With this lesson, we continue our survey of energy industries based on energy sources. In this lesson, we will review the coal industry--from mining and extraction to emissions from coal-fired power plants.
By the end of this lesson, you should be able to...
The table below provides an overview of the requirements for Lesson 6. For details, please see individual assignments.
Please refer to the Calendar in Canvas for specific time frames and due dates.
REQUIREMENT | SUBMITTING YOUR WORK |
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Read Lesson 6 content and any additional assigned material | Not submitted. |
Weekly Activity 6 | Yes—Complete Activity located in the Modules Tab in Canvas. |
Case Study--work with others on your Team to prepare Case Study, following course guidelines | Check Canvas calendar for all Case Study Due Dates. |
Coal is a combustible rock--a rock that burns. It is composed mostly of carbon and hydrocarbons. (A hydrocarbon is a molecule consisting of some combination of carbon and hydrogen, such as methane, CH4).
Coal is a fossil fuel, which means it was created over millions of years from dead plants trapped under layers of earth. The heat and pressure turned the plant remains into what we call coal today. Petroleum and natural gas are also fossil fuels, formed in similar ways.
A fundamental point to realize about all fossil fuels is that the energy we release by burning them came originally from the sun. How's that?
Plants grow as a result of photosynthesis, a process where carbon dioxide (CO2), water (H2O), and energy from the sun combine to create simple sugars, such as glucose (C6H12O6), and oxygen (O2). Photosynthesis is an endothermic chemical reaction (meaning that it requires the net input of energy to occur). The sun provides this necessary energy, which is used to create chemical bonds. The simple sugars created in photosynthesis may later be converted into other types of molecules that make up all the "matter/stuff" of a plant, including specialized carbohydrates, such as cellulose. (Source: Virtual Chembook [4], Elmhurst College, 2003, retrieved August, 2011).
Over millions (and often hundreds of millions) of years, heat and pressure causes the chemistry of the dead plants to change somewhat, and some carbon dioxide and oxygen are released, but the energy from the sunlight is generally retained. So, we can think of coal as a bundle of carbon and hydrocarbon molecules held together by bonds that were formed from the sun's energy millions of years ago. It is this very energy that makes coal so useful to us now.
To release this energy, we burn the coal. This is an exothermic chemical process called combustion. It releases energy stored in the chemical bonds that hold the molecules together. Remember Smokey the Bear? (He's still around right? Did I just date myself? Moving on...) The fire triangle has three necessary components for combustion (fire) to begin: fuel, oxygen, and heat. Once the fire gets started, a chain reaction takes over between the hydrocarbons in the fuel and available oxygen. Some energy is used to break the bonds in the fuel, but even more energy is released when the new bonds form with the oxygen. Overall, the reaction is exothermic--energy is released. In complete combustion of a pure hydrocarbon, the hydrocarbon is converted to carbon dioxide (CO2), water vapor (H2O), and heat (and light). Note that fossil fuels usually have impurities (e.g. nitrogen, sulfur, mercury), and thus other byproducts usually result from the combustion reaction.
See the reaction below for complete combustion of a hydrocarbon, and the reaction for complete combustion of methane. (Methane is a hydrocarbon composed of one carbon and four hydrogen atoms). Note that the "extra" heat energy released as a byproduct provides heat for the continued combustion process. Combustion will continue to occur until either the heat, fuel source, or oxygen is insufficient to continue the reaction.
Please note that the reactions above describe complete combustion, which means that all of the fuel is completely converted to the given byproducts. In reality, this process is rarely so simple. When incomplete combustion occurs, other byproducts such as carbon monoxide (a silent, tasteless, and odorless deadly gas) and carbon (e.g. soot) result. In addition, there are often impurities in the hydrocarbon that result in additional byproducts. For example, a lot of coal contains traces of sulfur, which forms sulfur dioxide (SO2) when combusted. Sulfur dioxide emissions from power plants are proven to cause so-called "acid rain," which became a major nonmarket issue in the 1980's in the U.S. Coal also often contains traces of mercury, which is released when combustion occurs. Coal combustion is the second leading source of mercury pollution worldwide [6] (just a little bit behind artisanal and small scale gold mining), and mercury is a major human health hazard. Interestingly, the chemical content of the air used in the combustion reaction can be a problem as well. Our atmosphere is mostly nitrogen, and a byproduct of combustion with air will be nitrogen dioxide (NO2). In short, the products of combustion depend on the specifics of all the compounds involved in the reactions, and the combustion of coal nearly always results in unwanted byproducts.
While we're on this topic, another interesting consideration is the amount of greenhouse gases formed during the combustion process. When we burn a fuel, a reaction takes place between a hydrocarbon and oxygen that yields carbon dioxide and water. When we burn one pound of coal, we produce about two and half pounds of CO2. How can that be?
The atomic weight of carbon is 12 and oxygen is 16 (grams per mole), giving carbon dioxide a total molecular weight of 44. So, each atom of carbon results in 3.7 times its weight in CO2. (44/12 = 3.7)
The typical carbon content for coal ranges from more than 60 percent for lignite to more than 80 percent for anthracite, according to the EIA [8]. Let's consider coal that is around 70% carbon. One pound of this coal results in about (0.70 lb carbon/lb coal) x (3.7 lb CO2/lb carbon) = 2.6 pounds of CO2.
There are four basic varieties of coal: lignite, sub-bituminous, bituminous, and anthracite. All are formed from ancient plant material. Variations are the result of different geologic forces which affect the carbon content and heating value--also the dollar value!
