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Behind each historic advance in our society lies a major shift in our primary energy. Now, with our pressing need for deep decarbonisation, can hydrogen step forward to break our fossil fuel addiction and take us into a sustainable zero-carbon future? In this article, climate specialists at Ricardo consider if this wonder fuel is up to the task of saving our planet.
Hydrogen is the most abundant element in the universe. It is also a useful energy vector which is used to convert, store and release energy, and which, when used, does not release greenhouse gases (GHGs). These three facts alone should mark it out as the perfect solution to help halt the accelerating spiral of climate heating emissions in a world hungry for energy.
“Of course hydrogen is a very attractive energy vector,” affirms Mike Bell, group strategy and transformation director at Ricardo, “but like every major step forward it is not always quite so simple. And like any fundamental shift it will require significant changes to national infrastructures and how we go about our business.”
What gives the experts such confidence in hydrogen as an energy vector is the fact that it can be generated in several different ways, some greener than others. If it is produced using renewable electricity it offers the potential for a zero-carbon footprint – and BP’s recentlyannounced green hydrogen tie-up with Danish wind power group Ørsted shows that even the oil majors are beginning to take it seriously. Other hydrogen production methods also promise near-zero or potentially even negative GHG emissions.
The European Union, the first major economic bloc to target net zero GHG by 2050, sees hydrogen as a central plank in its new Green Deal strategy for deep decarbonisation. “Hydrogen is a vital missing piece of the puzzle to help us reach this deeper decarbonisation,” said Kadri Simson, the EU’s energy commissioner, when presenting the strategy in July this year.
Yet, as Bell points out, the production of hydrogen should not release GHGs into the atmosphere. The end goal must target the production of green hydrogen, for example, via electrolysis using renewable electricity. At present, 96 percent of hydrogen comes from fossil sources, so there’s a long way to go. Some argue that a useful interim measure could be so-called ‘blue’ hydrogen which is made from natural gas but, with carbon capture and storage (CCS), which largely eliminates the release of GHGs. Natural gas is still cheap and available at scale, so a big advantage of this route is that it enables much of the hydrogen infrastructure to be built up while we wait for fully green hydrogen to ramp up to large-scale production – though others point to the dangers of prolonging the reliance on fossil gas.
“people are getting very excited about hydrogen and it can really help – but it is by no means a panacea”
Priority uses for renewable energy
The tapering off of fossil fuel dependence throws the focus back onto the renewables industry and the twin issues of available capacity and how to use that capacity to best overall advantage. The UK is a global leader in offshore wind power, with Ricardo involved at a high level in several programmes; nevertheless, Sujith Kollamthodi, strategy & innovation director at Ricardo Energy & Environment (REE), notes that, as the key element in the bigger picture, renewable electricity must be used as efficiently as possible. As a general rule, he reminds us, converting energy into another form results in losses, so for many applications – especially in certain industries and in the home – the electricity is best applied directly.
“So when converting electricity into hydrogen,” he explains, “we would want to target it at those specific areas where other [low-carbon] options are difficult to apply. So we would be looking at the heavier forms of transport, such as shipping and road freight, where the other options such as electrification aren’t so effective, and where alternatives such as biofuels are in limited supply.”
“Where the regulations currently sit, we will not achieve the Paris targets across all forms of industry,” adds Bell. “People are getting very excited about hydrogen and it can really help – but it is by no means a
panacea. For some industries with high temperature requirements, such as aluminium, steel, paper and cement, hydrogen would make sense; for others, [direct] electric forms of heat would be sufficient.”
In a similar vein, Bell refers to the results of a recent comprehensive life cycle assessment (LCA) study carried out by Ricardo for the European Commission (see page 14). Because of the energy losses involved in converting electricity into hydrogen, fuel cell electric light vehicles will always be less efficient overall than those storing their electricity directly in batteries. “All of that makes our point,” he says, “and the reality of it all is that both electricity and hydrogen will be competing applications. Where things go will be driven partly by economics and partly by technology and regulations: the other problem right now is that we haven’t got huge volumes of untapped hydrogen, so we have to create it.”
