Biofuels have a couple of (alledged) advantages: (apparently) they don’t contribute to the greenhouse emission, as all the carbon they have was captured from the atmosphere, and they can be a good economic opportunity for developing countries to have a source of energy. Sometimes they have even some fiscal advantages.
The advantages end here. Current biofuels are unsustainable and harmful for some reasons.
Food vs fuel. From my point of view, this is a catastrophic drawback of biofuels. The concept is very simple: you need to use land to produce biofuels instead of food. This leads to:
- Lower availability of food ↔ higher food price
- Strict correlation between food price and the oil price
There is another subtle effect, the Indirect land use change (ILUC): as the food price increases, farmers around the world push for having more crop fields, destroying forests and pristine lands in general. This can lead to an equivalent increase of greenhouse gases because of the removal of forests, and obviously can affect the biodiversity since pristine lands with very high biodiversity is replaced with crop fields that has a very low biodiversity. This is a general issue about farming that has caused a massive reduction of Amazon rainforest, even before biofuels were even considered.
Biofuels needs a huge area. That’s why I jokingly suggested to have crops on the tropical area of the Moon. Oil palm has a yield of 5 ton/ha/year and it is currently the plant with the higher yield. Other plants have 1 ton/ha/year. How much is the energy production per square meter? The answer is 0.66W/m2! A photovoltaic system with a 10% of efficiency in a South-European country (200W/m2) would use 1/30 of the area. Obviously producing biofuels is far cheaper than building photovoltaic systems, nevertheless this low efficiency of biofuel production leads to huge area requirement.
In example, let’s assume the US want to replace fossil fuels with biofuels. US consumed 25PWh of fossil fuels in 2006 , equivalent to 2.1 billion tons of biofuel. Producing all this biofuel will require 4,300,000 km2! It’s 43% of the US total area. Or 1.14 times the current US crop area! Unsustainable.
US are lucky, they have low population density. For European countries it would be even worse. Let’s take France, a country with an average population density (111pop/km2). France would need 250 million tons of biofuel to replace the current consumption of fossil fuels. Well, if France manages to use palm oil it would require…500,000km2, 74% of the whole area! And we are talking of palm oil, that is used mainly in tropical region. Biofuels in temperate climates have usually a lower yield. In Germany biofuels plantation occupy 2300km2 and they produce an average of 1 ton/ha/year.
So, let’s conclude that:
- Biofuels are a tempting investment, especially for emerging countries. They are not considered because of the alledged reduction of greenhouse gas emission. Brazil has never cared about CO2, indeed the policy is destroying the Amazon forest to make room for biofuel plantations.
- Biofuels require too much area. If we want to replace a good part of our fossil fuel consumption with biofuels we will need to sacrifice a huge part of our land to biofuel plantation, sacrificing food production and having a much higher food price. This could have potential catastrophic effects in poor countries where there is no food abundance.
- Biofuels are seen as a “Green” solution, so they are politically efficient compared to other energy sources (i.e. nuclear). A big nuclear power plant produces 30TWh per year. Replacing that with biofuels would require (yield=5ton/ha/year, efficiency=50%) 10,000km2 of biofuel plantations, a 100x100km square area.
- There is a hope. Second-generation biofuels are much more interesting as they aim to solve the food vs fuel issue. They are made from agricultural residues so they don’t affect food production (even if of course they can influence the ROI of a particular plantation). Third-generation biofuels, like algae oil, are even more promising: their yield can be over 100ton/ha/year. With this high yield, US fossil fuels consumption can be replaced by 215,000km2 of plantation, shown in figure. This is a much more promising and sustainable perspective.
So, it’s important to bear in mind that research on new generation biofuels (that obviously require an advanced processing technology) can be a very efficient way to produce fuels in a sustainable way, but it must not be confused with the biofuels currently produced that are threatening rainforests and rising the price of food.