Dedicating more land to biofuel production can lead to increased greenhouse gas emissions, which take decades to make up for. A new study shows that geography is a key factor determining how big that impact is.
A new study published in the journal Nature Climate Change shows that, when looking at the production site alone, growing biofuel crops can have a significant impact on climate depending on location and crop type. The study is the first geographically explicit life cycle assessment to consider the full range of greenhouse gases emissions from vegetation and soil carbon stock to nitrogen fertilizer emissions in all locations in the world.
Greenhouse gas payback times for corn-based bioethanol in intensively farmed crop locations, (where fertilizers and irrigation are used).
Elshout et al, 2015. Nature Climate Change
In the last couple of years, research has begun to raise questions about the sustainability of biofuels. Life cycle assessments—a method that calculates the environmental impact of a product through its entire production and use cycle—have returned uncertain results on biofuels, and new research has also begun to consider carbon emissions caused by land use change.
“When you convert wetlands or forests for biofuel production you lose a major carbon sink, so even if you are saving emissions by reducing fossil fuel use, in the short term you are increasing total emissions,” says IIASA Ecosystems Services and Management Program Director Michael Obersteiner, who co-authored the study along with researchers from IIASA, Radboud University in the Netherlands, and other partners.
In the long term, natural ecosystems such as forests and grasslands sequester carbon from the atmosphere and store it in vegetation and soils. While crops also absorb carbon from the atmosphere, they do not build carbon storage, and unsustainable agricultural practices can also lead to erosion and run-off that further degrades the carbon storage capability of soils.
The new study provides a method of accounting and evaluating biofuels based on a field-level high resolution greenhouse gas accounting. It calculates the time it would take, on a specific piece of land, for biofuel production to make up for the emissions it generates by converting from what was there prior to biofuel production. The researchers call this measure “greenhouse gas payback time.”
The study was led by Radboud University PhD candidate Pieter Elshout. He says, “Our model is the first that offers a global, spatially-explicit overview of biogenic gas emission resulting from crops used to produce biofuels. In developing this model, our calculations of the durations of payback times took account of the entire production chain for fossil fuels and biofuels with the accompanying greenhouse emissions.”
They find that the payback time varies widely around the world depending on the current land use of the specific location, crop type, and cultivation method. The most important factor was the location, according to the study, accounting for 90% of the variation on payback time.
“This study shows that geography is really the number one factor influencing the direct climate impact of biofuel production. We need to have more precise measurements of what is currently happening on a piece of land when evaluating the direct effects on biogenic carbon emissions of biofuels to be grown there,” says Obersteiner.
The researchers found that current land use and crop type played a big role in the payback time. When grown with no input (such as irrigation or fertilizer), rapeseed is found to have the lowest direct impact, with an average payback time around 20 years, and sugarcane the longest, with a global median of 60 years. When it comes to intensive agriculture, however, payback times systematically decrease for all crop types. The most efficient feedstocks appear to be cereals, such as winter wheat and corn, with payback times lower than 10 years.
While this study unearthed the value of high resolution information for the assessment of biofuels impacts, a broader sustainability perspective on agricultural products emissions remains indispensable, say the researchers. Previous IIASA research has shown that sustainability criteria limited to biofuels could prove inefficient by ignoring other agricultural uses and consumption changes in other parts of the world. [http://www.iiasa.ac.at/publication/more_XJ-13-089.php]
In addition, indirect land use change impacts can change the overall emission balance of biofuels, by displacing other crop production, through trade and demand responses.
IIASA is preparing a complementary study [http://www.iiasa.ac.at/web/home/research/researchPrograms/EcosystemsServicesandM...] on this matter, expected to be published this summer. It looks at a large range of crop-based but also advanced biofuels, using cereal straw or short rotation coppice.
“Today’s paper confirms that standard life cycle assessment approaches, by ignoring geography, have overly simplified biofuel greenhouse gas assessment. Bringing in the full agricultural system responses with indirect land use change could lead to even more nuanced insights on the final environmental merit of the different biofuel feedstocks,” says Hugo Valin, one of the lead authors of the ongoing study.
Elshout PMF, et. al. 2015. Greenhouse-gas payback times for crop-based biofuels. Nature Climate Change. doi:10.1038/NCLIMATE2642
+31 (0)24 365 2060
Ecosystems Services and Management
+43(0) 2236 807 460
Katherine Leitzell | idw - Informationsdienst Wissenschaft
NASA finds newly formed tropical storm lan over open waters
17.10.2017 | NASA/Goddard Space Flight Center
The melting ice makes the sea around Greenland less saline
16.10.2017 | Aarhus University
University of Maryland researchers contribute to historic detection of gravitational waves and light created by event
On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...
Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.
Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....
Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).
When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...
Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.
How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...
Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.
It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...
17.10.2017 | Event News
10.10.2017 | Event News
10.10.2017 | Event News
17.10.2017 | Life Sciences
17.10.2017 | Life Sciences
17.10.2017 | Earth Sciences