A solar power-to-gas storage solution?

A new solar cell technology to separate hydrogen from water could be a big part of the storage solution for a 100% renewables grid.

Lenz Blog

The way to go for large-scale storage of renewable electricity is 'power to gas', which means making hydrogen from water. Germany can store up to 200 terawatt-hours with the existing gas infrastructure, much more than the around 30 TWh needed in a 100 per cent renewable electricity scenario. And hybrid wind power plants with the ability to store energy over hydrogen are already starting up.

Most existing projects are wind parks. But now Spiegel reports about a new technology for solar power-to-gas.

Researchers have developed a solar cell that is able to directly split water. It does not produce electricity in a first step and split the water in a second step, but rather only has one step.

Just like plants’ photosynthesis produces carbohydrates directly, this solar cell will produce hydrogen directly.

It beats photosynthesis (efficiency of about 1 per cent) by a large margin, converting already 12.3 per cent of the solar energy into hydrogen energy, even at this early prototype stage. And this solar cell uses no expensive materials, which means it will be even cheaper than photovoltaic solar cells.

In the short-term, this will solve the remaining storage problems with a 100 per cent renewable grid even cheaper than already existing alternatives. In the long-term, this will replace oil.

Oil is ancient biomass. When storing the energy, the efficiency was only about 1 per cent. Then it took millions of years and random geological processes to actually create the oil.

It is obvious that there is no way this could be competitive, except for the fact that we are burning oil that is already in the ground. Which can be done exactly once for each barrel.

Once 'peak oil' becomes 'downhill oil' and then 'gone oil', making our liquid fuel ourselves as opposed to burning through the reserves will be the only alternative anyway. It took 5.3 million years to build up the fossil fuel humanity burns in one year. There is no way this is sustainable.

So we will need to make our fuel, instead of burning the reserves. One-step hydrogen production from cheap materials is a big deal for doing that.

Karl-Friedrich Lenz is a professor of German and European law, Aoyama Gakuin University, Tokyo. A free PDF file of his third global warming science fiction novel 'Last Week' is available here.

Originally published on the Lenz Blog. Reproduced with permission.

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