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Introduction to Biofuels

What are biofuels?

Biofuels are a type of fuel derived from organic matter (broadly described as biomass) produced by living organisms i.e. plants and animals. Biofuels can also be referred to as substitutes for fossil fuel sourced mainly from a range of agricultural and energy crops, forests and waste streams[1].


biofuel types

 Some types of biofuel feedstock


  
The uses of biofuels are varied; unprocessed biomass can be used to generate electricity via steam turbines and gasifiers, or heat by directly combusting the raw material. Biomass can also be converted to bioliquids and used as fuels for transport, as is the case with bioethanol and biodiesel. Finally, biomass can be converted to an energy-rich gas (biogas or bio-SNG) that can be used in boilers and gas turbines to generate heat and electricity, used in gas-fuelled transport as compressed biomethane (CBM) or supplied to the gas grid.

Biofuels can be categorised into two major types: 1st generation biofuels and 2nd generation biofuels. 1st generation biofuels are biofuels currently on the market today produced largely from food crops e.g. corn and 2nd generation biofuels are those fuels produced by utilising the whole plant rather than just the sugar/oil component of the food crops.

The drivers behind biofuels

The main factors driving the use of biofuels forward include the need to secure our energy supplies, the need to reduce our over-dependence on fossil fuels and the legally-binding obligation to reduce our greenhouse gas (GHG) emissions. Also, the fact that biofuels can be sourced and produced locally is a major driver and an added advantage for countries highly dependent on importing energy supplies, as well as rural villages that are off any energy grid.

What are the potential impacts of using biofuels?

The potential impact of using biofuels hinges widely on a number of factors. These include:
  • Environmental factors

Environmental factors include the issues around land used for biofuel feedstock production, the stress cultivation of biofuel crops put on water resources (water is required for irrigation purposes in some climates), the threat of possible biodiversity loss, and the net change in carbon emissions as a result of the final biofuel end-use.

  • Social and economic factors

The social factors include the risk of diverting land and seeds used to produce food crops such as corn, a major foodstuff in the less privileged parts of the world, for the production of biofuels which leads to the increase in the global market price of the commodity as a result of the reduced quantities specifically produced for feeding, and the fact that most food crops are traded on the global market.

  • Technical factors

There are a number of technical issues associated with biofuels, most of which are around the amount of energy used in the farming and cultivation stages of the feedstocks, and the amount of energy (in terms of fossil fuels) used to transport and convert the feedstocks into the final biofuel product. This is characterised by the "net energy gain" which is defined as the amount of energy released from the fuel less the amount of energy put into the manufacture of the fuel. The biofuel is regarded as unsustainable if this works out to be a negative number.

Below is matrix showing the impacts of using biofuels.


BIM

The Biofuel Impact Matrix (BIM)

Some interesting stats

The International Energy Agency (IEA) suggests that by 2050, biofuels could meet about 27% of total global transport fuel demand, as well as save 2.1 gigatonnes (109 tonnes) of CO2 emissions per year that would have otherwise been produced from fossil fuels. This claim has been reflected in the amounts of biofuels traded globally.

In 2010, the global production of biofuels increased by 17% to 105 billion litres, up from 90 billion litres the year before. And when this is compared with the amount of oil consumed in 2010, which was at 5074 billion litres, puts the global demand for biofuels into perspective

In 2008, biomass became the largest source of renewable energy generating around 50 exajoules (EJ) (1200 million tonnes of oil equivalent) of bioenergy globally, which accounted for a 10% share of the total primary energy demand in the same period. Projected world primary energy demand by 2050 is expected to be in the range of 600 to 1000 EJ, and various scenarios indicate that the future demand for bioenergy could be up to 250 EJ/yr, representing between a quarter of the future global energy mix[2].


global biofuel

Global biofuel production 2000 - 2010 (Source IEA)[2]


Biofuel production from biomass

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