Explanations of widely used biodiesel terms
It can be used as road fuel in compression-ignition (diesel) engines with little or no modifications.
Biodiesel is effectively carbon neutral – the carbon dioxide emitted on combustion replaces the atmospheric carbon dioxide originally extracted by the plants that were used to make the vegetable oil.
A diesel fuel’s cold-weather characteristics are measured by the cloud point, the cold filter plugging point, and the pour point, which occur in the following order:
The cloud point is the temperature at which small, solid crystals can be observed as the fuel cools.
The cold filter plugging point is the temperature at which a fuel will cause a fuel filter to plug due to fuel components which have begun to crystallize or gel. This is considered by many to be the true indication of low temperature operability.
The pour point refers to the lowest temperature at which there is movement of fuel when the container is tipped.
Compared to mineral diesel, biodiesel tends to have a much narrower range of temperatures between the cloud point and the pour point. This can be managed by altering the mixture of biodiesel/mineral diesel during cold weather periods.
A CHP power plant is an electricity generator, combined with equipment for recovering and using the heat produced by that generator. As a result, CHP plants can reach much higher efficiencies of up to 80%, compared with 50% achieved by Combined Cycle Gas Turbines, or 40% by coal-fired plants.
There are many types of CHP plants such as gas combustion engines or steam turbines, using many different fuels such as oils, natural gas, biomass, and municipal waste.
These are Quality Standards for biodiesel:
EN14214 is for automotive biofuels, and represents the uniform standard for Fatty Acid Methyl Esters (FAME) used across Europe.
ASTM 6751 is the equivalent American and Canadian standard for biodiesel.
EN14213 is the European standard for heating biofuels.
Feed-in-tariffs were introduced in April 2010. Administered by Ofgem, they provide financial incentives to encourage the uptake of mainly small to medium scale renewable electricity generation.
Payments are made by electricity suppliers for the amount of electricity generated (the generation tariff) and an additional amount for any electricity exported to the national grid (the export tariff).
Renewable energy refers to energy from resources that are naturally replenished over a relatively short period of time such as sunlight, wind, waves, tides and geothermal heat.
Biomass such as woodchips and biofuels such as biodiesel are only considered renewable if the woodlands or energy crop farms are replanted after harvesting.
The Renewable Heat Incentive (RHI) is a government scheme (administered by Ofgem), providing financial incentives to promote the use of renewable fuels for heating.
The commercial scheme was launched in November 2011, whilst the homeowners scheme was launched more recently, in April 2014.
Technologies eligible under the RHI include solar, ground and air source heat pumps, geothermal, biogas and biomass. However, bioliquids such as biodiesel are not currently included in the RHI scheme.
The Renewables Obligation (RO), launched in 2002, is the main financial mechanism by which the government supports large-scale renewable electricity generation.
The RO places an obligation on licensed electricity suppliers in the UK to source an increasing proportion of electricity from renewable sources. This obligation has increased from 3% in 2002 to 20.6% in 2013.
Ofgem administers the scheme and awards one Renewable Obligation Certificate (ROC) for each eligible megawatt of renewable energy generated by an accredited generator.
Suppliers must present sufficient ROCs to Ofgem to meet their obligation or, if there is a shortfall, pay a penalty into the buy-out fund (which is then shared amongst suppliers who presented sufficient ROCs).
The Renewable Transport Fuel Obligation (RTFO) requires transport fuel suppliers to ensure that a percentage of road transport fuel comes from renewable sources (biodiesel, bioethanol and biomethane) and is sustainable.
This percentage increased to 4.75% in 2013, but there are currently no plans for any further increases.
The Department for Transport administers the scheme and awards one Renewable Transport Fuel Certificate (RTFC) for each litre of sustainable biofuels supplied. For renewable fuel made from waste such as biodiesel from used cooking oils, 2 RTFCs are awarded for each litre supplied.
Suppliers must present sufficient RTFCs to meet their obligation or, if there is a shortfall, pay a penalty into the buy-out fund (which is then shared amongst suppliers who presented RTFCs).
Sustainability refers to ways of living and of operating businesses to ensure the ongoing endurance of our planet’s natural resources.
In terms of energy, it means using energy wisely (efficiently and reducing waste) and using energy from clean, renewable sources to ensure we have sustainable energy for future generations.
Tallow refers to the fats produced from the processing of meat and meat products mainly beef, mutton and pigs.
Tallow can be used for the production of biodiesel but requires more chemicals and care than vegetable oils, having a relatively high Cold Filter Plugging Point and therefore unsuitable in colder regions without coldflow additives.
Transesterification is a chemical process whereby the vegetable oils or animal fats are reacted with an alcohol to form esters and glycerol. A strong alkaline is used as a catalyst to allow the process to occur under relatively low temperature and pressure.
UCO is vegetable oil which has been used for cooking or frying food, often several times over. It is collected from restaurants, takeaways, canteens, food manufacturers etc, to be processed into biodiesel.
However, UCO is usually a mixture of different oils, contaminated with food, water, and animal fats, which must all be removed before being converted to biodiesel. Since the quality of the oil deteriorates as a result of the cooking process, more chemicals are required when using UCO compared to virgin oils.
Sustainability rules ensure that commercial biodiesel is made only from land and crops specifically earmarked for energy production.