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{{topic header| default.png |Biofuel}}
{{topic header| default.png |Biofuel}}
{{Lang|[[Biokraftstoff|Deutsch]] - [[Biofuel|English]]}}
{{Lang|[[Biokraftstoff|Deutsch]] - [[Biofuel|English]]}}
{{content from|Original:Biogas and liquid biofuels|Practical Action}}


'''Biofuel'' is a type of [[fuel]] which is made using animal or plant-based resources which are regenerated quickly. Biofuels are hence different from [[fossil fuel]]s as although fossil fuels too are created trough [[anaerobic decomposition]] of buried dead organisms, this process takes a very long time (exceeding millions of years).


{{content from|Original:Biogas and liquid biofuels|Practical Action}}
==Background==
==Background==
Biomass residues can be converted into various non-solid fuel forms. These fuels are referred to as biogas and liquid biofuels. The aim of this conversion process is to improve the quality, specific energy content, transportability, etc., of the raw biomass source or to capture gases which are naturally produced as biomass is micro biologically degraded or when biomass is partially combusted. Biogas is a well-established fuel for cooking and lighting in a number of countries, whilst a major motivating factor in the development of liquid biofuels has been the drive to replace petroleum fuels. In this fact sheet we will be looking at some of these fuels, their applications and the conversion technologies used to derive them.  
Biomass residues can be converted into various non-solid fuel forms. These fuels are referred to as biogas and liquid biofuels. The aim of this conversion process is to improve the quality, specific energy content, transportability, etc., of the raw biomass source or to capture gases which are naturally produced as biomass is micro biologically degraded or when biomass is partially combusted. Biogas is a well-established fuel for cooking and lighting in a number of countries, whilst a major motivating factor in the development of liquid biofuels has been the drive to replace petroleum fuels. In this fact sheet we will be looking at some of these fuels, their applications and the conversion technologies used to derive them.  

Revision as of 10:07, 19 July 2012

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'Biofuel is a type of fuel which is made using animal or plant-based resources which are regenerated quickly. Biofuels are hence different from fossil fuels as although fossil fuels too are created trough anaerobic decomposition of buried dead organisms, this process takes a very long time (exceeding millions of years).

Background

Biomass residues can be converted into various non-solid fuel forms. These fuels are referred to as biogas and liquid biofuels. The aim of this conversion process is to improve the quality, specific energy content, transportability, etc., of the raw biomass source or to capture gases which are naturally produced as biomass is micro biologically degraded or when biomass is partially combusted. Biogas is a well-established fuel for cooking and lighting in a number of countries, whilst a major motivating factor in the development of liquid biofuels has been the drive to replace petroleum fuels. In this fact sheet we will be looking at some of these fuels, their applications and the conversion technologies used to derive them.

In Europe and the United States, as well as in several developing countries, there is a move toward cultivating energy crops specifically for the production of biomass as a fuel. The potential for energy production from biomass throughout the world is enormous and as fossil-based fuels become scarcer and more expensive, as carbon emission levels are becoming of greater concern and as people realise the benefits of developing integrated energy supply options, then biomass could begin to realise its full potential as an energy source.

Biomass energy and the environment

There are two areas of environmental concern when considering using biomass as a form of energy. Firstly, there is the issue of land degradation and deforestation. This concern can be addressed by proper management of sustainable energy crops. Although much of the biomass requirement for energy production can be met through utilising residues from the food industry, from agriculture or from commercial activity, careful planning of energy cropping is required to prevent undue stress on the environment.

The large growth in the use of biofuels has promoted large scale mono-crop feedstock production and associated problems.

Localised decentralised biofuel production from feedstock grown using sustainable agricultural practices been shown to offer part of a sustainable energy portfolio.

With the recent global call to reduce carbon dioxide emissions, there is a strong case for promoting the use of sustainable biomass-to-energy technologies worldwide. Using modern technology, enormous reductions can be made in carbon dioxide emissions, particularly if liquid biofuels are used to replace their fossil-based equivalents. In fact, if biomass energy production is done on a sustainable basis, there is little net carbon dioxide addition to the environment.

There are other environmental concerns related to each fuel that need to be kept in mind, such as toxic emissions and production of tars and soots.

References and resources

  • Anderson, T., Doig, A., Rees, D. and Khennas, S., Rural Energy Services: A handbook for sustainable energy development. ITDG Publishing, 1999.
  • Ravindranath, N. H. and Hall, D. O., Biomass, Energy and the Environment: A Developing Country Perspective from India. Oxford University Press, 1995.
  • Karekezi, S. and Ranja, T., Renewable Energy Technologies in Africa. AFREPEN, 1997.
  • Kristoferson L. A., and Bokalders V., Renewable Energy Technologies - their application in developing countries. ITDG Publishing, 1991.
  • Johansen, T.B. et al, Renewable Energy Sources for Fuels and Electricity. Island Press, Washington D.C., 1993.

