# Nuclear Power: Savings lives

Nuclear power has saved over 1.8 million lives by replacing fossil fuel power sources.

A nuclear power plant!

I've mentioned that fossil fuel power plants kill people and shorten lives by emitting not only particulate matter and smog normally associated with pollution, but also NOx (natural gas power plants produce almost no particulate matter, but any time anything is combusted, the combustion process in a nitrogen rich atmosphere (78% on Earth) produces NOx, so natural gas power plants do produce NOx).

Coal fired power plants, even clean ones, belch yuckies into the air.

Shortly after harping on exactly this for several posts, a journal article came out that exonerated my aggressive stance on how nuclear power saves lives rather than ending them through nuclear disasters. Nuclear power has saved over 1.8 million lives, according to this peer-reviewed research. The authors didn't include long-term health ailments and non-death causing heart attacks related to climate change. Only death: full stop. They go on to say that replacing nuclear power with natural gas would cause 400,000 deaths by 2050. Replacing them with coal would cause 7 million. Meanwhile, the best estimates of long-term deaths caused by radiation exposure from the Chernobyl meltdown, mining uranium, and building nuclear power plants stands at about 5,000 No deaths arose from Three Mile Island or Fukushima. What about the radiation that Fukushima is spilling out into the ocean? It's less than 1/20th the radiation levels found in a banana.

I am a banana. Eating one of me makes you ingest more radiation than Fukushima ever will.

Critics are quick to point out that renewables like wind are cheaper and more effective at reducing CO2 emissions than nuclear. Great. Let's build more wind power. Except that there are not sufficiently good places to make wind effectively and cheaply. In an exhaustive (and depressing) article on the state of nuclear energy construction, it is pointed out that Germany has an installed capacity (recall, installed capacity is simply the name-plate power generation of a plant/turbine at best-case scenario) of 76GW of renewable energy. They then compared this to all of France's installed capacity of Nuclear at 63.1 GW. But, as we have talked about, renewables don't always work. While France's nuclear generators put out 407 TWh in 2012, Germany's renewables generated 136 TWh despite their larger capacity.

"Except like Jason's former manager at JPMorgan, I only work under ideal conditions!"

Moreover, Germany pledged to phase out nuclear power after Fukushima. What did they replace it with? Not renewables. Coal fired power plants. Meanwhile, as the US expands power generation from natural gas and ceased buying coal from the US, US coal producers are finding a new market for coal in Germany.

So let's look at Fukushima a bit more. Several things are bad about fukushima. First, it melted down when a tsunami overtopped its protective walls. The US Nuclear Regulatory Commission (NRC) had told Japan 20 years ago that their Fukushima walls were too low and they could be overtopped by a very realistic earthquake scenario. And now after the disaster, groundwater contamination with (less than 1/20th of a banana's levels) radiation is all a concern. Guess what? The NRC warned Fukushima to get their groundwater issue under control three years before the Fukushima meltdown.

That's right. The US NRC predicted that Fukushima was going to happen, and told Japan to get their house in order.

NRC: Telling Japan what to do since 1980. "We don't have much of a job to do in the US anymore since we haven't built a power plant in decades"

The US has a nuclear meltdown, too. You know what the consequences were? Pretty much nothing. It cost a billion dollar to clean up. That is a huge sum. But the meltdown was well-handled. And a lot was learned from the meltdown.

My point is, the US has it's matters sorted out when it comes to nuclear safety. And we are good at identifying risks in other parts of the world.

Finally, here's the big one, new reactor designs wouldn't allow for either three mile island or Fukushima to happen. With these new reactors, in the event of mechanical failure of the passive systems, the worst case scenario of the new designs is that it would take 3 full days before even needing to worry about meltdown beginning, leaving plenty of time to deal with the situation.

So yes. There are risks with nuclear. But there are guaranteed deaths with coal and natural gas.

The best solution by far is avoiding building new power plants and to massively increase efficiency and conservation. But people are slow at changing, and we aren't gonna change our lifestyles fast enough in the western world to avoid expansion of power use, and the developing world needs to build a ton of power capacity.

So let's stop being scared of nuclear power, cause it's saving lives rather than costing them.

- Jason Munster

Appendix

Oh, but what is this section? Just a bunch of extra information. Check out how long it takes for various countries to build nuclear reactors:

Average, min, and max times of nuclear plant construction for countries that have built them. Source

Hokay, so. I need to acknowledge the bad parts of nuclear power. The real ones, not the fear-mongering that happens.

First, nuclear power is more expensive than on-shore wind (which is a limited resource, there are not infinite good places to put wind farms), coal, and natural gas. There is no doubt about that. If we switched everything to nuclear, many parts of the US that don't have high electricity prices will experience a rate shock. That is, their electricity bills will rise. But hey, remember what we said earlier about efficiency and conservation being the best way to save lives and to arrest climate change? Slightly higher electricity prices would promote this conservation. The initial rate shock would be a bit of an issue, but I am betting that nuclear power's opponents overstate it.

Second, there is an alternative to nuclear that I want to acknowledge, with a caveat. Renewables can't provide baseload power. But renewables paired with load-following natural-gas fired plants can (recall from a prior article that gas turbine based power plants can spin up very fast, and no other major power plant type can) (we don't count hydro as a major power type because we can't build more hydro in the US, we are tapped [punny]). This is by far better than coal, and better than gas alone. But it still burns gas, which produces CO2 and kills people and causes asthma.

# Solving the Climate Problem

I started this site to get practice in writing science for the general populace. I've slacked off because I am a bit bored of reaching for topics. More importantly, I've been playing rugby with HBSRFC.

So here it is. A generalized and very incomplete version of my view on climate change, who it will affect most, and what we can do about it.

CO2, The Ugly One That Won't Leave You Alone

CO2 stays in the environment for more than 40,000 years. That is longer than nuclear waste lasts. Moreover, its effects are experiences by every person on the planet. What we do now has an effect on the entire planet. Luckily, technology will probably be able to fix this eventually. We can't count on this now, though.

Energy and Climate Change, How They Relate

Climate change is caused by emissions of CO2 by energy use, methane by agriculture and other things, and a host of other very powerful chemicals that are emitted from industry.

How do we solve climate change? The answer is straightforward, but far from simple: use much less energy from sources that produce CO2. Either switch to "green" tech, or conserve. Buy less things that require all the energy to produce. Travel less, or travel in ways that produce less greenhouse gases. Make fewer babies. None of these are easily accomplished, unless you are poor and can't afford any of them. Even then, everyone is striving for a wealthier, more CO2-heavy lifestyle.

So let's assume for a second that people aren't going to change their lifestyles and conserve. We need ways to get energy without belching CO2 everywhere.

Live in Smaller Houses, Buy Less Stuff

You can't convince Americans to live in houses that are the size that Europeans live in and you can't convince them to give up their cars to take public transportation and live in cities (at least in the short term). Houses require energy to heat and cool. Smaller houses mean fewer drafts, leading to less heating and cooling needs.