Visit the World Energy Council and see the publication "World Energy Resources 2016 [11]." You can download your own copy, or access the copy under the Lesson 6 tab. The information in this publication is not the most current, but it collects some interesting data in one place that will give you an idea for how coal is (still) used globally as a major energy source.
Please read the following in the Introduction:
In the main body of the report (this portion starts after the Introduction, which ends on p. 49) read:
As you read this, it will help to remember the international definition used by the United Nations for proved recoverable reserves: "the quantity within the proved amount in place that can be recovered in the future under present and expected local economic conditions with existing available technology" (World Energy Council [12]).
Note: reference cases are forward-looking scenarios (through 2050 and 2040, respectively), which does not incorporate prospective legislation or policies that might affect energy markets, including prospective greenhouse gas reduction policies.
The global energy market is a dynamic place. This is but one reason that it is exciting to be in the energy field (hopefully I'm not the only one who realizes this!). Read the following to get an understanding for recent trends in the global coal market.
The EIA and BP publish excellent (and free!) information, loaded with analysis and details far beyond the breadth and depth of this lesson. I encourage you to please keep these important publications and organizations (the International Energy Agency [19] and Yale Environment 360 [20] are great as well) in mind, however, as they may be helpful to you in other courses, research, and your professional life--now and in the future!
Coal is a solid that, if we are to use it, must be extracted from the earth. This is coal mining, going into the earth to remove coal for our consumption. The basic steps of mining and processing coal are described below.
There are two general methods of coal mining: surface mining and underground mining.
Generally called surface mining, the industry also calls it "opencast" or "open cut mining," while others may refer to it as "strip mining." In this type of mining, workers use explosives and heavy earth moving equipment, such as power shovels and draglines, to break up and scoop off the layers of soil and rock (overburden) covering the coal seam. Once exposed, the coal seam is systematically mined in strips. It is broken up using drills and explosives, and then smaller shovels lift the coal from the ground and load it into trucks or onto conveyors for transport to a coal preparation plant or directly to where it will be used.
Mountaintop removal is a variant of strip mining technology commonly used in West Virginia and eastern Kentucky where local topography provides adjacent valleys which can be used as repositories for overburden. In this type of mining, bulldozers are used first to remove all topsoil and vegetation from the mountaintop. Then explosives are used to break up the bedrock above the coal. Huge draglines (the bucket can hold 15-20 pickup trucks) then remove the overburden and dump the waste rock ("spoil") into the adjacent valleys. Then the coal seam is blasted and front end loaders scoop up the coal and load it into the huge dump trucks that carry the coal to the coal preparation plant. The video below provides a pretty dramatic birds-eye view of a mountaintop removal operation, including the overburden and the coal seams below it. It is also quite clear what the mountains used to look like, as evidenced by the scenery in the background. Please watch the following (3:18) video which shows the process described above.
Surface mining works only when the coal seam is near the surface. It is, however, usually more cost-effective than underground mining and requires fewer workers to produce the same quantity of coal. And the industry reports that 90% or more of the coal is recovered, a higher proportion than from underground mining. Recall also that from a previous lesson that the EROI of surface-mined coal is higher than underground mines.
The (6:43) video below from PBS provides a good sense of the scale of the largest mine in the U.S., the Black Thunder surface mine in the Powder River Basin in Wyoming.
PRESENTER: Coal. This one critical resource supplies nearly half of America's electricity. And this is the biggest coal mining operation in the country. The Black Thunder Mine in Wyoming's Powder River basin.
Black Thunder is one of 15 mines in the basin which stretches from Northeastern Wyoming into Montana. In the last 40 years, the area has been completely transformed.
This is what the barren landscape looked like in the 1950s. And here it is now. The terrain completely altered by mines like Black Thunder. Today, Wyoming produces more coal than any state in the nation-- far more than traditional coal mining locations like Kentucky and West Virginia. So what changed?
When you think about protecting the environment, the last thing that comes to mind is digging a giant coal mine in the middle of pristine ranch land.
Yet ironically, all this came about because of a government effort to clean up our air over 40 years ago. The environmental crusader who led the charge is the last person you might expect.
RICHARD NIXON: We can no longer afford to consider air and water common property free to be abused by anyone.
PRESENTER: With pressure from the growing environmental movement, President Richard Nixon signed the Clean Air Act of 1970 into law. It restricted emissions released into the air by big polluters like coal fired power plants. You might think that would have killed coal mining, but not here in Wyoming.
This stuff has a lot less sulfur than the coal mined elsewhere. So it burns cleaner, making the Powder River basin the new king of coal.
Josh Gardner drives one of the trucks that work these pits. It's a 6:30 AM shift change. Time to go to work.
Hey, morning Josh.
JOSH GARDNER: Hey, what's up? Hey.
PRESENTER: What's with you?
Our ride is basically a dump truck on steroids. It stands over two stories tall and weighs almost 200 tons.
But it seems dwarfed by the shovel at the base of the pit.
JOSH GARDNER: That's our first bucket in.
PRESENTER: It Felt like a small earthquake.
JOSH GARDNER: This actually is telling us how much weight we have on there. The first bucket was 68 tons. And then the second one, 60.
PRESENTER: Looks like it's raining coal.
JOSH GARDNER: So we got 174.
PRESENTER: Three bucketfulls and we're on our way. One truckload like this can produce enough energy to heat a home for more than 40 years or run your television for the next 2000 years.
