Monday, December 8, 2014

Flawed studies underpin low-carbon fuel policies

Nearly all of the studies used to promote biofuels as climate-friendly alternatives to petroleum fuels are flawed and need to be redone. This conclusion is just one of the findings of my advanced review paper, "The Liquid Carbon Challenge: Evolving Views on Transportation Fuels and Climate," recently published online by Wiley Interdisciplinary Reviews: Energy and Environment. The unhappy assessment is based on an in-depth review of the literature published on the topic over the past two decades.

Once the erroneous carbon accounting methods are corrected, the results will show that policies used to promote biofuels -- such as the U.S. Renewable Fuel Standard (RFS) and California's Low-Carbon Fuel Standard (LCFS) -- actually worsen the buildup of CO2 in the atmosphere rather than reducing emissions as promised. 

Monday, October 6, 2014

The Liquid Carbon Challenge

In addition to reducing how much fuel gets burned, cutting the climate risk from gasoline and other liquid fuels requires balancing their CO2 emissions by removing additional CO2 from the air in locations other than the transportation sector. 

Options for addressing carbon dioxide emissions from liquid transportation fuels

It's easy to take for granted just how important liquid fuels are in everyday life. Gasoline, diesel and jet fuel remain crucial for transportation. Petroleum fuels are the world's most widely used form of energy and rank second to coal as a source of global CO2 emissions, a situation unlikely to change for at least two decades. Although some worry about peak oil, in reality the world is not about to run out of fossil hydrocarbons that can be turned into convenient liquid fuels at an affordable price.

Sunday, September 28, 2014

Electric cars vs. smart cars

Over the past year or so, there has been a growing awareness that autonomous, self-driving cars could disrupt transportation in a big way and might even do so sooner rather than later. Some of us who closely follow automotive technology have seen this potential for a number of years. The topic is now getting a lot of airplay, sparked in large measure by Google's announcements about its R&D of self-driving cars.

I've been mulling over what it means for other automotive technologies, especially those associated with energy use, such as electric vehicles (EVs) that plug into the the power sector for fuel rather than rely on a liquid fuel such as gasoline. As noted in a post from a few years ago, EVs are not close to being cost effective for cutting carbon compared to ongoing improvements in gasoline vehicle efficiency. Hence my belief that policies that try to push EVs into the market are misguided, and that for the time being it makes more sense to foster the adoption of connected and automated vehicles.

This thinking has been explained in several short pieces published elsewhere, so no point in rehashing those arguments here (though thoughtful comments are welcome). Those posts on other sites include:

Of Carts and Horses, Cars and Smarts, on the University of Michigan Conversation blog.

The Smarter Road to Electric Cars, on Automotive Engineering International Online.

Driverless Cars before Electric Ones, on The Energy Collective. 

Cars Should Tune In Sooner, Plug In Later, as self-published on my AutoEcoRating site.

This last piece listed was the first one published and although it is substantively the same as the Energy Collective version, it may still be of interest because it's gotten the most flaming comments to date.

Postscript: I've since written an essay on "What's Next for the Automobile?" published as the introduction to a Scientific American special issue entitled The Rise of the Automobile, in January 2015.


Saturday, March 15, 2014

Cutting carbon while keeping oil -- say what?

In discussions that build on my recent papers, I've been pointing out how trying to "get off of oil" -- that is, replacing petroleum as a source of fuels for transportation in particular -- isn't actually necessary for climate protection. This conclusion challenges a lot of common thinking and especially questions the foundation for many of the public policies being pursued or advocated to address the car part of the climate problem.

Cover of The Atlantic
magazine, May 2013
Such reasoning certainly requires explanation, especially in terms that are easier to grasp than the academic papers that lay out the technical arguments. Those papers include "Factoring the Car-Climate Challenge" in Energy Policy and "Biofuel's Carbon Balance" in Climatic Change, both published last year (2013). A new paper further elaborating on this issue will be published soon.

It's critical to understand the meaning of the word necessary. I'm not saying that petroleum alternatives won't be helpful for cutting carbon; they might well be. But "necessary" is a very strong condition. Is it possible to imagine a world in which net CO2 emissions are reduced to a level that is a small fraction of what it is today -- within the bounds needed to avoid further buildup of CO2 in the atmosphere -- but which still relies extensively on petroleum a source of fuel?  The answer yes, and it just takes one hypothetical counterexample to show that getting off of oil isn't strictly necessary.

