Carbon payback times for crop-based biofuel expansion in the tropics: the effects of changing yield and technology

By Holly K. Gibbs, M. Johnston, J. Foley, T. Holloway, C. Monfreda, Navin Ramankutty, David P. M. Zaks. 2008

483 citations recorded by the source corpus.

Biofuels from land-rich tropical countries may help displace foreign petroleum imports for many industrialized nations, providing a possible solution to the twin challenges of energy security and climate change. But concern is mounting that crop-based biofuels will increase net greenhouse gas emissions if feedstocks are produced by expanding agricultural lands. Here we quantify the ‘carbon payback time’ for a range of biofuel crop expansion pathways in the tropics. We use a new, geographically detailed database of crop locations and yields, along with updated vegetation and soil biomass estimates, to provide carbon payback estimates that are more regionally specific than those in previous studies. Using this cropland database, we also estimate carbon payback times under different scenarios of future crop yields, biofuel technologies, and petroleum sources. Under current conditions, the expansion of biofuels into productive tropical ecosystems will always lead to net carbon emissions for decades to centuries, while expanding into degraded or already cultivated land will provide almost immediate carbon savings. Future crop yield improvements and technology advances, coupled with unconventional petroleum supplies, will increase biofuel carbon offsets, but clearing carbon-rich land still requires several decades or more for carbon payback. No foreseeable changes in agricultural or energy technology will be able to achieve meaningful carbon benefits if crop-based biofuels are produced at the expense of tropical forests.

Subfields: Agronomy and Crop Science, Biomedical Engineering, Renewable Energy, Sustainability and the Environment

View Paper: https://www.semanticscholar.org/paper/c02f7e3fbebb653fd4f7df4ec0d37395bb7f4c2c

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Agronomy and Crop Science

In Biomedical Engineering

In Renewable Energy, Sustainability and the Environment

Citations in the corpus

REDD in the red: palm oil could undermine carbon payment schemes (2009, background): “…to converting it for oil palm over the 30-year period, based on the difference in aboveground biomass between lowland tropical rainforests (225 Mg C per hectare) and oil palm plantations (76 Mg C per hectare) for tropical insular Asia (Eggleston et al. 2006; Rafli et al. 2007; Gibbs et al. 2008).”
Effects of US Maize Ethanol on Global Land Use and Greenhouse Gas Emissions: Estimating Market-Mediated Responses (2010, background): “These values suggest a “carbon payback time” (Gibbs et al. 2008, Fargione et al. 2008) of 28 years.”
High Bird Species Diversity in Structurally Heterogeneous Farmland in Western Kenya (2012, background): “…tropical conservation because small-scale subsistence farmlands are being converted at alarming rates into high-intensity farmlands owing to increasing international demands for biofuel crops, such as sugarcane, and increasing human population densities in tropical countries (Gibbs et al. 2008).”
Tropical forests were the primary sources of new agricultural land in the 1980s and 1990s (2010, background): “Regardless of the mechanism, concern continues to mount about the large emissions of carbon dioxide that result when tropical forests are felled and often burned to make room for new agricultural land (31).”
Proper accounting for time increases crop-based biofuels’ greenhouse gas deficit versus petroleum (2009, background): “This value is very important for GWI estimation because it affects how long biofuel production has to ‘pay back’ its initial LUC emissions [8, 6], and because it determines when postproduction LUC must be considered.”
Greenhouse gas mitigation by agricultural intensification (2010, background): “(27) and the 2006 Intergovernmental Panel on Climate Change (IPCC) Tier 1 GHG emissions calculations guidelines (47) and assume that carbon losses from land converted to cropland occur over 1 year and that carbon sequestration in abandoned cropland occurs over 20 years.”
The impacts and opportunities of oil palm in Southeast Asia: What do we know and what do we need to know? (2009, background): “2008) or in some cases, immediately (Gibbs et al. 2008).”
Biosecurity and sustainability within the growing global bioeconomy (2011, unknown): “Competition with food production will require a substantial part of these bio-energy requirements to be imported in many developed countries [30].”
Invasive species, climate change and ecosystem-based adaptation : addressing multiple drivers of global change (2010, background): “Additionally, land conversion for biofuel development, particulary of native forests and other ecosystem types, has been questioned in terms of its efficacy in reducing greenhouse gas emissions over a range of time-scales (Danielsen et al. 2008, Gibbs et al. 2008).”
Renewable energy and biodiversity: Implications for transitioning to a Green Economy (2017, background): “forests), exhibit the highest carbon debts and payback periods [251,252] (see Table 1).”