Clean Energy Group Warns Of High NOx From Hydrogen Gas Combustion

December 18, 2020

The Clean Energy Group (CEG), a nonprofit advocacy organization, is warning that hydrogen (H2) energy widely touted as a carbon-free source that can be used to limit greenhouse gases (GHG) could create “dangerously high” nitrogen oxide (NOx) levels if blended with natural gas and combusted for power generation.

With power companies requesting approval for a number of blended H2 and natural gas projects, CEG is suggesting that a moratorium might be necessary on permitting any project that proposes to blend and combust H2 with natural gas in any existing or new power plant because of the concerns about NOx emissions.

In addition, President-elect Joe Biden’s administration might want to examine the serious concerns about H2-related NOx that are being raised by environmental justice (EJ) groups because so little is known about those emissions, says CEG President Lewis Milford in an exclusive interview with Environment Next. Biden on the presidential campaign trail touted the need to fully consider EJ in all federal decisionmaking.

Milford points out that major cities are proposing novel projects blending H2 and natural gas for energy production, and says that EJ groups want to know more about the NOx emissions’ levels and impacts. The issue is “entirely new” and has not yet received policymakers’ attention, Milford adds.

CEG’s concerns follow the Oct. 5 release of an industry-backed “Road Map to a U.S. Hydrogen Economy” with numerous references to blending hydrogen in natural gas networks. “Replacing or blending some natural gas with low-carbon hydrogen would lower GHG emissions of residential, commercial, and industrial heating, without new infrastructure deployment,” according to the road map.

The road map was released at an event hosted by the Fuel Cell & Hydrogen Energy Association (FCHEA), which represents companies and organizations that support fuel cells and hydrogen energy. FCHEA did not respond to a request for comment on CEG’s concerns about potential NOx spikes.

In a Dec. 14 blog post, “Hydrogen Hype in the Air,” CEG says, “It must be noted that burning H2 for power production has never been done before in this country. It is a novel, untested, and potentially problematic environmental experiment that could play out in American cities."

To provide context for CEG’s involvement with the H2-NOx issue, Milford point out that the group has focused a lot in recent years on solar combined with storage as a potential energy source to replace fossil fuel plants, especially fossil fuel “peaker plants” that are used to keep electricity flowing when demand increases or “peaks” and that often are located in poorer urban communities. CEG worked with EJ communities on the issue, particularly in New York City, where plans have been proposed for a plant run on 100 percent H2 by 2040.

CEG’s blog post notes that NextEra Energy in Florida and Dominion in Virginia have released plans to begin inserting a 5 percent blend in some natural gas shipments beginning in 2021. And the Southern California Gas Co. and San Diego Gas & Electric have also announced plans to begin demonstration projects injecting a 5 percent blend into the natural gas grid starting next year, according to the blog post.

“These are real plans,” not just theoretical speculation about blending H2 with gas, Milford says. EJ advocates have asked CEG about H2, and “frankly it was new to us until just a few months ago,” he says.

CEG worked on H2 and fuel cells 15 years ago and was a strong supporter of the emissions-free technology because, at the time, solar and battery options were not available. But recently, seeing proposals to combust H2 with gas in power plants, CEG began raising questions about the scale, scope, and impact of such projects. At this stage, “a lot is unclear about the emissions impacts,” which will depend on how many projects are proposed and where, he says.

‘A Bit of a Red Flag’

Some science exists that suggests NOX emissions from H2 combustion are quite significant, Milford says. CEG is “raising a bit of a red flag,” or “flare,” about the issue so that policymakers, community groups, and others become familiar with the science, and the group is open to learning from industry if any of its concerns with H2 combustion are incorrect. “It’s important to get a public conversation going around this issue,” he says.

CEG references a Union of Concerned Scientists blog post that says “when hydrogen is combusted” as opposed to being used in a fuel cell “it can generate significant NOx emissions, commensurate with that of natural gas combustion -- or worse.” Without dedicated NOx-mitigation research and combustion improvements made, H2 combustion “may not be pollution free, unacceptably risking a further perpetuation of pollution harms.”

Even Mitsubishi, the developer of a new plant in Utah that will blend 30 percent H2 with 70 percent natural gas, said in a report that the mixture will produce NOx and carbon emissions “equivalent to those from modern natural gas plants,” Milford notes.

Community groups have seen little or no information about such plants, so as a “precautionary” measure CEG is calling for independent public health and air pollution studies to be done to obtain a full understanding of what the NOx potential could be from plants seeking permit approvals. The request comes in the context that most major U.S. cities are out of attainment under the Clean Air Act for NOx, it is a significant public health issue, and studies have linked NOx pollution with higher levels of COVID-related disease, Milford says.

“We would hope so,” Milford says about the possibility the H2 NOx issue would fall within EPA’s purview. “It’s something the incoming Biden administration might want to take a look at” for its potential public health and EJ impacts. EJ advocates have serious concerns about H2 projects that “seem to have come out of the blue,” he adds.

Blog post co-author Seth Mullendore, CEG’s Vice President and Project Manager, notes that in New York a proposal from the company Astoria Gas Turbine Power involving natural gas turbines for hundreds of megawatts of power are being developed to meet NOx emission limits in peaker plants that the old turbines cannot meet as the city aims to become 100 percent carbon-free by 2040. Astoria proposes to transition to H2 without any impact studies, raising concerns, Mullendore adds.

In a July 21 announcement, Japanese manufacturers Kawasaki Heavy Industries and Obayashi Corporation said that they had for the first time globally verified a 100 percent H2-fueled gas turbine with dry low-NOx combustion technology that performed more efficiently than conventional combustion technologies and with lower NOx emissions. -- David Clarke

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