Microalgal and Terrestrial Transport Biofuels to Displace Fossil Fuels

Abstract

Abstract:Terrestrial transport biofuels differ in their ability to replace fossil fuels. When both the conversion of solar energy into biomass and the life cycle inputs of fossil fuels are considered, ethanol from sugarcane and biodiesel from palm oil do relatively well, if compared with ethanol from corn, sugar beet or wheat and biodiesel from rapeseed. When terrestrial biofuels are to replace mineral oil-derived transport fuels, large areas of good agricultural land are needed: about 5x10 8 ha in the case of biofuels from sugarcane or oil palm, and at least 1.8-3.6x10 9 ha in the case of ethanol from wheat, corn or sugar beet, as produced in industrialized countries. Biofuels from microalgae which are commercially produced with current technologies do not appear to outperform terrestrial plants such as sugarcane in their ability to displace fossil fuels. Whether they will able to do so on a commercial scale in the future, is uncertain.

Why microalgal biofuels won't save the internal combustion machine

“…55 Lower numbers would obviously have signifi cant impacts on costs, net biofuel yield per ha, and relative environmental impacts. Unfortunately, only a few authors have attempted to calculate or determine the energy requirements of producing algal biofuels, 56 and these studies lead to the conclusion that -at best -the energy output exceed the inputs by a factor of two. If brackish or salt water is used, evaporation will concentrate the salts and necessitate regular dilution with fresh water, and/or treatment and disposal of highly saline waste water.…”

Innovative Biological Solutions to Challenges in Sustainable Biofuels Production

“…To date, almost all bioethanol has been produced from food sources such as grain or sugarcane (Mussatto et al, 2010;Somerville et al, 2010) and expanding biofuel production from such feedstocks is likely to exacerbate food insecurity and political instability (Payne, 2010). If terrestrial biofuels are to replace ~90 EJ (= 90x10 18 J) mineral oil-derived transport fuels, large areas of good agricultural land will be required: about 5x10 8 ha in the case of biofuels from sugarcane or oil palm and at least 1.8-3.6x10 9 ha in the case of ethanol from wheat, corn, or sugar beet, an area that is equivalent to the current worldwide cropland (~1.8x10 9 ha) (Reijnders, 2009). Moreover, bioenergy crops will potentially compete with food crops for inputs such as water and nutrients.…”

“…Agriculture accounts for ~70% of all the world's freshwater withdrawals (Rosegrant et al, 2009) and a decline in water availability is already a major constraint on agricultural productivity and global food security (de Fraiture et al, 2008). Thus, sustainable production of biofuel feedstocks requires the use of land that is not required or is not suitable for food production (Marko et al, 2009;Reijnders, 2009;Fritsche et al, 2010). Development of new capabilities for biomass production on marginal or abandoned land with minimized water and nitrogen supply would be the best strategy to avoid the biofuel versus food competition.…”

From harmful to useful algae

“…Also biodiesel from algae has been suggested as a climate friendly alternative for fossil fuels in the future (Ahmad et al, 2010) although several studies indicate that with current technologies the production of biodiesel from algae is not yet energy efficient (Reijnders, 2009). Others, however, argue that biodiesel may be the only renewable alternative for fossil diesel for heavy traffic (Mackay, 2010).…”