The environmental impacts of growing crops for use as biofuels are varied and widespread. The level of pollution and habitat destruction directly resulting from biofuel production is alarmingly high. Especially when considering the fact that few people take these problems into account when touting how “eco-friendly” biofuels really are.
To date, most biofuels have had their “ecological footprint” evaluated in terms of strictly their greenhouse gas (GHG) emissions levels. This creates an incredibly incomplete picture of the actual level of environmental impact of various biofuels. The following graph, taken from an article put out by the Smithsonian Tropical Research Institute, offers an excellent look into how speaking strictly from a GHG perspective, biofuels have incorrectly been hailed as the answer to all of our environmental problems. The findings highlight the enormous differences in costs and benefits among different biofuels. Biofuels that fare best are those produced from residual products, such as biowaste or recycled cooking oil, as well as ethanol from grass or wood.
Figure 1. Greenhouse emissions are plotted against overall environmental impacts of 29 transport fuels, scaled relative to gasoline. The origin of biofuels produced outside Switzerland is indicated by country code: Brazil (BR), China (CN), European Union (EU), France (FR), and Malaysia (MY). Fuels in the shaded are considered advantageous in both their overall environmental impacts and greenhouse-gas emissions.
So what are these other “environmental impacts” so commonly left out of the equation when calculating the negative effects of biofuels on our planet?
One of the most common factors affecting biofuel environmental impact is whether or not native species and ecosystems are destroyed in production of the biofuels. For instance, despite the fact that sugarcane is highly effective in producing ethanol, its overall efficiency quickly diminishes if carbon-rich tropical rain forests are being destroyed to create the sugarcane plantations and thereby causing massive increases in greenhouse gas emissions. Such comparisons become even more lopsided if the full environmental benefits of tropical forests–for example, for biodiversity conservation, hydrological functioning, and soil protection–are included.
Trace GHG Emissions from Fertilizers
Another effect commonly forgotten stems from crops that require the use of fertilizers, particularly nitrogen based fertilizers, in production. It is typically the crops with the most widespread use, such as corn and canola, that require these fertilizers. Once these fertilizers seep into the soil and enter the water table, the eventually re-emerge in local streams and rivers where, once exposed to the air, they can become a significant source of nitrous oxide, an important greenhouse gas that destroys stratospheric ozone. This is known as a trace-gas emission. When combining these trace-gas emissions with the actual, calculated GHG emissions used during production, certain crops may quickly be realized as worse for global warming than fossil fuels themselves. Not to mention the multitude of health and environmental hazards stemming directly from fertilizer use itself including soil nutrient depletion and toxic infection of local drinking water.
Water scarcity affects one in three people on every continent of the globe. The situation is getting worse as needs for water rise along with population growth, urbanization and increases in household and industrial uses. Use of water for agricultural production is currently one of the highest demands for water seen around the planet. By encouraging a dramatic rise in biofuel production, this problem could become much worse.
Large Scale Agriculture
To be an economically viable fuel source, biofuel crop production must typically occur on relatively large scale plantation style farms. This type of agriculture is incredibly degrading to the environment. Fossil fuels must be used to power the heavy machinery necessary to harvest such huge annual crops. Monoculture farming techniques (linked back to trace GHG emissions from fertilizers mentioned above) leaves the soil incredibly depleted and leads to continual deforestation as more and more land is needed to harvest the same amount of crop.