Hydrogen’s promise: How fuel cells might power lower-carbon datacentres

Although hydrogen has few technological rivals when it comes to lower-emission, compact footprint systems for backup or primary power, it is expensive compared with the current power grid, with diesel generators as backup and batteries for short-term discharges. Hydrogen itself also must be stored, expensively, under pressure or at very low temperatures.

Costs are starting to come down as the market grows, but regulation is another barrier. Although other industrial sectors already use hydrogen – such as glass and food production – a new framework of permissions, certifications and laws for hydrogen fuel is needed, says Castaldini.

Graham Smith, senior research scientist at the UK’s national institute of metrology, the National Physical Laboratory, calls lithium batteries “a non-starter” for daily, weekly or monthly storage on a countrywide grid scale, and in the UK, the tech and economics of other redox-flow battery types also remain unproven. That said, hydrogen could reuse existing UK gas infrastructure.

“Hydrogen storage can be done cheaply and at scale for a long time, filling underground caverns with compressed gas,” says Smith. “Storing hydrogen this way is one of the few methods available for storing enough energy to properly manage the variances in UK energy consumption from month to month and season to season.

“We already do it safely with natural gas. There are some engineering and economics questions, but they don’t require a breakthrough new technology.”

But there is a drawback: hydrogen technology for electricity generation – as opposed to transport or heating – is not quite ready for prime time yet, warns Smith, adding that the thermodynamic efficiency of the electrolysis process used in fuel cells is low – about 50%.

“This is commonly stated, but people miss the point that transitioning to a new paradigm where storage is difficult is expensive in relation to the cost of energy,” he says. “But we do still need to do it.”

Smith says a massive, energy-thirsty scale-up of UK capacity to produce electrolysers for creating hydrogen is needed – itself entailing a faster roll-out of sustainable, renewable and clean energy. Some five to 10 times the UK’s current electricity supply capabilities are needed to replace natural gas. Also, some electrolyser technologies use quite rare materials.

“For example, proton exchange membrane water electrolysis [PEMWE] solutions only use iridium-based catalysts, the supply of which is inelastic,” he says, adding that at the same time, for some 80% of end-use cases for hydrogen energy, alternatives exist, such as batteries or heat pumps.

Vidal Bharath, chief operating officer at UK hydrogen fuel cell company Bramble Energy, sees a mixture of fuel and energy sources in future, with fuel cells five times the price of a diesel engine and “thousands of pounds” per kW.

“We need to make a big step-change in the cost of exactly what we do,” he says. “Then you need quite complex, precise factories to build it. They exist but haven’t the full capacity for when you move on to the next generation of technology – and it takes 12 months to build a new factory.”

Bramble has developed a printed circuit board fuel cell (PCBFC) that it believes could be made in many printed circuit board factories. It has already launched a portable power product range and is developing a high-power density, liquid-cooled fuel system on a scalable, low-cost platform.

When it comes to safety worries, Bharath notes that society already deals daily with extremely flammable fuels, such as petrol.

But when hydrogen vents, it can happen quickly – making it potentially safer than natural gas in similar circumstances, not building up in a system before it blows. The right infrastructure can allow hydrogen to vent as and when into the atmosphere, he says.

“Loads of hydrogen” traverses UK roads every day – although the country is well behind the likes of Japan, California and Germany when it comes to hydrogen, with about 70Mt of hydrogen already used worldwide each year, says Bharath.

It can’t simply be about things like “adding more batteries to your electric vehicle” because that makes for more weight to transport, with fuel-cell systems possibly weighing 75% less for an equivalent energy requirement, he points out.

“If we commit to it, it can happen,” says Bharath. “We need to have more input from companies on ‘these are the areas that we think we could get to or we can decompose as quickly as possible’.”