All day long, Josh drives in a big loop filling his truck with coal, dumping it, filling it up again. In a single shift, he can haul 8,000 tons. And there's plenty to haul.
Typically, coal seams might be 10 feet thick. But here, they're 80 feet thick or more.
JOSH GARDNER: We're about 200 feet down. And you can see the definite line where the black starts up there and all the gray above it. And once we get done taking all the coal out of this seam, this shovel is done. Then they'll take all the dirt that sits above it. They'll blast it back down into this hole. And then they'll just start again.
PRESENTER: Again and again until the whole thing is cleared of all the coal.
JOSH GARDNER: Correct.
PRESENTER: And how long can they do that for? How much coal is there?
JOSH GARDNER: They say in the whole Powder River Basin, there's enough coal to last 150 years.
PRESENTER: So this coal will be around a lot longer than you or me.
JOSH GARDNER: Oh yeah.
PRESENTER: But digging it up may be the easiest part of the job where hundreds if not thousands of miles away from the power plants that need it.
So how to get this coal where it needs to go.
Trains.
But not just any trains. Some of them are a mile and a half long.
Carlin Vigil schedules the trains of Black Thunder. She's worked here nearly 30 years-- almost as long as a mine has been in business.
CARLIN SIGIL: We shipped our first train in December of 1977. And we were probably only loading a couple of trains a week at that time. And now you're looking at anywhere from 20 to 25 trains a day.
PRESENTER: This train is headed to a power plant in Montana. This one is on its way into Minnesota, Illinois, or Missouri. This one as far east as Georgia or New York.
And they all start out on the joint line. This 103 mile long set of tracks has developed into the busiest stretch of rail in the entire country.
It links these trains to national rail lines so the coal can get wherever it needs to go. The trains don't even stop as they roll under the chutes at the base of the tower.
CARLIN SIGIL: The coal runs right up this conveyor belt here. This tube that's down below us goes into the silos themselves. We can load a train out of here in about an hour and 20 minutes.
Generally, a good month is over 10 million tons of coal.
PRESENTER: 10 million tons of coal sounds like it's a big number. But I mean, what does that mean in terms of how much energy it's actually giving to the United States.
CARLIN SIGIL: It's actually 10% of the coal generated fuel for the United States.
PRESENTER: In the middle of nowhere, we've built ourselves the Grand Canyon of coal. With our vast reserves, it's no wonder America is still so reliant on the simple black rock to power the grid. Even though coal fired power plants are among the biggest air polluters in the US.
When the coal deposit lies deep below the surface of the earth, underground mining is used. Miners dig tunnels deep into the earth near the place where the coal is located. The tunnels may be vertical, horizontal, or sloping. Once deep enough, the tunnels interconnect with a network of passageways going in many directions. Entries allow fresh air into the mine and give miners and equipment access to reach the ore and carry it out. The coal extraction is done by either a room-and-pillar method or longwall mining.
When the room-and-pillar method is used, miners cutting a network of 'rooms' into the coal seam and leaving behind 'pillars' of coal to support the roof of the mine. Working from the tunnel entrance to the edge of the mine property, they remove sections of the coal while leaving columns of coal in place to help support the ceiling. This process is then reversed, and the remainder of the ore is extracted, as the miners work their way back out.
In the case of longwall mining, the area being mined is covered with hydraulically-powered self-advancing roof supports that temporarily hold up the roof while the coal is extracted. After the coal is removed, the roof is allowed to collapse. This method requires careful planning and appropriate geological conditions. Carl Hoffman in Popular Mechanics offers this vivid description [21] of longwall mining,
From an elevator-like entrance shaft deep underground, continuous miners—cutting machines on wheels—bore passages on both sides of seams of coal up to a quarter mile wide and a mile or more long. At the mine face, a massive shearer on self-advancing ceiling supports known as 'shields' slides back and forth across the face like a giant cheese grater. Water sprays constantly against the coal face to dampen coal dust. After each pass, the whole apparatus, as wide as 1600 feet, lurches forward, letting the area behind the shields collapse. A conveyor belt catches the coal, moves it to another belt running along the side passages, and takes it to the surface, often several miles away. When a panel of coal is mined out, the longwall machine is moved to the next one. Over time, mines become enormous labyrinths of passages, and it can take miners a half hour or more to travel miles to the mine face in low-slung vehicles called mantrips.
Please watch the following (3:30) video:
This song tells a story of a region, of a rugged landscape that challenges the eye, and a friendly people. It's all part of the legend of Virginia's great southwest. This is the most economically depressed area in the state. For decades, the best and practically only way to make a living in these rugged hills was beneath them in the darkness of a coal mine.
Well, I guess it just gets in your blood once you try it. It's just a daily routine.
A routine Emory Hess and thousands of other miners go through every day.
And over the last few years, you just had to continually move deeper and deeper.
This is Pittston Coal's Laurel Mountain Mine, one of about 290 licensed mines in a 10 county area.
How much longer will you be mining this particular mine?
Hopefully we can get another eight years in here. 8 to 10, anyway.
Every day, around the clock, miners make this journey underground and inside Virginia's hills and mountains. Mining is basically hit or miss. You've got to go where the coal is, and here's where it is. We're about 3 and a half miles underground, and there's about 700 feet of mountain right above us.
They've had to move a lot of rock to get this deep. Powerful machines help the miners chew and claw their way inside, and some places the shaft is less than 4 feet high. You practically have to crawl. They follow the vein, taking only the coal. This one is called the Jawbone Seam. It's hundreds of thousands of years old.
