Open Pit Mines (coal) vs. Solar Updraft Towers
Posted by carrie_roll
It has to be a kilometer tall, with a 1.5 mile radius of “greenhouse canopy”, just to power 200,000 homes only for 50 years? AND with a cost of 1Billion dollars/tower? And…??? Are you kidding me? How can you think this is a good idea?
Sometimes people fascinate me. Really.
I got that message after posting about solar updraft towers a few days ago.
I thought, and still think, that solar updraft towers as power plants are a great idea.
But I do think it’s good to take differing perspectives into account, and so I decided to look into this.
What I’ve found (as you’ll read below) has convinced me that solar updraft towers are not only a great idea, but one that we should be pressing our energy utilities to act on, or creating solutions to ourselves.
Here’s what I mean:
We currently use coal to generate significant amounts of electricity, right?
Coal is cheap. It’s “easy” to come by, and easy to use to generate power. (RIght?)
This is an aerial shot of one of the largest open pit mines in the world, the Black Thunder Coal Mine in Wyoming.
I learned from here, that “In 2004, Black Thunder became the first coal mine in the US to ship a cumulative 1,000Mst (907Mt) over its 27-year life to date.” and that “The combined operation is now producing coal at a rate of around 91Mt/y, equivalent to about 10% of total US coal production.”
I had no idea what those measurements meant.
Turns out it was easier than I thought. It’s 901 Million Tons total, or 91 Million Tons/year.
So the first complaint/rebuttal offered by this individual was It has to be a kilometer tall?
Well, how much concrete would be needed to build a solar updraft tower?
I know that in the world trade towers, 425,000 cubic yards of concrete were used. (It’s unfortunately an easy number to look up.)
1 cubic yard of concrete = 3,000 pounds (approx.) source
Less concrete would likely be needed for this kind of tower, but let’s assume it’s the right amount of concrete.
We would need 6,375,000 tons of raw material per tower. (I realize as well that there would be steel and other materials to build a solar updraft tower, but we’ll just go with the base material for now.)
Not comparing apples to apples here (at all) but go out on a limb with me for a second and say we were to make towers out of the material that has been extracted already (coal instead of concrete). From what has already been taken out of the ground there in 27 years (as of 2004), we could have built 151 towers. (907Million tons/yr. divided by 6 Million tons/material per tower). Coal’s not as dense as the material needed to make concrete, so let’s round that number down to 100 towers, just to give flex room in my figures.
So I realize that’s not apples to apples, but it gives a good base for understanding. From one (albeit large) mine, the raw material could have constructed 100 or more towers.
The next complaint offered by this person was It has to have a 1.5 mile radius of “greenhouse canopy”?
Well, just how big is that footprint?
The image below shows how many of these 1.5 mile radius greenhouse canopies could fit into the surface area of just the Black Thunder Coal Mine. (I left the scale on the map so you could see I was accurate to a 1.5 mile radius.)
I’ll save you the time in counting.
It’s 16 (or more).
So, for the same space used by this one coal mine over 27 years, we could build 16+ towers.
For the same (or similar amount) of raw material extracted from the earth by this one coal mine over 27 years, we could build 100+ towers.
The next issue offered by this person was this expense would be *just* to power 200,000 homes *only* for 50 years/tower?
Well, how much coal is needed for 50 years of powering 200,000 homes?
In 27 years, 907 million tons came out of the Black Thunder mine.
They say that met about 10% of the nation’s energy needs.
If that number is accurate, this means that in 25 years, the US used about 10 billion tons of coal. If energy consumption remained the same (which it won’t because consumption is increasing, but it’s easy for purposes of the example), the US would use 20 Billion tons of coal in 50 years.
According to the US DOE, it currently costs about $36 to mine a ton of coal and deliver it to a utility.
20 Billion tons of coal * $36/ton = 720 Billion dollars to get coal to utilities over 50 years.
That’s 720 solar updraft towers that can be built for the same amount of money.
But the utilities have costs to building and maintaining power plants for turning coal into electricity.
