I'm Jonathan Tompkin from the University of Illinois. Imagine the perfect energy source. What properties would it have? I'd like you to take a moment and just jot down some of the things that this perfect energy source, what features it would have. You might have mentioned some of the things that I've put on this list here. Things like it being plentiful, sustainable, cheap, concentrated, secure, nonpolluting, and so on. So, there's a whole range of things that a perfect energy source would have. Of course. We don't live in a perfect world, so we don't get to choose all of these things. The problem with fossil fuels is that they lack certain qualities that they, that we want. They're not sustainable and they are polluting. So, perhaps by moving to renewable energy sources, we can find new sources of power that are both sustainable, nonpolluting, and perhaps have other useful attributes. For example, maybe they'll be secure. Something their countries are not reliant on importing their supplies of energy. There's lots of different types of renewable energy. We're going to look at a survey often in this lecture and to sort of point out what the trends are. And how important they currently are and how they might be important in the future in countries' energy plans. So lets begin with a simple question. What's currently the largest single source of renewable electricity? The answer is hydroelectricity. And it's not a cutting edge technology. About ten percent of the U.S.'s electricity supply comes from hydroelectricity today. And for example, this has been going on for a long time. The Hoover dam was built in 1936. There are environmental impacts of using hydroelectricity however. They change the ecosystems of rivers and in particular they can impact the life cycles of fish. And so many places in the United States, decommissioning is now seen as an environmental good, to help the local ecosystems recover they take out the dams. What's more is that most of the major rivers in the world are now quite heavily dammed. And so, there isn't very much scope. For greatly increasing, the amount of hydroelectricity produced. So, hydroelectricity cannot build a bridge between, our current energy use and a renewable energy future on its own. Another suggestion of course, is solar photovoltaic cells or solar PV. Right now, this is a tiny source of energy around the world. So, for example, in the US, it's around one-tenth of one percent of electricity supply. Some countries have more, some countries have less. Maybe solar is a potential way to solve the renewable energy, problem. Backing up this argument, we can see that although solar currently now is not a very important part of the energy equation. It's a very quickly growing source of power. Solar power is not just growing, its growing exponentially. In 2011, the amount of installed power, produced by solar electricity increased by 73%. And in the last five years, the total amount of solar electricity increased by a factor of ten. Although some observers think that this is a bubble and will not continue too far into the future. If this trend is, something, to become relied upon, we could quickly see solar become a major part of industrialized countries', energy portfolios. Similarly, wind power is also growing very quickly. It's been doubling every three years or so, for the last decade. And we currently produce four times as much electricity from wind power as we do from solar. So, wind power is even more important, currently, when we talk about renewable energy sources. Nevertheless, wind power is still a tiny part of most countries' electrical needs. So, for example, in the United States, it's of the order of one%. Growth in the US has been rapid in the last decade. If you look at this map and pick out your state, you might be able to see how much the use of wind power has increased. If you live in the Southeast, you might notice that there hasn't been so much change. We'll look into that, the reason why the Southeast hasn't seen the same growth that's being seen in other places in the US in a minute. One of the drivers for all this growth is better technology, especially for solar cells. As solar cell technology improves, they become much more efficient. So, they capture more of the sun's rays to turn into electricity. At the same time, the price of a solar cell has been decreasing year on year for decades. If this trend continues, we could see solar cells become cost-competitive with fossil fuels within around a decade. Now, it's not clear that, that will happen. Some people think that the current slump in prices of solar cells is due to over-production. We will see. Renewables do have problems though. As mentioned before. They rely on natural processes, the wind blowing, the sun shining, and so they can't be relied upon as the base load for current energy grids. Another issue with electricity generated by these new renewable sources is, is that they're not very good for transport. Currently, battery technology does not store energy nearly as compactly as fossil fuels do. If we look at this graph, we can see that batteries have very low energy densities. So that is, as they don't have very much energy either per unit weight or by unit volume. So, that means that if we have, an electric car, for example, we either have extremely large sets of batteries and so less storage space or we have very short ranges because the batteries run out of