What are the well-to-wheel emissions of biofuels?

Reducing GHG emissions in transport sector is a big challenge as mitigation choices are limited, especially for aviation, trucks and shipping[70]. It accounts for 20% of all EU GHG emissions and this is expected to rise significantly[71]. Biofuels are one of the few options available to reduce GHG emissions in this sector.

Life-cycle analysis (LCA) is the methodology used to determine the total emissions of a product. For road transport, this is often termed “well-to-wheel” emissions[72].

Biofuels have lower GHG emissions than fossil fuels because…

Emissions: Biofuels vs Fossil Fuels

Typical well-to-wheel emissions savings for biofuels range from 30% to 90% relative to fossil fuels, but can be higher or lower depending on the processing and material used.

In 2010, biofuels saved between 23–25 million metric tonnes of CO2eq, or 53-60% savings compared to using gasoline and diesel – these figures exclude emissions from indirect land use change (ILUC)[73]. When GHG emissions from land use changes are included, the net reduction is smaller, however.

Advanced biofuels are expected to have well-to-wheel savings of 75-95% compared with fossil fuels, excluding land-use change impacts[74].

ILUC impacts may mean that some biofuels have higher emissions than fossil fuels. However; the EU has not yet adopted ILUC factors, unlike the USA biofuel policy[75].

What about indirect land use change (ILUC)?

The facts behind the research

The discussion about ILUC became a hot topic when Tim Searchinger claimed that ILUC adds 104 g of CO2 equivalents per MJ to corn ethanol’s carbon footprint – higher than the total carbon footprint of gasoline[77].

The Searchinger study has since been criticised for a number of shortcomings. As science has progressed, estimates of emissions arising from ILUC have decreased drastically, from 104g CO2 e/MJ by Searchinger[78] to 15g CO2 e/MJ in 2010 by Tyner et al.[79].The International Food Policy Research Institute has estimated ILUC factors related to the Renewable Energy Directive resulted in 12g CO2 e/MJ in 2011[80].

Difficulties modelling ILUC impacts

It is not possible to measure ILUC impacts directly as complex models which simulate the global economy, agricultural markets, and land use are needed. These models give a wide range of results[81], [82] as can be seen in the example below where values from models measuring GHG emissions due to ILUC are compared.

Source: Ahlgren, Di Lucia (2014) 90

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Nevertheless, models show that estimates of GHG impacts made at the beginning of the ILUC debate are generally much higher than now[83].  The emerging consensus is that many biofuels have a low ILUC risk, especially advanced biofuels[84], [85], [86]. The overall trend is that bioethanol has typically lower ILUC-related GHG emissions than biodiesel, and sugarcane-based ethanol has the lowest among conventional biofuels and palm oil based biofuels are among the highest.

Despite this, the European Commission considers ILUC results too uncertain to provide a reliable basis for adding ILUC factors to the well-to-wheel emissions assessed in EU biofuels policies.

What are EU requirements on biofuels' GHG emissions?

The EU’s Renewable Energy Directive (RED) requires biofuels to meet GHG emissions savings of 35% now, rising to a reduction target of 50% in 2017, and 60% for new biofuels plants[87].

Sustainability criteria for biofuels set in the RED include restrictions on the types of land that can be used for biofuels. Many biofuels sold in the EU are certified under voluntary sustainability schemes, which include criteria on land use. For example biofuels cannot be grown on wetlands, forests or highly biodiverse grasslands[88]. This criteria and other available frameworks and schemes (e.g. GBEP[89]), also recognise that land use responds to national political decisions.