Green Hydrogen

Learn about green hydrogen and its benefits. For a colorless gas, hydrogen is often described with a range of hues: black, grey, pink, red, blue, and green – each referring to how the gas is produced. Green hydrogen is made through a process called electrolysis, which consists of running electricity through a liquid, such as water, to trigger a chemical reaction, in this case, splitting H₂O molecules into streams of hydrogen and oxygen gas. ‘Green’ indicates that renewable energy sources power the electrolysis. This contrasts with the most common ‘colors’ of hydrogen – grey, brown, and black – which generate large amounts of greenhouse gases from the quantity of energy needed to strip hydrogen off of natural gas (grey hydrogen) or coal (brown or black hydrogen) as well as the carbon dioxide released as a byproduct. Pink and red hydrogen are produced by nuclear energy. A green hydrogen economy can help us achieve climate and energy goals. Benefits include: 

• Hydrogen can be used in place of natural gas. It burns in the presence of oxygen and thus can create the high temperatures needed for industrial processes, such as cement production, which generally uses natural gas. Hydrogen is more efficient than natural gas at generating electricity since the electrolysis process can be reversed with a hydrogen fuel cell rather than burning it. The only byproduct is water. 
• Green hydrogen can be a form of energy storage. Surplus wind and solar power can be used to make hydrogen that is subsequently ‘banked’ for use later or in a location that renewable energy sources can’t reach. 
• Since the green hydrogen energy is captured in a stable chemical bond, it can be stored in tanks or possibly in large underground formations.
• Green hydrogen is a crucial ingredient for making ammonia, an important chemical feedstock and refrigerant. It is also widely used as a fertilizer. Ammonia production demands more energy than any other chemical reaction and is responsible for 1 percent of humanity’s total greenhouse gas emissions. While much of the ammonia produced for agriculture could be reduced or replaced through regenerative agricultural practices (see Regenerative Agriculture Nexus), green hydrogen can meet the remaining ammonia demand. The production of green ammonia can be widely distributed, reducing dependencies on autocratic countries and allowing rural communities to produce their ammonia and keep the proceeds in their local economy.
• Steel production has traditionally required coal (or charcoal) to strip the oxygen out of iron ore, a process that generates about 2 percent of all global carbon dioxide emissions. Using green hydrogen instead could eliminate these emissions. 
• Green hydrogen can run hydrogen fuel cells, which create electricity by letting hydrogen and oxygen react with each other rather than through the heat of combustion. Hydrogen fuel cell passenger vehicles are commercially available, though they have not gained as much market penetration as battery-electric vehicles, partly due to the relative ease of building out EV charging infrastructure compared to a system of hydrogen refueling stations.
• A promising use of green hydrogen for transportation may be in long-haul trucking, shipping, and air travel, which either don’t require extensive systems of refueling stations and/or where the bulkiness of hydrogen gas tanks can be easily accommodated. Hydrogen-powered cruise ships and airplanes are being developed, and thousands of hydrogen-powered buses are operating.
• Water is the only byproduct when green hydrogen is used in fuel cells.
• Hydrogen can be turned into various fuels and chemical products by combining it with carbon dioxide, though increasing the efficiency and control of those reactions is an area of ongoing research.
• Green hydrogen could be ideal for industries that can’t be electrified and where green hydrogen can lead to 70-80 percent decarbonization.
• Two other low-carbon types of hydrogen are pink and red hydrogen, which utilize nuclear energy. Pink hydrogen is produced by the electrolysis of water using energy from a nuclear power plant, whose high temperatures considerably improve the efficiency of the process. It could replace fossil fuels in sectors of the economy that are hard to decarbonize, such as cement, steel industry, and aviation industries, as well as heavy transportation. Red hydrogen is generated by using the intense heat from nuclear reactions to split water catalytically. While pink and red hydrogen generate almost no greenhouse gases, their reliance on nuclear energy means significant safety and radioactive waste challenges must be addressed.

Learn about the hurdles facing the adoption of green hydrogen. The biggest challenge for green hydrogen is cost, which was several times higher than the cost of grey hydrogen for a long time. As the cost of renewable energy drops and the scale of electrolyzer production increases, the threshold of $2/kg of hydrogen is approaching; at this point, green hydrogen will be cost-competitive, not just with fossil fuel-derived hydrogen but with fossil fuels in general.

