November 2007

Jevons' Prius - why hybrid cars won't save the world

Welcome to the new trend of slow blogging. I should trademark that term and make myself a fortune, but, given my slowness, someone's bound to beat me to it.

Most blog posts are instant reactions to events of the day, and indeed, I started composing this one back in the summer. But slowness, as in the slow food movement, has its uses. In this case, I'm glad I hesitated, as what would have been another of Phil's Rants has now matured like a fine cheese (who am I kidding here?).

Anyhow, there I was, one summer's morn, doing my bit for global warming (hangs head in shame) by driving far too many miles to work, when, to my surprise, I found myself following a Toyota Prius hybrid car. And I got to thinking.

Do Prius owners, given their cars' fuel economy, drive more because it is cheaper to do so?

This kind of conundrum is not a new one and was first postulated by the British Coal Board economist, William Stanley Jevons, back in 1865. Jevons' observation that the increased efficiency of Boulton and Watt's steam engine resulted in an increase in consumption of coal, not a decrease, as the lower running costs of steam engines encouraged their rapid uptake by industry, is now referred to as Jevons' Paradox.

Jeff Vail also draws attention to another side effect in an article over at The Oil Drum. Reduced fuel expenditure results in more cash in the drivers' wallets, which then gets spent on (gasp) energy-consuming consumer goods. This rebound effect results in the realised efficiency gains being somewhat less than at first expected.

Or, in simple terms, do our hypothetical Prius owners spend their monetary savings on fuel on holidays in the sun in far away lands?

Last month, the UK Energy Research Centre released the most thorough and in-depth review of rebound effects ever undertaken, reviewing over 500 papers and reports. On the direct rebound effect on private transport, their report concludes that "taken together, our review of 17 studies suggests that the long-run direct rebound effect for personal automotive transport lies somewhere between 10% and 30%." Secondary rebound effects must also be considered: "A comprehensive switch to green consumption patterns in travel, food and housing is estimated to have a rebound effect of 35%".

Damned plasma TVs and those flights to Majorca!

According to a highly acclaimed new study, Growing Cooler: the Evidence on Urban Development and Climate Change, the alarming rate at which we burn fuel is merely symptomatic of a larger issue. Disastrous development patterns require ever greater fuel consumption, and limit our choices of where to work and live and how we move around. The authors note that "the growth in driving is due in large part to urban development, or what some refer to as the built environment. Americans drive so much because we have given ourselves little alternative. For 60 years, we have built homes ever farther from workplaces, created schools that are inaccessible except by motor vehicle, and isolated other destinations—such as shopping—from work and home. From World War II until very recently, nearly all new development has been planned and built on the assumption that people will use cars virtually every time they travel. As a larger and larger share of our built environment has become automobile dependent, car trips and distances have increased, and walking and public transit use have declined. Population growth has been responsible for only a quarter of the increase in vehicle miles driven over the last couple of decades. A larger share of the increase can be traced to the effects of a changing urban environment, namely to longer trips and people driving alone."

Even with massively increased fuel efficiency, "the rapid increase in driving would overwhelm both the increase in vehicle fuel economy and the lower carbon fuel content. In 2030, CO₂ emissions would be 12 percent above the 2005 level, and 40 percent above the 1990 level. For climate stabilization, the United States must bring the CO₂ level to 15 to 30 percent below 1990 levels by 2020 to keep in play a CO₂ reduction of 60 to 80 percent by 2050."

It's not just the Americans who have monumentally screwed up their urban planning. A prime example of our lack of joined-up thinking is the trend of the UK's National Health Service to move more and more services to centralised specialist hospitals. A great strategy, perhaps, in an era of cheap fuel, but a total tragedy in our time of growing resource scarcity.

There's still one factor we have yet to consider. The uptake of hybrid cars. Can hybrids make a difference in the near future? asks Chris Vernon over at The Oil Drum. The answer, not surprisingly, is a resounding no.

Vernon writes: "let’s assume a quarter of the UK’s new cars were fitted with hybrid technology. This would be over half a million new hybrids per year, more than twice the current combined UK sales of Toyota and Honda (the only two car companies offering hybrids in the UK). Let’s further assume these hybrids were 50% more efficient than today’s fleet average. By multiplying the numbers together we only get a 0.7% fleet-wide improvement in efficiency."

So, next time I see a Prius, I'll stop for a moment and ponder yet again.

Are hybrid cars part of the solution or a mere diversion from the real problems and their solutions?