5X5 Episode 102
|5X5 Episode 102|
|8th February 2012|
|5X5 101||5X5 103|
|S: Steven Novella|
|R: Rebecca Watson|
|B: Bob Novella|
|J: Jay Novella|
|E: Evan Bernstein|
You're listening to the Skeptics' Guide 5x5, five minutes with five skeptics, with Steve, Jay, Rebecca, Bob and Evan.
S: This is the SGU 5x5 and tonight we're talking about Biofuels. A biofuel is any fuel that derives from organic material, typically plant-like material. Technically, fossil fuels can be considered biofuels, but the biological material they come from was sequestered into the Earth millions of years ago, therefore they are categorised as fossil fuels. But biofuels refer to those fuels which are made from plants that are grown recently, or today, and there are certain advantages to this, such as the carbon dioxide that is released into the atmosphere from burning biofuels is essentially the same amount of carbon dioxide as was captured by those plants when they were grown. Therefore, in terms of the fuel itself, biofuels are carbon neutral.
R: Of course, one of the problems with biofuels is if you're taking a living plant, for instance, out of its ecosystem, what kind of effect is that going to have on the rest of the ecosystem? Particularly if you're doing it in very large quantities.
S: Right, in order for biofuels to have a large impact on our energy use we would have to make it in extremely large quantities. That's going to have an impact on anything. For example, there are concerns that using farms to grow corn to make ethanol has had an impact on food prices.
J: A lot of experts are starting to think that algae may be a good new biofuel, and there's a few reasons why they think this - I actually agree with them about it. One, algae isn't a part of the existing human food chain, so its not going to be taking away any food resources if we use it to create biofuel. Also, algae can actually grow in waste water, which can solve a problem we've been having recently, which is an over-abundance of waste water and not an easy way to process it and actually get it back to a pure level. So algae, I think, would be a good solution here.
E: Algae in seaweed farming has been shown to help preserve coral reefs. It increases diversity where these algaes and seaweeds have been introduced and it provides this added niche for local species of fish and invertebrates and there are reported cases and studies in which this has shown to be true, especially in areas such as Indonesia.
S: Yeah, there was a recent study Evan, looking at seaweed - which is essentially macro algae - as a source of polysaccharides which could be turned into ethanol for biofuel. This could be a viable option, however, the impact of farming massive amounts of seaweed and pulling all of that matter and energy out of the oceans needs to be evaluated. As I said, we could have impacts on farmland if we grow grasses or use cellulosic stocks then we're maybe having impacts on forests or other ecosystems; if we're pulling tonnes of seaweed out of the ocean we're going to affect that ecosystem. So, while the concept of biofuels is a good one - growing fuel in a carbon neutral way at least to offset our reliance on fossil fuels - the entire process from beginning to end needs to be considered, including the impact on whatever ecosystem is supporting the growth of the plants that are being used to feed the fuel.
J: Steve did you know that in 2008 biofuel production was accountable for 3 to 30 percent of the increase in food prices?
S: Yeah, those are the estimates, so again, it gets back to the impact on farming.
B: Using seaweed seems really, really interesting. There are a lot of unknowns but the positives to this look really fascinating. What they did was used engineered forms of e-coli bacteria to digest specific sugars that are in the seaweed. There's lots of different sugars in seaweed, the most prevalent though is called alginate, but the problem is that normal microbes couldn't metabolise it. There are other sugars in there as well and they ferment readily, but this one major form they couldn't do. So by bioengineering them they were able to actually increase the yield - the ethanol yield - to 80 percent of its maximum which is fairly significant; and that's approximately double that of sugar cane and five times that of corn. So there does seem to be a lot of promise in this one area of research.
S: Yeah, there's definately a lot of research going on looking at ways of converting different parts of different plants into ethanol or biodiesel or essentially fuel, and it does seem promising. But I think the lesson here for the whole biofuel question is that its a complicated web of factors that all need to be considered before we understand what the net effect it is having. In fact, for example, with ethanol derived from corn - which is not a great source of energy - by some calculations it costs more energy than you get out of the ethanol. In fact, some of that energy is fossil fuel which can be used as a fertiliser to grow corn. So if you're essentially pouring gasolene on cornfields to grow the corn and then turning the corn into ethanol, you may get less energy out of that process than is put into it. So the entire process from beginning to end needs to be considered for energy efficiency as well as land or water use efficiency, impact on the environment, and it shouldn't be considered a good idea just because it seems a like green idea, or because it is carbon neutral looked at in isolation. But it doesn't mean that someday we wont get to a point someday where we can mass produce a biofuel based upon a source that will not be disruptive to our farming or the environment and that will actually be a net producer of energy. You know I'm not sure if we're at there yet, perhaps sugar cane - which is more energy dense - is more efficient but I don't think corn-ethanol is - if it is it's just barely so - because it's all controvertial. So we'll see where this leads to in the future and how much of an impact it can have on our overall energy use.
S: SGU 5x5 is a companion podcast to the Skeptics' Guide to the Universe, a weekly science podcast brought to you by the New England Skeptical Society in association with skepchick.org. For more information on this and other episodes, visit our website at www.theskepticsguide.org. Music is provided by Jake Wilson.