Welcome to my musings on whatever topic catches my eye, plus stories, recipes, handyman tips, welding, photography, and what have you. Oh, and analog/digital hardware design, and software. Please comment on the blog post so everyone who visits can see your comments.

Tag: coal

To Support Coal Buy an EV


What? Yes, it’s true. Read on.

This post is intended for my fellow West Virginians. West Virginia is coal country so a lot of West Virginians support the coal industry.

I look at the big picture as an engineer. Now that the pollution problems associated with coal were mostly solved decades ago, I see coal as just another fossil fuel that we burn to obtain energy. It also happens to be what we have an abundance of in West Virginia.

I’ve watched climate change coming since 1990 and it’s going to bring huge difficulties. You ain’t seen nuthin’ yet. The bottom line is humans have to eventually stop burning things to obtain energy. Achieving this goal is going to take a long time. I’m a realist. It’s going to take far longer than we can afford but that’s how it’s going to be. We’ll be burning coal for a long time to come.

However, that doesn’t mean there’s nothing we can do to reduce our CO2 output. In fact, there’s something we can do to reduce CO2, save our hard-earned money, and support the coal industry, all at the same time. Sound impossible? It’s not. I’ll explain why.

Power Plants and Efficiency

To explain this we need to talk a bit about engineering, but this is something anyone can and should understand. It’s not complicated. Engineers who design machines or electronics are always interested in efficiency. In simple terms, efficiency means how much “input stuff” do you have to put into a device or system to get a certain amount of desired “output stuff” and how much is lost along the way.

In the simple case of an electric motor, if you put in 100 watts of electric power and get 75 watts of mechanical power out, the motor is 75 percent efficient. The other 25 percent is wasted/lost as heat. Nothing is ever 100 percent efficient. There are always losses.

If you have two or more devices one after the other (in series), you multiply together the efficiencies of each device to find out what the total system efficiency is. So, taking some typical figures, if we have a gasoline engine that’s 25 percent efficient, followed by a transmission (geartrain) that’s 80 percent efficient, the total efficiency at the output of the transmission is 0.25 times 0.80 equals 0.20 or 20 percent efficiency. The other 80 percent is lost as heat. This principle will become important below.

Power plant technology has improved continuously since the steam engine was invented. Efficiency is, by far, the most important factor in the design. Power plant efficiency means how much of the chemical / thermal energy in the fuel ends up coming out of the plant in the desired form and how much is lost as heat. Early steam engines were horribly inefficient. Only a few percent. Coal-fired power plants built in the 1970s achieve an efficiency of around 35 percent. So 35 percent of the thermal energy in the fuel leaves the plant as electricity. It may not seem like it, but this is pretty impressive. Modern coal plants built in recent years reach 45 percent efficiency and this is probably close to the maximum possible.

As an aside, natural gas power plants can employ designs that are not possible with coal. The most advanced natural gas plants can reach an unbelievable 60 percent efficiency. But, we’re not talking about natural gas here, we’re talking about coal. But I’ll mention this figure once more at the end of the article.

It probably goes without saying but I’ll point it out anyway. The more efficient a power plant is, the less fuel it consumes, but also the less CO2 it produces to generate a given output. This will become important below.

Internal Combustion Engines (ICE)

Now let’s look at internal combustion engine (ICE) cars. The overall efficiency of modern cars ranges from 12 to 28 percent. That’s the system efficiency measured from the energy in the fuel to moving the car down the road. But the 28 percent figure only applies to certain cars under certain conditions. My little Corolla probably gets close to that 28 percent figure when on a flat highway, at a reasonable speed, no headwind, I’ll get 38 mpg. When city driving, that figure drops way down and I get 24 or 25 mpg. Many cars, SUVs, pickups, do much worse. At no time does any ICE powered vehicle reach the efficiency of the oldest coal-fired power plant. Most of the time the coal plant is 2 to 3 times as efficient at turning fuel into usable power.

Ignoring the frictional losses of all the moving parts in an internal combustion engine, a problem it’s had since it was invented is something called the “power curve”. An IC engine produces maximum power at a certain RPM, maximum torque at a different RPM, and maximum efficiency at yet another RPM. At low RPM it produces little power or torque. At idle, it produces no usable output but still consumes fuel.