The many colours of hydrogen
Hydrogen may be a uniform and chemically simple gas, but the different ways it can be generated make a profound difference to the GHG impacts it produces. There is a distinct hierarchy here, as Colin McNaught, technical director at Ricardo Energy & Environment, explains:
“For us, the focus is on both green and blue hydrogen as they’re both zero carbon, or pretty close to it. How they compare depends on when and where you’re talking about. Green hydrogen is produced using fully renewable energy, so there’s no argument about that; with blue hydrogen, which is produced from natural gas via steam methane reforming (SMR) with carbon capture and storage, I guess some people may still question how long the carbon will stay in the geological store – even though the IPCC report suggests 10,000 to 100,000 years.”
Also critical here, of course, is the issue of how much of the CO2 from the SMR process is actually captured by the CCS system. Naser Odeh, Ricardo Energy & Environment knowledge leader in CCS, points to the world’s first major industrialscale CCS installation, on the coal-fired power station at Boundary Dam in Canada. “It started at well below the planned 90 percent capture rate but now it has improved to 85 or 90 percent,” he says.
Naser Odeh, for his part, is keen to highlight the potential of biomass- and biomethane-derived hydrogen. “Steam reforming to produce blue hydrogen using biomethane rather than natural gas, followed by CCS, offers the potential of giving you negative emissions, and that would be a big benefit. The same also applies to hydrogen produced by biomass gasification combined with CCS.”
The thinking behind this technology is that the plants that grow to form the biomass will absorb CO2 from the atmosphere. With CCS making the SMR process very nearly carbon neutral, the net result is carbonnegative overall, drawing CO2 out of the air at the same time as providing hydrogen fuel. Technology readiness levels (TRL) are low, however, at 5 or 6, and Odeh estimates it could be a decade away. One more candidate technology is the production of hydrogen through the pyrolysis of natural gas, leaving the carbon content as solid graphitic carbon which can be used as a construction material. The promises are of much cheaper hydrogen but, again, this process is at an early stage of research & development.
“steam reforming to produce blue hydrogen using biomethane rather than natural gas, followed by CCS, offers the potential of giving you negative emissions”
Colin McNaught sees the current interest in the many options for generating hydrogen as a sign of its growing importance. Nevertheless, he observes that “the core issues are the GHG credentials and the cost: standards to define low-carbon hydrogen are being developed and the costs are falling, and this addresses two of the key challenges.
And hydrogen is of course an important building block for a whole spectrum of other green fuels – all the way from ammonia for shipping to sophisticated ‘designer’ fuels for aircraft.
The hydrogen value chain
Though there are many different ways of generating electricity, there is only one method for turning that electricity into hydrogen – the electrolysis process, which splits water into its constituent elements of hydrogen and oxygen.
Several different types of electrolyser are available, using a variety of technologies each with its own level of efficiency. Costs have fallen by 40 percent since 2015, according to Bloomberg New Energy Finance, and typical efficiencies are now in the 80 percent region. In effect, the electrolyser works like a fuel cell in reverse but, unlike fuel cells, electrolyser technology is not yet suitable for mass production in the same way as, say, solar panels. As a result, most of today’s available electrolyser units are modular systems about the size of a shipping container and with a rating of 1 MW.
Iberdrola in Spain will soon install 20 MW of electrolyser capacity for its Puertollano green hydrogen plant, which is set to come on stream in 2021. The facility comes as part of Spain’s commitment to provide 4 GW of green hydrogen by 2030, representing 10 percent of the 40 GW pan-European target set out in the EU’s hydrogen roadmap.
“what surprises many people is that the natural gas grid infrastructures in most countries can be used for hydrogen, too, albeit with some small upgrades”
Once the hydrogen has been produced, it must then be prepared for delivery to the end user. Today’s distribution networks rely on compressing or liquefying the gas for storage in special transportation containers, and the modular nature of hydrogen generation presents the potential for much smaller localized systems which avoid the extra costs and emissions of long-distance distribution. It is quite possible, for instance, to envisage a neighbourhood filling station which uses local solar and wind generation to power electrolysers and provide the hydrogen for local cars and trucks, perhaps feeding any surplus into a future hydrogen grid.
Storage and distribution
What surprises many people is that the natural gas grid infrastructures in most countries can be used for hydrogen, too, albeit with some small upgrades: indeed, some hydrogen is often blended into the supply. It is currently only a limited percentage – perhaps 2 to 10 percent by volume. Not all end-user appliances are yet compatible with stronger concentrations of hydrogen; under current UK regulations, for instance, all appliances sold after 1996 must be able to sustain 23 percent hydrogen. Some components in the gas pipelines will need to be upgraded from steel to plastic for the higher concentrations of hydrogen. Pressures may need to be raised, too, for hydrogen needs three times the flow area to deliver the same energy content as today’s natural gas. But in principle it is perfectly possible.