How about green energy? We have reviewed those technologies. There isn't enough wind to provide sufficient wind power, and the wind isn't always blowing, so sometimes we won't have power when we want it. Hydro power is pretty much fully tapped. Tidal power is a joke in the big scheme. Solar could be an option, but it is currently far too expensive. It is not "deployable" in that with solar, you only get what the sun decides, so we will always need some backup power that can be turned on when we want. Solar doesn't work well at night, for instance. Moreover, the best places for solar are far from cities, so figuring out how to get the electricity from the countryside to the cities is a monumental task, especially in the US (even with eminent domain, getting the land to be the transmission lines through several states would be nearly impossible). So here we stand with three good reasons that solar won't solve our problem in the near future, and with the other resources insufficient. Pretty much, even if we do use solar to solve a lot of our problems, we still need some other energy source to provide baseline power.

Too small! Turn back!

What about buying less stuff? The amount of CO2 that goes into making cars, laptops, etc., is pretty big. How much stuff do you buy that you never use afterwards? Or you maybe use once a year or two? All of that, you could have rented, saved money, and saved space. Even better? The things that go into making electronics like cellphones are not easy to pull out of the ground. Tantalum in your cell phone is pretty much produced by indentured servitude in Africa. The other stuff that goes into electronics, the rare earth metals, these are not so rare. It just turns out that it is difficult to produce it without destroying the environment. The US has plenty of rare earth's the reason it is done in China is that they don't mind wrecking the environment and their workers (see bottom of that post). Yeah, we need electronics to communicate and keep things moving. We don't need a new iphone every 6 months. Those things last at least 2 years.

Energy for Transportation

This is a much larger hurtle. 35% of US energy consumption is in transportation. Transportation requires that the energy source be within the vehicle (unless you are in South Korea, where the energy source is induction and is beneath the road. Pretty badass, if you ask me). Batteries currently weigh a lot, don't have nearly as much energy per pound as gasoline, and require a long time to charge. The problem is not as bleak as it seems, however. Most driving in the US could easily be done with all-electric cars.

Your bus is ugly, but it charges while driving without producing its own CO2. Well done, South Korea.

Cars

I've also written about Electric Cars.

This is an area with a lot of potential. 120 million Americans commute to work by car. The average person lives fewer than 20 miles from work. Substantially all of them commute alone. The Nissan Leaf gets 75 miles before it needs to be recharged. The Tesla model S goes about 275 miles. No matter what the source of energy for an electric car, it produces less CO2 than a normal car. Going by the numbers available on these cars, we see that with the standard US energy mix (some renewables, lots of nuclear, a whole lot of natural gas), they produce between 33% and 50% the CO2 as a combustion engine.

Bicycles

I've written about bicycling. It's good for you, and saves the environment. Unless you eat only beef. Then you have other problems.

Power Generation: What Works

Wind power makes sense everywhere that there is a lot of wind, as long as it is onshore. Wind is pretty much going up everywhere that makes sense. It costs less than a new coal power plant, and is far cleaner.

Solar power is expensive. Is there anywhere it works well? Sure, just take a look at the electricity rates paid by different types of consumers. Commercial real-estate (stores, offices) and residential places (our homes) pay a huge premium on electricity. In most states, residents and commercial consumers pay nearly 15 cents per kwh, while industrial consumers pay closer to 7 center for a kwh. How does this stack up to costs to produce? Let's return to my favorite chart:

