Let's move on to solar. I know you've seen solar panels because they're one of the most conspicuous forms of energy right now. But do you know how a solar panel actually makes electricity? Basically, the sun hits the panel and then converts the photons into electrons of direct current or DC electricity. These electrons float out of the solar panel and into an inverter. The DC power is then converted into alternating current, or AC. AC power is what's used when we plug in our stuff. The cost of PV has gone down, and that means it's grown a lot. Solar can take a lot of forms, from utility scale or large solar or community solar, that can power many homes and businesses. Two individual panels on folks' rooftops. >> Let's start with just rooftop solar and that's where individual homeowners will decide to purchase a solar system, put it on their house. Normally, they're trying to offset their utility bill that we send them and that process works really smooth because of the convenience of the meter that we use for those systems either goes forwards or backwards. And you can be sitting in your house watching television and your television's being supplied by the solar. And then a cloud comes over, and all of a sudden, you're being supplied by the grid. And you, inside your house, have no idea that that switch occurred, or it could occur many, many times. There's no switches or anything, there's no blinks, flickers, nothing. It's seamless as to how the energy is supplied to your various electrical appliances. And that is important because most people don't want to be inconvenienced, they don't want their television show interrupted because a cloud came over or anything like that, so that kind of convenience is very important. Those home's systems typically get a nice federal tax credit. People do want to offset their utility bill, and that's primarily why they do that. Now, community solar, and just for a moment I'll brag that United Power was the first community solar in the state of Colorado back in 2009, but in that particular case, we have a remote location where we have a little solar farm, and consumers can actually purchase those panels, lease those panels. And all of the energy that, that panel makes is credited on their normal home bill. So it's as if the panel was sitting on their house, but it's not and the benefit to that is, and I don't know the exact percentages but I'll say that maybe 20 to 30% of the homes in our service territory are solar ready which means that they have enough roof space, southern exposure, and no shading. That means that various people that couldn't participate in the solar because they don't own a home could actually buy a panel, or lease a panel on the community solar farm, and participate in solar, get the credit as if it was in their home, and that's the other 70% that we were able to to work with because of community solar. A pretty good idea, it allows everybody to participate in solar at some level no matter what. Now, the utility scale solar and many utilities have a legal requirement to have a certain amount of renewable generation. They're encouraging utilities to put as much solars they possibly can on the system and we can agree with that. However, on the other side of the coin, our members and customers still ask us to keep the rates as low as possible. And so, actually, the utility scaled solar as you see out in this field is really the most cost effective and puts more solar on the system quicker than trying to support the small solar on the homes type thing. So, at least at United Power, we think of it as a balanced approach again. We want to support the small solar on the homes because that is local jobs, local businesses, contractors, and individual members that are participating in that. We like the community solar because it opens up solar for the other 70% that can't do the rooftop solar. And we like the utility scale too because it brings a lot of renewable generation onto the grid at the lowest possible cost which, at the end of the day, helps to keep our rates lower, and stabilizes our rates over the 20 year period that this particular farm is in operation. >> As with wind, there's a lot of information out there that's taken out of context. Of course, saving the planet is a big reason people choose solar. Probably a bigger reason for consumers and businesses is that it costs them less. I say them because, like wind, there's more than meets the eye to it because of the subsidies in place to encourage adoption. Taxpayers and other rate payers are most often how these are funded. >> Really what we're seeing in solar energy is that the panels have dropped in, again 85% in price in the last eight so years and that's largely due to the fact that as the installations went up, the manufacturing processes improved to be less hands on and more automated, and more a continuous process. So they're able to produce panels at a much, much lower price than they were before which then drives the price down for the installations, which then increases the installation and the economies of scale. So these types of early stage incentives help get the technology into the market and achieve these economies of scale until it can reach the, basically, grid parity and compete fully with other types of technologies. >> Of course like every other generation source, it's not without its faults. And I bet you know enough now to see what those might be. Like wind energy which is only available when the wind is blowing, solar panels only generate electricity while the sun shining. Evenings and cloudy days are a problem. So that whole base load backup issue remains with this type of electricity production. >> Base load is critical and what that essentially means is power that's always on, always accessible day or night. I mean it doesn't take a rocket scientist to understand that when the sun is not out, you're not getting electrons from your solar panels. When the wind's not blowing, you're not getting electricity from the wind turbines. Really, what base load is, is that power that's always on and always accessible throughout the day. Really, you get your physics folks in here that can talk to you about the need to sort of balance the system, that you need a constant supply of electrons on the system to keep it running and operating. What's more important though than base load really is that sort of intermediate power, that power you can bring on when these renewable resources come on and come off. We need to have resources that we can call upon at a moment's notice to meet that gap, that energy demand. You can see it in hot summer days as the sun begins to set and the infamous Duck Curve, if you're familiar with that out of California, where your solar power starts to wane off but you're demand for the evening is starting to peak. They're not necessarily perfectly aligned. You need a resource to make up that gap and what we see in the space right now is that's natural gas. You have either peaking turbines or combined cycle units that you can dispatch quickly to sort of match and marry that gap, and the power that's either coming off or conversely when it comes