1. Can biofuels help mitigate climate change?
By-products from biofuel production such as proteins for animal feed make a positive contribution to climate change mitigation because they save energy and greenhouse gas emissions that would otherwise have been needed to produce the feed by other means.
Producing first generation usually yields reductions in greenhouse gas emissions of 20 – 60%.
Ethanol produced from sugar cane and second generation of biofuels typically reduce emissions by 70 – 90%.
Figure 1: Life-cycle analysis for greenhouse gas balances
2. What changes to agricultural land would biofuel production require?
Expansion of cultivated land
Since land-use changes have a significant impact on greenhouse gasemissions, it is important to know whether increased biofuels production will be met through improved land productivity or through expansion of cultivated area.
Figure 2: Potential for cropland expansion
3. How will biofuel production affect water resources?
Water availability
Crops such as sugar cane, oil palm and maize have relatively high water requirements and are best suited to high-rainfall areas, unless they can be irrigated.
Water quality
Producing more biofuel crops will affect water quality. For example, converting pastures or woodlands into maize fields may increase problems of soil erosion and runoff of excess nitrogen and phosphorous into surface and groundwater. Pesticides and other chemicals can also wash into waterbodies.
Figure 3: Potential for irrigated area expansion
4. How will biofuel production affect biodiversity?
Biofuels production can affect biodiversity in some positive way, for instance through the restoration of degraded lands, but many of its impacts will be negative, for example when natural landscapes are converted into energy-crop plantations or peatlands are drained.
5. How will biofuel production affect soil?
Removing plant residues that would otherwise nourish the soil and permanent soil cover that prevents erosion can reduce the quality of soil.
Reference
http://www.greenfacts.org/en/biofuels/l-3/4-environmental-impacts.htm