Chris de Beer, Hydrogen leader
It’s 2050 and the world has risen magnificently to the challenge of halting climate change. Globally, an affordable and workable zero-carbon energy system has been created, with hydrogen providing the backbone.
Hydrogen is an essential counterpart to renewable generation, providing a means of storing energy to overcome intermittency and balance supply with demand. It is also supremely versatile, meeting electricity supply, transportation, industrial and domestic needs.
Developing a hydrogen-based energy system will not be easy, however. Several technical, policy and investment steps are still needed to evolve the hydrogen industry, alongside continued rapid expansion of renewables.
This is the first of three articles looking at the issues that must be addressed.
Hurdling barriers to renewable generation
The debate over manmade global warming has been won almost everywhere. The 2015 Paris Agreement was signed by 195 nations – very nearly every country in the world. When it comes to action to implement the Paris Agreement, European nations are most advanced. Many are working out the best way of transitioning to a zero-carbon energy system by 2050. However, the falling cost of renewables, and solar photovoltaics especially, has seen a surge in zero carbon electricity generation.
In 2018, nearly two thirds of all new power generation capacity added worldwide was from renewables; at the end of the year total renewable energy generation capacity reached 2351GW, around a third of total installed electricity capacity.*
On the supply side, seasonal and weather-related intermittency of wind and solar power is the chief obstacle to renewables’ total dominance of electrical energy, with supply-demand balance and grid frequency regulation challenges also presenting barriers.
On the demand side, barriers are principally the huge potential cost of electrifying heating systems and the energy-intense nature of high temperature industrial processes.
It is becoming apparent that the most cost-effective way of addressing these issues is to use hydrogen. In a hydrogen-based energy system, renewable electricity would be converted to hydrogen by splitting water – H2O – into its molecular components. Hydrogen would be stored and transported via modified gas networks to provide both back-up to renewables, and a primary fuel.
Converted back to electricity via fuel cells or direct combustion in thermal power units, hydrogen would respond rapidly to meet peaks in demand, or fill longer troughs in supply. It would also supply residential, commercial and industrial customers with energy in the form of hydrogen for heating, cooking and industrial processes – creating, by 2050, a zero-carbon system across heating as well as power. Meanwhile, in the transport sector hydrogen fuel cell vehicles would compete with those powered by electric battery.
“Hydrogen can act as a storage medium and as an energy carrier – like conventional hydrocarbons. As an energy carrier, it has different uses in a variety of sectors, including the ability to take surplus renewable energy generated during the summer and store it for winter, reducing dependence on natural gas as a backup to renewables in the power sector,” says Chris De Beer, energy storage engineer at Mott MacDonald. To get there, large-scale hydrogen production plants must be piloted, while pipeline networks and end-use appliances need to be converted to use hydrogen.
Advancing electrolysis
Currently most hydrogen is made from natural gas, through steam reforming. Most experts anticipate that electrolysis will become the main zero carbon hydrogen production option, as opposed to adding carbon capture and storage to methane conversion (or other emerging methane-to-H2 processes).
The first step is to cut the cost of electrolysis, which currently is expensive and consumes more energy than can be produced by the hydrogen product. Next generation electrolysis promises higher performance. Powered by renewable energy, hydrogen production costs should tumble.
Polymer electrolyte membrane (PEM) electrolysis is a working technology, but only at the early commercial stage, and is still undergoing refinement before wider large-scale deployment. PEM produces hydrogen at higher pressures, enabling it to be injected directly into the gas network, saving costs on compression. In Germany, Siemens is most advanced in this field, with a commercial multi-megawatt system. ITM Power is among the active companies in the UK.
More novel approaches include using solid oxide electrolysis or direct photo electrolysis – a modified photovoltaic system that has an electrolysis process embedded in it. This involves sunlight hitting a panel with water circulating around it, which is split into hydrogen and oxygen. This approach has already been trialled at small scale with some success, but still needs to be proved at scale. A further direct solar-to-hydrogen approach being tested at bench scale is photoelectrochemical water splitting (artificial photosynthesis).