Hydrogen Could Have Much Bigger Climate Impact Than Most Estimates, Study Shows

Standard frameworks used to assess the climate impacts of hydrogen production are vulnerable to broad miscalculation, according to new research by scientists at Environmental Defense Fund. As governments, investors, and industry look to hydrogen to help meet climate goals, the researchers say it is critical to get this accounting right.  

Published today in the journal Environmental Science & Technology, the study shows that the most widely used lifecycle assessment frameworks fail to include three critical factors: 1) the warming effects of hydrogen emissions; 2) measured real-world methane emissions intensities; and 3) the near-term warming impacts of emissions.

To more accurately gauge the potential impacts of hydrogen deployment, EDF reanalyzed a previous lifecycle assessment of hydrogen. They found that when these factors are included, hydrogen systems could be considerably better or worse for the climate than the fossil fuel technologies they are replacing.  If hydrogen and upstream methane emissions are high, blue hydrogen pathways (natural gas with carbon capture) could actually increase near-term warming by up to 50% compared to fossil fuels. By contrast, if those emissions are low, it could decrease warming impacts by over 70%. For green hydrogen pathways (renewable-based electrolysis), high hydrogen emissions can reduce the climate benefits in the near-term by up to 25%.

“It’s important to get the emissions accounting right, both to accurately assess climate impacts of hydrogen systems and to identify opportunities to reduce them,” said EDF climate scientist and lead author Tianyi Sun. “When we consider all climate warming emissions and their impacts over the near- and long-term, our analysis shows that hydrogen deployment can have far greater impacts than expected.”

Furthermore, the new analysis demonstrates how other factors such as lack of renewable electricity resources or insufficient carbon capture rates could further reduce anticipated climate benefits of hydrogen deployment. Consistent with other studies, the EDF analysis found that adding renewable electricity to local systems is necessary to help ensure the climate benefits of green hydrogen development. Otherwise, renewable electricity used to produce green hydrogen is likely replaced by natural gas or coal, resulting in full elimination of intended climate benefits to 3 times increase in emissions at the system level.

With respect to carbon capture rates for blue hydrogen, the previous assessment uses 98%, a rate which has not yet been consistently achieved. When applying a lower rate of 60%, the climate benefits of blue hydrogen pathways are reduced by 15-50% in the near-term, and 20-60% in the long-term.

“As we build out the hydrogen economy, we have a very real opportunity to ensure the enormous investments in hydrogen projects worldwide yield the climate benefits being sought – and avoid unintended climate consequences. We need robust assessment methods and data to ensure the potential is achieved in practice,” said Ilissa Ocko, EDF Senior Climate Scientist.

“Important decisions are being made about future clean energy systems, with implications for decades to come,” said Steven Hamburg, EDF Chief Scientist. “Hydrogen can be an effective decarbonization tool in many cases, but only if we ensure that its climate impacts are kept to a minimum. This requires upping our game on emissions accounting of climate impacting gases including hydrogen itself.”  

To help advance the science and identify best practices to maximize the benefits of hydrogen systems, EDF is working with new sensor technology by Aerodyne Research and industry partners to begin to measure real-life emissions from hydrogen facilities. As the market becomes more aware of the need to measure and mitigate emissions along the value chain, this technology will play a key role in providing better understanding, and ultimately solutions, to the hydrogen emissions challenge.

To read the full paper, see Environmental Science & Technology.