Once miners gather the coal, a conveyor belt takes it outside to be processed. Three a half miles underground means a 20 minute ride on the belt before coal sees the light of day.
Once the prize industry of southwest, coal mining is quickly losing its steam. Coal demand is down. Mines are closing, and that means layoffs. In some coal counties, the unemployment rate is 50%.
If you were looking at a crystal ball, you would see that coal mining wouldn't exactly be the thing to be trying to start into right now.
Uh, right, that's a pretty good assumption, pretty good-- [UNINTELLIGIBLE] with a crystal ball, yes.
Some coal companies are trying to mine coal a cheaper way. This is the White Stallion surface mine, also owned by Pittston, where miners literally rip off the top of the mountain to take out the coal. They're mining the Dorchester Seam here, more than 1,000 feet above the Jawbone below.
Today, the remnants of a hurricane hundreds of miles away have turned this site into a mountain of mud. But the work continues. Day and night, it never stops.
There have been better times here in southwest Virginia. Coal mining was once an old, reliable way to make a living. It isn't so reliable anymore. The people here realize that, but there's not a whole lot of other ways for them to make a dollar.
Once the coal is removed from the mine, it is taken to a coal preparation plant where the raw "run-of-mine" coal is processed to separate the coal from undesirable waste rock and minerals. The finer waste from this process (including silt, dust, water, bits of coal, and clay) is discharged as a thick slurry into a man-made impoundment. This structure is used to confine refuse or slurry, along with any chemicals used to wash and treat the coal at the coal preparation plant. Coarser waste from the preparation process, rock, is dumped back into the pit once mining has ceased or is used in the construction of an impoundment dam.
Please watch the following (5:43) video:
Man has used coal as a fuel for over 3,000 years, and it remains one of the world's most vital natural resources. It generates more than 40% of the world's electricity and every year we go through 6 billion tons. Somehow, mines must ensure a constant supply, or our cities would be plunged into darkness and industries would grind to a halt. So how do they do it?
Pittsburgh, Pennsylvania. This industrial east coast city is famous for steel production and shipbuilding. But Pittsburgh is also surrounded by rich coal reserves. And here, just 30 miles from the city, are the Bailey and Enlow Fork mines. This is the largest underground mining complex in North America. And every year it produces more than 20 million tons of coal.
There are millions of dollars invested in this vast complex, and with more than 200 men working underground at any one time, keeping it running is a major logistical challenge.
At 4:00 in the afternoon, the day shift clocks off after eight hours of hard work, while the next shift makes its way into one of the lift cages to begin the 650 foot descent into the mine. Mining is one of the toughest jobs imaginable, and there's an unspoken bond between these men who spend every working day deep underground.
Once they arrive at the bottom of the shaft, they still face a long journey to the coal face. After almost 20 years of continuous mining, a vast network of underground tunnels now extends for an extraordinary 35 square miles. The miners face a five-mile journey to get to the section currently being mined. It's a cramped and uncomfortable ride aboard one of the mine's small trains, as the cars rattle their way through the maze of dark tunnels, following a network of rails that are now so busy they require traffic lights.
First up is a monster machine, known as a continuous miner. Armed with a 16-foot cutting drum, this ferocious beast chomps away at the scene, carving out a series of access tunnels. As it bores its way forward, it feeds the cold behind it to a crab-like loader and shuttle car. The continuous miner produces up to five tons of coal every minute-- more than a miner in the 1920s produced in a whole day. But its job is actually to prepare the way for the real monster-- the longwall shearer.
Armed with a set of teeth to put a Tyrannosaurus to shame, its cutting edge is over 1,000 feet long, and it can smash an amazing 50 tons of coal out of this seam every minute. Think about it. That's almost one ton of coal every second, enough to meet all the energy needs of an average household for 78 days. But there are 3 million tons of coal in this 13-foot-high seam. Despite its ferocious appetite, it will still take six months of shuttling back and forth before it has finished digging it all out.
Before the coal is fit for shipping, they first need to remove rock, soil, and contaminants, which account for up to 30% of the raw feed. So the material is fed via conveyor into the processing plant. To ensure it's all properly processed, it's first graded according to size. Next, to separate the coal from the waste rock, it's fed into this giant floatation tank. Because the rock is heavier than the coal, it sinks to the bottom where it can be removed, while the coal floats to the surface.
It's now soaking wet. So just like your home laundry, they load it into a spin dryer.
This industrial dryer spins the coal at high speed until excess water is removed. This water is then fed into vast tanks where the contaminants are removed before being disposed of as waste slurry.
Meanwhile, the different sized pieces of coal are recombined, crushed into a uniform mix, and fed into a giant hopper. Incredibly, just 15 minutes after entering the plant, it's ready for transport by rail. As they park beneath the hopper, a controller opens a chute to allow 6 tons of coal to fill each car. Once full, every train is able to transport over 10,000 tons of coal to power stations across North America.
Thanks to some extraordinary coal crunching machines and the guys who labor 24/7 to keep them working, this essential resource keeps flowing to the world's power stations, and there's enough electricity to power the wheels of the modern world.
Methane (CH4) is a gas that forms naturally in the process of coal formation. It is also a potent greenhouse gas [22], with a global warming potential (GWP) over 20-30 times greater than CO2 over a 100 year period, despite the fact that it remains in the atmosphere for a shorter time (about 12 years vs. hundreds or thousands of years for CO2). When coal is mined, methane is released. According to the EPA [23], about 9% of global anthropogenic methane emissions comes from coal mining, most of which is purposefully vented to maintain safe mining conditions. Steps to reduce methane emissions can have relatively near term effect. The Global Methane Initiative [24] reports, "of all the short-lived climate forces, methane has a large reduction potential and cost-effective mitigation technologies are available."
