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The truth about thermoelectrics


Among the many technologies contending for a role in the future energy mix, thermoelectricity is one area where researchers have hoped that a big breakthrough in technology could reap equally large benefits in improving energy efficiency.

Up until this point thermoelectric technologies, which use materials to draw electricity from heat, haven’t been widely applied to electricity generation owing to their high cost and inefficiency. But changing the materials and their properties could — in theory at least — make a wide range of products more energy-efficient at a lower cost.

Last year the field made some important gains and seemed to be at a high point in terms of both the science and business potential. Early in the year, a MIT spin-off focused on energy efficient thermoelectric products won seed funding from venture capitalists Kleiner Perkins Caufield & Byers. Then in July researchers reported in Science [subscription] that adding trace amounts of thallium to lead telluride, a thermoelectric material used to produce electricity onboard deep space probes, could double its performance.

But in a Commentary just published in Nature Materials [subscription], Cronin Vining, a thermoelectrics consultant based in Alabama and past president of the International Thermoelectric Society, argues that the technology will not see the success some have hoped for as far as tackling climate change is concerned, and suggests that we should focus efforts elsewhere. Vining writes:

The most promising thermoelectric power generation application with ‘greentech’ implications is vehicle waste heat recovery to improve fuel economy.

Here the technology offers efficiency increases of 10% at most, and as Vining highlights in the commentary, competition from other technologies is fierce. In other areas such as converting industrial waste heat into energy, thermoelectrics are likely to result in negligible energy savings and emissions reductions, he says.

By way of this example, Vining argues that we need a new system to assess emerging technologies:

A better framework is needed such that scientists, engineers and technology advocates generally, first and foremost ask themselves: can this technology contribute to solving the climate crisis? Although the response will sometimes be ‘no’ or ‘not greatly’, an answer of ‘no’ can be as important as ‘yes’ because it allows resources to be more effectively redirected.

An editorial in the same issue of Nature Materials takes a big-picture view of how we might deal with the climate crisis and on the issue of energy concludes:

Although picking a winner would be simplistic and dangerous in the long term, R&D should focus on accelerating the development of a portfolio that can guarantee enough green energy within the next few years, even at the expense of less-promising routes.

Olive Heffernan

Image: A typical thermoelectric device. Snyder, G.J. et al, Nature Mater. 2, 528-531 (2003)


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