Electric Motors and Cars

Modern electric vehicles are powered by 3-phase induction motors. Small electric motors achieve 70 or 80 percent efficiency but the efficiency rises rapidly for larger motors. At the 100 horsepower level, such 3-phase motors are more than 95 percent efficient. Larger ones are even more efficient. And that’s running on fixed mains power at a fixed voltage and frequency.

The 3-phase motors in cars are powered by a sophisticated motor controller that varies the voltage and frequency as the motor’s speed and load changes. That gives these motors a flat power curve and even higher efficiency. At low RPM / low speed they produce lots of torque. At high RPM / high speed they produce the horsepower the car needs. The efficiency stays constant at all speeds.

So what’s the system efficiency of an electric car? The lithium batteries used in electric vehicles have a charge/discharge efficiency around 85 percent. So 85 percent of the electricity you put in comes back out to power the car. Fast charging pushes that number down towards 80 percent. Charging slowly at home pushes it up close to 90 percent.

So the motor gives at least 95 percent efficiency, the motor controller is 98 percent efficient, the battery 85 percent, there is no transmission. Multiplying those together we have around 79 percent efficiency from the charger plug to moving the car down the road. I’m ignoring regenerative braking that harvests the energy from braking to charge the battery. No ICE vehicle can do that, harvest the energy from the brakes and convert it into gasoline.

The electrical grid that transports electric power from the power plant to the home or charging station is very efficient. Over the short distances found in West Virginia, it’s nearly 100 percent efficient and can be ignored.

Conclusion

And so we’ll pull all the numbers together here: coal-fired power plant at 35 percent efficiency and 79 percent efficiency in the vehicle means 27 percent system efficiency from coal to moving the vehicle, any vehicle, down the road. All the time, city, or highway. That’s equal to my Corolla under rare perfect conditions. With a more modern coal-fired plant, it’s 36 percent efficient from coal to moving the vehicle down the road. Well beyond what an ICE vehicle can achieve. “Fueling” an EV from coal generates, on average, one-half to one-third the CO2 of burning gasoline or diesel in an internal combustion engine.

What’s more, the cost of that energy is much lower than buying gasoline or diesel. For example, a high-end Tesla Model S with the big battery pack option, completely discharged, at the electric rates we pay in West Virginia, costs about $12.00 to “fill up”. On top of that, your money isn’t going to a company in Texas, Mexico, Venezuela, The Netherlands, Saudi Arabia, or Russia. It stays right here in West Virginia. West Virginia generates about twice as much electricity as it uses locally. The rest is sold to out-of-state utilities. Availability of locally generated power is not a problem.

For those of you not in West Virginia or coal-country, if your electricity comes from hydro, wind, solar, or nuclear, like in the Pacific Northwest, no fuel is burned and no CO2 generated to power an EV. If your power comes from a modern gas-fired plant like in Florida, efficiency is 2 to 4 times that of an ICE vehicle and about one-third the cost.

As soon as I can solve the charging-at-home problem, I’ll be getting an EV and it will have a bumper sticker that says “This Car is Powered by Coal”.

tl;dr version: It’s more efficient, cheaper, and produces less CO2 to “fuel” an EV with coal-generated electricity than an equivalent ICE vehicle burning gasoline or diesel. Roughly twice as efficient and at one quarter the cost.

Coal Mining Isn’t What It Used To Be

When I was growing up in the 1950s and 60s, the term “coal miner” conjured up a stereotypical image of a man covered head to toe with black coal dust, wearing a hard hat, and swinging a pick or shovel. The work was grueling, dangerous, deadly, and paid terrible wages. In the United States, a shocking 90,000 men lost their lives in coal mines between 1900 and 1950. If there was ever a line of work that could be called “the widowmaker”, it was coal mining. The rest of society viewed coal miners as the bottom of the social hierarchy.

You load sixteen tons, and what do you get?
Another day older and deeper in debt.
Saint Peter don’t you call me ’cause I can’t go,
I owe my soul to the company store.

 –Tennessee Ernie Ford

Harry Fain, 1946 National Archives Photo

Today, coal mining is used as a political football by politicians. Politicians know that it conjures up powerful images that are based on the stereotype I described above. Most recently, President Trump invoked these images repeatedly during his campaign, and it created the desired effect on his listeners.

