What Is The Cleanest Renewable Fuel?

Renewable sources are natural, they are a resource that is able to renew itself faster, or equal to the rate of consumption. They can come in many forms such as:

  • Solar power
  • Wind energy
  • Tidal energy

As an everlasting resource, using these helps to minimise the damage humans leave on Earth, and ultimately will help aid its survival.

What are renewable fuels?

Renewable fuels come from renewable resources. They can be manufactured from renewable energy such as solar and wind or can come from non-petroleum sources such as crops, and animal or urban waste. They include liquid and gas fuels, and electricity derived from renewable biomass energy sources. Using renewable fuels instead of non-renewable (fossil fuels) contributes less to the carbon cycle and in some cases emits lower amounts of greenhouse gases. Renewable fuels are a popular alternative for governments because they strengthen a country’s economy and allows the nation to become more energy independent. As well as being a sustainable source, in some cases they re-use waste and are more cost effective – not just from buying the cheaper fuel itself but also because it can lengthen an engine’s life.

Which type of renewable fuel is the cleanest?

There are different types of renewable fuels, and as each come with their own pros and cons it is hard to determine which is the cleanest. However, as prices of petroleum based fuels rise because of its lack of resource, it is important that research is continued into renewable resources in order to sustain our planet, and humankind. Renewable fuels are sometimes grouped with ‘alternative fuels’ – not all alternative fuels are renewable as they are combined with non-renewable sources, but in general they produce lower emissions.

Hydrogen fuel

Hydrogen fuel

Hydrogen is thought to make up 90% of the atoms of the world, which means the potential to use this as a renewable fuel is extremely far-reaching, although its production is still a current area of research. The use of hydrogen gas as an energy carrier is hydrogen fuel. To create its most common form it can be refined from natural gas to create an alternative fuel. Another way it can be made is by passing electricity through water in a process called electrolysis. To be used in an engine there needs to bea sophisticated fuel management system, and little development has been done in this area to make this accessible. However it is also used in fuel-cells. This chemically alters the hydrogen instead of burning it, and is the most efficient way to create power from hydrogen which can then be used in electrical vehicles. However there aren’t currently any retail fuel-cell vehicles available that run on hydrogen.

Hydrogen isn’t manufactured in a traditional sense, it is extracted from other compounds. As a safe and reliable resource it is also plentiful and produces no harmful emission. However it has a low energy content and doesn’t easily burn efficiently in an internal combustion engine. The production of hydrogen is costly but storage is the biggest problem to overcome when trying to use it to its full potential. Range can be limited as it has to be liquefied or highly compressed and stored in a high pressure tank to be transported, it also requires safe handling.



Derived from vegetable oils, animal fats or recycled cooking grease this fuel is both renewable and biodegradable. It can be used in diesel vehicles when blended with petroleum diesel, or some vehicles can be converted to burn it in its purest form.When compared with petrol and diesel, it produces lower emissions such as carbon monoxide, particulates and hydrocarbons. Some petrol stations already stock this, if the pump says B5 or B20 then it is a biodiesel blend. Although it can be one of the easiest renewable fuels you can implement into your life, it does have limited production and as a blend is not fully renewable. As a cleaner alternative to diesel, it supports local agriculture and gives your engine a longer life (it is a natural lubricant). Its smell when burned is also much more pleasant, giving the aroma of fried food/barbeque. However it has to be handled correctly in cold weather and has a slightly less energy content than diesel. It can also deteriorate non-synthetic/natural rubber fuel system parts such as hoses. In some engine cases there can also be a higher emission of nitrogen oxides – which contributes to global warming.



Electricity is currently being used as an alternative fuel resource. Some cars (hybrids) are battery operated and are recharged through standard electrical sources, some are fuel-cell which run on electricity produced through combining hydrogen and oxygen – producing an electrochemical reaction. Pure electric cars using fuel-cells produce electricity without pollution, and zero emissions. Hybrids produce very low emissions but the source of the electricity is an important factor. If the electricity is being sourced from coal or natural gas this will contribute to global warming, it is only a fully renewable fuel when the electricity is produced by renewable energy sources such as sunlight or wind. However, when compared with normal combustion engine cars, even if the electricity is sourced from non-renewable supplies there is a still a 10% reduction of emissions. The research into electricity as an alternative fuel is still heavily dependent on breakthroughs in development, particularly whenexamining longer lasting and more efficient/economical batteries.



Made from corn and other plant materials, specifically by fermenting and distilling crops such as corn, barley or wheat, or from agricultural waste, ethanol is a widely used renewable fuel source. It can also be chemically extracted from ethylene (hydration). For vehicle use it can be blended with petrol to create a transition fuel, improvingon emission production and increase octane levels, though not renewable. It is not yet sold as a stand-alone but most commonly as E85 (85% ethanol and 15% petrol). Ethanol reduces smog pollution, is clean burning and reduces o-zone forming emissions. However vehicles have to be designed as flex fuel in order to burn high concentrates such as E85. When it isn’t blended, it is renewable however it has a lower energy content then petrol, equating to a reduced fuel mileage.Due to its production techniques, with its requirement of a large amount of farmland and labour, it could have a negative impact on food prices and availability. However this technique supports local agriculture. Compared with petrol it has a reduced chance of explosion and is less toxic, however it is more corrosive particularly on non-synthetic and natural rubber fuel system parts.



Renewable methanol is considered the oldest form of methanol production, however much of today’s methanol is non-renewable as it comes from the methane in natural gas. It can be used as an alternative fuel, and could be used as a source of the hydrogen needed to power fuel cell vehicles, however methanol-powered vehicles are no longer being manufactured. It has similar chemical and physical fuel properties to ethanol. It has lower production costs, and improved safety due to its lower risk of flammability. It is renewable when produced in one of four ways:

  • Municipal waste
  • Industrial waste
  • Biomass (to produce bio methanol)
  • Carbon dioxide

For the first three, gasification and catalytic conversion technology is used. For the latter, carbon dioxide, water and renewable electricity building blocks are used. It produces a significantly lower amount of greenhouse gas emissions.