In addition to being a serious greenhouse gas, methane is highly combustible with serious implications for the safety of mine operations. Methane is highly explosive at concentrations of only 5 to 15%. You may remember the Upper Big Branch mine disaster [25] in West Virginia in 2010 that killed 29 people. This was a result of methane building up and exploding.
Methane is generated during the natural process of coalification (the transformation of plant material into coal) and is contained in the coal microstructure. Because natural gas is made up mostly of methane, coal bed methane can be seen as a useful "unconventional" source of natural gas. When concentration levels are high, methane recovered from coal mines can be fed into the existing gas pipeline network along with or in place of conventional natural gas. The gas can be used for cooking and heating or for electricity generation with gas turbines and gas engine systems, among other things.
A range of technologies are used to recover methane from coal. They may be broken down into three categories.
Underground mines account for the vast majority of global methane emissions from coal mines. Surface mines also emit, but less, because there is less pressure to trap methane in the coal. Methane emissions also occur during post-mining operations, including processing, storage, and transportation. Coal can continue to emit methane for months after mining, especially when it is crushed, sized, and dried. And, methane emissions from coal mines can continue after operations have ceased (Source: EPA [26]).
According to the U.S. Environmental Protection Agency's Coalbed Methane Outreach Program's most recent assessment [27]:
U.S. coal mines emitted nearly four billion cubic meters or 61 million metric tons of carbon dioxide equivalent (MMTC02E) in 2015. Between 1990 and 2015, U.S. emissions decreased by 40 percent, in large part due to the coal mining industry's increased recovery and utilization of drained gas and decrease in ventilation air methane emissions.
By 2020, global methane emissions from coal mines are estimated to reach nearly 800 MMTCO2E, accounting for 9 percent of total global methane emissions. China leads the world in estimated coal mine methane (CMM) emissions with more than 420 MMTCO2E in 2020 (more than 27 billion cubic meters annually). Other leading global emitters are the United States, Russia, Australia, Ukraine, Kazakhstan, and India.
Methane is also the main component in natural gas, a valuable source of energy. Because of this, coal producers worldwide deploy technology to capture methane from coal mines. According to the EPA [28], there are more than 200 coal mine methane capture projects in 15 countries worldwide which will capture more than 4 billion cubic meters of methane annually, which is equivalent to over 60 MMTCO2e. In 2015 in the U.S., over 33 billion cubic feet of natural gas were recovered from coal mines. As a point of reference, the U.S. consumed approximately 27,500 billion cubic feet of natural gas in 2015, according to the EIA [29].
According to the U.S. EPA [30], fossil fuels are the leading source of global carbon dioxide emissions, and according to data available [31] from the International Energy Agency (IEA), coal is responsible for just over 44% of all energy-related emissions worldwide. Coal is the most carbon-intensive fossil fuel, which means it emits more CO2 than an equivalent amount of oil, natural gas, or other fossilized hydrocarbon. According to the EIA's 2019 International Energy Outlook (IEO2019 [32]), coal became the leading source of world energy-related carbon dioxide emissions in 2006. Projections through 2050 indicate that it remains the leading source, even though the IEO2019 projects that natural gas emissions will rise the most year-on-year (1.1% per year increase for natural gas vs. 0.4% per year for coal). According to the IEO2016, all of this coal-based emissions growth in the reference scenario is in non-OECD countries, as you can see in the chart below.
As described previously, burning coal also releases other dangerous pollutants, including soot and fly ash, sulfur, nitrogen oxides, and mercury. There is no known technology that can eliminate all of these pollutants. Even if they could, there are environmental consequences of coal extraction and processing. That is why the term "clean coal" is controversial, and frankly speaking a misnomer - there is no such thing as "clean" coal, only coal plants whose CO2 emissions are reduced or eliminated. But that aside, coal resources are abundant, coal-fired power plants are extremely reliable, and coal is relatively cheap (ignoring externalities of course), though in the past 10 years or so natural gas has been replacing coal as the power generation fuel of choice because it is less expensive [34].
Worldwide, efforts and projects are underway to mitigate the environmental impact of carbon combustion. Some of the technologies involved include scrubbers, selective catalytic reduction, fluidizer bed boilers, gasification, and carbon capture and sequestration (CSS).
The National Mining Association has published a helpful Clean Coal Technology Backgrounder [35]. The following is an excerpt, which describes currently available technologies.
Power plants being built today emit 90 percent less pollutants (SO2, NOx, particulates, and mercury) than the plants they replace from the 1970s, according the National Energy Technology Laboratory (NETL). Regulated emissions from coal-based electricity generation have decreased overall by over 40 percent since the 1970s, while coal use has tripled, according to government statistics. Examples of technologies that are deployed today and continue to be improved upon include:
Fluidized-bed combustion–Limestone and dolomite are added during the combustion process to mitigate sulfur dioxide formation. There are 170 of these units deployed in the U.S. and 400 throughout the world.
Integrated Gasification Combined Cycle (IGCC)–Heat and pressure are used to convert coal into a gas or liquid that can be further refined and used cleanly. The heat energy from the gas turbine also powers a steam turbine. IGCC has the potential to improve coal’s fuel efficiency rate to 50 percent. Two IGCC electricity generation plants are in operation in the U.S.
