Need energy? Let's talk biofuels

In the most general sense, any non-fossilised organic matter (biomass) that is used by humans as a source of energy for external ‘work’ (beyond food that is) can be referred to as a biofuel. In virtually any situation where a source of fuel is needed, there is a biofuel that could do the job. Richard Bawden reports on an energy solution you've never heard of.

In the most general sense, any non-fossilised organic matter (biomass) that is used by humans as a source of energy for external ‘work’ (beyond food that is) can be referred to as a biofuel. From this perspective our earliest ancestors were using biofuels when they burned wood or animal dung for heating and cooking. In similar vein, the oils, resins, fats and other material of animal, plant, algal, and even insect origin that have been used for millennia in torches and lamps to generate light, would also qualify.

While the advent of the industrial age resulted in an exponential increase in the range of uses for biofuels, the word itself has come to only refer almost exclusively to processed liquid fuels. Over the decades, liquid biofuels have found applications in transport, electricity generation, a multitude of industrial processes, as well as both commercial and domestic heating and lighting. Indeed in virtually any situation where a source of fuel is needed, there is a biofuel that could do the job. And just as industrialisation has provided the motivation for the development of efficient and cost effective biofuels, so too has the industrialisation of biofuel production led to their ever-increasing conversion efficiencies and cost effectiveness. It has also led to ever-decreasing detrimental environmental impacts with a particular emphasis on reduced greenhouse gas emissions.

Conventionally these progressive developments have come to be expressed in terms of four different generations of biofuels that can be differentiated both by their respective ‘feedstocks’, or basic biological materials, and/or the actual class of organic fuel that is the end product. First generation biofuels for instance, which included ethanol, propanol, and butanol, utilise starches from such crops as sugarcane, wheat, corn, and even potatoes. Whilst these continue to be the most common biofuels in use around the world, they suffer the very significant disadvantage that they threaten food security by displacing agricultural crops that are grown for food. Second-generation biofuels that include methanol, cellulosic ethanol, and a range of algal-based biofuels have addressed this food-versus-fuel threat by switching the feedstock to plants that do not represent competition for arable land, such as trees and grasses, or are inedible or non-utilisable parts of food crop plants. They also represent the introduction of algae as a potential feedstock.

Development of the emerging third generation of biofuels is focusing on very significant expansions of the processing of algae that are being deliberately cultivated on a very large scale in brackish and straight seawater—the oceans have come to replace the land as the medium for feedstock. As far as the infant fourth-generation is concerned, the medium has shifted from nature entirely to the industrial laboratory where biological organisms, including algae, are metabolically engineered to actually secrete ethanol and butanol.

Given that biomass, in contrast to fossil fuels, is a renewable resource, given that the environmental impact of biofuel generation and use is significantly less than that of fossil fuels, and given that biofuels can be generated from so-called ‘waste material’, logic would suggest that by now they would be playing a much more major role in supplying our energy needs than in fact they currently are. While the situation regarding the replacement of fossil fuels by biofuels is clearly influenced by an exceedingly complex mix of natural, social, political, economic, cultural, and technological factors, three crucial issues can be identified as being at the heart of the matter ‘on the other side’ of such complexity: Availability, affordability, and acceptability.

These are worthy of our attention.

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