If the world is to reach net-zero emissions, hydrogen will play a vital role, according to the landmark Intergovernmental Panel on Climate Change’s Mitigation of Climate Change report, which was signed off by all 193 governments at the UN earlier this week.
The enormous document, drafted by 83 scientists from around the world, essentially sets out a broad roadmap on how the world can decarbonise, with much of the attention from the global media focused on the report’s views on fossil fuels, direct-air carbon capture (DACC) and the need to peak emissions by 2050.
But within its 2,913 pages, the IPCC also explains how the world should use clean hydrogen — and the roles it should play in heating, transport, heavy industry and energy storage — as well as the significant challenges facing its production and use.
And its views may disappoint those bullish hydrogen advocates who believe H2 is needed in sectors such as heating and cars.
While it explains that H2 could theoretically be used for electricity generation, heat, transport, heavy industry and energy storage, it states that “future energy systems would not use hydrogen for all end uses”.
“They would use hydrogen to complement other energy carriers, mainly electricity, where hydrogen might have advantages.
“Hydrogen could provide long-term electricity storage to support high-penetration of intermittent renewables and could enable trading and storage of electricity between different regions to overcome seasonal or production capability differences.
“It could also be used in lieu of natural gas for peaking generation, provide process heat for industrial needs, or be used in the metal sector via direct reduction of iron ore. Clean hydrogen could be used as a feedstock in the production of various chemicals and synthetic hydrocarbons.
“Finally, hydrogen-based fuel cells could power vehicles. Recent advances in battery storage make electric vehicles the most attractive alternative for light-duty transport [ie, cars and vans]. However, fuel cell technology could complement electric vehicles in supporting the decarbonisation of heavy-duty transport segments (e.g., trucks, buses, ships, and trains).”
Products derived from clean hydrogen, such as ammonia and synthetic fuels, would probably also be needed to decarbonise shipping and aviation, it adds.
Many Western natural-gas companies, particularly distributors, are trying to argue that clean hydrogen will be pumped around existing gas grids and used to heat people’s homes, in the same way that gas boilers do today. But the IPCC is lukewarm on the idea.
“Electrification is is expected to be the dominant strategy in buildings as electricity is increasingly used for heating and for cooking,” it explains.
“Heat pumps are increasingly used in buildings and industry for heating and cooling. The ease of switching to electricity means that hydrogen is not expected to be a dominant pathway for buildings.
“Using electricity directly for heating, cooling and other building energy demand is more efficient than using hydrogen as a fuel, for example, in boilers or fuel cells. In addition, electricity distribution is already well developed in many regions compared to essentially non-existent hydrogen infrastructure, except for a few chemicals industry pipelines.”
Later on in the document, it says that while “converting gas grids to hydrogen might be an appealing option to decarbonise heat without putting additional stress on the electricity grids... the delivered cost of heat from hydrogen would be much higher than the cost of delivering heat from heat pumps, which could also be used for cooling”.
“Repurposing gas grids for pure hydrogen networks will also require system modifications such as replacement of piping and replacement of gas boilers and cooking appliances, a factor cost to be considered when developing hydrogen roadmaps for buildings.
“There are also safety and performance concerns with domestic hydrogen appliances. Over the period 1990-2019, hydrogen was not used in the building sector and scenarios assessed show a very modest role for hydrogen in buildings by 2050.”
The IPCC says that “batteries are currently a more attractive option that hydrogen and fuel cells for light-duty vehicles” and that H2 represents “the most expensive option for LDV [light-duty vehicles], mainly due to the currently higher purchase price of the vehicle itself”.
And while it adds that fuel cells could be become a viable technology for cars and vans in the coming years, “the issues regarging the extra energy involved in creating the hydrogen and its delivery to refuelling sites remain, however”.
“The levelized cost of hydrogen on a GJ [gigajoule] basis is lower than conventional fossil fuels, but higher than electricity.”
The report seems slightly keener on the use of hydrogen in trucking and rail, but is hardly bullish, pointing to cost and production challenges.
“In general terms, electrification tends to play the key role in land-based transport,” the study says, but adds: “Land-based, long-range, heavy-duty trucks can be decarbonised through battery-electric haulage (including the use of electric road systems), complemented by hydrogen- and biofuel-based fuels in some contexts.
“These same technologies and expanded use of available electric rail systems can support rail decarbonisation (medium confidence).”
But it states: “These technologies nevertheless face challenges regarding driving range, capital and operating costs, and infrastructure availability. In particular, fuel cell durability, high energy consumption, and costs continue to challenge the commercialisation of hydrogen-based fuel cell vehicles. Increased capacity for low-carbon hydrogen production would also be essential for hydrogen-based fuels to serve as an emissions reduction strategy (high confidence).
And the report later adds: “Improvements in fuel cell technologies are needed to make hydrogen-based transport economically viable.”
Shipping and aviation
The IPCC study — officially known as AR6 [Assessment Report Six] Climate Change 2022: Mitigation of Climate Change — points out that electrification is not a viable solution for decarbonising long-distance shipping or aviation, which instead requires “high energy density, low carbon fuels” that have not yet reached commercial scale.
“Decarbonisation options for shipping and aviation still require R&D, though advanced biofuels, ammonia, and synthetic fuels [derived from hydrogen, such as methanol, methane and petroleum] are emerging as viable options (medium confidence),” it states, adding that electrification could only play a niche role in aviation and shipping for short trips.
“Improvements to national and international governance structures would further enable the decarbonisation of shipping and aviation (medium confidence). Such improvements could include, for example, the implementation of stricter efficiency and carbon intensity standards for the sectors (medium confidence).”