Table 1. Estimated levelized cost of new generation resources, 2018
U.S. average levelized costs (2011 $/megawatthour) for plants entering service in 2018 Plant type Capacity factor (%) Levelized capital cost Fixed O&M Variable O&M (including fuel) Transmission investment Total system levelized cost Dispatchable Technologies Conventional Coal 85 65.7 4.1 29.2 1.2 100.1 Advanced Coal 85 84.4 6.8 30.7 1.2 123.0 Advanced Coal with CCS 85 88.4 8.8 37.2 1.2 135.5 Natural Gas-fired Conventional Combined Cycle 87 15.8 1.7 48.4 1.2 67.1 Advanced Combined Cycle 87 17.4 2.0 45.0 1.2 65.6 Advanced CC with CCS 87 34.0 4.1 54.1 1.2 93.4 Conventional Combustion Turbine 30 44.2 2.7 80.0 3.4 130.3 Advanced Combustion Turbine 30 30.4 2.6 68.2 3.4 104.6 Advanced Nuclear 90 83.4 11.6 12.3 1.1 108.4 Geothermal 92 76.2 12.0 0.0 1.4 89.6 Biomass 83 53.2 14.3 42.3 1.2 111.0 Non-Dispatchable Technologies Wind 34 70.3 13.1 0.0 3.2 86.6 Wind-Offshore 37 193.4 22.4 0.0 5.7 221.5 Solar PV1 25 130.4 9.9 0.0 4.0 144.3 Solar Thermal 20 214.2 41.4 0.0 5.9 261.5 Hydro2 52 78.1 4.1 6.1 2.0 90.3 Solar PV costs less in sunny areas than buying from the grid, as long as you are residential or commercial. A big industrial complex gets really cheap power, so they will never use something as expensive as PV. The Future of Solar Even if solar power is widely deployed in the future, it doesn't work at night. A lot of people in Houston, and other places that are unlivable without modern tech, would be unhappy if they couldn't sleep in AC. We don't have massive-scale battery tech to compensate, so we will still need baseload. Baseload Power There are two viable places to get baseload power. The first is nuclear power. The second is burning fossil fuels and then catching their CO2 and putting it underground. Carbon Capture and Storage This is a very unproven technology. We don't know if we can hold the CO2 underground forever (which is what would be necessary) or whether we can find a place for it. And there are only a few test cases for it. The numbers above are completely unreliable in terms of cost. This might be better in the future, but I would guess that it isn't viable for at least 15 years. Another issue? You can't just start capturing CO2 emissions from any old power plant. Retrofitting the plant is expensive or impossible. Power plants are built to last 50 years. Even when we figure out carbon capture and storage, we can't easily retrofit old plants to make them work well. Baseload? So we need baseload. There are no green baseload sources. Making coal based powerplants green is not currently viable. Nuclear power doesn't produce much CO2, but it has nuclear waste. Nuclear waste lasts a long time. But it is the only power source that contains all its waste. It's manageable. And it decays faster than the Earth will take down CO2. nuclear power plants are my favorite What's the biggest problem with nuclear? I'll describe this in more detail later. The long version: it can't get financed. Short version: people are afraid of Nuclear. Cause three powerplants have blown up. Fukushima was completely preventable. The US literally told Japan twice to get their house in order, cause there was trouble.The USGS warned that the walls of Fukushima were not high enough to prevent tsunami flooding years ago. Had they followed through with the USGS recommendations, Japan would not be spewing radioactive waste into their groundwater. Moreover, the US Nuclear Regulatory Commission told Fukushima and Japan that they had a groundwater problem, and that a breach would cause widespread contamination; that if it ever melted down, it would dump nuclear waste into the ground through the water. They indicated Japan should divert the flow of the groundwater to prevent this. Still, no one died in this meltdown. When Russia melted down a nuclear plant, it was a big mess. When the US melted down a nuclear plant, no one was harmed and not much was released. It was just expensive to clean it. Short version? The US is good at nuclear. Korea seems to be good at it. People shouldn't be afraid of it. But they are. So the plants don't get financed, they don't get built, they aren't allowed to go forward. As a result, if someone did want to finance them in the US, they would have to pay such massive interest rates that it would never pull a profit. You know who is building them? Korea. China. Korea is also building power plants in the middle east. Other countries will follow suit. We need to get our house sorted out so our country can build power plants here and elsewhere, too. Summing it Up Live in smaller houses, it won't make you less happy. Buy less stuff, it also won't make you less happy. You also don't need to drive an SUV. Or drive as much as you do. Commuting sucks anyways. Until all that happens, we still need a ton of electricity. Nuclear is probably the best way to do it for now. That's my rant Seriously. I'm pretty much done. Thanks for reading all along. There might be a few more posts on this stuff. - Jason Munster # Geoengineering So. Science can fix anything, right? Only if we have lots of time and money. And grad students that function as indentured servants in a pyramid scheme to get tenure. Back to the point. The truth is that science can't fix everything on short time scales. Climate is one of them. Geoengineering can help to a degree, but it will only get us part of the way there to avoid the worst consequences of climate change. Let's discuss some. White roofs, white roads, white buildings. Two articles back, we discussed albedo, or reflecting sunlight. Ice reflects 90%, water reflects 90%. Whatever is reflected tends to go to space and not stay in the Earth system and warm it up. In fact, whatever is absorbed then gets in the greenhouse trapping loop, warming up the Earth a good bit. Dark surfaces (our roofs, our roads, most of our buildings) reflect little and absorb a lot. So, paint them all white, and more light is reflected. Excellent! "But Jason," you say, "Cities are only a small percentage of land area. How could this possibly help? I mean, the rest of the Earth will still absorb just as much heat. Right?" And to you I say, "Excellent, sir! That is true. Making all our stuff white won't do much for the overall heat budget of the Earth. I am so proud of you for reading most of my website so you quickly figure stuff like that out." So what does it do? The heat island effect is based on the fact that cities are covered in dark buildings and pavement, and have a very low albedo, so they absorb heat Cities are fucking warm. They suffer from this thing called the "heat island effect." That is a fancy way of saying that they are so dark, they absorb the sunlight and are easily 10 degrees F (around 5 degrees C) warmer than they should be. Turn everything white, and you can cool the city. This will actually have a very large effect on how hard our AC units have to work in the summer. Imagine if your city was suddenly 10 degrees F cooler. How sweet would that be? I posit that it would be pretty rad. This one seems to help a bit, but we will still be using tons of energy and producing CO2 in all other ways. Moreover, it won't solve the problem of the agriculture, ice caps, and acidifying ocean. Putting CO2 in the ground There are two ideas of sequestering CO2 in the ground. The first is capturing it at the source. Like power plants. This sounds like an easy idea, but the first problem is the energy it takes to capture it. Thermal power plants take in atmospheric air. Which is 78% nitrogen, and 21% O2. Even if all the O2 were converted to CO2, what comes out of the power plant stack is still 78% nitrogen. Separating the two to store the CO2 takes more energy. In fact, the power plant is roughly 30% less efficient. So it needs to burn a lot more coal or natural gas to produce the same amount of power, and will cost a lot more to build. And any fancy idea you have to get around this 30% efficiency hit won't work. No matter what, you either have to pre-concentrate O2 to get a pure stream of CO2 on the other side, or separate the CO2 on the emission side. The next problem is where to store it once you get it. Gases like to leak out of things. Some companies are trying to store the CO2 underground, much like petroleum is stored underground in a lot of places. This is why you need to separate it from the nitrogen in the air. There just isn't enough space to store both the CO2 and the nitrogen, and also it is expensive to pump stuff underground. Another issue is that it is unclear how long storing CO2 will last in the ground, since it more or less needs to be done indefininately. Finally, since 35% of our energy use is from cars driving down the road, and it is impossible to capture that CO2. So Carbon Capture and Storage (CCS) from the source still won't do everything we need. Direct Capture The next idea is to capture CO2 directly from the air. We have increased CO2 in the atmosphere from 280 parts per million (.028%) 400ppm. The idea of direct capture is to do the opposite. Draw down the CO2 and then store it somewhere. Some might suggest we store it in trees, but that is an awful lot of trees, and unless we bury them trees somewhere underground, they are just gonna get consumed by bacteria and become CO2 again. Other options are to mechanically and chemically separate CO2 from the air, and them store it underground as above. This is very expensive. It might work in the future, but for now it won't. The bonus of this, if it ever works, is that it is the best way to reverse our issues from an engineering standpoint. We can turn back the clock. Stratospheric Injection Injecting small sulfur or other particles into the atmosphere cools the entire globe by reflecting some small portion of sunlight before it hits the rest of the Earth. We know this cause when mountains like Pinatubo and St. Helens explode, they launch particles into the stratosphere and we get a cold year. SO2 increase in the stratosphere by exploding volcano Some people have suggested that we could do this. Just inject stuff into the stratosphere to reflect sunlight. The problem? It turns out that everything small enough to cause the proper scattering just happens to be the right size to promote adsorption of water particles. Which then allows for rapid recycling of CFCs in the stratosphere. "But Jason," you say, "I thought recycling was good!" Recycling plastics is good. Stratospheric recycling of CFCs is bad. Cause what happens is a CFC reacts with ozone, breaking it apart, wrecking the ozone layer, and then usually is all like, "Man, I am exhausted from catalyzing that reaction, I am gonna take a break." But that water that adsorbed onto our reflective particle provides an excellent place for it to re-radicalize. Which means it is ready to take out another Ozone particle. That's right, our CFC goes to chill out on some water droplets, effectively taking a restful timeout at a pool, and gets ready for work again destroying the ozone layer. Let's pull this all back together. We try to put stuff in the upper stratosphere, if could make CFCs more effective at destroying the ozone layer, and then we are all screwed in a much much larger way than climate change. Cause the ozone layer is what protects us from getting fried by a lot of UV rays. Here's where things get fun. Imagine you are a small country of 1 million people living on an island. And that island is going to get inundated with water in 20 years unless climate change is reversed. You don't give a damn about a chance of destroying the ozone layer. You only care about saving your people and your country. Stratospheric injection isn't exactly nuclear science. We aren't going to have rogue nations stumbling through how to do this, and failing all the time. I'll leave you to ponder what all that means, cause it is more fun that way, and we are already at 1200 words. The upshot of this is that it also fails to solve the acidifying of the ocean, we don't know how well it will work, and we don't know what will go wrong. Solar Reflector Another idea is to put huge mirrors in space and reflect a chunk of the sunlight coming in. This could work. Wasn't this a plot in some Bond movie, though? Also, it would be mad expensive. Probably much more expensive than some other options. And much like the option directly above, we still acidify the ocean. Review Hokay, so. Most of the technologies for fixing our problem don't exist, don't work, are too expensive, or could kill us all. And if they do work in the future, they won't solve all the problems we are creating. Even the one that does solve all the problems, direct capture from the atmosphere, won't do crap for our plight if we rely on that alone. As a species, we can easily outstrip any CO2 removal measures just by burning more things. Even if after rigorous testing proved all these work, we would need to some combination together to get anywhere. And even with that, we need to reduce the continued growth of emissions worldwide, otherwise no science or engineering solution will stop climate change. Depressing, eh? Thanks for reading, - Jason Munster # Other Alternatives Here we will cover a few more electricity producing alternatives, specifically geothermal in its different flavors, and the waste of money that is tidal power. Before that, let's make a quick roadmap of what we have covered, where that is going, and what we haven't yet covered. Pretty much, we have talked about electricity producing resources. We have only briefly touched on energy as a whole. In the US, for example, 35% of all energy use is petroleum for transportation. None of the stuff we have discussed is useful to replace that without better battery technology. Nonetheless, it is likely that at some point in the next century, much of our domestic energy needs, including transport, will be covered by electricity. And we will require a lot more of it. An upcoming post will assess all the different tech for producing energy we have discussed, and which ones can be potential solutions. # Geothermal Geothermal energy exists because it gets hot underground. In general, the temperature of the Earth rises by 30 degrees C for every km you go underground. This temperature increase in depth is called the geothermal gradient. If you go 7km underground, you are pretty much guaranteed temperatures of higher than 200 degrees C. Which, as we all know, is hot enough to boil water. 7km underground is pretty deep, however. In some places, the underground is much hotter. The temperature rises much more rapidly. It could be due to volcanic activity in the area, or radioactive decay underground. Either way, when hot temperatures are closer to the surface, that heat can be harnessed to drive a turbine. Map of the geothermal resources available in the US. In general, this represents areas of higher temperature gradients. Geothermal comes in two main flavors. One directly harnesses the steam from the ground to produce electricity (called flash steam, cause the pressurized hot water comes out, flashes to steam at atmospheric pressure, and drives a turbine), the other uses a heat-transfer mechanism where pressurized hot water from the subsurface (it needs to be pressurized, because it is above the boiling point of water at atmospheric pressure) is run through a set of heat-exchanging pipes before being put back underground. There is a third type discussed later in the article called hot dry rock. Surprisingly, the first mechanism of directly using steam, in practice, is unsustainable and produces pollution. This is because the used steam is often vented to the atmosphere. The steam produced underground has pollutants. Like CO2 and sulfur, amongst other things. If the steam is used directly in a turbine and then expelled to the atmosphere, these pollutants come with it. If the used steam is instead re-injected into the formation, this problem is avoided. Reinjecting the steam is easier and more common in the heat-exchange mechanism. The super heated stream of steam from underground is already isolated, and re-injection is pretty simple. And here comes the fun part. If the steam is used and then vented rather than reinjected, the formation will run out of water. Instead of being a renewable resource, the geothermal will be a depletable resource that will only last for 10 or 20 years. This is because the pressure of the formation will drop, and the steam will no longer be able to rise. Does this sound familiar? Oil and gas production need to do this all the time to get maximum recovery rates. Reinjection of fluids is rather easy, and has been pretty well developed by the oil and gas industry. Hot Dry Rock The next major innovation takes a cue from the oil and gas industry. Hot dry rock is exactly what it sounds like. The rock starts off hot and dry. It has plenty of heat in it, but there is no steam or water to produce and then make energy from. How is this dealt with? Hydrofracking and injection. A well is drilled, the drill hole goes horizontal, it is fracked to drastically increase the surface area that the well hole can be exposed to, and water is