Innovation: A clean start for green power

Colin Barras, New Scientist 5 Mar 09;

Innovation is our new column that highlights the latest emerging technological ideas and where they could lead

So-called clean technologies have a dirty secret: despite their potential to provide power without pumping out tonnes of planet-warming gases, some methods are not actually very environmentally friendly or sustainable.

A paper published last month by the sustainable manufacturing research group at Loughborough University, UK, warns that, despite its potential to deliver power stations with near-zero emissions of some greenhouse gases, the burgeoning solid oxide fuel cell business is threatened by the fact that the cells use anodes containing nickel oxide – a powerful carcinogen.

It's likely that the compound's use will be carefully controlled under new and emerging environmental legislation, and even possible that it will be banned outright, says the Loughborough team..

Research teams are busily identifying alternatives, and the threat of a nickel oxide ban should spur on that effort.
Basket bet

Dangerous compounds are not the only issue. The solar cell industry is currently reliant on materials that work well but may soon become depleted. Electricity from even the most commercially viable solar cells is already five times the price of that from coal plants, and if material or construction costs rise further solar technology will become even less economically sound.

Part of the reason for the photovoltaic industry's expensive tastes is a notion championed in the late 20th century by economist Julian Simon that resources would get cheaper as global population expanded, because human ingenuity would identify synthetic alternatives.

Simon won a high-profile, decade-long bet with Stanford University ecologist Paul Ehrlich that a $1000 investment in a basket of different metals would shrink. When the bet ended in 1990 its value was just $430.

But that same investment is now worth $1500 in real terms, points out Daniel Kammen at the University of California in Berkeley. Growing industrial demands have in fact driven up costs – Julian Simon was wrong.
New direction

Kammen thinks that this new economic reality will spur a wave of innovation into cheaper solar cell materials as the industry attempts to minimise costs and shelter from volatile market forces. His team even studied the extraction costs and availability of 23 semiconducting materials to point photovoltaic research in the direction of the more low-cost, sustainable alternatives.

So instead of making efficiency gains using exotic but expensive thin-film solar cell materials like copper indium gallium selenide (CIGS) and cadmium telluride, the industry will likely turn to cheap alternatives such as pyrite and copper oxide.

The groundwork for this switch has already got under way. Inspired by Kammen's analysis, engineers at Berkeley have created solar cells using cheap copper oxide and zinc oxide.

These prototype cells developed by Peidong Yang and Benjamin Yuhas' are inefficient, but their low cost means they only need to produce a third as much power as a commercial silicon cell to be commercially viable.

All this demonstrates that researchers are beginning to consider the impact of real-world factors on the future of the renewable energy sector, and that existing technology needs to change.

We need a new wave of green innovation to bring truly sustainable technology from the lab to the commercial market.