Hydrogen: The Swiss Army Knife of energy sources
A whole suite of technologies is needed to decarbonise the planet and achieve the goals of the 2015 Paris Accord. Hydrogen is the most abundant molecule in the world and is emerging as an important energy solution. The chemical element will aid individual countries in their bid to achieve net zero emissions by 2050. Hydrogen contains no carbon and is one of the few large, long-term energy storage options.
Today, hydrogen is commonly used as a catalyst in oil refining, ammonia and methanol production. It has broad future applications as a clean energy source in transportation, heating, electricity generation and industry. Angel Wileman, manager of Thermofluids at Southwest Research Institute (SWRI) and a self-proclaimed hydrogen enthusiast, characterises hydrogen as the Swiss Army Knife of energy sources. It can do everything, although it might not always be the best option for the job, she says.
Wileman delivered the keynote address on the future of hydrogen entitled Hydrogen is Here. Are we ready? during the STLE Annual Meeting in Long Beach, California, U.S.A., from May 21-25, 2023. Wileman joined Southwest Research Institute (SwRI®) in San Antonio, Texas, U.S.A., in 2011 and is focused on researching alternative energy and trying to understand water resources and hydrogen.
Hydrogen emerged in the transportation sphere as early as 2005, with BMW undertaking limited production of the BMW Hydrogen 7 from 2005-2007. The German automobile manufacturer’s revolutionary vehicle burned hydrogen in the internal combustion engine (ICE). At the time, significant government funding was available, fuelling research efforts in material science and energy storage.
Almost as soon as it arrived, the hype around hydrogen was gone again. “It sort of faded into oblivion,” says Wileman. The thermal fluids system engineer attributed the near disappearance of hydrogen research to successful advancements in battery technology—which solved many energy storage challenges, and the perfection of hydraulic fracturing enabling access to vast natural gas resources. The United States went from not having enough natural gas to so much that it began exporting it.
The pendulum is swinging back to hydrogen again, says Wileman. The significant ramp-up in funding of hydrogen can be seen by comparing the U.S. Department of Energy’s (DOE) investment of USD280 million with last year’s announcement of around USD8 billion for hydrogen technology and infrastructure as part of the Bipartisan Infrastructure Law signed by U.S. President Joseph Biden. Most of the funding is directed into a regional network of “hydrogen hubs.”
The hydrogen hubs aim to overcome the difficulty of transporting hydrogen with the creation of centres for generating and using hydrogen in the same location. Applications to develop the hubs closed on April 7, 2023, with requests received from throughout the country—primarily around ports and industrial regions.
Wileman noted that the current approach to develop hydrogen does not follow a typical pattern of supply and demand. The government is investing in generation, end-use applications and infrastructure. This means that the entire spectrum of hydrogen is “ripe for research,” she says. The real demand driver is the need to decarbonise the economy, she says.
The clean combustion of hydrogen offers many benefits, but there are major technical challenges that need to be addressed. Hydrogen is a very energy-dense fuel by weight, but not by volume, and therefore needs to be stored at extremely high pressures of up to 10,000 pounds per square inch (psi), or 700 bar. This is a serious challenge, says Wileman. The physical characteristics also make it difficult to move around. Almost four times as much power is required to shift hydrogen via pipelines, she says.
Hydrogen “does not play nicely with materials,” says Wileman, with components sometimes cracking in the presence of hydrogen. Researchers are attempting to design equipment that can handle extremely high pressure. Efforts to advance sealing mechanisms and other technologies to make compression more reliable are ongoing.
SwRI designed a linear motor reciprocating compressor (LMRC) to compress hydrogen as a fuel source in hydrogen-powered cars. LMRC applies dynamic seals that are hermetically sealed to prevent leakage and allows increased compression efficiency. Wileman anticipates greater research into understanding the interaction of hydrogen with materials, wear patterns and lubricant requirements.
Vehicles powered by hydrogen still require significant lubrication. However, Wileman noted that hydrogen is an extremely dry fuel and can cause problems with friction and wear. The small molecules can also easily permeate materials. A further obstacle is that lubricants do not mix well with the by-product of hydrogen combustion, water, and further research is required in this area, she says.
Hydrogen is an explosive material and concern around safety is prevalent during hydrogen combustion. Wileman emphasised the need to watch for auto-ignition or pre-ignition and outlined the role of computational modelling in deploying hydrogen on a large scale—to understand the potential impacts of accidental explosion.
Cost is a significant barrier to the uptake of clean hydrogen. The DOE has established the Energy Earthshots Initiative to deliver more abundant, affordable and reliable clean energy solutions. The first initiative, announced on June 7, 2021, aims to reduce the cost of clean hydrogen by 80% by the end of the decade and to accelerate demand.
Green hydrogen is produced by running an electrical current across water to split it into H2 and O2. Hydrogen can also be produced via fossil fuels with natural gas using steam methane reforming and from coal gasification and oil. Currently, less than 1% of global hydrogen production comes from renewable energy sources, according to Paris, France-based International Energy Agency (IEA).
Trying to clean up this process is a key challenge for the industry, says Wileman. Methane pyrolysis is a promising new approach that involves the thermal breakdown of methane into hydrogen gas and solid carbon that can be used to make things like carbon fibre. Investigations into how to scale up this process are ongoing, she says.
It is generally acknowledged that hydrogen will be an important part of our decarbonisation journey. However, questions remain about exactly what role it will play. It is not a silver bullet, says Wileman. The reality is it will play a supporting role, with a smaller overall impact than behaviour change and reductions in demand, she says.
The DOE hydrogen roadmap indicates that 90% of hydrogen use in 2021 was refining related (ammonia, metals and chemicals). However, there is a slow transition to making synthetic fuels and upgrading biomass. The SwRI representative also highlighted immediate plans to blend up to 20% hydrogen into natural gas pipelines in some areas of California.
Wileman believes the best applications for hydrogen are in the hard-to-abate heavy-duty transportation and long-term energy storage sectors. While some forecasts suggest hydrogen fuel cell electric vehicles will become a USD40 billion market by 2030, as of April 2023 there were only 60 public hydrogen refuelling stations in the entire United States—59 in California and one in Hawaii.
Funding is important for advancing technology, but what really changes behaviour is regulation, says Wileman. The SWRI representative believes two recent regulations from the California Air Resources Board (CARB) will have a notable impact on hydrogen advancement in the U.S— the In-Use Locomotive Rule, passed on April 27, 2023, and the Advanced Clean Fleets rule, which was passed a day later.
The In-Use Locomotive Rule aims to reduce emissions from all switch, passenger, industrial and freight line haul locomotives, whereas the Advanced Clean Fleets Rule puts an end to combustion truck sales in California in 2036. Heavy-duty trucks account for 6% of the traffic on California roads but a quarter of greenhouse gas emissions. Trains are worse. One train produces more nitrous oxide and diesel particulate than 400 heavy-duty trucks, according to CARB.
Despite its application in California, the new regulation will have a significant knock-on impact for the rest of the U.S. Currently, 40% of imported goods arrive in California and are distributed to the rest of the U.S. Decarbonised trade routes from Los Angeles will start to filter throughout the entire country.