injected into the rock. The water heats up a lot, then it is produced via a separate well to make steam. It is fairly complicated, and costs a lot more. EGS EGS stands for enhanced geothermal systems. You will run across this term a lot these days. It more or less means that the heat in the field is managed by either fracking beforehand, injecting water afterwards to maintain pressure in the field and extend the life of the geothermal power plant, or a combination of both. It drastically increases the lifetime and viability of a geothermal site. Cost The capital costs of geothermal pretty much will dictate the average cost of electricity produced. It looks like flashed steam will cost the least. In reality, unless the steam is reinjected afterwards, the field won't last as long, and the capital investment costs will have to be paid out over a shorter period of time, resulting in higher costs. Hot dry rock will undoubtedly always remain more expensive because of the costs associated with fracking and reinjection. Footprint and other Most of our power plants produce heat above ground, and need storage for either spent nuclear fuel or a coal pile (except for gas plants. They just need pipelines). So geothermal power plants don't take up a ton of space fun uses of geothermal: geothermal heat is produced and used in Iceland to melt snow on the roads and such. Tidal I tend to think that tidal power sucks. In part because it is very expensive, and in part because at best it could provide all of 1% of world electricity. Tidal power has two main problems: it uses salt water and it has only a few areas that it will work. There needs to be tides of sufficient strength that it can produce electricity, and even then, salt water is corrosive, limiting the lifetime of these power plants and making the levelized capital cost very high. Tidal power also comes in two main flavors. One is tidal impoundment. Think of it as creating a hydroelectric dam every time the tide goes out. The tide comes in, fills up the area behind the impoundment dam, and then as the tide goes out, the area behind the impoundment dam is filled, and as it flows out, it generates electricity. As you recall from the hydropower article, the energy produced from a hydro dam directly relates to its height. The height of a tidal impoundment dam is limited by the height of the tide. In most parts of the world, this is not very high, so it is not very efficient. Moreover, it kinda messes with natural habitats. The other type of tidal power is more or less an underwater wind turbine. The problem is that all the moving parts are underwater in the ocean. Where decay and breakdown happens quickly. Moreover, looking at the equation of energy produced via such a turbine:  where A is area, and v is velocity, we quickly realize that the area of the rotor for a tidal turbine is small (wind turbines have 40m blades, and we aren't gonna have 80m of water depth in most places to replicate that scale in tidal areas), and the speed is slower (water doesn't flow at 6-8m/s very often). Tidal power can't scale and produce as much energy as wind. And the environment is unfavorable. In short, this is not a viable resource for large-scale energy production. And it costs a lot. Hokay, that is all for today! Thanks for reading! -Jason Munster # Solar 2 Photovoltaic solar cells. Solar PV. This is not an easy thing to describe. For some, you may want to just skip past the technical section, cause it is pretty technical. Solar PV: they used to take as much electricity to make as they produced in their lifetime. Now they they produce about 5x as much energy as they take to make, and the time to break-even on emissions compared to our cleanest fossil fuel stations is about 6 years (see Kannan, 2005, Lifecycle Assessment Study of Solar PV). Of all the clean technologies (nuclear power excluded), this is the only one with the potential to supply world energy needs (that is the subject of a later post). In other words, when you hear some fool saying that solar panels take as much energy to manufacture as they ever produce, they are referring to a specific type of solar cells called thin film. A type that was made in the 70s and 80s and only goes into things like calculators. Feel free to ask them to stop being foolish. Some Math The light we see is not a homogenous single color. In fact, the light we see is not even all the light that is coming from the sun. Infrared and UV rays are also light, but we cannot see them at all. All this light is just an electromagnetic wave. The waves have different wavelengths, but the same speed, and so all the different wavelengths travel together. What we see is a blend of a tiny part of the electromagnetic spectrum. This is the electromagnetic spectrum. Visible light, what we can see, is only a small part of it. The amount of energy contained in a photon is equal to  where  is the wavelength. h and c are Planck's constant and the speed of light, respectively. Smaller (shorter) wavelengths give more energy. This is easily shown just by plugging a smaller number into the denominator. Stuff in the infrared is long wavelength, and stuff in UV, X-ray, Gamma ray, etc, are really short wavelength. Technical Stuff There is no easy way to do this. I am going to use some terminology that most of you all are unfamiliar with. A Photo Voltaic (PV) solar panel is a sandwich of two materials. The materials are largely the same, with a few key differences. Both are likely made of silicon (processed sand). But each one has very specific impurities put into them, in a process called doping (not the same type that Lance Armstrong does). This doping is incredibly technical, and very skilled chemists are paid a ton of money to figure out how to do it. Doping I won't get into specific materials. Some elements cause there to be a shortage of electrons, or a electron hole, in the whole material (p-type semiconductor). Other elements cause an excess of electrons (n-type semiconductor). So you have one material that can accept electrons, and another material that can give electrons. Putting them together (literally stacking them together) makes magic happen. And by magic, I mean quantum mechanics. Which to most people, including many who study it, is no different than magic. Just because one has more electrons doesn't mean it wants to be nice and share them. The electron in the n-type literally needs to be excited to be shared. And in PVs, what turns the n-type material on is sunlight. More specifically, photons. Photons are particles of light. ("But Jason!" you say, "Isn't light, like, a wave?" to which I say, "It is both a wave and a particle! Please don't ask me why, just accept it.") Photons contain energy based on their wavelength. Shorter wavelength, more energy (see above). Here's the fun part. It takes energy to make the n-type semiconductor want to party with the p-type semiconductor. There is a threshold level of energy that needs to be met to kick that electron up from the n-type to the p-type. Too little energy, and the photon doesn't get excited enough to go to the electricity-production party. If there is enough energy from the particular wavelength of light to make that electron jump, then is does jump. But what if there is more than enough? This threshold level is pretty much determined. Any extra energy will be wasted. This is why PV cells are not particularly efficient. There is a huge amount of light that is too low-energy (all of infrared) for the cell to gather any energy from. There is a lot of light that has much higher energy than required to meet the threshold energy as well. The excess energy is wasted as heat. This can be solved by having a multiple junction cell (multiple junctions just means it has a bunch of different width absorption gaps, so it can harness tons of different energy levels in light). It is capable of absorbing more wavelengths of light, increasing efficiency. And since it has multiple junctions, it is also more expensive and complicated to produce. Hokay, so, what happens next? You have an electron that has jumped the gap. Then you close the circuit by connecting them with a wire. The electron will go home, back to the n-type, and create an electric charge on its way down. That's about it. New Methods Transistors are expensive. Normal glass optics are relatively cheap. The transistors absorb about 20% of the light that hits them. So it would make sense to use cheap optics to focus more light on the transistors and make the transistors small, yes? One problem with these cells is how warm they get. If they warm up too much, they begin to lose efficiency. Here we see that we have a tradeoff. We want more optics and fewer cells, but if we do this, they get too warm. They stop being efficient. Some scientists and engineers are working on increasing the efficiency of the cells instead, to get more electricity from light. Otherwise, there are clever ways that some mechanical engineers are trying to get around these issues. One new design uses focusing mirrors and liquid cooling to get around this issue. The pertinent stuff Everything pertinent, like insolation and weather, was in the last solar article. Next post: rounding up some of the stray power sources: tidal, geothermal, wave, and then I am pretty much done. Thanks for reading. -Jason Munster # Some dams Dams. They provide clean electricity. Sometimes they cause earthquakes that kills thousands of people. As I mentioned before, hydro is a tapped resource in all places except Asia, Africa, and South America. In other words, it works great in developing countries. It is not an option for developed countries. Despite that I provide references where I can, this post is pretty unprofessional. Also, since I didn't post last week, this will be a mid-week post. It is as close as I will get to a blog rather than a collection of science-based articles. Hydro Plants Causing Earthquakes Three gorges dam represents the domination of Man over Environment like nothing else on the planet. Remember that earthquake in Sichuan earthquake in 2008 that killed 60,000 people? This earthquake was likely caused by the three gorges dam. three gorges dam! "I cause Earthquakes" says Three Gorges. How do earthquakes happen in general? Stress builds up in the Earth, usually from shifting tectonic plates. Loading a massive amount of water in an area increases the stress by huge amounts. Dams load billions of tons of water into an area. Dams are not the only way to do load the environment to prime it for an earthquake. Downtowns of cities with skyscrapers also do a pretty good job of it. But dams are way better at it. Pros and Cons of a hydro plant Let's look at more information on Three Gorges. I've recommended y'all read When A Billion Chinese People Jump. In that book, we find that the past several presidents of China have been hydrological engineers. The most recent one didn't show up at the opening of Three Gorges because, because in some ways, it is very controversial. It has very strong benefits and issues. Despite negative effects, it produces 22.5GW of electricity. In other words, it replaces 22 very large coal fired power plants. And in China, that means 50 years of 22 unfiltered powerplants not belching harmful pollutants into the atmosphere. In case you haven't heard, China in general and Beijing have some of the worst air pollution in the world. Before you start judging, remember all those jobs that are being outsourced to places like China? This is the result of that. We are exporting our trash and our pollution to poor countries, where environmental regulations are more lax. Getting back to the point, those 22 coal fired power plants that are being replaced would probably have caused more long-term deaths than the earthquake. Moreover, China is a very dry country. Like most dry countries, it is prone to flooding without controls. Containing the river behind the three gorges prevents the downstream from ever being flooded again. So they saves the homes and such of millions of people, but had to move millions behind the dam, and it also flooded historic areas. How's that for controversial? Serious positive and negative implications. No dam embodies the pros and cons of building a dam more than Three Gorges. Other uses of dams It turns out that producing electricity is only a small part of what dams do. Many are used for irrigation, for flood control, for reservoirs, and to protect the environment. We are mostly an energy blog, so we don't give a damn about all that stuff. Except one major point: electricity is less than 10% of the economic benefit from dams. A huge amount is in flood control, irrigation, and recreation. FEMA says these are the benefits of dams. Notice that hydroelectric is tiny. Hoover Dam Hoover "meh" Dam When you think of a huge American dam, you think Hoover. This is silly. It is a 2.5GW dam. It is 10% the size of Three Gorges. It is like comparing Bangor ME, to Boston, MA. One is just tiny. Why do people care about Hoover? I dunno. Maybe after spending too much time in Vegas they decide they want to see something natural? Hoover dam is tiny. It only replaces 2 or so coal plants. Hoover Dam, you are not worth wasting words on. Grand Coulee Dam Grand Cooulee Dam is one of the largest dams in the world. Notice the size of the houses for scale. You know which dam is an American dam? Coulee Dam. This dam produces 7GW. Fully 3x of Hoover, and near 1/3 of Three Gorges. It is also in Washington state, which, compared to Nevada, is better in every way except for gambling and prostitution. Which shouldn't be family activities. Why don't more people visit Grand Coulee instead of Hoover? This is not a rhetorical question. Someone please tell me. Grand Coulee has this other sweet feature I already discussed. They have pumped hydro storage. In other words, they pump from the area behind the dam to another dam that is far higher up. This is a great way to make a giant battery. It recovers about 60% of the electricity that is put into it. Interesting note: While scouting around the interwebs looking for information on the pumped hydro storage at Grand Coulee (it is really difficult to find), I stumbled across a blog that already has written posts that are way more in-depth maths about many of the things that I write about. If you are one of my sciencier readers, you might want to check his page out. I will poke around there some and give you more info on it later. Dams produce clean power. They are environmentally friendly! Or not. We have discussed how dams get backed up and leave heavy metals in the sediment, and more or less create environmental issues. And how they block fish from swimming upstream. I wanted to touch on one thing again. In China, many places that built clean hydro plants attracted industry, cause industry loves inexpensive power. And hydro power is amongst the cheapest. So the skies and waters became quickly polluted with industrial wastes. Like, red polluted. Image from the link above. It looks like the Earth is bleeding. I don't think this is healthy. And all my Boston readers are afraid of the Charles. Outsourcing manufacturing seems even a bit crappier than it used to, doesn't it? Sure, we lose jobs, but they lose lives and the environment. Alright, that's about it for my quite unprofessional rant. Thanks for reading. -Jason Munster # Power Grid I was struggling to write a post about PV solar panels (the struggling part came in while trying to describe the quantum mechanics that take place), and realized that I need to describe how our power grid works in far greater detail than I had before. What follows is the gory details about how power is transmitted to your home. This is important because while solar power costs 5x as much as coal on the wholesale market, it only costs about 2x as much as coal at your house. Sometimes less. This is because coal-powered electricity is wheeled and dealed through several players as it reaches you, and is marked up every time. Solar power dumps straight into your home. Some of you are gonna love this article, others have already closed it. On a logistical note, I haven't posted in the last two weeks cause I am too busy with life things to write both the blog and play computer games. Computer games sometimes win out. Thanks, X-Com: Enemy Unknown. Generators, LSEs, Home Energy Generators are all the different types of power plants we have discussed. They produce power, and in a deregulated market, sell the power to the grid. They are given a price based on demand. We have discussed how each power plant will "bid in" a day ahead and say how much power they can produce at which prices. As more power is demanded, the price will rise to bring more expensive power online. No matter what the power plant bids in, if they are online, they will get the per-MWh payment of the most expensive plant to come online. In other words, the marginal cost of energy production is what each power plant gets paid per MWh. If an expensive power plant is brought on-line for$1000/MWh, for instance, every single plant that is operating will receive that.