• Black, brown, and grey hydrogen are derived from coal, lignite (‘brown coal’), and natural gas/oil refining, and together made up more than 98 percent of the global hydrogen market in 2018. These types of hydrogen are relatively cheap since it does not factor in the cost of its associated greenhouse gas emissions.
• Another hurdle for green hydrogen is blue hydrogen, which is grey, black, or brown hydrogen paired with carbon capture technology – technology that is not yet widely available and faces multiple challenges. When factoring in methane leakage and inefficiencies of production, distribution, and utilization, blue hydrogen is estimated to be 20 percent more polluting than using natural gas directly. That has not stopped the fossil fuel industry from stalling investments in green hydrogen infrastructure by lobbying for equal subsidies for blue hydrogen projects.
• Another challenge is defining what counts as ‘green hydrogen.’ While hydrogen from an electrolyzer hooked up to solar panels or wind turbines is clearly green, it’s less clear where facilities are connected to a regional electric grid with a mix of renewable and fossil fuel sources. This is a timely question in the United States, given the soon-to-be-available Clean Hydrogen Production Tax Credit and the recent finding that ‘green’ hydrogen made by typical grid electricity can be worse for the climate than natural gas.
• Platinum and other rare metals are needed to build one of the most common electrolyzers for creating green hydrogen, along with most fuel cells used to turn hydrogen into usable electricity. As with most renewable technologies, mining these critical minerals may have to increase until alternatives can be found. In addition to adverse environmental impact, this could lead to stubbornly high prices for green hydrogen, particularly if production scales beyond the availability of proven platinum reserves. A recent breakthrough may have found an alternative using non-precious metals.
• Although hydrogen isn’t a greenhouse gas, when it leaks into the atmosphere, it increases the longevity of methane, which is more than 100 times as potent as carbon dioxide. As a result, leaked hydrogen could substantially contribute to short-term global heating. This makes careful storage of hydrogen a critical priority.
• Hydrogen storage is tricky, partly because hydrogen is the smallest molecule in the universe. It can leak out of welds. It can also cause embrittlement of many common types of steel, increasing the likelihood of leaks. While hydrogen has an incredibly high energy density per unit weight, it is so light that it must be stored at high pressures for a given volume of hydrogen gas to have the same amount of energy as natural gas. As a result, expensive tanks, often with special plastic lining or thicker steel, must be used. With underground storage, especially in salt domes, it may be possible to store enormous amounts of hydrogen without leaking or contamination, but it requires special geologic conditions and does not help with storage in vehicles.
• Embrittlement and weld leakage, along with a variety of other issues, means that it is unlikely for existing natural gas infrastructure to be repurposed for green hydrogen without extensive retrofitting. 
• Leaking hydrogen can also create safety hazards since it can burn in the presence of oxygen. Even relatively slow leaks can lead to dangerous buildups of hydrogen gas in enclosed spaces.
• When combusted in air rather than used in fuel cells, hydrogen produces small amounts of nitrogen oxide (NOx) pollution, similar to burning natural gas. The technology to overcome this issue is expensive, so policy changes may be required to manage pollution from hydrogen combustion, particularly if it becomes widely used as a heat source for industrial processes.

Support organizations advocating for green hydrogen. The groundswell of interest recently in green hydrogen means that many projects and groups could use support.

• With more than 250 GW of green hydrogen projects in the pipeline, you may be closer than you think to a project that could use your local support or advocacy. The Hydrogen Map can help you find a green hydrogen project near you.
• The Green Hydrogen Catapult is an initiative launched through the leadership of the Rocky Mountain Institute and the backing of the United Nations.
• The NW Renewable Hydrogen Conference offers a way for green hydrogen advocates to learn more and engage directly with industry leaders.
• H2 Energy News is a clearinghouse of the latest news about global green hydrogen.

Produce green hydrogen, not grey or blue hydrogen. From 1990 to 2018, demand for hydrogen roughly doubled. The hydrogen industry must commit to replacing 100 percent of retiring grey hydrogen infrastructure with green hydrogen generation.

• In Europe, HyDeal Ambition is working to link 95 gigawatts (GW) of solar panels to 67 GW of electrolyzers to generate 3.6 million tonnes of green hydrogen annually by 2030.
• In Kazakhstan, Kazakh Invest has teamed up with Germany-based Svevind Energy to create Reckaz, an endeavor to produce 3 million tonnes a year of green hydrogen using 45 GW of solar and wind installations by 2028.
• Plug Power Inc. in Finland is installing 2.2 GW of electrolyzer capacity to produce green hydrogen to create sustainable ammonia and steel. Part of this work will involve repurposing an old coal plant.
• A subsidiary of the large, multinational corporation Heidelberg Materials is working with Swansea University in the United Kingdom to build a clean cement demonstration plant that could help establish a viable path forward to reduce the stubborn emissions from the cement industry.

Partner with scientists to commercialize novel green hydrogen products. The breadth of uses of green hydrogen means many emerging discoveries must be made from the lab to the marketplace.

