We also talked briefly about biofuels. The two major examples are biodiesel, which is a diesel replacement fuel made from biological products, and ethanol, which is essentially or can act as a gasoline replacement, but it's made from biological products typically corn or sugarcane or can be made from other things as well. This technology we'll call it, biofuels is like CSP, it's not doing that well from a global perspective. One way to measure that is annual investment. As you can see, in 2006-2007, biofuels received very large investment, $20-25 billion a year. Well, that's faded to less than $5 billion for the last few years. There are different types, so-called regular and 2G, which are second-generation advanced, but you can see that global interests in biofuels is measured by investment, has dropped dramatically and it's way down. To summarize some of the issues of biofuels, if you make ethanol from corn, which the US does a lot of, it's not clear what the CO_2 benefit is. It may be relatively modest because of all the other energy inputs that are required to turn corn into ethanol. It's a very energy intensive process. If one looks at a scenario where we use large amounts of land and grow crops, could be corn, could be sugarcane, could be other things to make a fuel, well, what are the effects on land use? What are the effects on food prices? These are difficult issues, but certainly worth thinking about if one is considering a scenario which biofuel production ramps up. Biofuels compete economically with oil based products. Biodiesel competes with diesel, ethanol competes to some degree with gasoline. The cost effectiveness varies with oil prices and oil prices vary all the time, which makes it hard to build a viable, stable biofuel industry if it's competing something moving all the time. This has been particularly apparent in Brazil, which produces a lot of ethanol and has vehicles that run on an ethanol, but in some cases drivers are choosing to fuel with gasoline because it's just less expensive. That's a continuing challenge for this market. As we noted, the global investment in biofuels is falling quickly. There's a different technology called 2G, second generation cellulosic biofuels. Very promising research topic that has a potential for a very attractive low cost maybe, unclear, significant CO_2 reduction. There are many ways, in theory, at least or in the laboratory one could make biofuels, maybe even from algae. But this is a research topic, so not quite a commercial product yet. Another factor for biofuels is looming competition from electric vehicles. Biofuels have the advantage of being essentially at low concentrations have drop-in replacement. You can take your existing gasoline car and run it on low concentrations of ethanol. But what if your existing car is electric? You bypass the whole need for biofuels. That's another challenge for the biofuel industry. We then moved on to enabling technologies, which we defined as technologies that support or promote or ease the transition to renewable energy future. Some of those enabling technologies like batteries address the grid integration issue. How do we integrate variable renewables, wind and solar PV into electricity grid? Some enabling technologies, like electric vehicles, contribute to electrification. Moving end-uses, in this case is transportation from fossil fuels to renewable electricity, and some, hydrogen, allow for a more fundamental change in the entire energy system. Let's talk a little more detail about those three enabling technologies. The first was batteries, which are type of storage, and just give an example of what that can do. This is the duck curve, famous example of how renewables have essentially challenged the electricity system. The concept here is with a lot of solar PV on the system, that's solar PV produces a lot of electricity during the day. The net demand curve for the system, thick red line, what's left over after the solar PV, does it's bid. Shows the solar PV essentially takes a big bite out of mid day demand. That can be a challenge for the system because all these power plants that were supposed to run all day, all of a sudden aren't needed during the middle of the day, but all of a sudden they're all needed and in a very short time period. That's called a steep ramp. Well, that's a problem that storage batteries can help address. What do the batteries do? They charge up during the middle of the day when there's lots of solar PV and they discharge at night and thereby smooth the curve and make the whole system work a lot better. That's an example of what storage, including batteries, can do. We'll take a break there and come back and talk more detail about storage.