The example involves mechanisms that remove carbon from the atmosphere at a rate much faster than is happening now and indeed fast enough to fully counterbalance the amount of CO2 that spews into the atmosphere when petroleum fuels are burned. Those emissions currently amount to about 3 petagrams per year (Pg/yr; a petagram is the same as a billion metric tons) on a carbon mass basis, or about 11 billion metric tons per year of CO2 emissions, representing about one-third of total anthropogenic CO2 emissions (see the Global Carbon Project for the latest detailed estimates).

That amount of CO2 removal is an enormous challenge, but there's no scientific reason to rule it out as a long-term solution. For perspective, plant growth on land plus biological and chemical CO2 uptake in the ocean together remove carbon from the atmosphere at a rate of about 200 Pg/yr. Most of that gets re-emitted annually, but a concerted effort at large-scale carbon management could change the balance enough to offset a large portion of fossil-based CO2 emissions. Such carbon dioxide removal ("CDR") strategies can help to address any form of excess CO2 emissions, but they are particularly important for addressing liquid fuel use because it is not feasible to capture carbon from car, truck or jet exhausts (in contrast to large stationary sources such as power plants).

This post just examines the necessity question. Other questions certainly arise regarding costs and issues of timing (i.e., what can be done to mitigate emissions sooner rather than later, and also what must be done to achieve very deep reductions over the long run). In terms of cost, improving fuel efficiency offers a greater carbon-cutting bang-for-buck than non-petroleum alternatives, at least for the foreseeable future. Nevertheless -- and especially in the face of globally growing transportation activity -- efficiency will not suffice for getting emissions down to the very low levels likely to be needed.

That leaves another question hanging: if getting off of petroleum isn't necessary but merely using it more efficiently isn't sufficient, then what?  Well, that is indeed a tough question, and it's a key question that the research discussed here will both address and pose as a challenge to others.

Thursday, January 23, 2014

The RFS and the climate challenge

The Renewable Fuel Standard (RFS) confronts many issues but perhaps its ultimate test is how well it helps meet the climate challenge. The world isn't running out of oil and so the business case for renewable fuels hinges on their role in reducing CO2. That role is much more restricted and farther into the future than RFS advocates, including many green groups, have assumed. From a carbon perspective, the very premise of the RFS is fatally flawed.

Recent analysis reveals that fuel lifecycle models, such as those used in policies including the RFS and California's Low-Carbon Fuel Standard (LCFS), make a serious mistake in their baseline assumptions. This error cuts to their very core but is only just now coming to light. This isn't another debate about net energy or processing efficiency. Rather, it's about how these policies build in an assumption of carbon neutrality without first verifying the conditions under which it is true. 

The RFS assumes that just because biomass recycles carbon, then substituting a biofuel for a fossil fuel automatically neutralizes the CO2 coming out the tailpipe. That's not true for the biofuels now produced at market-meaningful scale.
Does a corn field absorb more CO2 from the atmosphere when it
is harvested for fuel than when it is harvested for feed or food? 

Let's think about what occurs when you substitute ethanol for gasoline, and let's start with the facts on the ground. There, the threshold question is this: does a harvest keep more CO2 out of the air when it's used for fuel than when it's used for other purposes? For example, does corn that goes into biofuel remove more CO2 from the atmosphere than the corn that goes into cornmeal? The answer is no.

Now, if we grew feedstocks on barren land, say in a desert where nothing was growing before, then that would absorb more CO2 than was otherwise being absorbed. But that's not what's happening. The vast majority of renewable feedstock is harvested from land that was already in production.

You might argue, well, doesn't carbon stay in the ground when you use a biofuel instead of gasoline?  Yes, carbon stays in the ground, but that doesn't necessarily mean that less gets into the air. A reduction occurs only if you increase the net rate at which CO2 is removed from the air in other locations. 

Remember that at the car, the amount of CO2 directly emitted varies little among liquid fuels. And so as far as climate is concerned, if biofuels have a benefit, it's not when they're burned. 

It always comes down a question of how much more CO2 gets taken out of the air somewhere else. Lifecycle models completely gloss over that question. Because they leave existing land use out of the equation, their carbon balance calculations are incorrect. This problem is more fundamental than the issue of indirect land-use change (ILUC), which only adds to the uncertainties involved. 

In short, lifecycle policies such as the RFS and LCFS are a mistake as far as climate is concerned. They risk doing more harm than good. Policymakers need to go back to the drawing board and do the careful homework that was never done before these programs were put in place. 

This post reflects remarks made at the SAE Government-Industry Meeting panel on "Crosscutting Challenges for the Renewable Fuel Standard," held in Washington, DC on January 23, 2014. Supporting information is available in a technical brief released that day, and the remarks also draw on the paper, "Biofuel's carbon balance: doubts, certainties and implications," published in
Climatic Change 121(4): 801-814,