• A pair of Harvard scientists have developed bacteria that produce bioplastic feedstocks when fed carbon dioxide and hydrogen. They are actively looking for industry partners.
• Scientists from Monash University found a way to create green hydrogen and split inert nitrogen from the air simultaneously, thereby producing green ammonia at room temperature. They are now looking to commercialize this insight through the spin-off company Jupiter Ionics.

Retrofit smaller airplanes to run on hydrogen. While engineering breakthroughs will be required to transform long-haul flights to run on green hydrogen, we are on the cusp of seeing smaller regional flights shifting to hydrogen power via retrofitted fixed-wing propeller aircraft.

• A partnership between Icelandair and Universal Hydrogen has positioned the former as the first airline in the world to offer all-hydrogen-powered domestic aviation.
• In Alaska, North Pacific Airways (trade name: Ravn Alaska) placed an order for 30 of ZeroAvia’s ZA2000 powertrains, aiming to retrofit its fleet of De Havilland Dash-8 for zero-emission operations. Ravn is the primary airline servicing several remote, majority-Alaska Native communities that could begin producing green hydrogen locally to alleviate the burden of high-cost aviation fuel.

Research ways of using green hydrogen. More research is needed on how to make use of green hydrogen in a variety of sectors. Shipping and aviation will find it hard to decarbonize sectors without green hydrogen. However, there are still basic questions about optimizing certain types of hydrogen-powered vehicles for safety, efficiency, and affordability. Particularly important are hydrogen-powered semi-trucks, ocean-going vessels, and airplanes. 

• Rather than changing our vehicles to run on green hydrogen, we can convert hydrogen into electrofuels or eFuels, which are liquid fuels made from green hydrogen and carbon dioxide and can be used like traditional kerosene and diesel in planes, ships, and trucks. However, more research is needed on how to produce them efficiently, cheaply, and at scale.

Research new ways of green hydrogen production. Further investigation is needed into the optimal methods of turning green energy into hydrogen. Finding ways to create cheaper electrolyzers is one significant research need, but there are questions about whether electrolysis is the best method. Other methods in need of deeper investigation include thermochemical water splitting and photobiological and photoelectrochemical hydrogen production.

• An international team of scientists recently published their findings on a breakthrough setup that achieved a 9 percent efficiency, directly converting sunlight into hydrogen gas. 

Investigate hydrogen leakage. There are safety and climate concerns surrounding the leakage of hydrogen from infrastructure and vehicles. Leakage must be kept below 9 percent for green hydrogen to be a climate solution rather than a net accelerator of climate change. This has led to calls from scientists for efforts to prevent, detect, and fix hydrogen leaks from our infrastructure.

Use green hydrogen for energy storage and load management. Green hydrogen production can take excess renewable energy from intermittent sources and turn it into electricity when those sources are not available. Facilities are now coming online that use only solar panels, green hydrogen, and batteries to produce consistent reliable power output. The ability of electrolyzers to turn on and off with relative ease means that these facilities could be good candidates for interruptible service contracts. This can keep the cost of electricity low by allowing utilities to shut off power to certain users during intervals of spiking demand rather than paying for costly ‘peaker plants’.

• Green hydrogen could be a viable means of long-term energy storage, thereby allowing high levels of intermittent renewable energy sources like solar and wind. This is a key enabler of the goals of the movement to electrify everything (see Energy Storage Nexus and Electrify Everything Nexus).

Invest in distributed green hydrogen production. Many smaller communities will likely be early adopters of sustainable aviation as smaller retrofitted propeller planes start being used for the first hydrogen-powered commercial flights in the coming years. Producing green hydrogen locally can turn aviation fuel from a significant drain on rural economies to a new source of revenue while also reducing emissions. This could be particularly valuable for off-grid communities across the Arctic and the Global South.

• Enapter, a company with offices in Germany, Italy, and Thailand, produces small, modular electrolyzers that can produce green hydrogen even at small scales. 
• SilPac sells 1 MW-scale electrolyzer systems designed to fit in Conex shipping containers that could be efficient turn-key solutions to generating green hydrogen to meet aviation needs in small remote communities.

Replace ammonia with green ammonia as a stepping stone to regenerative agriculture. Ammonia is a common nitrogen fertilizer or ingredient in mineral fertilizers. While truly regenerative agriculture may not require chemical fertilizers, converting existing operations may require time. Green ammonia made from green hydrogen and renewable energy sources is starting to hit the market in some regions and could provide a medium-term solution for reducing a farm’s climate impact. The growth of this market is projected to increase by more than 70 percent per year between 2023 and 2030.

• It is possible to produce your own green ammonia fertilizer with small modular devices developed by Jupiter Ionics.