Okay, we have also seen the cost to produce power in several posts. It makes sense to repeat it here.

U.S. AVERAGE LEVELIZED COSTS (2011 $/MEGAWATTHOUR) FOR PLANTS ENTERING SERVICE IN 2018 PLANT TYPE CAPACITY FACTOR (%) LEVELIZED CAPITAL COST FIXED O&M VARIABLE O&M (INCLUDING FUEL) TRANSMISSION INVESTMENT TOTAL SYSTEM LEVELIZED COST Dispatchable Technologies Conventional Coal 85 65.7 4.1 29.2 1.2 100.1 Advanced Coal 85 84.4 6.8 30.7 1.2 123.0 Advanced Coal with CCS 85 88.4 8.8 37.2 1.2 135.5 Natural Gas-fired Conventional Combined Cycle 87 15.8 1.7 48.4 1.2 67.1 Advanced Combined Cycle 87 17.4 2.0 45.0 1.2 65.6 Advanced CC with CCS 87 34.0 4.1 54.1 1.2 93.4 Conventional Combustion Turbine 30 44.2 2.7 80.0 3.4 130.3 Advanced Combustion Turbine 30 30.4 2.6 68.2 3.4 104.6 Advanced Nuclear 90 83.4 11.6 12.3 1.1 108.4 Geothermal 92 76.2 12.0 0.0 1.4 89.6 Biomass 83 53.2 14.3 42.3 1.2 111.0 Non-Dispatchable Technologies Wind 34 70.3 13.1 0.0 3.2 86.6 Wind-Offshore 37 193.4 22.4 0.0 5.7 221.5 Solar PV1 25 130.4 9.9 0.0 4.0 144.3 Solar Thermal 20 214.2 41.4 0.0 5.9 261.5 Hydro2 52 78.1 4.1 6.1 2.0 90.3 So the cost to produce is the total system levelized cost (and now you should realize that producing power for$1000/MWh is ridiculously high. Except it has happened recently and momentarily in New England).

