The global scientific community recently gathered in Paris for a preparatory meeting as part of the lead-up to the United Nations Climate Change Conference (COP-21) being held in the French capital this December.*
With the elusive goal of forging a legally binding global climate agreement just a few months away, climate scientists are weighing how to get the world on track to limit climate change to a two-degree Celsius increase.
The International Energy Agency estimates that the window for achieving this target is almost closed — but not quite. Achieving deep reductions in greenhouse gas (GHG) emissions in the transportation sector by 2050 will need to play a key part since transportation accounts for 25% of energy-related carbon dioxide equivalent (CO2e). The IEA estimates that at least a 50% reduction in transportation CO2e GHG emissions will be needed globally in that time frame. (Additionally, a nearly complete phase out of CO2e for all energy sectors will be required by 2075.)
A new article** that I and several co-authors (Lee R. Lynd, Alexander Körner, Nathanael Greene and Luke R. Tonachel) have just published in Biofuels, Bioproducts and Biorefining looks at the feasibility of hitting such 2050 and 2075 transportation targets—and in particular at the question of whether the world can hope to reach these kind of targets without a strong contribution from biofuels. In short, we address the question of whether the world needs biofuels by examining the feasibility of doing without them.
Our conclusions are clear: Even with aggressive reductions in global passenger and freight travel growth, shifts to mass transport modes, strong efficiency improvements and deep market penetration by vehicles running on electricity and hydrogen, there could remain a large demand for “dense” liquid fuels in 2050 (80% of transportation fuel) and even in 2075 (50%). This liquid fuel demand is due largely to aviation, ocean shipping, and long-haul trucking. Electricity and hydrogen may not be suitable in such cases, but “drop-in” biofuels will be.
Acknowledging the significant uncertainties involved in such projections and the challenges faced by all candidate technologies and fuels, we conclude that it will be difficult to achieve a low-carbon transportation sector without widespread use of biofuels, and that aggressive efforts to develop sustainable, low-carbon biofuels alongside other options are warranted.
Why did we focus on biofuels? There is a notable lack of consensus about whether biofuels can contribute to future energy supply on a scale large enough to meaningfully impact global energy challenges. While major challenges exist across all three potentially very low CO2e fuels (biofuels, hydrogen, and electricity), biofuels especially have become the focus of the question “can they play a major role?” but also “should they?”
In our article, we explore scenarios where electricity and hydrogen are utilized to as great a degree as we find plausible, in order to identify the gap that would have to be filled by biofuels. This helps us understand what the situation will be if we are not able to achieve truly sustainable, low GHG biofuels in large volumes around the world—currently a significant possibility.
We focus on scenarios that achieve the very low targeted CO2e emissions, reflecting the consensus that deep reductions are needed to avoid radical changes to the world’s climate with great attendant risks. We conduct this analysis in the context of the IEA scenarios and, in fact, base it specifically on the Energy Technology Perspectives 2012 scenarios, which I and one other of the authors were involved in developing. The article fleshes this ETP 2012 scenario out further, showing how much of different types of fuels we might see adopted by various modes over the coming decades, in what is truly a very ambitious low-carbon pathway.
In summary, we demonstrate in this paper that to achieve transportation two-degree targets it will take very strong actions across all transportation modes, worldwide – maximum efficiency improvement, maximum use of the most efficient modes, and curbing demand growth. But ultimately it also will take large volumes of very low-carbon fuels.
We find that if the world does not continue to develop very low-carbon, advanced biofuels (such as cellulosic ethanol and drop-in gasoline and diesel replacement fuels), it is unlikely that we can achieve transportation targets. There is some reason for optimism as larger advanced biofuels facilities begin to come on line in the U.S. and in other countries. But given the pace of progress so far, this is far below what will be needed.
A significant ramp up in advanced biofuel research, development, and demonstration efforts is needed—supported by policies to strongly stimulate deployment and uptake of advanced biofuels, while discouraging the “wrong” kind of biofuels: those that do not have inherently low GHG life-cycle scores or that could trigger strong indirect effects. And such policies must be consistently applied in many countries around the world in order to have a chance to reach the needed volumes.
We must be very careful to avoid stimulating production of destructive biofuels that adversely impact global land use and even elevate rather than reduce transportation CO2e emissions. At the same time we must avoid shutting down the promising potential for advanced, low-carbon biofuels, as we seek a sustainable global future. Above all, we must redouble efforts to carefully assess and scale up the most promising technologies and pathways.
Photo: Switchgrass may play an important role in a sustainable biofuels future.
Lew Fulton previously wrote about biofuel innovations and advanced biofuels in a July 2014 GreenLight blog and co-authored research study.