Flue Gas Desulfurization– Also called “scrubbers,” and removes large quantities of sulfur, other impurities, and particulate matter from emissions to prevent their release into the atmosphere.
Low Nitrogen Oxide (NOx) Burners– Reduce the creation of NOx, a cause of ground-level ozone, by restricting oxygen and manipulating the combustion process. Low NOx burners are now on 75 percent of existing coal power plants.
Selective Catalytic Reduction (SCR)– Achieves NOx reductions of 80-90 percent or more and is deployed on approximately 30 percent of U.S. coal plants.
Electrostatic Precipitators – Remove particulates from emissions by electrically charging particles and then capturing them on collection plates.
If you're interested in more detail, try visiting the DOE's Clean Coal News [36] site.
For a summary of the various clean coal technologies, as well as some of the pros and cons, please read the following:
There are two general approaches to addressing anthropogenic climate change: mitigation and adaptation. Adaptation refers to adjusting to the impacts of climate change that occur or are projected to occur, while mitigation refers to preventing greenhouse gas emissions from impacting the climate in the first place. (Keep in mind that planning - of both the market and nonmarket variety - can address both simultaneously.)
There are two general ways to mitigate emissions. Prevention is most often the focus of mitigation efforts. The most common examples are using renewable and carbon-free energy sources, and energy efficiency. However, Carbon Dioxide Removal (CDR) technologies and methods can also be effective mitigating agents. CDR technologies are frequently mentioned by many governments and organizations, including by the Intergovernmental Panel on Climate Change [39] (IPCC) in their Assessment Reports, including in their most recent report, the Sixth Assessment Report [40] (AR6). (The Physical Science Basis section of AR6 was published in August 2021, with the full report released in the spring of 2022. This section may have been subject to some revision.) The IPCC also noted the possible need for CDR in their oft-cited Special Report [41] that was published in 2018. The IPCC is the most prominent and well-regarded international organization studying and proposing solutions to climate change. Carbon capture and storage (sometimes referred to as carbon capture and sequestration), or CCS, is a prominent CDR technology. The IPCC states the following in the Executive Summary of Chapter 2 [42] of their 2018 report.
All analysed pathways limiting warming to 1.5°C with no or limited overshoot use CDR to some extent to neutralize emissions from sources for which no mitigation measures have been identified and, in most cases, also to achieve net negative emissions to return global warming to 1.5°C following a peak (high confidence). The longer the delay in reducing CO2 emissions towards zero, the larger the likelihood of exceeding 1.5°C, and the heavier the implied reliance on net negative emissions after mid-century to return warming to 1.5°C (high confidence). The faster reduction of net CO2 emissions in 1.5°C compared to 2°C pathways is predominantly achieved by measures that result in less CO2 being produced and emitted, and only to a smaller degree through additional CDR. Limitations on the speed, scale and societal acceptability of CDR deployment also limit the conceivable extent of temperature overshoot. Limits to our understanding of how the carbon cycle responds to net negative emissions increase the uncertainty about the effectiveness of CDR to decline temperatures after a peak. {2.2, 2.3, 2.6, 4.3.7}.
CDR deployed at scale is unproven, and reliance on such technology is a major risk in the ability to limit warming to 1.5°C. CDR is needed less in pathways with particularly strong emphasis on energy efficiency and low demand. The scale and type of CDR deployment varies widely across 1.5°C pathways, with different consequences for achieving sustainable development objectives (high confidence). Some pathways rely more on bioenergy with carbon capture and storage (BECCS), while others rely more on afforestation, which are the two CDR methods most often included in integrated pathways. Trade-offs with other sustainability objectives occur predominantly through increased land, energy, water and investment demand. Bioenergy use is substantial in 1.5°C pathways with or without BECCS due to its multiple roles in decarbonizing energy use. {2.3.1, 2.5.3, 2.6.3, 4.3.7}
It is a widely shared belief that unless policies are enacted to aggressively reduce CO2 emissions that carbon capture technologies will be necessary to avoid the worst impacts of climate change. The video below from the British Geological Society provides a good introduction to this process. Please watch the following (4:45) video.
MIKE STEPHENSON: Carbon capture and storage, or CCS, is an important new geoengineering solution to climate change. The idea is simple-- we capture CO2 from large point sources, like power stations, cement factories, and oil refineries, and store it, or dispose of it deep underground. This stops the CO2 from getting into the atmosphere.
But we want to know that CCS works, and most of all that it's safe. CCS could be an industry the size of present-day North Sea oil within a few decades. It's simply the reverse of the oil and gas business, putting climate-changing CO2 gas back in the ground after fossil fuels have been burned. This new technology is one of the ways that Britain could reduce its emissions, as well as other big CO2 producers, reduce theirs.
Point sources would be connected in clusters to pipelines that would take CO2 across the country and onshore to wells, where it can be injected into former oil or gas fields, or deep aquifers. The argument is that if the underground storage structure is good enough, the gas will stay there for millions of years, just as natural gas does. Scientists have already shown, at a small scale, that they can capture, transport, and store CO2.
In Britain, we're lucky in being close to one of the largest areas of potential storage for CO2 in Europe. The rocks under the North Sea could absorb about 22 billion tons of CO2, which is 180 years of the UK's 20 largest point sources. This is a really hefty reduction in Britain's emissions.
We're very confident the CO2 won't leak. One of the reasons why is that we know a lot about natural gas, or methane, in the North Sea. We've been extracting natural gas from the North Sea for many years in this country. And as geologists, we know that that methane or natural gas has been in those structures for literally millions of years. It's actually stayed put for millions of years.
