Hydrogen’s role in a net-zero world
Depending on who you listen to, hydrogen is the answer to the question of a sustainable future. Yet, as is often the case with such major questions, the issues around hydrogen are not simple. Here we dig into the evidence to discover the role that hydrogen has to play in facing the greatest challenge of a generation.
Hydrogen is the most abundant element in the universe, estimated to make up 75 per cent of all matter. With an atomic number of one, it is a colourless and odourless gas that is highly flammable. On Earth, it only exists when combined with other elements, notably as water (H2O), with two molecules of hydrogen bonded to one of oxygen.
According to the hype, hydrogen is going to be a central element of a future sustainable world. As countries and corporations race to slash their emissions, many new announcements in the hydrogen field are being made, and the picture is continuously updating. However, when examined closely the advantages of hydrogen are not so straightforward. An important issue is the sequence of energy inefficiencies and losses that are necessary before hydrogen can be burned as a fuel.
Interestingly, most of today’s hydrogen production is as a feedstock for industrial processes, often in oil refining, to make ammonia for fertiliser manufacture and to produce methanol. A small but growing proportion is being produced for use as an energy source.
Fossil fuel versus renewable
Today, hydrogen can be made from gas, coal, oil, renewables or nuclear. It is bound up with energy politics, and the pivotal issue of whether fossil fuels can have a future in a net-zero emissions world. This involves blue hydrogen, a name for combining fossil-fuel-produced hydrogen with carbon capture and storage (CCS) to bury CO2 emissions underground. Hydrogen could offer the fossil fuel sector a lifeline into the future, where it can disguise the dirty origin of what sounds like a clean product.
At present, about 95 per cent of the world’s hydrogen is made from coal or gas without any underground sequestration. According to the master plan, this “grey” hydrogen is going to be rapidly replaced with the blue variety. The other big player in terms of new investment is green hydrogen from renewables via electrolysis. Hydrogen CCS is expensive, and largely unproven, with only two known examples, in Alberta (Canada) and Texas.
Another potentially useful technique under development is turquoise hydrogen, from the pyrolysis (heating in an atmosphere without oxygen) of methane, which produces no waste products other than solid carbon. It requires several times less electricity than both electrolysis and conventional gas-sourced production. Here the gas is used as an industrial feedstock rather than an energy source.
On the downside, gas is a non-renewable resource, and gas production is associated with fugitive methane emissions that contribute to climate change. This can be avoided by using as a feedstock renewable-sourced biogas from methane digesters, preventing it from becoming a polluting greenhouse gas. A number of hydrogen biogas projects are in the pipeline.
A 2021 study in Energy Science & Engineering raises some serious questions about blue hydrogen, which was found, on a lifecycle basis, to be associated with only 9–12 per cent lower CO2 emissions than for grey hydrogen. For the heat produced, blue hydrogen caused 20 per cent higher greenhouse emissions than burning natural gas or coal for heat, and 60 per cent more than diesel oil. From a climate perspective the world would be far better off burning diesel than blue hydrogen, which is sometimes erroneously described as being carbon-neutral.
Five days after this study was published, Chris Jackson, the head of the UK Hydrogen and Fuel Cell Association, resigned, saying that he felt the country was heading down the wrong track with blue hydrogen. Despite this, the hype of blue hydrogen has not abated, and it remains an energy focus for the USA and the UK.
Electrolysis and green hydrogen
Electrolysis can be achieved via either nuclear power or renewables. Given nuclear’s inability to be competitive on cost, it is unsurprising that nearly all future plans for hydrogen electrolysis involve renewables. Yet renewable-generated hydrogen has some challenges.
• It currently makes up only a tiny percentage (about 1 per cent) of total production, although this number is growing fast.
• Nine litres of water, fresh or salt, are required for every kilogram of hydrogen produced.
• Green hydrogen is currently two to three times more expensive to produce than blue. However, the price of green hydrogen is dropping as a result of the falling cost of renewables and small improvements in electrolysis efficiency. There are hopes to bring down the price to about US$2 a kilo by 2030.
At the time of writing, new green hydrogen plants are on the drawing board around the world.
Hydrogen versus electricity
For domestic purposes, hydrogen is less cost-effective than electricity from renewables. Better options for heating water are solar hot water or solar photovoltaic, or an electric heat pump in less sunny climates. Because the heat pump is five to six times more efficient than a hydrogen boiler, using hydrogen in its place would multiply severalfold the quantity of renewable generation needed to heat water.
The choice between hydrogen and electricity for domestic purposes will have ramifications. If there is a finite supply of renewable energy, then hydrogen production and electricity will be in competition with one another as usable end products. For hydrogen production and supply, cumulative inefficiencies from each stage of the process add up, making it less desirable than electricity when the two are compared side by side.
Because electricity is a more efficient use of energy than green hydrogen, it makes sense to largely restrict hydrogen to niche uses where electrification is difficult or unfeasible. This points to a select number of industries including steel, cement, aluminium and shipping. Where there are gaps in grid electricity from battery-backed renewables, hydrogen can provide “dispatchable” power.
Investing in a hydrogen-compatible gas grid could block the path towards full electrification, and consumers would have no say over which type of hydrogen is used. However, the speed of the shift towards electrification and spreading bans on gas connections in new homes could stop hydrogen infrastructure from dominating. Predictably, the hydrogen lobby is pushing for the fuel to be expanded in areas where it is not the most efficient option.
