Efforts to scale up the use of green hydrogen, made from renewable energy resources, have taken a major leap in 2020 on a wave of ambitious cross-sector policies and projects launched around the world, the latest of which is Canada's new national strategy unveiled Dec. 16.

But climate and clean energy advocates in North America and Europe, where the EU earlier this year set aggressive near-term targets for commercializing green hydrogen, are expressing deep concern over certain aspects of the gathering momentum around transforming the ubiquitous energy carrier, harnessed almost exclusively from fossil fuels today, into a clean energy enabler.

A series of reports, regulatory filings and blog posts in recent days from the Natural Resources Defense Council, Union of Concerned Scientists, Clean Energy Group, Friends of the Earth and other environmental organizations ranged from measured reality checks on the extent of hydrogen's role in decarbonizing the economy to allegations that deep-pocketed fossil-fuel interests are behind a concerted "greenwashing" campaign.

"Industry's hydrogen hype machine is in full swing," said a report released in December by Corporate Europe Observatory, Food & Water Action Europe and Re:Common. Based on their analysis of documents obtained through freedom of information rules, the groups claim a hydrogen lobby led by natural gas companies poured at least €59 million into a lobbying effort to steer Brussels toward directing its hydrogen strategy at fossil fuels as well as renewables.

As technology suppliers, oil majors, power and gas giants, and other hydrogen proponents seek to advance their mounting pipeline of projects, they likely will face more such skepticism and calls for deeper analysis of environmental benefits.

On the front lines

That is already happening in New York and California, which are seeking to transition their economies off fossil fuels before midcentury to fight climate change. In both states, hydrogen distrust spilled over into key regulatory proceedings in December.

In San Jose, Calif., city councilors on Dec. 15 voted unanimously to ban natural gas use in most new construction, becoming the largest U.S. municipality to adopt a citywide building electrification mandate. But an eleventh-hour exemption for facilities that use natural gas-powered fuel cells sparked backlash from environmentalists and forced a two-week delay in the ordinance's approval.

In defending the exemption, Bloom Energy Corp. representatives said the company endeavors to run its fuel cells on renewable natural gas and hydrogen. Supporters said green hydrogen can transform the gas grid into a large-scale renewable energy storage device. Environmentalists painted that assessment as overly optimistic, arguing that green hydrogen is not widely available today and noting the uncertainties over its impact on pipeline integrity and end-use equipment.

In New York, developer Danskammer Energy LLC came under attack for its proposed roughly 600-MW repowering of the Danskammer Energy Center in Newburgh, N.Y., a facility designed with hydrogen-compatible turbines from Mitsubishi Power Americas Inc., a subsidiary of Japan's Mitsubishi Heavy Industries Ltd., that would initially run on up to 30% hydrogen and 70% natural gas.

"This is essentially a standard fossil gas plant permit application using a smokescreen of a future technological utopia to justify its present construction of new fossil fuel infrastructure amidst a climate emergency," Food & Water Watch said in a Dec. 15 filing to the New York Public Service Commission, calling for denial of the application.

Danskammer is one of a host of recently pitched gas projects relying on Mitsubishi turbines that are intended to ultimately transition to 100% green hydrogen, once that technology becomes available. The turbine developer has additional hydrogen co-firing and storage projects in Utah, with Intermountain Power Agency and the Los Angeles Department of Water and Power, and Texas, with utility Entergy Corp.

Nitrogen oxide concerns

The Union of Concerned Scientists and Clean Energy Group are supportive of hydrogen fuel cells, long-duration hydrogen storage and using hydrogen to decarbonize sectors of the economy not easily addressed with renewable energy and electrification, such as steel and cement manufacturing and heavy transport. But both groups have flagged concerns about such hydrogen combustion projects because of dangerous nitrogen oxide, or NOx, emissions that occur even with green hydrogen.

While burning hydrogen is free of carbon-dioxide emissions, "an oft-overlooked fact is that unless dedicated NOx-mitigation research is advanced and combustion improvements made, hydrogen combustion may not be pollution free," Julie McNamara, a senior energy analyst at the Union of Concerned Scientists, wrote in a Dec. 9 blog post.

Paul Browning, CEO of Mitsubishi Power America, acknowledges there is work to be done to reduce NOx emissions but is optimistic the company can build on past success to establish hydrogen-burning power plants as critical components of decarbonization and reducing local pollution.

"We've used nearly 100% hydrogen in gas turbines in the past using older combustion technology that was not as low in emissions of pollutants like nitrogen oxide and carbon monoxide," Browning said in a recent interview. "But with the most recent combustion systems that are extremely low emission of those other pollutants, those right now are capable of using about 30% hydrogen. We're working on giving them the capability to use 100% hydrogen."

Nevertheless, Clean Energy Group, in a Dec. 14 blog post, floated the idea of a moratorium on permitting such projects, pending "independent public health studies" on the impacts of NOx emissions.

"The last thing serious climate proponents of hydrogen need is to trip over avoidable and potentially irreversible environmental problems with high profile, proof of concept demonstrations," the authors said. "That could tarnish and possibly hijack the more responsible, long-term hydrogen climate project, which is valuable and should be pursued."