Until piped hydrogen grids are more established, hydrogen will continue to reach its end applications in compressed or liquefied form. For mobile applications, both the mass and the package size of the hydrogen container are of critical importance, as Cedric Rouaud, Ricardo global technical expert for thermal systems and fuel cell R&D leader, explains: “For a heavy truck, for instance, we would need tens of kilogrammes of hydrogen. With compressed gas it is still a heavy solution: for 60 kg of hydrogen, to give a range of 500 to 700 km, the tank would weigh two tonnes.
The alternative solution of liquefied hydrogen helps reduce the weight to 1.2 tonnes for the same 60 kg of hydrogen, he continues. “But for the same space as the conventional compressed gas tank we can store more hydrogen when it is liquid, so we can extend the range from 600 to 1000 km.” Also being investigated, says Rouaud, are combinations of compression and cryogenic storage, known as cryo-compressed. Another promising avenue, which will soon be demonstrated in a London bus field trial, is solid-state storage using a metal hydride. This solution, developed by London South Bank University with Ricardo’s assistance, is lighter than compressed gas for the 60 kg of stored hydrogen, reveals Rouaud. What is more, he says, it has the key advantages of operating at normal temperatures and pressures, and it is cheaper than a complex carbon fibre pressure tank.
One way or another, however, it is clear that heavy, bulky and costly storage is still a significant brake on the potential of hydrogen, especially where aircraft and lighter applications such as passenger cars are concerned.
National and international strategies
Many nations have already launched their own hydrogen strategies, most notably Japan, whose economy depends almost exclusively on imported energy. Public and private hydrogen programmes had been in existence since the 1970s, but in 2017 Japan’s energy security programme set up supply chains for liquefied hydrogen from other countries such as Australia and established ambitious targets for fuel cell powered cars, trucks and buses, and for co-generation schemes in industry. Indeed, the postponed 2020 Tokyo Olympics had been planned as an international showcase for hydrogen powered vehicles. Some hydrogen imports will soon be in the form of ammonia as a hydrogen carrier.
Australia, in a rapid about-turn from its earlier and much-criticized coalcentric energy policy, is reinventing itself as a major international hub for green hydrogen and is aiming to meet 3.5 percent of global demand. Norway’s green hydrogen will come from hydro and wind power, linked to high-temperature electrolysis.
But probably the most ambitious of all is the European Union’s Green Deal roadmap for clean energy, intrinsic to the Union’s commitment to achieve net zero GHG emissions by 2050. The priority, states the EU plan, is to deliver 40 GW of green hydrogen electrolysers by 2030, using mainly wind and solar energy: the roadmap details targets for the large-scale rollout of those renewable energy installations and electrolysers. The UK’s just-announced 10-point plan for a ‘green industrial revolution’ also includes important roles for hydrogen in its many bold undertakings. But, as with all of these ambitious strategies, what is equally critical is the political will and the budget to make them a reality.
Outlook
For many decades hydrogen has been idealized as a dream fuel, the fuel of the future. But now, with many indicators signalling we are close to an environmental tipping point, the need to decarbonize every sector, especially transport, has become doubly important. Fortunately, hydrogen is in a good position to help.
Hydrogen is likely to take off for a combination of reasons, says Ricardo’s Mike Bell. “It can help decarbonize difficult sectors like land and sea transport, which account for 27 percent of all GHG emissions, and regulations and incentives are at last aligning to favour this type of sustainable solution.”
But most of all, says Bell, it is the greater deployment of renewable energy to decarbonize the electricity grid that will be key. So does that mean there will be a time when electricity and hydrogen are our only energy sources?
“Probably not, or at least not in the next 30 years,” says Sujith Kollamthodi. “It comes down to all the different use cases and resource availability – and biomass and sustainable biofuels will also play a role. These fuels can help decarbonize the existing vehicle parc.”
So, is hydrogen still the fuel of the future? The consensus among, engineers, climate specialists, legislators and Ricardo experts is that it is no longer simply the fuel of the future – it’s the fuel of now.
