This post originally appeared on CARMA.org.
The airwaves have recently been filled with advertisements heralding a plethora of clean energy technologies. GE promoted its smart grid technologies in a Wizard of Oz-themed Super Bowl ad. Vestas, the largest wind turbine manufacturer in the world, has branded itself No. 1 in Modern Energy. Various groups have designed commercials touting the potential of "clean coal," including a GE ad featuring models-turned-miners (tagline: "Harnessing the power of coal is looking more beautiful every day."). And environmental groups have struck back against the branding of coal as "clean" with satirical advertisements (tagline: "Clean coal harnesses the awesome power of the word ‘clean!’". In this maelstrom of marketing, who can say which clean energy technology is best?
Marc Jacobson, apparently. In his recent paper "Review of solutions to global warming, air pollution, and energy security," the Stanford professor incorporates findings from a variety of studies to rank clean energy technologies by their lifetime carbon dioxide emissions per unit of energy produced. Jacobson’s calculations include not only direct emissions, but also indirect emissions due to construction, mining, transportation, and other factors.
The addition of indirect emissions produces some compelling results. Even though coal with carbon capture and sequestration (CCS) has few direct emissions, its overall emissions are over 80 times greater than those of the least-emitting technology, wind. In fact, every other clean energy technology considered in the paper - wind, photovoltaic, geothermal, tidal, wave, hydro, and nuclear - emits less than coal with CCS. Coal with CCS emits about as much as a natural gas power plant, roughly 60% less than coal without CCS.
The findings are important for all nations considering how to invest scarce resources for cutting emissions, but perhaps especially for the World Bank, as the steward of the proposed Clean Technology Fund (see David Wheeler’s latest discussion of this).
Jacobson doesn’t factor in the cost of each technology, but for policymakers deciding where to focus research and development, the implication is clear: coal with CCS is less "clean" than is often claimed. Rich and developing countries - and those designing various clean technology funds - would do well to take note.
See below for a graph of Jacobson’s estimates, read his paper, or watch a presentation of his findings.
(From Jacobson’s presentation slides. The blue bar is the lower bound of the estimated emissions; the red bar is the upper bound. All emissions values referenced above are the average of the lower and upper bound.)