas, and are only 18%-25% less than for gray hydrogen. Our analysis assumes that captured carbon dioxide can be stored indefinitely, an optimistic and unproven assumption. Even if true though, the use of blue hydrogen appears difficult to justify on climate grounds.
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Primary colours of the rainbow
Green hydrogen is extracted using a method that does not produce GHG emissions. As the name suggests, its production is sustainable and environmentally friendly. Green hydrogen is most commonly produced using a device called an electrolyser. Electrolysers use electricity to split water into hydrogen and oxygen. The key to this method of producing green hydrogen is that the electricity that powers the electrolyser comes from renewable sources, such as wind, solar, which have no associated GHG emissions. There are also pathways to produce green hydrogen from waste biomass.
Blue hydrogen is produced using a process called ‘steam reforming’, which uses steam to separate hydrogen from natural gas. This process does produce GHGs, but carbon capture and storage technologies capture and store those emissions.
Grey hydrogen is also extracted from natural gas using steam reforming but in this case, relevant technologies don’t capture resulting emissions. Instead, they are released into the atmosphere.
Brown and black hydrogen
Brown hydrogen (made from brown coal) and black hydrogen (made from black coal) are produced via gasification. It’s an established process used in many industries that converts carbon-rich materials into hydrogen and carbon dioxide. As a result, gasification releases those by-products into the atmosphere.
However, if technology ends up storing those emissions, that hydrogen can sometimes be called blue.
Turquoise hydrogen describes hydrogen produced when natural gas is broken down into hydrogen and solid carbon via pyrolysis. This method uses heat to break down a material’s chemical make up. It’s seen as ‘low carbon’ as the hydrogen production process doesn’t emit any GHGs. But there can be emissions associated with the mining and transport of natural gas that is used as the starting product.
Jet Zero Council keeps up momentum with £3 million government funding for zero emission flight infrastructure
30th June 2021
Competition will fund critical research into electric and hydrogen aircraft to support aviation reach net zero by 2050.
Launching the first round of the ZEFI competition, delivered by the Connected Places Catapult – the government will award businesses and universities around the UK up to £50,000 each to pioneer critical research into infrastructure, such as charge points and hydrogen fuelling tanks, that will enable the mass uptake of electric and hydrogen aircraft.
- government launches first round of £3 million Zero Emission Flight Infrastructure (ZEFI) competition, supporting development of infrastructure required to aid electric and hydrogen aircraft such as charge points for planes
Hydrogen Strategy | Four key takeaways for civil engineers
17 AUG, 2021
BY CATHERINE KENNEDY (New Civil Engineer)
Government reveals plans for £4bn hydrogen investment by 2030
Low-carbon hydrogen economy could also create thousands of jobs
The government hopes to attract at least £4bn of investment to the hydrogen economy by 2030 under plans to produce the equivalent of enough hydrogen to replace fossil fuel gas for heating and cooking in about 3m households in the UK.
The government has published its long-awaited plans for a UK-wide hydrogen economy, which it says could be worth £900m and create more than 9,000 high-quality jobs by the end of the decade, rising to £13bn and 100,000 new jobs by 2050.
The strategy document lays out its efforts to attract investment in 5 gigawatts of hydrogen production by 2030, which would mostly power heavy industry, as well as transport and up to 70,000 homes. It suggests hydrogen could cover 20-35% of the UK’s energy consumption by 2050, providing a clean alternative to oil and gas in energy-intensive industries, power and transport.
It proposes a series of industry consultations to help establish a subsidy system to support large hydrogen projects to decarbonise areas that cannot run on electricity.
However, the plans remain dogged by uncertainty over how the government will determine a fair subsidy for the multibillion-pound projects and whether the cost will be shouldered through household bills or by the Treasury. The government has promised more clarity after an industry consultation later this year.
Matthew Fell, the chief UK policy director at the CBI, said the strategy included important steps for the economy-wide hydrogen sector.
“However, to truly capitalise on those large-scale economic opportunities, and unlock the private sector finance needed, firms will now be looking for the government to provide detailed policies and standards for hydrogen production and application,” he said.
The hydrogen projects under development include “green hydrogen” schemes, which extract hydrogen from water, leaving only oxygen as a byproduct, and “blue hydrogen”, which extracts hydrogen from fossil fuel gas before trapping the greenhouse gas emissions that are left behind.
However, last week a study by academics at Cornell and Stanford universities in the US, warned that blue hydrogen could be up to 20% worse for the climate than fossil gas owing to the emissions that escape during its production, multiplied by the amount of gas required to make the equivalent amount of energy from hydrogen.
The government says it will set out emissions standards for blue hydrogen projects to ensure they capture enough greenhouse gas emissions during hydrogen production to qualify as “low carbon”, but many environmentalists and green energy producers have put pressure on the government to drop its support for blue hydrogen altogether.
The strategy paper does not set out a vision for the balance of blue and green hydrogen in the future, despite a clear instruction from its official climate advisers at the Committee on Climate Change (CCC) to include a pathway for each to 2035.
Doug Parr, the chief scientist for Greenpeace UK, warned that producing large quantities of hydrogen from fossil gas would lock the UK “into costly infrastructure that is expensive and … may be higher carbon than just burning the gas”.
Dan McGrail, the chief executive of RenewableUK, said the national strategy “doesn’t focus nearly enough on developing the UK’s world-leading green hydrogen industry” and should “set out a clear ambition for green hydrogen”.
“We’re urging the government to set a target of 5GW of renewable hydrogen electrolyser capacity by 2030 as well as setting out a roadmap to get us there, to show greater leadership on tackling climate change,” he said.