Engineers unveil improved algae-powered fuel cell

Jan. 10 (UPI) -- Researchers at Cambridge University in England have designed an improved algae-powered fuel cell. The technology is five time more efficient than current plant-powered models.

The new fuel cell is a type of biophotovoltaic, or BPV, a solar cell that uses biological mechanisms to convert solar energy into electricity. The photosynthetic abilities of microorganisms like algae can be used to harness the power of the sun.

Inside the biophotovoltaics, or biological solar-cells, the algae converts sunlight into electrons which are funneled out of the cell in the form an electric current. Current BPVs locate the entirety of the operation inside a single device.

The latest technology -- described this week in the journal Nature Energy -- features two chambers. One chamber contains the conversion of sunlight into electrons, and a second features the conversion of electrons into electric power.

"Charging and power delivery often have conflicting requirements," Cambridge chemist Kadi Liis Saar said in a news release. "For example, the charging unit needs to be exposed to sunlight to allow efficient charging, whereas the power delivery part does not require exposure to light but should be effective at converting the electrons to current with minimal losses."

By bifurcating the process, researchers we able to focus on each conversion separately and make each component more efficient.

"Separating out charging and power delivery meant we were able to enhance the performance of the power delivery unit through miniaturization," said Tuomas Knowles, a professor of chemistry at Cambridge. "At miniature scales, fluids behave very differently, enabling us to design cells that are more efficient, with lower internal resistance and decreased electrical losses."

Researchers improved the first component by engineering more efficient algae. The new algae cells dissipate less energy during photosynthesis.

Though five times more efficient than previous models, the new technology is still significantly less powerful than traditional solar cells. However, the new BPV model has other advantages, including lower production costs.

"While conventional silicon-based solar cells are more efficient than algae-powered cells in the fraction of the sun's energy they turn to electrical energy, there are attractive possibilities with other types of materials," said Christopher Howe, a professor of biochemistry at Cambridge. "In particular, because algae grow and divide naturally, systems based on them may require less energy investment and can be produced in a decentralized fashion."

By separating the cell into two components, solar energy converted into electricity by microorganisms can be more easily stored -- as opposed to being used immediately.

Researchers suggest the technology could prove particularly useful in rural locations and in less developed countries where power grids are nonexistent.

"This a big step forward in the search for alternative, greener fuels," said researcher Paolo Bombelli, from the Department of Biochemistry. "We believe these developments will bring algal-based systems closer to practical implementation."