So if we engineer the structures in which we hope to store our carbon dioxide to the same level, there's no reason why they should leak at all. The CO2 should stay down there for millions of years. We're also very confident from the science because, for example, we've been injecting CO2 for a long time.
There are various places in the world where CO2 is successfully injected into rocks. For example, in the United States, CO2 is injected for enhanced oil recovery in oilfields, where it flushes the oil, the last remaining oil out of fields. And also, in the Sleipner field in the North Sea, we've been injecting CO2 for well over 10 years, very successfully.
Finally, we feel that we can image, or we can actually see the CO2 collecting in reservoirs. Using very sophisticated seismic techniques, we can actually see the layers of CO2 as they collect. So overall, science gives us a lot of confidence that our containers, the structures where we hope to store CO2 will not leak.
The UK is taking a lead in CCS worldwide, both in terms of British government support for CCS, but also because British scientists are exporting knowledge and expertise to big emitters in the developing world, like China and India.
Large-scale CCS can't happen until we know that it's viable, and that the CO2 won't escape. Would money spent on CCS be better spent on renewable energy, like wind farms? Is CCS a big opportunity for the UK? These are reasonable questions to ask. To answer them, scientists are working around the world to find out whether CCS is a viable long-term option.
There are many good sources of information about CCS, including The Global Status of CCS: 2021 [43], research by the World Resources Institute [44], also from the Energy Information Administration [45], and the International Energy Agency [46]. The best source of current and balanced information on this topic, at an appropriate level of depth and detail are from the source below, which has links to referenced studies.
For an updated (but CCS industry-based) perspective, feel free to page through the Global CCS Institute's The Global Status of CCS: 2019 [48], which is the most recent report as of September 2020.
SourceWatch [52], and others (PRWatch [53], desmogblog.com [54],) cite a 2008 report prepared by the executive of a public relations (PR) firm working on behalf of the American Coalition for Clean Coal Electricity. The lengthy report to "friends and family" outlines the work the PR firm did on behalf of "clean coal." Whether you agree with the message or not, this letter presents a fascinating accounting of a remarkable orchestration of highly effective, well-funded nonmarket action.
Read this fascinating report in its entirety, To Hawthorne Friends & Family (this is an archived version saved by Kevin Grandia at Desmogblog [54], as the original version was removed by the Hawthorn Group following a backlash). Keep in mind the source, a public relations firm working on behalf of the American Coalition for Clean Coal Electricity. Feel free to read this article [55] for additional insight into how the Hawthorne Group tried to influence this issue in public and private arenas.
A note from the original author of this course: I saw this strategy in action, maybe you have at some point as well? At a 2008 event in Levittown, PA where President Obama was speaking, Clean Coal hats were everywhere. On my way in, I, like most others, was offered one (free) in the parking lot.
Please review Canvas calendar for all due dates related to your Nonmarket Analysis Case Study.
Complete "Weekly Activity 6," located in the "Weekly Activities" folder under the Modules tab. The activity may include a variety of question types, such as multiple choice, multiple select, ordering, matching, true/false, and "essay" (in some cases these require independent research and may be quantitative). Be sure to read each question carefully.
Unless specifically instructed otherwise, the answers to all questions come from the material presented in the course lesson. Do NOT go "googling around" to find an answer. To complete the Activity successfully, you will need to read the lesson, and all assigned readings, fully and carefully.
Each week a few questions may involve research beyond the material presented in the course lesson. This "research" requirement will be made clear in the question instructions. Be sure to allow yourself time for this! You will be graded on the correctness and quality of your answers. Make your answers as orderly and clear as possible. Help me understand what you are thinking and include data where relevant. Remember, numbers should ALWAYS be accompanied by units of measure (not "300" but "300 kW"). You must provide ALL calculations/equations to receive full credit - try to "talk me through" how you did the analysis.
This Activity is to be done individually and is to represent YOUR OWN WORK. (See Academic Integrity and Research Ethics [56] for a full description of the College's policy related to Academic Integrity and penalties for violation.)
The Activity is not timed, but does close at midnight EST on the due date as shown on the Calendar.
If you have questions about the assignment, please post them to the "Questions about EME 444?" Discussion Forum. I am happy to provide clarification and guidance to help you understand the material and questions (really!). Of course, it is best to ask early.
In this lesson, you learned about the coal industry--from mining and extraction to greenhouse gas emissions, as well as estimates of coal reserves around the world and global demand for coal. We also reviewed the status and technologies for managing the carbon impacts of coal, including new methods of combustion and carbon capture and storage.
You learned:
You have reached the end of Lesson 6! Double-check the list of requirements on the first page of this lesson to make sure you have completed all of the activities listed there.