People at home don't see the price that a generator gets. Do you notice that you pay about 20 cents per KWh in MA (I use MA cause apparently all my readers are here), it is $200 per MWh. What gives? All these power plants are producing power for way less than that. Except for solar thermal and offshore wind, which both suck and are expensive. The reason for this is that home/commercial retailers do not buy from the generators and from the wholesale market. Things called Load Serving Entities (LSEs) buy from the wholesale market. Often they will just be your utility company. They then distribute it to end-users or to other complicated things that we don't care about. The end users are your households and commercial things like shopping malls and stores and offices. Sidebar: One important thing to note is that industry usually buys directly from generators. So while we pay$200/MWh for electricity, a Ford power plant might pay $60/MWh. This has implications that we will discuss later. So, the LSE buys electricity off the wholesale market. And then marks it up and sells it to consumers. That is why you pay$200/MWh.

RTOs, system management

This section is getting specific, some of you may want to skip to the end of the article, the implications part.

Who tells generators when to come online and manages the wholesale market? Regional Transmission Operators. In New England, our RTO is called ISO-NE, for Independent System Operator of New England. They take bids and determine which power plants produce. They have important things to consider, like making sure a regional power line isn't too congested.

Line Losses

Nearly all power lines lose a percentage of their power as heat. Transmitting long distances loses around 8% of power. This is because there is always some resistance to the flow of electricity. It is like friction for the flowing of electrons. Power lines also have a limit to how much power can flow through them. If you try to go past the limit, they heat up rapidly and lose a ton of power.

The latter is something that the RTOs manage, to make sure that there won't be problems. The former has massive implications for renewable energy. Most of our renewable energy is wind and solar. Like wind in the sparsely populated midwest. And solar in completely unpopulated deserts. Transmitting this power to cities incurs huge line losses. With current capabilities, transmitting power from Iowa wind farms to NYC would make power more expensive than just building the wind farm near NYC, despite that wind in NY sucks (heh, punny). I don't have a source for this, I just saw it at a talk at Harvard.

Implications for installing renewables at home, commercially, and in industry

We pay $200 per MWh of power as residents in Boston. Solar PV in the best cases is$144. This will be in deserts. In MA, we don't get as much sunlight. But for the sake of argument, lets say that the average cost of solar in MA comes out to be $200-$250. With subsidies, it will be less. So would you pay $200 per MWh from your utility, or$200 per MWh to produce your own energy and stick it to the man? Also your own power would be clean, with far less CO2. With subsidies available in places like MA and NJ, solar comes out to less than $200/MWh at home. Next lets consider commercial places. They also buy from LSEs. This is why you see a ton of them building solar panels. It makes sense economically and gives them a good vibe that the public likes. Finally, let's consider industry. They buy directly from the wholesale market. So they pay closer to$100/MWh. They won't give two shits about renewables. Because they won't save money by installing renewables on their sites.

And this, my friends, is the trend we see. On-site renewables are adopted by commercial real estate and by residents, and industry is highly unlikely to ever embrace it. Interesting, eh?

-Jason Munster

# Solar Power

Solar power. It comes in two primary flavors: photovoltaics (PV) and concentrated solar power (CSP). The latter is easy. I decided to do solar power this week, and go back to the dams next week. Big picture: CSP is a bridge technology at best; an investment in most places is little more than a show that the investor is serious about green tech. Moreover, not all places are created equal to invest in solar power. Many of the places that offer the best incentives to have solar power (NJ, MA, Germany) are far from the best places to have solar power.

