Ecosystem carbon payback time Palm
Sugarcane Cassava Coconut Rice Maize
Soybean Wheat Castor
Sugarcane Cassava Palm
Coconut Wheat Rice
Groundnut Soybean Castor
Sugarcane Cassava Rice
Years 24 100 200 500 Figure 3.1.6 Ecosystem carbon payback time 1 000 2 000 3 000 5 000 6 000
The ‘carbon debt’ of biofuels on the other hand, is the number of years it can take to offset the carbon emissions generated by converting land for biofuels. It can take decades or centuries for some pathways to bounce back, depending on the type of land that was converted. Particularly challenging is when crops are grown on converted peatland or forest, or areas with underground carbon storage. The figures are disputed, but even lower figures still raise serious concerns that need to be addressed. Analysis applying the concept of ‘ecosystem carbon payback time’ is useful to identify the right options for converting land to biofuel production.
Grassland Woody savanna Disturbed forest Forest Peat forest
NB: Calculations made for tropical humid habitats with a payback period for potential biofuel production based on crop yields circa 2000, but with today’s expertise in agriculture and technology.
Indirect land-use change induced by inc 2020 estimates for top 10 European countries
France Source: IIEP, Anticipated Indirect La Figure 3.1.7 Indirect land-use change induced by increased biofuels production
Demand development Figure 3.1.7 indicates land requirements for biofuels production in response to current biofuels mandates. Depending on projected biofuels demand and available arable land, additional land requirements may exceed a nation’s own resources, and hence have a spill-over effect on other countries and regions.