Nevertheless, significant questions remain about the cost of cleaner shipping and aviation fuels, the report continues.
“It is not clear if and when the combined costs of obtaining necessary feedstocks and producing these fuels without fossil inputs will be less than continuing to use fossil fuels and managing the related carbon through, for example, CCS [carbon capture and storage] or CDR [carbon dioxide removal].”
While many hydrogen advocates have argued that H2 will be needed to provide high-temperature heat for heavy industry, the IPCC does not seem to agree.
“Industrial process heat demand, ranging from below 100°C to above 1000°C, can be met through a wide range of electrically powered technologies instead of using fuels... The main use of hydrogen and hydrogen carriers in industry is expected to be as feedstock (eg, for ammonia and organic chemicals) rather than for energy as industrial electrification increases,” the report says.
But later in the study, it states that options for industrial heat also include hydrogen, biofuels and CCS.
“Electrification is emerging as a key mitigation option for industry (high confidence). Using electricity directly, or indirectly via hydrogen from electrolysis for high temperature and chemical feedstock requirements, offers many options to reduce emissions. It also can provide substantial grid balancing services, for example through electrolysis and storage of hydrogen for chemical process use or demand response.”
Interestingly, the report also suggests that industrial production might be relocated to places with strong solar and wind resources.
“The geographical distribution of renewable resources has implications for industry (medium confidence). The potential for zero emission electricity and low-cost hydrogen from electrolysis powered by solar and wind, or hydrogen from other very low emission sources, may reshape where currently energy and emissions intensive basic materials production is located, how value chains are organized, trade patterns, and what gets transported in international shipping.
“Regions with bountiful solar and wind resources, or low fugitive CH4 [methane] co-located with CCS geology, may become exporters of hydrogen or hydrogen carriers such as methanol and ammonia, or home to the production of iron and steel, organic platform chemicals, and other energy intensive basic materials.”
Hydrogen and its derivatives could be useful for seasonal electricity storage — ie, H2 can be produced in the summer, stored for months and then converted back into electricity for use in cold winter months — the IPCC states.
“Hydrogen may prove valuable to improve the resilience of electricity systems with high penetration of variable renewable electricity. Flexible hydrogen electrolysis, hydrogen power plants and long-duration hydrogen storage may all improve resilience,” the report explains.
It does, however, point out that a “significant amount” would be needed “due to the low roundtrip efficiency of converting electricity to fuel and back again”.
“Electricity-to-hydrogen-to-electricity round-trip efficiencies are projected to reach up to 50% by 2030,” the study says.
The IPCC paper explains that while “low- or zero-carbon produced hydrogen...” — ie, green and blue H2 — “is likely to have a significant role in future energy systems, due to its wide-range of applications (high confidence)”, it is currently not cost-competitive for large-scale applications.
“Key challenges for hydrogen are: (a) cost-effective low/zero carbon production, (b) delivery infrastructure cost, (c) land area (ie, ‘footprint’) requirements of hydrogen pipelines, compressor stations, and other infrastructure, (d) challenges in using existing pipeline infrastructure, (e) maintaining hydrogen purity, (e) minimizing hydrogen leakage, and (f) the cost and performance of end-uses. Furthermore, it is necessary to consider the public perception and social acceptance of hydrogen technologies and their related infrastructure requirements.”
Later in the report, it states: “The potential role of hydrogen in future energy systems depends on more than just production methods and costs. For some applications, the competitiveness of hydrogen also depends on the availability of the infrastructure needed to transport and deliver it at relevant scales.
“Transporting hydrogen through existing gas pipelines is generally not feasible without changes to the infrastructure itself. Existing physical barriers, such as steel embrittlement and degradation of seals, reinforcements in compressor stations, and valves, require retrofitting during the conversion to H2 distribution or new H2 dedicated pipelines to be constructed.”
It continues: “About three times as much compressed hydrogen by volume is required to supply the same amount of energy as natural gas. Security of supply is therefore more challenging in hydrogen networks than in natural gas networks.
“There are also safety concerns associated with the flammability and storage of hydrogen which will need to be considered.”
However, the report adds: “The capacity to leverage and convert existing gas infrastructure to transport hydrogen will vary regionally, but in many cases could be the most economically viable pathway.”
Electricity more efficient
The IPCC’s opinions on the use of hydrogen can be summed up in the following statement from the report:
“As a general rule, and across all sectors, it is more efficient to use electricity directly and avoid the progressively larger conversion losses from producing hydrogen, ammonia, or constructed [ie, synthetic] low GHG [greenhouse gas] hydrocarbons. What hydrogen does do, however, is add time and space option value to electricity produced using variable clean sources, for use as hydrogen, as stored future electricity via a fuel cell or turbine, or as an industrial feedstock.”
And it is worth pointing out that, of course, hydrogen will play a relatively small role in the overall race to net zero emissions.
“Net Zero energy systems will share common characteristics, but the approach in every country will depend on national circumstances,” the IPCC states.
“Common characteristics of net zero energy systems will include: (1) electricity systems that produce no net CO2 or remove CO2 from the atmosphere; (2) widespread electrification of end uses, including light-duty transport, space heating, and cooking; (3) substantially lower use of fossil fuels than today (4) use of alternative energy carriers such as hydrogen, bioenergy, and ammonia to substitute for fossil fuels in sectors less amenable to electrification; (5) more efficient use of energy than today; (6) greater energy system integration across regions and across components of the energy system; and (7) use of CO2 removal (e.g., DACCS, BECCS [bioenergy with carbon capture and storage]) to offset any residual emissions. (high confidence).”