So this time: insolation, what it means, where it happens. And CSP. PV comes later. Cause it involves quantum mechanics.

So, first, solar insolation map, AKA "Where is the sun shining all the time" map.

Solar power resources in the US. Darker colors indicate better regions for solar power.

Who is not surprised that Alaska is awful for solar power? But check out MA and NJ. Why are they giving tax breaks to install solar cells? Easy answer. To drive the technology forward. Solar panels are really useful in places without any other power source. Like small villages in Africa and other depopulated places. California also has big incentives to build solar, and at least that makes sense, yes?

What determines how much insolation a place gets? Well, you need sun to have solar power. The sun doesn't come out to party at night, so no solar power. A huge one is how much atmosphere the sunlight has to pass through on the way to the the solar panel. More atmosphere means more absorption and dispersing of sunlight (the atmosphere reflects, absorbs, and spreads out sunlight). So higher elevation, like mountains, helps. Less atmosphere. On a related note, the latitude is also very important. Far northern places don't get as much sun annually (Canada, Alaska). Finally cloud and moisture make a huge difference. If there are clouds or moisture in general, sunlight is blocked. This explains most of the east coast of the US, as well as why Nevada, a giant desert, has great insolation. It has a high elevation, and no moisture to make clouds or block sunlight.

The equivalent amount of sunlight hitting the earth at a high latitude spills out over a larger area. In other words, there amount of energy per area is lower. link

CSP is easy. There are a bunch of mirrors, either flat or parabolic (to focus the light even more intensely), and they reflect light to a single point. It produces heat and and then that heat is used to make steam and drive a turbine, just like the basic thermal power plants we have discussed. The heat is typically stored in molten salt, cause it can store a whole lot of energy before it rises a degree in temperature (kind of like water). The heat from this molten salt is slowly released to make that steam for the thermal part.

CSP in action. Lots of light reflected to a single point that then gets very hot. link.

Given that some places on Earth receive upwards of 500W/m directly to the surface (assuming no clouds, no pollution, and daytime), a CSP plant that is 500m*500m could produce 125MW of power. Sounds great, right? 'Cept we know from basic thermodynamics that a thermal power plant that this thing is likely going to be 30% efficient. So something with a quarter of a square kilometer footprint might produce 40MW of power.

So why don't we use this? First, the depiction above is too rosy a picture. CSP is not all that efficient, because if you look at the picture above, you see that not all the area is used for gathering light. There are plenty of empty spaces. Moreover, the transfer of heat from the salt to water is not very efficient. Cause the high temperature and low temperature of the Carnot cycle are closer together (review the thermal power plant post for a review of Carnot efficiencies for all heat engines). Finally, this stuff is expensive. It is easily 2x as expensive as almost any other power technology (other than PV). It requires water to clean the mirrors and has other maintenance costs, the mirrors themselves are quite expensive, and the entire design is expensive. And, if you want to harness the power of the sun, there are better alternatives. Like PV.

As you can tell, I don't have a very high opinion of CSP. Why is that? Take a look at this guy again:

U.S. average levelized costs (2011 \$/megawatthour) for plants entering service in 2018
Plant type Capacity factor (%) Levelized capital cost Fixed O&M Variable O&M (including fuel) Transmission investment Total system levelized cost
Dispatchable Technologies
Conventional Coal 85 65.7 4.1 29.2 1.2 100.1
Advanced Coal 85 84.4 6.8 30.7 1.2 123.0
Advanced Coal with CCS 85 88.4 8.8 37.2 1.2 135.5
Natural Gas-fired
Conventional Combined Cycle 87 15.8 1.7 48.4 1.2 67.1
Advanced Combined Cycle 87 17.4 2.0 45.0 1.2 65.6
Advanced CC with CCS 87 34.0 4.1 54.1 1.2 93.4
Conventional Combustion Turbine 30 44.2 2.7 80.0 3.4 130.3
Advanced Combustion Turbine 30 30.4 2.6 68.2 3.4 104.6
Advanced Nuclear 90 83.4 11.6 12.3 1.1 108.4
Geothermal 92 76.2 12.0 0.0 1.4 89.6
Biomass 83 53.2 14.3 42.3 1.2 111.0
Non-Dispatchable Technologies
Wind 34 70.3 13.1 0.0 3.2 86.6
Wind-Offshore 37 193.4 22.4 0.0 5.7 221.5
Solar PV1 25 130.4 9.9 0.0 4.0 144.3
Solar Thermal 20 214.2 41.4 0.0 5.9 261.5
Hydro2 52 78.1 4.1 6.1 2.0 90.3
Solar thermal is expensive. And the capacity factor is junk. There are places for it, but those are so few that it is not worth further exploring this technology.
That's it for now. Thanks for reading!
-Jason Munster

# Hydro Power

Hydroelectric Power is pretty simple, yes? Build a dam, run water through turbines, get energy out. Turns out that it is a bit more complicated that that. But not by much, actually. So I am going to do a quick summary of how hydropower works, the environmental disaster that it can be (always with the tradeoffs, eh?). I was going to profile three major power plants: Hoover, Grand Coulee, and Three Gorges. But I ran out of space. Next week we will discuss pumped hydro to make the biggest batteries on the planet, and also these three dams in details.

Hey! Finally! A picture I took myself! I was at the three gorges dam as they were just completing it. Also, China has air pollution issues.

How does water power work? Put simply, water falls from a height and the energy of it is harnessed by spinning a turbine. More complicated, it is mass*gravity*height:



Schematic cross-section / block diagram of a hydropower plant. link.

Now we also need to round down for efficiency. Our thermal power plants are limited by carnot efficiency, yes? And even the best don't really break 50% efficiency all that easily. What would you guess the efficiency of a hydro plant turbine is, then?

That depends on the type of turbine used. It turns out that turbines are some of the most efficient parts of any generating facility. In short, expect these guys to have 90%+ efficiency, probably closer to 95%. Different styles are used depending on the height of water drop (water moving really fast from a half-kilometer drop will have very different dynamics than water moving from a 20m drop).

The general design of a hydropower turbine. Water flows through the blades and the generator is, in turn, spun quickly. link

So let's figure out how much water we need to move to make 100MWh of electricity from a 200m drop! Now 1 MWh is  , so 100MWh 





 of water needs to be moved. In other words, it takes 18 thousand kilotons of water movement to produce 100MWh. Or, looked at another way, 18,000 cubic meters of water. Still not following? It's about 8 olympic sized swimming pools worth of water. Dropping 200m. Or 1/8 a mile, for you Americans out there that don't play in Metric.

Hokay, enough maths for now. This sounds great, right? Why don't we build these things everywhere? When I take courses on how to fix the environment, there are always a majority of people that assume we can build more hydro power plants. But we can't in the US. Why not?

Well, it turns out that you need to have a large height drop to make this work. You also need a lot of water flowing into whatever reservoir is behind the dam, a ton of land behind that dam to flood, and you also need enough high terrain behind it so the water doesn't spill out everywhere. Moreover, you need a massive height difference between the upper reservoir and lower reservoir to make it work. Example: the Amazon river has a huge % of total world river flow, but we can't get electricity out of it, cause the elevation drop of it is so tiny. In short, there aren't a ton of places where where hydro works well. And imagine if a few people live there. Most aren't gonna take to kindly to their homes being put under tons of water. But you know where this can happen? China! They moved 1.3 million people to build Three Gorges. More on that later. Also, Africa has a ton of places that are building dams. Turns out that China is funding a lot of these. Cause China is starting to do humanitarian things internationally to make allies with the countries that will be the source of most world growth over the next 50 years. Upsides and downsides of a command economy, right?

