Use of Euphorbia sp. (Euphorbiaceae) as biofuel feedstock for semi-arid and arid lands

Abstract

Plant-based biofuels are globally accepted renewable alternatives to fossil fuels. Both biodiesel and bioethanol can be derived from various plant-based feedstocks using conventional and advanced conversion technologies. However, the use of conventional first-generation plant feedstocks creates a ‘food versus fuel’ conflict through competition with agriculture for arable land and freshwater resources. In this regard, succulent, latex-yielding species of Euphorbia (Euphorbiaceae) have advantages as feedstock for liquid biofuel production. These include high levels of primary productivity, a remarkable ability to grow on marginal lands under xeric conditions, and a relatively small bioenergy freshwater footprint. In addition, yields of Euphorbia-based biofuels are relatively high, and the fuel has chemical, physical, and combustive properties that are comparable to or exceed those of fossil fuels. In this review, we summarize the status of biofuel research using Euphorbia feedstock. Harvesting and drying of biomass, extraction, characterization and refinement of biocrude, blending with diesel, fuel properties, effects on engine performance and emissions, and use of spent residues for production of bioethanol and other valuable co-products are discussed. Major challenges and future opportunities associated with Euphorbia-based biofuel development are considered.