A new piece of high-profile research suggests that biofuel products such as biodiesel and ethanol actually produce more harm to the environment than fossil fuels. The biofuel market has long been heralded as offering a carbon-neutral source of power because the organic materials that are used absorb atmospheric C02 during their growth period, which otherwise causes global warming.

The study, carried out in the US, discovered that biofuel crops only actually absorb a third of the carbon dioxide that is later expelled into the atmosphere when they are incinerated - meaning that there is a net increase in carbon dioxide in the atmosphere as a result of using biofuel products.

This is concerning, as policies that have underpinned the promotion of biofuel as a sustainable and green energy choice may actually have been predicated on incorrect science.

The research group, from the University of Michigan, have now called on governments to review their findings and re-assess their carbon subsidy policies in light of this latest finding.

Biofuel usage has long been controversial, as it means using agricultural land that could otherwise be used for food farming - diverting food production to fuel production in effect, particularly where generous subsidies are involved. Currently, biofuels represent less than 3pc of the world's total energy usage, but adoption of biofuels in the USA grew to 14.6 billion gallons per annum in 2013, compared to just 4.2 billion gallons in 2005.

In the UK, the use of these fuels is mandated by the Renewable Transport Fuel Obligation, meaning that all transport fuels must contain at least 4.75pc of renewable fuels - typically crop-derived ethanol. Policy-makers will now have to consider how they progress with targets and support for what could be a less certain means of producing green power.