Hokay, I got distracted there. Environmentalists don't like dams because they mess up fish migrations, destroy natural habitats, destroy the landscape in general, and in many countries, since hydro power is so cheap, heavy industry moves in next to them to get the cheap electricity. China is a great example (sorry I keep using you as an example, China, but I haven't read about other countries much). Along many rivers, supposedly clean hydro power goes in, only to be followed by very polluting industries. Rivers turn funny colors, the water is terrible to drink, and you can't see the sun through pollution on several days. This is getting better, cause China is making the middle-income transition, and citizens are demanding safer living environments.

I got distracted again. Other problems with dams? They tend to be on rivers. Rivers carry sediment. Much like wind can pick up grains of sand and throw then around, rivers do the exact same thing. They carry a lot of sand in them. But when they hit a damn, the river stops. The sediment load drops to the ground. After several decades, sufficient sand has dropped to clog the dam. Adding to this problem is that these sediments have a bunch of heavy metals that have been leached from the local environment. In short, a hydro dam leaves behind a mess that is quite hazardous. Cleaning it up can be difficult. Still, hydropower doesn't cause many deaths, unlike coal-fired power plants.

Focusing on that last point, what does hydro power not produce? CO2. Mercury. SO2. NOx. It produces none of the nasty things that coal fired power does (even gas-fired plants produce NOx and CO2). It tends to be very inexpensive. It is much prettier to look at a hydro plant than a coal, gas, or nuclear plant (Except on a polluted day in China, look at that picture again!).

We are running out of space in this article (I am calling them articles cause I am pretending they are articles on a web page instead of a blog post, cause I am pretentious). To summarize, hydro power is cleaner than other power supplies. It is cheaper than most. It does have its drawbacks, including displacing people and destroying land, but these are smaller than the drawbacks of coal and natural gas. It is also a nearly completely tapped resource in the US.

-Jason Munster

End-note: if you have a lot of interest in this sort of thing discussed here, I would highly suggest the book When A Billion Chinese People Jump by Jonathan Watts. It is an amazing book

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# Wind Power

I haven't posted anything in a while because I am teaching this semester (Earth Resources and the Environment), which has made me incredibly busy, and also I was playing a computer game for the past month. Anyways, some friends told me they actually read this, so I am gonna start up again.

Today we discuss how wind power works, how a wind turbine works, and limitations on placement of wind turbines.

Block diagram of a wind turbine. Wind spins the blades, which in turn goes through a transmission to spin a turbine to produce electricity.

Wind power harnesses the power of wind to turn a turbine. Unlike every other power plant we have discussed, this is not a thermal plant. How does wind even happen? As we all know, the sun shines more directly near the equator than it does the poles. And so the equator is heated more than the poles. The Earth doesn't like having one part heated and another not, so the major prevalent winds are the way the Earth redistributes this uneven heating from the equator to the poles. Smaller winds are local manifestations of this phenomenon. In short, wind power is extracting the energy deposited by the sun.

Next: the design

The mechanical design of a wind turbine. Link

The rotors of a wind turbine catch the wind, and thanks to Bernoulli's principle, the wind forces the turbine to spin. Think of it as creating an area of low pressure behind the blade, so the blade is getting sucked, or pulled, rather than pushed in a circle. These blades are attached to a hub, which spins with it. The entire box behind the turbines is called the Nacelle, and contains all the parts that produce power. The hub itself spins somewhat slowly, but thanks to a gearbox, the shaft that goes to the generator spins much more rapidly. The windvane senses the wind direction, and a motor beneath the hub rotates the entire turbine to face directly into the wind.

Wind power plants face four primary limitations. First, they don't work when wind isn't blowing. So you aren't placing these things in windless or low-wind locations. Second, depending on the design of the turbine, each has a maximum wind speed where it most efficiently extract energy. In fact, during high winds, they have to shut down to prevent damage. Third, there is a factor called the Betz limit that indicates that the most energy you can extract from wind is about 60%. In reality, the best might be 45% efficient. A corollary fourth limit is that you cannot place wind farms too closely, because they become far less efficient if you place them nearby. They literally suck out the power from the wind. In the end, availability of location is the most important

This photo from NOAA uses LIDAR to track the turbulence produced in the wake of wind turbines. It visually depicts the limitations of putting turbines in the same place. The turbulence behind the turbines can damage the props on the next turbine, requiring further replacement. It also reduces the efficacy of the next turbine. link to NOAA.

Ultimately, the largest problem is where to site wind farms. You can't put them in places without wind, or you spend a ton of money on them and they don't return the payment.

This map indicates regions and their use for wind farms. It shows that many areas are not great for wind farms. Click the link for a more detailed image.

There are two closely linked issues associated with wind power. In most places, wind does not always blow. When the wind is not blowing, power cannot be extracted. This is called intermittency. It means that wind power cannot provide baseload power. In some places, like California, the intermittency is dealt with by power up peaking gas-powered power plants. In other places, the intermittency is seen as an insurmountable issue (California surmounted it. Those other places are foolish.) Other methods of dealing with it are compressed air storage (more on that later), batteries, and pumped hydro (more on that later).

Another important feature of wind turbines is size. To get more power from a single turbine and reap larger economies of scale, you build a taller turbine. Also, taller turbines reach farther up into the part of sky where wind it a bit more constant. But those huge turbines, that can produce up to 5MW each (recall a larger power plant is 1000MW), are relatively new. We are not sure how long they last in the wild. Maybe 50 years (like a normal power plant) or maybe 20. This is important, because per MW, wind power used more resources to build than almost anything else.

Now, offshore wind is a different beast entirely.

Offshore wind turbines become progressively more expensive as you move to deeper waters.

These things need to be moored to the ocean floor, or have very expensive floats. It can increase production cost by a factor of three. Ameliorating this fact is that wind is often more consistent offshore. But these things face waves, corrosive ocean water, severe storms, etc., and need to be built very strong, increasing costs. Moreover, they need a way to connect them together, and then very powerful regional lines to transfer the power to mainland. Expensive. If you remember my post comparing the cost of nuclear power to other types, offshore wind is mad expensive.

Another interesting point about wind power (and solar): they produce DC power. This is direct current, like a battery. The power we get from the wall is AC power. It alternates. Anything with a motor likes AC power a lot. Many electronics prefer DC power, hence needing AC adapters for all your electronics. Batteries use DC. Another fun fact about AC vs DC? Electricity make your muscles constrict. If you grab something with AC, since it alternates you let go. You grab something with DC, like a car battery or a taser while being arrested, that stuff causes constriction and you can't let go. Point is, stay away from DC electricity.

Back to the point: Somewhere in the process, whether at the turbine or at a collection station, this electricity needs to be converted to AC to use on the electrical grid. More expenses. In short, offshore wind is incredibly expensive, and only for countries that are afraid of nuclear power. In a later article, I hope to compare the resource costs per MW of constructing each of these types of power plants.