Green, ethical, energy issues in the news

Unlike conventional solar cells, the new device essentially does the work of plants, converting atmospheric carbon dioxide into fuel, solving two crucial problems at once. A solar farm of such “artificial leaves” could remove significant amounts of carbon from the atmosphere and produce energy-dense fuel efficiently.

The idea of using sunlight to consume CO2 and make fuel “has been around for awhile, but the challenges have been too great and there hasn't been a nationally focused effort,” Bell adds.

To date, reported solar-to-fuel efficiencies have been less than 7 percent, so reaching 18 to 20 percent would be a vast improvement, says Alexis Bell, professor of chemical engineering at the University of California, Berkeley, who led the research. Natural photosynthesis typically has an efficiency of between 0.5 percent and 1 percent, and is rarely higher than 2 percent.

Bell envisions a scenario where such a solar-fuel device could be coupled with large solar energy installations. Surplus solar energy that is not immediately used as electricity could produce fuel that would be stored for a rainy day.

This type of solar storage might be preferable to batteries, which typically have low energy density, Bell says. Today’s battery technology for storing solar energy could not supply electricity for a rainy week in the U.S. Midwest, he says.

In addition, he says, while an attractive prospect is to obtain the carbon dioxide directly from the atmosphere, a more realistic solution would be to use carbon dioxide generated at natural gas wells. While there is a lot of CO2 in the atmosphere, he says, it is "too diffuse" for it to be a good source; so until cost effective methods are developed to gather and condense atmospheric carbon dioxide, artificial photosynthesis will need other sources.

Fortunately (or unfortunately), there are currently plenty of man-made CO2 sources to choose from.

Martyn1981 wrote: »

The Daily Telegraph is talking up renewables and storage, and talking down Hinkley. :shocked:

Mart.

The biggest offshore companies have together vowed to cut costs to €80 per MWh - or £69 - by 2025. If so, the strike prices may start to match the wholesale price of electricity in the UK market. They may even come below the market price, in which case they will pay money back to society under Britain's 'contract for difference' system.

The Government's next three offshore auctions will see a staggered fall in strike prices to a maximum of £85 per MWh by 2020, and they will arguably keep falling step by step thereafter until market forces prevail.

The industry's research arm Inwind is already drawing up plans for the next generation of 10-20 MW turbines. The Sandia National Laboratories in the US are exploring 50 MW monsters with 'segmented ultralight morphing rotors' - once science fiction - that could in theory halve costs again.

The reality is already remarkable. The European Wind Energy Association says the average 'capacity factor' for new offshore plants has risen to 42pc from 30pc a decade ago. The wind flows at sea are less variable than on land, and they can be anticipated.

"The newest offshore wind farms deliver annual load factors around 50pc. Projects such as Dogger Bank have the potential to be even higher. The National Grid can predict tomorrow’s wind power more accurately than tomorrow’s electricity demand," says Matthew Knight from Siemens.