Biodiesel

Feedstocks

There are various raw materials that can be used as feedstock for biodiesel production. To begin with, edible vegetable oils are the most common source. For instance, rapeseed is the most important feedstock in the European Union, palm oil in Malaysia, and soy in Brazil and the United States. The fact, however, that neat edible oil competes with food supply has resulted in biodiesel from such sources becoming increasingly embroiled in controversy.

Consequently, using nonedible oils so as to avoid conflict with food consumption has emerged as an attractive policy option. Jatropha, castor, and rubber seed serve here as representative examples. Jatropha in particular was once thought of as the “miracle crop” for the production of biodiesel, given that Jatropha is a drought-resistant, nonedible perennial that can be planted on marginal land and requires limited water or agrochemical supply. So far this potential has not been realized, as there are still large knowledge gaps that need to be addressed before fully commercializing Jatropha oil.

Waste oils, grease, and animal fats can also been used as feedstock for biodiesel production. One of the benefits of relying on such sources is that doing so eliminates the environmentally damaging practice of having to dispose of them. Yet developing the requisite collection infrastructure and dealing with logistics and quality control issues can be major challenges, especially with regard to waste oils and grease. Relying on animal fats poses less of a hurdle, given that the slaughter industry is generally well managed in such respects. There is, however, a biosafety concern that needs to be taken into account, as contaminated animals could potentially be the source of animal fats.

Finally, algae has been receiving growing attention in terms of biodiesel production as it does not impact food production and has a far superior yield per hectare over conventional oil crops. Producing algae to harvest oil for biodiesel has not been undertaken on a commercial scale due to high production costs and the several scientific uncertainties that still need to be addressed.

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