on. >> We'll take a summer month like June, which has a lot of sunlight hours. This particular single access tracking field will basically come up to full production around 7:30 in the morning, and it will stay there, if no clouds, but it'll stay there until 5:30, 6 o'clock at night. Maximum production during that entire period where the fixed panel system is more of the traditional bell shaped curve. It slowly comes up in the morning, and it basically peaks for about a three to four hour period, maybe between 11 and 2 PM is when its peak occurs and then it starts to go back down again. So, just being able to get more hours at a higher production is where that additional energy comes from. >> It also takes a lot of real estate space to generate electricity and many homes and businesses just don't have the room. Another complaint is you can't do much with the land that the solar panels are on. So you can't multi-purpose it like you can with wind. There are some ways around that with community and utility or large scale solar. I had the opportunity to visit a utility-scale solar project. Let's learn more about how utilities are integrating solar into their operations. >> Yeah, this is, actually I'm kind of excited, I don't want to get into a lot of technical detail, but this is a 13 megawatt solar field. It probably could serve maybe around 3,000 homes, their entire electric needs for the year. It's on about 130 acres, and I believe there's about 160,000 solar panels associated with this. One of the unique features of at least this field is that it's a single access tracker. So, it actually follows the sun throughout the day. And because of that, it can get probably 20 to 30% more energy than a fixed panel system. And this is kind of the new wave of how these utility sized fields are being developed. Before it was a lot cheaper to just do the fixed panel. The actual tracking device is a mechanical device that has moving parts where they can get dirty and need maintenance every once in a while, and it just wasn't cost effective to do the single axis tracker. Until now, and we are seeing with this field, it's been in operation for a couple of months now. But the production that this field offers us first is a fixed panel system that we did a couple years ago is remarkably different. Both good. One of the unique properties of this particular field is not only that it's a single axis tracker but it's a load following. And what does that mean? Most solar fields are just plug and play. You plug them in, whatever energy they produce goes on to the grid and gets dispersed among the homes and businesses in the general area. What happened here is we worked with our developer, which in this case was Silicon Ranch, so that because electricity has to be used when it's made, there is no storage out here. So if we don't have the load to use the energy, then these guys can't produce it. And so, this particular field is not a plug and play, it's a throttled sort of field which is a bit unique in the industry. And so, if our load goes below the 13 megawatts that this field is rated, this field will actually throttle itself down to the 11 or 10 megawatt level to accommodate the load that happens to be on the lines at that time. Now when the load goes back up, the solar field comes back up, too. But that's a very unique thing that we worked with the Silicon Ranch, the developer on this project, to have that kind of load following, putting a throttle on a solar field. And again, that is kind of unique but very, very, very valuable to us as a utility. Obviously, we only make electricity with solar when the sun is shining. People still want to watch television at night. So we would, obviously, have to have some sort of other types of generation so that you could do that. And I think at the end of the day that is part of the solution as we move forward, is a balanced approach. We can't do 100% solar and wind. We don't want to do 100% coal and natural gas. But that it's a combination of all those things that, put together, complement each other and provide the power to people as they want to use it. >> If you're going to watch a topic area after this course, I would recommend keeping your eye on this one. I know this is one of the areas that's going to change a lot, and is going to be a catalyst for major change in the industry. Let's end our discussion of renewable energy with two energy sources that get very little attention. Biomass and geothermal. They're relatively small so we won't spend as much time on them but biomass is the oldest primary fuel source. If you remember, it's also what early electric local utilities competed against, and it's still around. Biomass works by using organic waste, whether wood or even animal waste. The biomass feedstock is then burned in a boiler and well, you know the rest. >> So the biomass co-firing program involves principally taking wood fiber and adding it to the coal stream as we burn it in small percentages up to 5%, so that we can safely combust it in the boilers with the coal. In terms of greenhouse gas savings, roughly, for every ton of wood we burn, we generate a saving of just over one ton of carbon dioxide avoided from not burning coal. >> So we have dedicated ourselves to develop technology that takes waste from another sector, puts that into something valuable so it can move on and keep adding societal and economic value. >> The benefits of biomass are that it uses stuff that would otherwise have not been very useful. Unless the waste is being produced on location, it has to be transported though. Incidentally, the pulp and paper industry is known for using this form of electricity generation with waste they generate on site. Geothermal energy also receives so much lesser attention than its brothers and sisters. You might not even know it if you saw it. It only accounts for about 3% of renewable energy electricity. It's not a new technology and it actually uses heat from the Earth's core. Here's how it works. Hot water is pumped from a deep underground well. The water comes back up to the surface and the temperature drops. This makes the water turn into steam and the rest is all about that spinning turban and then the generator. >> Geothermal uses the energy from the earth, typically it's in areas where they have volcanic activity or have the Earth's heat very close to the surface and it's heating up the water. So geothermal actually collects that heat and runs a steam turbine with it. The beauty of geothermal, where you have that resource, is that it is a base load power. I mean it's a consistent power. It's not like solar and wind where you have to worry about when the sun is shining or the wind is blowing but geothermal is always going to be working. So there are some countries that are nearly 100% renewable because of geothermal power. So, and now we are starting to look at more advanced geothermals where you can work it with lower temperatures, different types of drilling, and different areas like that. So, geothermal has been a base power for many places, many locations for a long time and it's really starting to advance in some new locations and new technologies.