Solar hydrogen: Renewable powered electrolysis

There are two primary ways to generate solar hydrogen: hydrogen produced from solar energy. The first is via a photochemical process, using solar energy directly to split water. The second is solar powered electrolysis, which uses solar cells to generate electricity and power electrolysers.

While the photochemical process is appealing due to its direct hydrogen production, it must still undergo significant innovation to reach scalability. Solar powered electrolysis, on the other hand, uses already established technologies and can therefore more immediately be used to provide certain geographies with the opportunity to produce large amounts of green hydrogen.

Current solar hydrogen capabilities

In systems that solely generate electrical energy, process efficiencies can reach up to 30%. A primary reason for such low efficiency is the large amount of heat lost within these systems. One solution is hybrid photovoltaic-thermal systems which convert solar energy into both electricity and useable heat, improving process efficiencies up to 80%.

In both systems, excess energy can be stored as hydrogen and used at some point in the future instead of going to waste. Hybrid systems have the added bonus of producing heat that can be fed into electrolysis processes (which are more efficient at higher temperatures) – or used to heat buildings.

Solar hydrogen projects

Manilla Community Solar array – New South Wales

A $2.3 million grant was awarded in 2020 to a project in rural New South Wales for a 4.5 MW solar array and a 2 MW solar hydrogen storage system.

The installation will also be one of the first commercial scale projects to use solid-state hydrogen storage in the form of sodium borohydride (NaBH₄). This “H2Store battery” technology was developed by the University of New South Wales and the cost is comparable to existing chemical battery storage technology.

First Solar & Nel Hydrogen

The American solar system manufacturer First Solar has partnered with Norway’s Nel Hydrogen to develop a power plant to provide solar generated hydrogen and low cost electricity.

BP, Iberdrola, & Enagás

BP is teaming up with Iberdrola and Enagás to install a photovoltaic powered, 20 MW electrolyser that will allow them to transition from grey hydrogen consumption to green.

Soto Solar España

Independent producer Soto Solar España plans to develop a 1 GW photovoltaic park with a 100 MW electrolyser by 2024.

Baofeng Energy

The Chinese coal mining company Baofeng Energy announced in 2021 plans for two 100 MW solar power generators to power electrolysis as part of their efforts to half CO₂ emissions by 2030. Baofeng Energy claims this is the world’s largest solar hydrogen generation project.

Sinopec & Longi

The oil firm Sinopec has partnered with the solar technology manufacturer Longi to work on the company’s decarbonisation efforts by developing green hydrogen production infrastructure. It will be interesting to see how projects and technologies here advance, as some speculate China has the potential to accelerate adoption of hydrogen technologies like they did with solar technologies.

Conclusion

Using solar energy to power electrolysis provides a good opportunity for sunny regions to produce green hydrogen and alleviate dependency on fossil fuels, especially as solar and electrolysis technologies continue to advance. In the short term, this will be ideal for expanding our solar hydrogen generation capacity, and it will certainly be interesting to see if a breakthrough in photochemical hydrogen production disrupts the expansion of solar powered electrolysis down the line.