power before we go 100, 200, 300 kilometers. This is a clear case where the high energy density of fossil fuels as an advantage. A further disadvantage of renewable energies, is that on current prices, the only reason that we're seeing this large growth is because of government support. Even with recent reductions in costs, solar power is three to four times as expensive as traditional sources of electrical energy, and so clearly, if we would try and make a change towards, say current technology solar PV, we would be paying much more for the energy that we use. Furthermore, we can't always build power plants near the people who use them. This is important because we lose energy when we have to transmit it through the grid. Wind power, for example, is not in the southeast of the United States because the wind doesn't blow very heavily there. Instead, the fastest winds in the United States are found in places like the Rocky West. Not very many people live in the Rockies. If we have a challenge that we have to transmit electricity from one part of the continent to another, then we will lose we'll lose efficiency because there will be losses through the electricity grid system. The sine issues apply to solar. The sunniest places are not always the places that have the highest population centers or the most industry. So again, to use the United States as an example, we might talk about the Southwest as being the sunniest place in the United States. You can get lots of energy from, for solar power there. Not very many people live in the desert. So again, we might have an issue that the efficiency loss from trying to transmit electricity across the continent would outweigh, any benefits you might get. Some countries such as Germany, have put a lot of, financial support into producing Solar PV. But of course, as you can see from this graph. Germany, being close, closer to the pole than the equator, has little insulation, and so is a relatively poor place to install solar power. Further, more renewables are highly land intensive. If you have a small dense country, you might not have the space you need to install the wind farms or solar arrays that you need to produce enough electricity to power your, your country's needs. Similarly, biofuels are very highly land intensive. And they can, and they displace land that could be used for crops for growing food. Food versus fuel is a big issue for biofuels by the way. From 1974 to 2005, real food prices when adjusted for inflation dropped by about three quarters. Since then, prices had re-inflated, had doubled or tripled. And, some experts think that a large part of that is the switch to biofuels in some of the advance countries. Another worrying thing about the use of biofuels is that studies suggest that they also produce a lot of carbon dioxide. So then, although they might be in some ways a renewable energy source, they are not nonpolluting. Corn production for biofuel in the US is thought to produce more carbon dioxide per unit of energy than burning petroleum. And I mentioned that biofuel was space-intensive. It's been estimated that to replace the US' use of fossil fuels in transport, that is, to replace gasoline with ethanol. Approximately, the entire U.S. Corn crop would have to be turned into biofuel. And that is an enormous area. And again, of course, that would push up food prices enormously. So current, or so-called first-generation biofuels, are in most places in the world, no solution. They push up prices of food. One estimate from the World Bank suggested by as much as seventy-five percent. There's a terrible energy return on energy invested. Barely above one for corn and soy. They don't reduce the carbon footprint, and they can't replace petroleum. There's not enough land available. Research continues into so-called second generation biofuels that might be more efficient. For example, Miscanthus grasses. But they still await technological breakthroughs before they can become useful. So, we might ask ourselves then, is it even possible to move to a renewable energy future? An I think it probably is. We would have to accept some changes. Firstly, it would take decades to transition a grid. Secondly, most of these new renewable energy sources are highly space-intensive. They need lots of land. So, some countries like the United States would be better placed than other countries such as in Europe, like Britain or Germany. Also, it seems quite clear that prices would be much higher. So, if we had a renewable energy portfolio we would be paying more money to heat our homes, light our buildings, and so on. Furthermore, we don't have a good solution for transport as yet. Batteries are not a good solution. They're not energy dense, and also they have their own sustainability issues with the mining of things like rare earths, which are not a renewable, supply. It does appear though that in many countries if we are to accept the limitations it would be possible at great expense and perhaps at our inconvenience. We might not be able to travel as much, we might have interrupted supplies of electricity, to switch to lower carbon technologies that were renewable. This switch might be too painful for most nations. Is there a better way? Well, some experts think there are. Instead of looking for more sources of energy, maybe we just need to look for ways to use less. Produced by OCE Atlas Digital Media at the University of Illinois Urbana-Champaign.
