A few years ago, the promotion of biofuels an as alternative energy source, especially to replace gasoline, reached a high point. Since then several issues, such as concern about food prices, and whether or not more energy is needed to produce the fuels than we get out of them, have meant that biofuels have begun to fall out of favour. Nevertheless, many people and organizations are still pushing biofuels despite the fact that they cannot be used sustainably on any large scale.
First, let's look at the issue of energy by itself. There are many different types of biofuel, but for many of them, the amount of energy needed to make them is higher than the amount of energy we get out of them by burning in a gas tank or power plant. Fossil fuels are needed to make the fertilizer to grow the biofuel crop, more fossil fuels are needed to run the farm machinery, and yet more is needed to process the crops into a usable form of biofuel. Ethanol is one of the most popular and widely used forms of biofuels. The Wall Street Journal references one study that says:
They've found that it takes more than a gallon of fossil fuel to make one gallon of ethanol--29% more. That's because it takes enormous amounts of fossil-fuel energy to grow corn (using fertilizer and irrigation), to transport the crops and then to turn that corn into ethanol.
Other types of biofuel have similar problems, such as oil from sunflowers, which requires roughly twice as much energy to make as it provides. Other biofuels, including those produced from soybeans or sugarcane, on the other hand, may provide a net energy benefit. However, we have to also consider all the other impacts from their production, which we will see below.
Regardless of whether a given biofuel may be produced at a net energy loss or gain, they are still dependant on the use of fossil fuels. As oil supplies begin to decline after peak oil, their use in agriculture (either for food crops or biofuel crops) will start to become limited. Those supplies still available will likely be several times more expensive, which will also limit their use for agriculture. Already today, many biofuel crops, such as ethanol, can only be financially justified because of large subsidies. Without subsidies and cheap oil, they just don't make sense.
Just as many biofuels require more energy than they provide, unsurprisingly, many of them produce more carbon emissions than fossil fuels, when their entire lifecycle is taken into account. However, this is not always true, many biofuels, especially "next generation" kinds, can save as much as fifty percent of emissions as compared to fossil fuels. Many of these crops can only grow in certain parts of the world though, and can provide only a relatively small supply using current cropland.
This is where the calculations break down. In order to grow enough crops to produce large amounts of biofuel, vast areas of land need to be cleared and dedicated to their production. Aside from the obvious ecological damage, this is catastrophic in terms of carbon emissions. A study published in the journal Science puts it starkly:
...converting rainforests, peatlands, savannas, or grasslands to produce food-based biofuels in Brazil, Southeast Asia, and the United States creates a ‘biofuel carbon debt’ by releasing 17 to 420 times more CO2 than the annual greenhouse gas (GHG) reductions these biofuels provide by displacing fossil fuels.
Brazil is often held up as an example of a country which is successfully using biofuel to sustainably power their automobiles. Yet, Brazil has reclassified 200 million hectares of natural habitat to be used for biofuel, mostly sugarcane. Forty percent of their biofuel comes from soybeans, and the Amazon rainforest is being cleared by roughly 325,000 hectares a year in order to increase its production. And for all this Brazil only has roughly 8 million vehicles powered, partly, by biofuel. The latest standards require 25 percent ethanol, but the other 75 percent is still gasoline or diesel. Far from being sustainable, Brazil is desperately destroying their country in order to just partly offset their use of fossil fuels, on which they remain entirely dependant.
But, what about the US? The US has roughly 250 million vehicles on the road! Do we even have enough land left to clear to grow enough biofuel to power all of that? Humans are already over carrying capacity, yet we are still continuing to destroy more natural habitat, precisely when we need to be protecting and restoring it. There is no way we can produce enough biofuel just to power our cars, let alone any type of electricity generation, without rapidly accelerating our destruction of the environment.
Our agricultural methods are already unsustainable and badly depleting soil and water, as well documented by Lierre Keith in her book The Vegetarian Myth. We urgently need to transition to a more sustainable way of producing food. The last thing we need is an expansion of agriculture in order to produce biofuels designed to allow us to maintain an extremely inefficient transportation system. Instead, we need to reduce the number of cars and trucks and switch to rail instead.
Biofuels are not completely useless, however. On the small scale, they can serve to provide small amounts of power for local needs, such as operating tractors, or charging batteries. The reuse of food waste to make biofuels, for example, is likely a good idea in some cases. This type of small-scale biofuel use can fit in with a larger alternative energy strategy that can help us live sustainably, though at a much lower level of consumption than today.
Those working on biofuels may be honestly interested in reducing the use of fossil fuels and helping the environment. But there is no way they can provide enough energy to replace them, while allowing us to continue our lives as before. If we honestly want to reduce our use of fossil fuels, the solution is simple, we need to drastically reduce our use of energy, our waste, and our general overconsumption.