Liquid fossil fuels, such as paraffin (kerosene) and fuel oil, have been with us for many years. Over the past decade, similar fuels, made by processing plants, trees and organic waste products have become much more widely available. The rapid growth in the use of biofuels stems from the soaring price of fossil oil, growing concern over security of supply and the environmental impact of fossil fuels. The three main types of liquid fuel looked at in this document comprise:
- Ethanol, made by fermenting sugar cane, grain, straw, grass and wood.
- Biodiesel, made from new or recycled vegetable oils and animal fats (e.g. from palm oil)
- Oils made by compressing seeds (such as jatropha oil). Production from algae is currently being researched.
Grown sustainably, biofuels have the potential to alleviate global warming and other negative environmental issues such as the disposal of vast quantities of organic wastes.
Used responsibly, biofuels can have a major impact on levels of pollutants, both within the homes of those living in poverty, and in the crowded cities of the developing world.
When biofuels first became widely available they were heralded as the new sustainable way to provide the world with energy. More recently, the use of land for growing crops which are solely for energy has led to major environmental issues.
The market in biofuels has grown very fast, as shown in the figures for biodiesel provided by the Biodiesel 2020 survey (Emerging Markets Online). As a result, environmentalists are calling for stricter global controls on production.
Of all opportunities for renewable energy from energy plantation biomass, sugar cane makes the most sense. In many African countries where sugar was developed under colonial economies, sugar was produced (mainly for export to Europe and beyond), while the residues, such as molasses, were dumped into the rivers, leaching the oxygen from the water and destroying life. These sugar factories were very dirty operations – many still are.
Developing a market for ethanol can form part of a beneficial re-use strategy that can clean sugar factories and use the residues that previously had no value and were dumped. With advanced technologies now available, biomass, such as trees and grasses, can also be used as feedstocks for ethanol production.
A vast variety of oil plants originate in the tropics and subtropics. Many oil-bearing plants, whose oils are often toxic to humans, grow on low-grade land, or in marginal locations unsuitable for food crops. Some of these plants are cultivated on waste lands to prevent further erosion and to inhibit desertification. Use of these oils for energy provision does not need to compete with food production. Examples of these oil plants are the Physic nut tree (Jatropha Curcas L.), the castor oil plant varieties (Ricinus communis L.) and the babassu palm (Orbignya phalerata Mart.), among others.
Some oil plants grow in symbiosis with food plants by being used, for example, as shade trees, or to provide barriers against animals; jatropha is not eaten by animals so can be used in this way. Plant oils from seeds such as jatropha (which grow in many regions of tropical and subtropical countries), can be harvested and the oil extracted using hand tools. This local oil production strengthens decentralized supply, provides employment and income opportunities for the local population and promotes sustainability. The presscake, a byproduct of the oil processing, can be used either as fodder or as high-quality fertilizer. In general, all plant oils which are liquid at ambient temperatures can be utilized as cooking fuel (Stumpf, 2002).
Large-Scale Cultivation of Biofuels
The problems associated with growing biofuels stem from the industrialized world trying to grow its way out of its dependence on the internal combustion engine, and the huge profits that are to be made from growing palm oil and other high energy crops. A single hectare of oil palm may yield five tonnes of crude oil (Mongabay.com) and where rainforests are cleared, for example in Malaysia, further profits can be made through the sale of timber from land clearance. There is evidence that not all cleared land is suitable for palms and that hardwood is the main objective. This indiscriminate culling of forests has led, for instance, to oil-palm plantations covering 5.3 million hectares of Indonesia (2004). The destruction of prime forest has led to major social and cultural upheaval for indigenous peoples whose rights have been ignored (Mongabay.com).
After 25 years, lands are often so leached of nutrients that they are abandoned and become scrubland where few plants will grow. In the USA, which is seeking to reduce its dependence on overseas oil products, subsidies may mask the costs of spraying both pesticides and fertilizers, and from using of large-scale farm machinery.