The energy sector is undergoing a period of significant change with the rapid emergence and adoption of renewable technologies, notably solar PV and wind. Developments in storage promise significant disruptions in the medium term, alongside smart grids, and by the mid 2020s we could see new generation nuclear technologies and tidal power adding to the mix.

But innovation doesn’t end there. In this post I explore a handful of scientific developments and interesting inventions ranging from potentially game changing breakthroughs to rather more niche ideas.

 

The bionic leaf

In 2011, MIT scientist Daniel Nocera developed a pioneering bionic leaf. Now at Harvard, Nocera and his colleague Pamela Silver have further developed the process of artificial photosynthesis making liquid fuel from sunlight, carbon dioxide and water. Their process, described in the June 16 issue of Science, achieves an efficiency of 10%, which compares very favourably with natural photosynthesis which is only about 1% efficient.

The system uses a pair of electrodes, a photoanode and a photocathode, separated by a membrane, to split water into hydrogen and oxygen. The hydrogen, along with carbon dioxide, is fed to a specially bio-engineed bacterium, which coverts them into liquid fuels. The photoanode is made of gallium arsenide, which absorbs light very well but can oxidise when exposed to water. To avoid this, the anode is protected by a layer of titanium dioxide, with a layer of nickel on top to act as a catalyst. When exposed to sunlight, the photoanode oxideses water molecules, generating oxygen as well as protons and electrons, which pass through the membrane and are recombined by the photocathode to form hydrogen.bionic leaf

The system is fully integrated, with no wiring, and is made of elements which are all abundant in nature, meaning it should be affordable. Unfortunately the device isn’t yet stable, suffering some degradation with use, but the team believes these problems can be resolved.

A number of other teams are also working on artificial photosysnthesis, using a variety of approaches. Start-ups Joule Unlimited and LanzaTech are developing systems to produce biofuels from carbon dioxide and hydrogen using bacteria that consume carbon monoxide or carbon dioxide rather than hydrogen.

The Joule SolarConverter® modular array would typically encompass 1,000 acres, with each module containing tailored catalysts, water and micronutrients. Waste carbon dioxide is pumped in, keeping the catalysts in motion, and maximising their exposure to sunlight to drive photosynthesis. Charged from the sunlight, the catalysts consume the CO2 and continuously produce fuel or chemical molecules into a liquid medium. The medium circulates through a separator that filters the end product. The process occurs continuously for numerous weeks before the module is flushed and reinoculated on a staggered basis.

LanzaTech’s process involves biological conversion of carbon through “gas fermentation”, which uses a proprietary microbe rather than the sugars used in traditional fermentation, to transform carbon-rich waste gases into useful liquid commodities. LanzaTech’s microbe is a naturally-occurring organism in the family of acetogens, or gas-fermenting organisms which utilise only gases for their entire life cycle.

The Joint Centre for Artificial Photosynthesis is working on an approach that uses inorganic catalysts instead of bacteria to convert hydrogen and carbon dioxide to liquid fuel.

bionic leaf

These processes are years away from commercialisation, but the benefits are large, so more development can be expected.

 

Continued…

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