However, coal mining today isn’t what it was in 1910. The above stereotypes are completely false today. Coal mining has changed radically as have the men and women working in that business. President Trump’s rabble rousing was based on fantasy and imagery that no longer exists.

Back around 1910, there were thousands of coal mines. Larger mines employed hundreds in each shift. Virtually all coal mining was done underground, not on the surface. This meant entering or descending into deep mines. The standard mining technique was room and pillar, which dates back to ancient times. A room is hollowed out with pillars of coal left standing to support the roof. The size of the pillars was based on the opinions of experienced miners. Sometimes, they were wrong. There’s a tradeoff involved. Making the pillars larger provides increased safety but reduces the amount of coal that can be extracted.

Room and pillar is still used today in mines where there’s a valuable enough deposit, like anthracite (hard coal) and surface mining isn’t feasible. However, instead of relying on seat-of-the-pants guesses, science and engineering is involved. The force on the ceiling can be calculated, the compressive strength of the coal deposit can be measured. Optimal column sizes can then be calculated and actual stresses measured so danger can be detected and averted.

For added excitement and profit, one can still get the material left behind in the pillars by a method called retreat mining. Once a room is exhausted, the pillars can be destroyed, one by one, starting with the deepest one. The ceiling is allowed to collapse and the coal recovered. Needless to say, this is a dangerous business. My two coal miner friends here in West Virginia do this kind of work. With modern technology, it can be done successfully and accidents kept to almost zero.

My friends still come home from work with black faces and clothes full of black coal dust — hard shiny anthracite coal particles that sparkle when you look at them. They use the two washing machines at the laundromat set aside especially for coal miners. Unlike their counterparts a hundred years ago, they don’t use a pick and shovel, are highly skilled, and are paid well. But, they are in the minority. The majority of coal is produced nowadays using surface mining, including the infamous mountaintop removal mining technique. Fortunately for the environment, the number of mountaintop removal permits has dropped to about half of what it was ten years ago. This might be from political pressure, or because coal sales have dropped sharply since 2008. I don’t know. The economic collapse of 2008 started a sharp decline in coal sales that continues today. Demand has dropped. Again, President Trump’s rhetoric about increasing jobs in coal could only happen if demand increases. Coal mines are not gold mines, where the demand is essentially infinite. Coal mines produce only the amount of coal that is needed.

Surface mining, which produces the majority of coal today, is done by comparatively few highly skilled workers using gargantuan machines worth millions of dollars each. These machines are so large that you have to see them in person to comprehend. Imagine a bulldozer that could drive down one side of your neighborhood and obliterate every house on one side of the street in a single pass, without the least effort. Or, a dump truck so large that it’s not apparent where the driver is located. You have to climb three flights of stairs to reach the cab. Coal mines of this type employ more people who are mechanics, machinists, welders, engineers, and explosives experts than those who actually do the mining. It’s a whole different world from coal mining in 1910. What’s more, over the next ten years, more of these machines will become robotically controlled with no operator. In twenty years, surface mining will likely be done entirely by computer and robots.

Let’s look at some numbers. In 1900 the population of the country was 76 million and the coal industry employed 500,000 men. So, the better part of one percent of the population, or 1 out of every 152 men in the country, was a coal miner.

In 1900, annual coal production was about 275 million tons. From 1900 to the present, coal production increased to a peak of almost 1,200 million tons in 2008. In 2008, the US population was about 307 million, and the coal industry employed about 70,000 people, nationwide, or 0.02 percent of the population. In 2008 we had one seventh the number of people producing five times as much coal as we did in 1900. Coal production efficiency per worker is 35 times what it was in 1900.

To put these employee numbers into perspective, consider that Walmart employs 1.5 million people in the USA. Amazon employs 570,000. The US Postal Service employs 503,000. The coal industry employs 70,000. To increase production, the coal industry would add a few more machines and a few more employees to accommodate demand. So, to base a political campaign promise on increasing jobs in coal mining is disingenuous at best, stupid at worst. Coal is one of the worst sectors to choose to make such a promise. The number of jobs in coal mining will not increase significantly no matter what happens. The only reason to make such a promise is because it has strong emotional appeal to voters because they still have the old coal miner stereotype in their head and don’t know how things have changed.

© 2022 Shuttersparks

Theme by Anders NorenUp ↑

Find me on Mastodon