Links
[1] https://www.flickr.com/photos/untitledprojects/538285355/
[2] https://www.flickr.com/photos/untitledprojects/
[3] http://creativecommons.org/licenses/by-nc-nd/2.0/
[4] https://web.archive.org/web/20150303153243/http://www.elmhurst.edu/~chm/vchembook/306carbon.html
[5] http://www.physicalgeography.net/fundamentals/9l.html
[6] https://www.epa.gov/international-cooperation/mercury-emissions-global-context
[7] https://web.archive.org/web/20090213163521/http://www.fueleconomy.gov/feg/CO2.shtml
[8] http://www.eia.gov/coal/production/quarterly/co2_article/co2.html
[9] https://commons.wikimedia.org/wiki/File:Lignite_Klingenberg.jpg
[10] https://www.flickr.com/photos/stannate/2092270895/
[11] http://www.worldenergy.org/publications/2016/world-energy-resources-2016/
[12] https://www.worldenergy.org/publications?cat=16
[13] https://www.eia.gov/outlooks/ieo/pdf/IEO2021_Narrative.pdf
[14] https://www.euractiv.com/section/energy/news/a-tale-of-three-countries-how-czechia-germany-and-poland-plan-to-ditch-coal/
[15] https://www.world-energy.org/article/19838.html
[16] https://www.e-education.psu.edu/eme444/sites/www.e-education.psu.edu.eme444/files/Germany%20Flirts%20With%20Power%20Crunch%20in%20Nuclear%20and%20Coal%20Exit%20-%20Bloomberg.pdf
[17] https://www.bp.com/content/dam/bp/business-sites/en/global/corporate/pdfs/energy-economics/statistical-review/bp-stats-review-2022-full-report.pdf
[18] https://e360.yale.edu/features/as-investors-and-insurers-back-away-the-economics-of-coal-turn-toxic
[19] http://www.iea.org/
[20] https://e360.yale.edu/
[21] http://www.popularmechanics.com/science/energy/coal-oil-gas/dangers-in-longwall-coal-mining#ixzz1ZNqC3epG
[22] http://epa.gov/climatechange/ghgemissions/gases/ch4.html
[23] https://www.epa.gov/sites/production/files/2018-03/documents/cmm_developments_in_the_us.pdf
[24] http://www.globalmethane.org/about/methane.aspx
[25] http://www.nytimes.com/2010/04/10/us/10westvirginia.html?pagewanted=all
[26] http://nepis.epa.gov/Exe/ZyNET.exe/2000ZL5G.TXT?ZyActionD=ZyDocument&Client=EPA&Index=2006+Thru+2010&Docs=&Query=430R06003&Time=&EndTime=&SearchMethod=1&TocRestrict=n&Toc=&TocEntry=&QField=pubnumber%5E%22430R06003%22&QFieldYear=&QFieldMonth=&QFieldDay=&UseQField=pubnumber&IntQFieldOp=1&ExtQFieldOp=1&XmlQuery=&File=D%3A%5Czyfiles%5CIndex%20Data%5C06thru10%5CTxt%5C00000000%5C2000ZL5G.txt&User=ANONYMOUS&Password=anonymous&SortMethod=h%7C-&MaximumDocuments=10&FuzzyDegree=0&ImageQuality=r75g8/r75g8/x150y150g16/i425&Display=p%7Cf&DefSeekPage=x&SearchBack=ZyActionL&Back=ZyActionS&BackDesc=Results%20page&MaximumPages=1&ZyEntry=1&SeekPage=x&ZyPURL
[27] https://www.epa.gov/cmop/frequent-questions#q6
[28] https://www.epa.gov/cmop/frequent-questions#q8
[29] https://www.eia.gov/dnav/ng/ng_cons_sum_dcu_nus_a.htm
[30] https://www.epa.gov/ghgemissions/global-greenhouse-gas-emissions-data
[31] https://www.iea.org/data-and-statistics?country=WORLD&fuel=CO2%20emissions&indicator=CO2%20emissions%20by%20energy%20source
[32] https://www.eia.gov/outlooks/ieo/pdf/ieo2019.pdf
[33] https://www.eia.gov/outlooks/ieo/pdf/0484(2016).pdf
[34] https://phys.org/news/2018-05-natural-gas-prices-war-coal.html
[35] http://www.nma.org/pdf/fact_sheets/cct.pdf
[36] https://www.energy.gov/fe/listings/clean-coal-news
[37] https://www.c2es.org/content/carbon-capture/
[38] https://www.popularmechanics.com/technology/infrastructure/news/a27886/how-does-clean-coal-work/
[39] http://www.ipcc.ch/
[40] https://www.ipcc.ch/report/ar6/wg1/#SPM
[41] https://www.ipcc.ch/sr15/
[42] https://www.ipcc.ch/sr15/chapter/chapter-2/
[43] https://www.globalccsinstitute.com/news-media/latest-news/media-coverage-the-global-status-of-ccs-2021/
[44] http://www.wri.org/our-work/project/carbon-dioxide-capture-and-storage-ccs
[45] http://www.eia.gov/
[46] https://www.iea.org/fuels-and-technologies/carbon-capture-utilisation-and-storage
[47] https://19january2017snapshot.epa.gov/climatechange/carbon-dioxide-capture-and-sequestration-overview_.html
[48] https://www.globalccsinstitute.com/resources/publications-reports-research/global-status-of-ccs-report-2019/
[49] https://www.wri.org/insights/direct-air-capture-resource-considerations-and-costs-carbon-removal
[50] https://blogs.ei.columbia.edu/2019/09/27/carbon-capture-technology/
[51] http://spectrum.ieee.org/energywise/green-tech/clean-coal/carbon-capture-is-not-dead-but-will-it-blossom
[52] http://www.sourcewatch.org/index.php?title=Clean_Coal_Marketing_Campaign#cite_note-16
[53] http://www.prwatch.org/node/9033
[54] http://www.desmogblog.com/coal-lobby-pr-firm-memo-boasts-about-manipulating-democrats-and-republicans
[55] https://www.energyandpolicy.org/hawthorn-group-pr-firm-paid-actors-new-orleans-entergy/
[56] https://www.ems.psu.edu/undergraduate/academic-integrity/academic-integrity-undergraduates