[MUSIC] In week three, we're going to talk about biofuels and in particular, the applications of synthetic biology to biofuels. So biofuels by definition are solid, liquid, or gaseous fuels that are produced from contemporary or non-fossilized biomass, including agricultural products, microorganisms, etc. And this is in contrast to traditional fossil fuels, such as petroleum and coal. Interest in biofuels has been increasing, and is driven by concerns about climate change, sustainability of current fuel sources, agricultural policy, energy security, energy costs, etc. The field has certainly had its ups and downs, but it continues to be a main focus of research. Now ideally, any biofuel that's developed would be cost-effective, right? In particular, now fossil fuels have been priced fairly low recently. So the challenge being cost competitive with existing fuel sources is important. Energy efficient, compatible with existing storage and distribution infrastructure for petroleum-based transportation fuels. We've had gas and diesel cars for a very, very, very long time. Our infrastructure is largely built around those fuels, so ideally, any biofuel that you developed would be compatible with this existing infrastructure. We would like any biofuel to be sustainable, and to minimize any negative effects on food security, land and water use, biodiversity, etc. And we'll talk more about these issues [COUGH] in other videos this week. Few important definitions. So first generation biofuels are conventional biofuels such as ethanol and biodiesel from food crops. So here in the US, for example, that's largely ethanol from corn, in Brazil, sugarcane. Palm oil, is another example. Second generation, or advanced biofuels, come from lignocellulosic biomass, such as wheat straw, corn husks, trees, prairie grass, etc, including waste and surplus biomass from existing agricultural or forestry systems. Third generation biofuels are advanced biofuels that, rather than being derived from land crops, are derived from marine biomass. Now the boundaries between the various generations are not always perfectly clear. But these are helpful designations for our purposes. Now what are some of the challenges of biofuels? First, certainly in the application of synthetic biology to biofuels, there is the engineering, right, actually getting the science right. And effectively engineering organisms to produce these biofuels, or to work in processing, or the development of biofuels. Yields, right, you need to be able to produce enough of this biofuel to actually make a dent in current demand. Scalability, cost, also related, cost are already discussed, briefly cost competitiveness, in particular, with traditional fossil fuels. The food versus fuel debate, which we will talk about more in later videos. So for example, I mentioned that the US relies primarily on corn for ethanol as our first generation biofuel of choice. But corn is a food crop. So you are investing all of that effort and infrastructure and land and water, etc, in a food product that then is used for fuel. This is a really important debate in biofuels. And environmental impact, right, you're still talking about the use of various kinds of biomass for fuel production and what are the environmental impacts of that. You need to ensure that the byproducts of biofuel use are less problematic, ideally, than the byproducts of fossil fuels. And again, we'll come back to some of these issues in, we'll come back to many of these issues in later videos. Another important piece of vocabulary is feedstock, which is the raw material that is used to manufacture biofuel. The organisms that are used, and in particular in the application of synthetic biology to biofuels, are the focus of a lot of the research are E coli and Saccharomyces cerevisiae. Yeast, which of course, are extremely well-characterized and understood model organisms for which lots of tools have been, genetic tools and other kinds of research tools have been developed already. Algae or microalgae, in particular, it's used in third generation biofuels. Now algae naturally produce oils already. So a good target organism for biofuels production. And then there are others such as bacillus subtilis. There are several different ways that you can apply synthetic biology to these organisms or use synthetic biology to modify these organisms in the service of production of biofuels, including engineering an organism to directly generate a biofuel. You could modify one of these organisms to more efficiently break down cellulosic biomass. Or you could develop hybrid processes wherein the engineered organism plays an important role in the development of that biofuel, but is not, in fact, generating it. So it'd be a combination, for example, of an engineered organism and chemical processes that lead ultimately, to the production of a biofuel. And then production platforms vary as well. You have fermentation reactors, bioreactors, photobioreactors, adding light in particular, for algae. And you can have an open pond as a production platform, in particular, in the use of algae in the production of third generation biofuels. And each of these engineering approaches, organisms, production platforms is going to come with its own set of risks and benefits and considerations. Some examples of biofuels and potential biofuels include conventional biofuels that we already produce, such as, as I mentioned before, ethanol from corn or sugarcane. Palm oil is used in some regions, biodiesel from oils and fats. Examples of potential synthetic biology-based or contributing biofuels, include biodiesel from algae, propane from E coli, fuel precursors from cellulosic biomass via a modified yeast, and ethanol and higher alcohols, also from yeast.
