Biofuels are good, as people say. But
why? Being an undergrad, I felt an urge to understand.
And in the end, I found biofuels are
not necessarily good.
First, we have to understand the reason of biofuel production.
It seems that fossil fuel is the main factor. Not only that we're running out of fossil fuels, they also release greenhouse gases (GHG; in this short essay, CO
2 will be the primary GHG discussed. ) that is claimed to be the main contributors of global warming. Therefore, we need something to substitute fossil fuels in order to fill our hunger for energy and mitigate the negative impact of our fuel production. Here comes the suggestion, why don't we use plants or animal waste as fuel feedstock?
Biofuel feedstock, which is the material for production, can be anything that is derived from the biosphere and can be oxidized to produce energy. However, if its
net energy per biomass (GJ/t) produced is not able to compete with the net energy produced by fossil fuel, we discard this feedstock and find another one. In addition, if carbon output is more than carbon input during production, we also discard the feedstock.These two main considerations, net energy value and net CO
2 emission, generally judge the "green" quality of a biofuel.
For example, the popular corn-based and soybean-based biofuels are currently hot in USA. However, these biofuel that are derived from food crops (I am sure you eat a lot of corns and soybeans annually) have various negative impacts to the environment, such as (1) high GHG emission due to excessive use of nitrogenous fertilizers and use of fossil fuel during production (transportation and power generation for biorefinaries), (2) pollutions caused by pesticides, and (3) competition with food market. In short, these kind of biofuels will not be "green" enough before their negative impacts are outweighed by advantanges.
In conclusion, all you have to know (as part of the public) is:
- We must bear in mind that biofuels also have negative impacts on Earth;
- We need to find solutions for these negative consequences to enhance the "green" value of biofuels;
- We are not eliminating all negative impacts of biofuels, instead we are mitigating them and trying to outweigh them with the benifits of biofuels;
- Biofuels cannot stand alone to sustain our energy needs, i.e. a cocktail of alternative renewable energy sources (e.g. solar+nulear+wind+biomass) is more feasible.
"Alright lads, tuck this tube into your backsides when you wanna fart. I need some methane for biofuel."
p/s: Thank you Prof. Gasparon for the idea of methanol from sheep.
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