Merged material, to be integrated

Biofuels are a form of indirect solar energy, including any fuel that comes directly from biological sources:

Like fossil fuels, biofuels produce carbon dioxide. But unlike fossil fuels, the carbon dioxide produced comes from plants that sucked it out of the air last year, rather than millions of years ago. This means that biofuels are a form of closed-end recycling, whereby the waste product goes directly into production of the fuel.

Pollution is any byproduct that cannot be fed back into the closed-end system. For biofuels, this includes particulates and unburnt hydrocarbons (smoke), oxides of nitrogen, carbon monoxide, and a few others. These are typically much lower level than when fossil fuel is combusted, but they remain a problem.

What is pollution for one technology may be the biofuel in another. For example, if wood is heated anaerobically (with limited oxygen), it produces carbon monoxide, which is normally considered a pollutant, but if collected, can be burnt as a biofuel.

Source: Biofuel from the EcoReality wiki.

Biofuels from cellulose - not yet economic

Scientists have long known how to turn trees into ethanol, but doing it profitably is another matter. We can run our cars on lawn cuttings today; we just can't do it at a price people are willing to pay.
The problem is cellulose. Found in plant cell walls, it's the most abundant naturally occurring organic molecule on the planet, a potentially limitless source of energy. But it's a tough molecule to break down...
No one has yet figured out how to generate energy from plant matter at a competitive price. The result is that no car on the road today uses a drop of cellulosic ethanol. - Cellulosic Ethanol: One Molecule Could Cure Our Addiction to Oil, Evan Ratliff, Wired Magazine October 24, 2007. (The article continues, describing the history of attempts to transform cellulose, and current research.)

Biofuels in engines

With most biofuels the incompatibility with available engines provides an additional barrier to the adoption as reliable operation requires expensive engine modifications. 'flexi-fuel' engines are available in some regions, commonly spark ignition engines able to run straight petrol(US-gas) or petrol/ethanol blends.

Lists of the suitability of engines and engine components

Engines

It is possible to use biofuels in numerous different types of engines. Reliability and performance of the engine will depend on:

  • biofuel material compatibility - the compatability of fuel system and engine components to the fuel
  • Engine parameters, such as fuel delivery or spark timing, being optimised for the given fuel
  • a suitable maintenance regime


Compressed Ignition or Diesel Engine

It is possible to use a wide range of biofuels in a diesel engine, most commonly lipid based biofuels are used either in their pure form, pure plant oil, or transesterified as biodiesel.

Diesel engine fuel delivery can be altered to suit the fuel.

wikipedia diesel engine page

Spark Ignition, Petrol or Gas Engine

wikipedia internal combustion engine page detailing spark ignition and compressed ignition engines

Biofuels

Additives can be applied to fuels to improve their performance

Pure plant oils

Pure plant oils - link to PPO main page

also known as straight vegetable oil (SVO) or when using used cooking oils, waste vegetable oil (WVO). The use of animal derived oils and fats uses the same principle.

Theoretically it is possible to modify any diesel engine to run on pure plant oils (PPO). The modifications necessary to allow reliable operation vary greatly depending on the design of the engine, the type of oil to be burnt and the ambient temperatures in which the engine will be operated.

For reliable operation with PPO it is highly recommended to perform an engine health check before switching fuels as the use of PPO requires the engine to be in good order.

A widely used method for reliable operation is to convert the engine to dual fuel and fit a PPO two tank system. The engine is started on diesel fuel and switched to PPO as the engine warms. Before the engine is stopped for an extended period the fuel supply is switched back to diesel fuel for enough time to allow the fuel system to be purged of PPO. The engine is then ready to be cold started on diesel fuel.

It is possible however to modify cold start and fuelling parameters to allow engines to be started on PPO - this is known as a PPO single tank system

wikipedia SVO page

Biogas

wikipedia biogas page

Alcohol

wikipedia alcohol page

Alcohol can be a gas

Converting a vehicle to run on Ethanol

Fuel Ethanol FAQ

Biodiesel

wikipedia biodiesel page

Collaborative Biodiesel Tutorial

[1] Some innovative DIY biodiesel equipment

Wood gas

assessing differing feed stocks for woodgas systems

Engine & fuel engineering - designing long-life engines for home biomass energy systems

Around Sweden with wood in the tank

Gasifier Experimenters Kit (GEK)

Interwiki links

External links

Open Biofuel Engine Development - Collaborative biofuel engine tuning
Biofuel Bay - Biofuel primer and educational resource
Biofuel Debate Forum - Biofuel, Biodiesel and Bioenergy discussion forum


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