At first sight, hydrogen may be heaven. Because it can deliver and store huge amounts of energy, hydrogen is an ideal candidate for a zero carbon emissions society. It’s the simplest and most abundant chemical compound in the universe. On earth, it doesn’t exist in its pure form so it must be produced from either natural gas (by steam methane reforming) or by splitting water into oxygen and hydrogen through electrolysis. In the last case, there are no GHG emissions: when hydrogen evaporates, it bonds itself to water again.
Low round trip energy efficiencyAt a second glance however, using hydrogen has caused headaches for energy experts. Two conversion processes – first electrolysis, then re-electrification or direct (end) use - require a lot of energy. During electrolysis, 20 to 30 percent of all energy contained in hydrogen is lost. Compression or cooling for storage and transportation takes 5 to 35 percent. Energy efficiency at the second conversion (on-site or fed in to a gas network) is around 70 percent, making round trip efficiency of hydrogen as low as 30 to 40 percent, even ESA (Energy Storage Association) admits (the lower limit appears when hydrogen is used in fuel cells, stationary as well as mobile).
Although there are some promising projects and start-ups for small-scale applications – like HyTech Power from Redmond, Washington, Vandenborre Energy Systems from Kasterlee, Brabant – most viable answers will be large-scale in order to surpass the threshold of the low round trip efficiency. In other words, the better the economies of scale, the more resilient a hydrogen economy will be. According to a 2017 report of consultancy DNV GL, there’s a potential of 66 billion m3 hydrogen (710 PJ) demand in the Netherlands alone. That’s six times more than the current demand for hydrogen, mostly used in refinaries and the production of ammonia.
Nowadays, the discussion focuses upon prices of electrolysers and electricity, the biggest hurdles for large-scale implementation. The last few years, huge improvements in both areas have been made. Ad van Wijk, professor future energy systems at TU Delft, recently published a paper in which he states that the costs of main types electrolysers have decreased sharply: ‘whereas the CAPEX for PEM (proton exchange membrane) systems was around €2000 per kW in 2013, by April 2018 it had fallen to €450 for large-scale projects’. At the same time, energy efficiency has improved from 75 to above 80 percent. According to the professor, the same applies to alkaline-based electrolysers.
Prices are coming down
As soon as prices of sustainable electricity (i.e. generated by wind and/or solar) will start to nosedive or, in some instances, even turn negative, the better the case for hydrogen production and storage. At that moment, Elektor Magazine quoted Ben Madden April this year, ‘capital costs of electrolysers are disappearing’. Moreover, German independent market expert Energy Brainpool, expects that, given enough surplus of renewable electricity, hydrogen can become more cost-effective than natural gas.
Converting excess energy into hydrogenExcess of renewable energy supply is already happening on the Orkney Islands since 2013 where over 50 Megawatt wind, wave and tidal energy have been installed. As of May 2018, Gasworld writes, community-owned wind turbines on Shapinsay and Eday are often ‘curtailed’ and losing 30 percent of their annual output on average. Therefore, the EU project BIG HIT stepped in. Negative energy, as related to curtailment, provides for hydrogen production using a one Megawatt PEM electrolyser. Costs of reinforcing grid connections are thus prevented.
In the North of the Netherlands and Northern Germany, two major hubs in Europe for hydrogen applications, consortia are frantically researching production, transport and storage of hydrogen. Take HYGRO, a consortium led by research institute ECN and wind turbine manufacturer Lagerwey. They’re developing a wind turbine that will be connected to a hydrogen gas network because transporting gas is significantly cheaper than using an electricity grid. This innovative wind turbine will be operational next year.
From a systems point of view, hydrogen offers a variety of solutions electricity does not have. It can be injected into the natural gas network or stored in huge amounts in salt caverns or empty natural gas fields without huge technical obstacles, the 2017 report of DNV GL claims. Also, hydrogen can be used in existing gas turbines with only small alterations. Because of its low density hydrogen is difficult to export. But a 2017 report from Australia’s Council of Learned Academies explores the possibility of converting hydrogen into ammonia for transportation purposes and converting it back to hydrogen on site. Australia has a well developed infrastructure for exporting liquified natural gas (LNG) which could be utilized for exporting ammonia. The report names Japan as a possible trade partner because of that country’s ‘limited domestic energy resources’ and its ‘recent investment and national economic strategy directed towards hydrogen projects, including hydrogen- powered vehicles and fuel cells.’ This convertion proces could provide isolated Australia with a solution to export its surplus solar energy to other countries.
Image: Hydrogen Fuel Station from ITM Power, the energy storage and clean fuel company that provided equipment for the hydrogen project at the Orkney Islands. Source: Bexim at Wikimedia, CC BY-SA 4.0 licence.