Australian Gas Infrastructure Group (AGIG) is already adding 5 per cent green hydrogen to gas supplying new homes in the Adelaide suburb of Tonsley Park. Up to 20 per cent hydrogen can be safely injected into the existing gas grid. Future infrastructure upgrades will be expensive, with pipeline compressors needing replacement above 40 per cent hydrogen, and further network upgrades to reach 100 per cent. For existing gas pipes to be made hydrogen-compatible, they will need to be entirely replaced by polyethylene pipes, given that hydrogen makes steel pipes brittle.
Cars and transportation
While hydrogen is not the most efficient renewable fuel for powering cars, there are some benefits from using it in large trucks. To be electrified, these vehicles need large and heavy expensive batteries.
Some considerations for hydrogen cars are:
• A rough calculation in an article published by The Conversation added up losses through every stage from electrolysis to putting the vehicle in motion, and found that green hydrogen was about 38 per cent efficient. In comparison, battery-electric cars achieve a figure of about 80 per cent.
• Unlike electric cars that are pollution-free at the point of use, hydrogen does emit some pollution in the form of nitrogen oxides (NOx). This is a consideration for cities such as Delhi whose smog problems are worsened by NOx.
• Hydrogen would be an option worth considering if the vast quantity of minerals needed to make billions of electric vehicle (EV) batteries cannot be sourced without massive ecological damage.
• While hydrogen currently offers a longer range than the average EV, it is likely to be overtaken.
• There is a very limited number of refuelling stations worldwide, and no hydrogen vehicles are available to consumers in Australia and New Zealand at the time of writing.
Globally, hydrogen-powered buses and trains are becoming more common.
Hydrogen in Australia
Australia’s hydrogen strategy is technology-neutral, which means that government funding could support either the blue or green variety, or another type. Currently most of the investment is going into green hydrogen, and much of this is due to the energetic efforts of Australian mining billionaire Andrew Forrest. His ambition includes plans to set up a global green hydrogen empire in numerous different countries. In September 2021, he launched GH2, a global green hydrogen organisation with offices in Australia and Europe.
As things currently stand:
• There are plans for a number of large-scale hydrogen hubs around the country, largely in existing industrially oriented regions such as Gladstone, the Hunter and the Pilbara.
• Concerns have been raised over a proposed wood-fired hydrogen and biochar plant in the Hunter region, based on the gasification of woodchips sourced from native forests. Gasification, like its sister process pyrolysis, is promoted as cheaper and more energy-efficient than electrolysis, which is its main competition.
• Government moves to modify the role of the Australian Renewable Energy Agency (ARENA) to allow it to fund blue hydrogen projects were blocked in the Senate. These projects have been misleadingly described as “clean” in government circles.
• The Australian Hydrogen Centre has been established in South Australia, chosen due to that state being a renewables leader, especially with wind power.
• AGIG has a plan to make 100 per cent hydrogen available to new housing developments from 2025.
Australia is the world’s largest natural gas exporter, and has an ambitious vision for establishing a comparable hydrogen industry. This will involve hydrogen being compressed to a liquid, chilled and transported in huge ships. Inevitably, this energy-intensive process represents an efficiency loss. If the countries purchasing hydrogen were to restrict it to niche uses, perhaps they could produce modest quantities domestically from renewables rather than relying on long-distance imports.
Ammonia is a very energy-intensive chemical to produce, and chemical engineer Rose Amal at the University of New South Wales is looking at green renewable ammonia, which paradoxically stores more hydrogen than liquid hydrogen itself. Another important advantage is that, compared to hydrogen, it requires only a fraction of the energy to keep chilled while being exported.
New Zealand developments
New Zealand’s government meanwhile favours green hydrogen. The New Zealand Hydrogen Association, made up of private and public sector organisations, is focused on “low-emission” hydrogen. Another group is the Germany–New Zealand Green Hydrogen Alliance, a research-focused partnership between the two countries.
First gas Group has plans to blend hydrogen into the existing North Island gas grid from 2030, and to convert the national gas network to 100 per cent hydrogen, starting in 2035 and completing by 2050. This will involve 15 North Island production hubs; likely sites include Palmerston North and New Plymouth.
On the fringe
The notion that vehicles could run on water is generally considered unscientific nonsense, due to the fact that conventional electrolysis requires a greater energy input than it yields as an output. However, a couple of inventors claimed to have transcended this limitation.
One of these was Stan Meyer in Ohio, who built a water-injected dune buggy that was reported to have used an unusual form of electrolysis. He died very suddenly in 1998 during a restaurant meal, just after reportedly lining up funding for a US$50 million research centre. Despite the negative evaluation of his work on sites such as Wikipedia, contemporary coverage during his active period tended to be favourable.
Another American, Andrija Puharich, stated that he drove around the States in a motor home during the 1970s, using water as a fuel. The invention that enabled him to do this was called a “thermodynamic device”. The concept behind it was to break the hydrogen–oxygen bonds using electrical waveforms, and using resonance in place of electrolysis. He left behind a scientific document outlining his invention, available online, where he claimed that the most effective frequency for water dissociation was 600Hz.
If such technology works and were to be deployed, then it would greatly reduce the expense of running vehicles without fossil fuels, and would simplify the associated technological complexities and hurdles. However, it would also challenge multiple vested interests, while offering a negligible contribution to GDP figures.
Hopefully the direction taken in deciding where to deploy hydrogen, and where renewables make more sense, will be guided by environmental common sense and not by economic interests.
GH2 (green hydrogen) gh2.eu.
New Zealand Hydrogen Association nzhydrogen.org.
Martin Oliver is a writer and researcher based in Lismore.