Selected tags: Nature

Nature: The Rebound Effect Is Overplayed

This commentary was originally posted on EDF's Market Forces blog.

Trying to put the rebound effect for energy efficiency in its rightful place is like playing a game of wack-a-mole. Predictably every couple of years, someone new discovers the counter-intuitive appeal of showing how more efficient energy policies may lead to more energy use. Wham! Told you there's something wrong with those clean-car standards. Well, not so fast.

Yes, the rebound effect is real. But it's also small. And what's there is actually positive! Why shouldn't people who can now afford to due to more efficient energy technologies be able to improve their lives?

Together with three co-authors (Ken Gillingham at Yale, Dave Rapson at University of California, Davis, and Matt Kotchen, currently on leave from Yale to serve as Deputy Assistant Secretary for Environment and Energy at the U.S. Treasury), I surveyed a bajillion+1 energy efficiency rebound studies. Nature then made us cut down those references to 6. We settled at 9.

We couldn't find a single study that has the rebound be above 100% or anything close to it, what's necessary to nix energy efficiency savings. The maximum number you can get is 60%, and that's already quite a stretch. Think 30% as the upper bound for actual behavioral responses. Yes, we are more efficient today than we were a hundred years ago, and we also use more energy today. But that's far from talking about the rebound effect. It's simply economic growth.

Establishing a causal link between efficiency and energy use isn't quite as simple. In the end, the rebound effect comes in four forms. Buy a more fuel-efficient car, and driving that next mile just became cheaper. The result: a bit more driving, to the tune of 5 to a maximum of 30%, although most likely much closer to 5-10% of the initial fuel savings. Then there's the indirect effect: Drivers may now use some of the savings to buy other products that consume energy.

You can already see that we can't just add these two effects. If you spend some of the gas money on driving more, you have less to spend on that plane ticket, and vice versa.

Then there are two macroeconomic effects: one via the price and one via technological advances. They are the trickiest to pin down and could, in theory, be the largest. But theory lends a helping hand in getting an upper bound: the basic demand-and-supply relationship tells us that the macroeconomic price effect can't be more than 100%.

And once again, all these effects aren't anywhere near that threshold. 60% is as high as it gets for the combined effect, and only in rare circumstances. For the most part, it's much closer to 5 to perhaps 30%.

So where does that leave us?

When designing energy efficiency policies like clean-car standards, consider the rebound effect, much like the government already does. The Department of Energy's model uses a highly appropriate 10% rebound figure for the car standards. And that's about it. Not much else to see here.

If you did want to take it a step further — full disclosure: a step I couldn't convince my three co-authors to take in the Nature piece itself — everything else equal, the existence of the rebound effect may prompt us to use even stricter energy efficiency standards. If you have an overall target in mind, and the rebound effect shaves off a bit, you ought to consider using a slightly stricter target to get back to where you wanted to be.

For more, check out the full Nature piece. Well worth the $32 to put the rebound effect in its rightful place once and for all.

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Measuring Fugitive Methane Emissions

In recent days, news reports and blog posts have highlighted the problem of fugitive methane emissions from natural gas production — leakage of a potent greenhouse gas with the potential to undermine the carbon advantage that natural gas, when combusted, holds over other fossil fuels. These news accounts, based on important studies in the Denver-Julesburg Basin of Colorado and the Uinta Basin of Utah by scientists affiliated with the National Oceanic and Atmospheric Administration (NOAA) and the University of Colorado (UC) at Boulder, have reported troubling leakage rates of 4% and 9% of total production, respectively —higher than the current Environment Protection Agency (EPA) leakage estimate of 2.3%.

While the Colorado and Utah studies offer valuable snapshots of a specific place on a specific day, neither is a systematic measurement across geographies and extended time periods  and that is what’s necessary to accurately scope the dimensions of the fugitive methane problem. For this reason, conclusions should not be drawn about total leakage based on these preliminary, localized reports. Drawing conclusions from such results would be like trying to draw an elephant after touching two small sections of the animal’s skin: the picture is unlikely to be accurate. In the coming months, ongoing work by the NOAA/UC team, as well as by Environmental Defense Fund (EDF) and other academic and industry partners, will provide a far more systematic view that will greatly increase our understanding of the fugitive methane issue, though additional studies will still be needed to fully resolve the picture. What follows is a briefing on the fugitive methane issue, including the range of measurements currently underway and the need for rigorous data collection along the entire natural gas supply chain.

Why methane leakage matters. Natural gas, which is mostly methane, burns with fewer carbon dioxide emissions than other fossil fuels. However, when uncombusted methane leaks into the atmosphere from wells, pipelines and storage facilities, it acts as a powerful greenhouse gas with enormous implications for global climate change due to its short-term potency: Over a 20-year time frame, each pound of methane is 72 times more powerful at increasing the retention of heat in the atmosphere than a pound of carbon dioxide. Based on EPA’s projections, if we could drastically reduce global emissions of short-term climate forcers such as methane and fluorinated gases over the next 20 years, we could slow the increase in net radiative forcing (heating of the atmosphere) by one third or more.

Fugitive methane emissions from natural gas production, transportation and distribution are the single largest U.S. source of short-term climate forcing gases. The EPA estimates that 2.3% of total natural gas production is lost to leakage, but this estimate, based on early 1990’s data, is sorely in need of updating. The industry claims a leakage rate of about 1.6%. Cornell University professor Robert Howarth has estimated that total fugitive emissions of 3.6 to 7.9% over the lifetime of a well.

To determine the true parameters of the problem, EDF is working with diverse academic partners including the University of Texas at Austin, the NOAA/UC scientists and dozens of industry partners on direct measurements of fugitive emissions from the U.S. natural gas supply chain. The initiative is comprised of a series of more than ten studies that will analyze emissions from the production, gathering, processing, long-distance transmission and local distribution of natural gas, and will gather data on the use of natural gas in the transportation sector. In addition to analyzing industry data, the participants are collecting field measurements at facilities across the country. The researchers leading these studies expect to submit the first of these studies for publication in February 2013, with the others to be submitted over the course of the year. Read More »

Posted in Methane, Natural Gas | Also tagged , , | 4 Responses, comments now closed