On the basis of available data, it is also possible to draw general conclusions as to the question of whether categories of transport biofuels are better or worse regarding life cycle greenhouse gas emissions than conventional fossil transport fuels, such as diesel and petrol. The latter have a life cycle greenhouse gas emission of about 3.6kg CO2 equivalent kg-1 fuel (EUCAR et al. 2007; Reijnders and Huijbregts 2008b). In the following, comparison between fuels will be made on the basis of equal energy generation.

Transport Biofuels from Crops on Peat

Transport biofuels from crops grown on peat land do badly as to greenhouse gas emissions. This is linked to the large carbon losses from peat land when used for cultivation. This has been shown for bioethanol in Europe (Reijnders and Huijbregts 2007) and for palm oil from Southeast Asia (Danielsen et al. 2008; Fargione et al. 2008; Reijnders and Huijbregts 2008a). This will also hold for produce of the sago palm, which often grows on peat land (Melling et al. 2005a, b; Singhal et al. 2008). Sago has been called the ‘ starch crop of the twenty — first century ’ and suitable for the production of the transport biofuel ethanol (Singhal et al. 2008). The yield of sago plantations is 2-3 Mg starch year-1ha-1 (approximately 0.6-0.9 Mg C) (Singhal et al. 2008), but the annual loss of C from peaty soil is approximately 11 Mg C year-1 ha-1, partly as methane (Melling et al. 2005a, b). When mineral soils have a high carbon content, as in the case of peaty clay, net greenhouse gas emissions will also be relatively high (Reijneveld et al. 2009), making transport biofuel production on such soils relatively unattractive for mitigating climate change.