Rapeseed biodiesel has a weak greenhouse gas balance - study

The energy balance and the greenhouse gas (GHG) balance of biofuels are two important criteria to judge whether these fuels are energetically interesting and whether they can be a weapon in the fight against climate change. We already know that fuels made from crops grown in the South have both a very strong energy balance as well as a GHG balance that proves they substantially reduce emissions of most climate destructive gases. For biofuels made from crops like rapeseed or corn, the situation looks more problematic.

A new study now claims that the use of biodiesel made from rapeseed - the main feedstock for biodiesel in the EU - could potentially result in greater emissions of greenhouse gases than from conventional petroleum derived diesel. This is the conclusion of an analysis reported today in Chemistry & Industry, the magazine of the Society of the Chemical Industry. However, the study's scope is limited and incomplete, which is why it will be criticized by the biodiesel industry (see below).

Analysts at SRI Consulting - group catering to the petrochemical industry - compared the emissions of greenhouse gases by the two fuels across their overall life cycles from production to combustion in cars.

Eurekalert indicates that the results from the study show that biodiesel derived from rapeseed grown on dedicated farmland emits nearly the same amount of greenhouse gas emissions (defined as CO2 equivalents) per km driven as does conventional diesel:
bioenergy :: biofuels :: energy :: sustainability :: rapeseed :: biodiesel :: greenhouse+gas+balance :: energy balance :: climate change :: EU ::

However, if the land used to grow rapeseed was instead used to grow trees, petroleum diesel would emit only a third of the CO2 equivalent emissions as biodiesel.

Petroleum diesel emits 85% of its greenhouse gases at the final stage, when burnt in the engine. By contrast, two-thirds of the emissions produced by rapeseed derived biodiesel (RME) occur during farming of the crop, when cropland emits nitrous oxide (N2O), otherwise known as laughing gas, that is 200-300x as potent a greenhouse gas as CO2.

The petrochemical constulting group that made the report thinks the results of this analysis should have big implications for policymakers. The 2003 EU Biofuels Directive aims to increase the levels of biofuels to 5.75% of all transport fuels by 2010, up from roughly 2% currently. This will be further increased to a 10% share in 2010, the Commission announced in January this year.

Transportation currently accounts for more than a fifth of all greenhouse gas emissions emitted in the EU. Rapeseed-derived biodiesel is the major renewables-derived biofuel used across Europe and, as well as helping to improve energy security, is expected to play an important role in helping to meet the EU’s Kyoto commitment to reduce levels of greenhouse gas emissions by 8% by 2012 relative to 1990 levels, and by 20% by 2020.

Incomplete study
Even though we would agree that biodiesel made from crops grown in temperate climates does not make sense because of the weak energy balance and greenhouse gas balance of these fuels, and because they perpetuate subsidy schemes and trade barriers that are detrimental to farmers in the South, we think this study has some major weaknesses. Some key elements are not included in the analysis, which is why the European biodiesel industry will dispute its findings.

First of all, there is a problem with the authority of SRI Consulting. The group caters to the petrochemical industry, the sector that is trying to work against the large-scale introduction of biofuels. Independent analysts from academic institutions, whose interests are not linked to a particular industry, have shown stronger greenhouse gas balances for rapeseed based biodiesel.

Secondly, and going straight to the substance of the matter, the 'boundaries' of the study are too narrow. It doesn't take into account the greenhouse gas emissions that are avoided because of the use of biodiesel byproducts as animal feed or as a fuel feedstock. The major byproduct of biodiesel is glycerol (glycerin), a chemical compound that can be used for the production of biofuels such as biogas or synthetic biofuels (more particularly biokerosene). For each ton of biodiesel produced, 100kg of glycerin becomes available. The use of biofuels made from this byproduct displaces fossil fuels, and hence improves the greenhouse gas balance of rapeseed biodiesel.

Alternatively, scientists have found that glycerol can be used as a feed component for poultry and pigs. Adding glycerol to the diet displaces other feed components whose greenhouse gas balance must be calculated, and substracted from that of rapeseed biodiesel. Fractions of up to 30% glycerol can be introduced into the diet of several industrially produced animals.

Thirdly, the study assumes that growing trees as carbon sinks on the land used for rapeseed would be a sensible strategy to take CO2 out of the atmosphere. This is incorrect. Quite substantial research shows that trees grown in mid- to high-latitude regions are actually net CO2 contributers (earlier post). These findings were recently confirmed by other scientists (here and here). There is no consensus yet as to how large the contributions of different types of forests grown in mid-latitudes are.

These weaknesses in the study will allow those with vested interests in biodiesel production from rapeseed to counter the findings once again. In general, it would be best for both parties - the petrochemical industry and the biodiesel industry - to delegate this type of sensitive studies to more objective researchers, from academia.

Tropical biofuels perform better
The energy balance of rapeseed biodiesel may be more positive than its greenhouse gas balance. Even tough on this aspect, the fuel has major obstacles to overcome: scientists from France published data showing that the application of nitrogen fertilizers makes up the largest contribution to the energy inputs needed to grow the fuel (earlier post).

For corn based ethanol, researchers have found an equally weak greenhouse gas balance (previous post). Using this fuel would not contribute much to reducing greenhouse gas emissions, whereas it's energy balance is close to 1. Fuels made from crops grown in the South, such as cassava (the energy balance of which was recently calculated) or sugarcane both have far better energy and greenhouse gas balances.

However, the rationale behind growing biofuels in the Global South fundamentally differs from that of the EU: in the developing world, the primary drivers are energy security and the substitution of costly fossil fuels. Crop based fuels are primarily a tool for development that allows poor countries with energy intensive economies to reduce their dependence on imported fossil fuels.