Friday, August 24, 2007

The Long Energy Horizon

Periodically, we need to step back from our current energy challenges and consider the long-term future of energy. That's particularly true, given the likely duration of the climate challenge that parallels our energy concerns. Should we expect a century of incremental improvements on existing energy systems and technologies, to make them more efficient and reduce their impact on climate change, or do we face the prospect of more radical change? One of the persistent themes of this blog has been the absence of silver bullets. Whether we're talking about truly zero-emission cars, biofuels, or pollution-free energy from nuclear fusion, our options are likely to take longer, cost more, and present more trade-offs than we might wish. And we could be dealing with the consequences of our near-term choices for decades to come.

I believe it matters whether we view today's energy decisions as ad hoc responses to circumstances or as components of a major energy transition. Do we intend to shift away from the fossil fuels that still make up 86% of global primary energy supplies and toward less concentrated forms of renewable energy, or merely from one form of fossil fuel reliance to another: from petroleum-based liquid fuels to fuels derived from natural gas, coal and unconventional hydrocarbons? And if the hydrogen fuel cell is as much of a dead end as its critics suggest, does that mean we will remain wedded to the internal combustion engine for another 100 years?

One reason the answers to these questions matter is infrastructure. It shouldn't take falling bridges to remind us that infrastructure choices have consequences that last for decades. Our highly efficient petroleum product infrastructure, moving fungible products through common-carrier pipelines, makes it harder to distribute alternative transportation fuels at a competitive price. The investment required to build a parallel infrastructure for ethanol, hydrogen, or any other vehicle fuel incompatible with existing pipelines is enormous and will probably only be made once a clearly superior fuel emerges. Alternative fuels might require subsidies for decades, until we reach that point. Conversely, a premature investment in alternative energy infrastructure, such as ethanol pipelines, could result in some very expensive stranded assets later.

For all the recent enthusiasm about the potential of carbon sequestration to make our continued use of coal fit into a world being warmed by anthropogenic greenhouse gas emissions, it's hard to see this as a long-term solution, rather than a temporary measure to facilitate our transition to something else. The challenges of retro-fitting sequestration to existing facilities look daunting, and the high energy cost of extracting sequesterable CO2 from a coal power plant effectively shortens the life of our known reserves of coal. Peak Coal is as inevitable as Peak Oil, and carbon sequestration could hasten its arrival by decades.

Will a new, highly-concentrated form of energy emerge in time to provide a viable alternative to a world otherwise forced to rely on widely dispersed, low-intensity renewables--and much higher efficiency? A fascinating article in yesterday's MIT Technology Review newsletter casts serious doubts on the timing of nuclear fusion, including the version based on mining Helium-3 from lunar deposits. Nor is it clear that conventional fission power could expand sufficiently to take up the slack from fossil fuels.

With uncertainties like these, few of our current options look very robust. Despite my hesitation about the rate at which plug-in hybrid cars could enter the vehicle fleet, the PHEV technology looks like an excellent hedge against these big unknowns. It's a shame that ethanol-burning cars have hijacked the "flexible fuel vehicle" designation, because that's the essence of what a PHEV provides: the ultimate flexibility to switch between liquid fuels from oil, synthetic hydrocarbons or biomass, and electricity from any source, using infrastructure that's already largely in place.

No one can predict what the global energy system and primary energy mix of 2100 will look like, and even 2050 appears nearly as uncertain. However, it's not too soon to wonder how our current energy choices will mold and constrain that future, just as the choices for oil and internal combustion engines helped shape the last century.

Energy Outlook will be on vacation until after Labor Day. New postings will resume on September 4.

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