Green hydrogen has the potential to decarbonize entire industries, but there’s a long way to go

(xh) Long road to green hydrogen in New Zealand

Hydrogen has been called the “Swiss Army Knife” of decarbonization because it can do so much. But not all of them make sense.

Today, the world uses about 100 megatons of hydrogen per year (MT/a), but it is almost entirely produced from fossil fuels. To use hydrogen for decarbonization, we must move to zero-emission forms.

Global forecasts for green hydrogen production from renewable sources vary widely, from today’s demand (100 tons per year) to an optimistic 700 tons per year by 2050. Bloomberg’s recent forecast for 2050 suggests a downward trend. Despite this, the transition of today’s demand to green hydrogen poses significant challenges.

In our research, we use the “clean hydrogen ladder” to sort and quantify the different uses of green hydrogen.

Hydrogen demand in New Zealand

Our research shows that New Zealand’s total green hydrogen requirement would be around 2.8 million tonnes per year if all technically feasible applications switched to hydrogen. If we prioritize the use of green hydrogen, which is the only decarbonization option, the demand will be up to 1 million tons per year.

Fertilizers and methanol are at the top of the list. They are considered “inevitable” because there are no other alternatives to decarbonization. Together they will require about 0.2 million tons per year.

Next on the list are things like shipping and jet fuel (via hydrogen-based synthetic fuels), steel production and long-term grid storage. This could add another 0.7 million tonnes per year.

At the other end of the ladder is hydrogen, which is not competitive because there are better alternatives such as battery electric vehicles or heat pumps.

To produce 1 tonne of green hydrogen per year, New Zealand would need to triple its installed renewable power plant capacity and build massive 10GW electrolysers (devices that use electricity to produce hydrogen from water).

Long-term hydrogen storage

The strategic use of hydrogen is for long-term storage to move cheap solar energy from summer to winter, beyond what hydroelectric reservoirs can balance.

Hydrogen can be stored in complex chemical structures, barbecue-sized tanks, and gas tankers (ships). But very large volumes of hydrogen will have to be stored underground, and the most promising places are depleted natural gas reservoirs.

There are several problems that need to be solved to move hydrogen to storage three kilometers or more underground and bring it back to the surface. First, as a molecule, hydrogen does not behave very well. It tends to flow through materials that may contain it. This means we need to use specialized (expensive) materials and carefully detect leaks.

Second, recent discoveries of thriving microbial communities in New Zealand gas fields raise the prospect of renewable gases becoming a food source for microbes rather than an energy source.

Iron production

Another pressing application of hydrogen is to decarbonize steel production (which accounts for 8 percent of global greenhouse gas emissions).

Today, coal is used to remove oxygen from iron ore and provide combustion heat. Renewable electricity can provide heat and hydrogen to replace coal. The so-called hydrogen-based direct reduction of iron (H2-DRI) process is feasible on a large scale, as demonstrated by Midrex, HYBRIT and POSCO.

Working with Victoria University of Wellington on a zero-carbon metals project, we found that electricity prices below NZ$0.13/kWh are needed for hydrogen steel production to compete with the standard coal-based process . Solar PV systems are already well below these daytime costs and are close to battery backup.

Hydrogen export

New Zealand’s interim hydrogen roadmap projects hydrogen exports to be around 0.5 million tonnes per year. Meeting domestic demand for hydrogen is challenging enough, but export ambitions add another layer of complexity.

Hydrogen is difficult to transport because it is a very light gas and takes up a lot of space. But it can be compacted. Previous studies have examined the feasibility of exporting hydrogen from New Zealand, taking into account cryogenic liquefaction, ammonia conversion and toluene hydrogenation.

Liquid hydrogen, despite its lower cost, boils at minus 253°C and requires specialized insulated transport vessels, while noticeable losses are expected when boiling off. Additionally, there is currently no infrastructure to ship large volumes of liquid hydrogen around the world.

Ammonia transported at a temperature of minus 33°C suffers less from boiling off and is more practical. Next-generation catalysts, such as those from Liquium, could make ammonia even more profitable. The third option, toluene-MCH, has higher costs but is being tested on a commercial scale in Japan.

Recent research highlights a fourth alternative: e-methanol produced from green hydrogen. E-methanol is promising because of its modularity and because we already know how to transport and store it. However, other researchers see e-methane as more promising because it can leverage existing port and pipeline infrastructures.

Hydrogen cost

From a cost perspective, hydrogen has a long way to go.

Electrolysers can be scaled up to reduce costs, although this increases equipment costs and creates a trade-off between capital and operating costs. In addition, electrolyzers use expensive and scarce materials such as platinum and iridium. Our research focuses on developing low-cost electrolysers using earth-rich materials.

Interestingly, other non-emission alternatives to hydrogen are emerging. Good examples are so-called “golden” and “orange” hydrogen (from the natural accumulation or transformation of olivine into serpentine, respectively). Surprisingly, New Zealand’s unique geology offers the potential for both finding “gold” and producing “orange” hydrogen.

Ultimately, hydrogen’s success will depend on its competitiveness relative to alternative solutions, mainly electrification and biofuels. For applications where there is no easy alternative, emission-free hydrogen is a straightforward option.

Yannick Haas is Senior Lecturer in Sustainable Systems at the University of Canterbury; Aaron Marshall is Professor of Chemical Engineering at the University of Canterbury; Andy Nicol is Professor of Geosciences at the University of Canterbury; David Dempsey is an Associate Professor in the Department of Natural Resources Engineering at the University of Canterbury; Ian Wright is Professor of Marine Geology at the University of Canterbury; Matthew J. Watson is Professor of Chemical Engineering at the University of Canterbury; Rebecca Peer is a Senior Lecturer in Natural Resources Engineering at the University of Canterbury.

– This article originally appeared on Talk.