According to the DOE, “Each ton of coal consumed at an electric power plant produces about 2000 kilowatt hours of electricity.”
According to APPVoices, a traditional coal power plant costs approximately $1,300 per kilowatt hour of generation capacity. Therefore, a 500 megawatt plant costs about $650 million. (Integrated Gasification Combined Cycle plants and Fluidized Bed plants are more expensive at more than $1,400 per kilowatt hour, or more than $700 million for a 500 megawatt plant.)
We’re going to use the lower number of those numbers, $1,300 per kilowatt hour of generation capacity.
This means that (in 50 years) 20 billion tons of coal produced around 40 trillion kilowatt hours of electricity.
40 trillion kilowatt hours * $1300/kilowatt hour, is a a total cost (just in production of electricity from coal) of 520 trillion dollars (over 50 years).
Assuming each tower would cost 1 Billion dollars, we could *only* build 520,000 towers for what it would cost (at the current price of coal), to power the United States for 50 years.
(I know coal was less expensive in the past, but it will likely cost more in the future, especially with the dropping value of the dollar. So just stick with the example here.)
A single tower could power 200,000 homes. The US Census Bureau reports 126,316,181 housing units as of 2006. That equates to 632 of these towers to power the entire US. Let’s round that up to 640.
(Significantly more than $640 Billion was spent in the Iraq war, 20 billion was spent so GM could go into bankruptcy, but I digress…)
After the first 50 towers were built, construction efficiency would increase and as a result costs would decrease. But let’s assume that didn’t happen.
Compare these numbers next to each other.
$520,072,000,000,000
$ 640,000,000,000
For the same space used by one coal mine over 27 years, we could build 16+ towers.
For the same (or similar amount) of raw material extracted from the earth by this one coal mine over 27 years, we could build 100+ towers.
For the same costs as the entire coal industry over 50 years, we could build 520,000 towers.
For the same electricity production as the entire coal industry (to power the United States over 50 years), we could save more than 520 TRILLION dollars.
Is my math flawed? Am I missing something here? Please let me know if I am.
Even if my numbers are way off, and there are all sorts of unaccounted for expenses in building the solar updraft towers, the cost to power the United States for the next 50 years is so much better when looking at the solution proposed by solar updraft towers.
And this ignores the real costs of coal.
Coal cleanup (after mines are carved into the earth)
Coal pollution (health challenges)
Trucking/Equipment pollution and oil price fluctuations
Coal cleanup
What will happen with an open pit mine once all the coal has been extracted?
From Wikipedia
After mining finishes, the mine area must undergo rehabilitation. Waste dumps are contoured to flatten them out, to further stabilise them. If the ore contains sulfides it is usually covered with a layer of clay to prevent access of rain and oxygen from the air, which can oxidise the sulfides to produce sulfuric acid, a phenomenon known as acid mine drainage. This is then generally covered with soil, and vegetation is planted to help consolidate the material. Eventually this layer will erode, but it is generally hoped that the rate of leaching or acid will be slowed by the cover such that the environment can handle the load of acid and associated heavy metals. There are no long term studies on the success of these covers due to the relatively short time in which large scale open pit mining has existed. It may take hundreds to thousands of years for some waste dumps to become “acid neutral” and stop leaching to the environment. The dumps are usually fenced off to prevent livestock denuding them of vegetation. The open pit is then surrounded with a fence, to prevent access, and it generally eventually fills up with ground water. In arid areas it may not fill due to the deep groundwater levels.’
What will that cost 10-100 years from now in terms of the lost productivity of land and in cleaning up groundwater supplies? If the clay breaks down and the acidity leaks into groundwater supplies, or if the clayed mines fill with water and the acidity overflows to the surface levels during heavy rains, what are the real costs?
Health Challenges:
While coal pollution has been dramatically reduced in recent years (and while the coal industry has called the studies invalid or highly suspect) MSNBC cites a report which says:
“Health problems linked to aging coal-fired power plants shorten nearly 24,000 lives a year, including 2,800 from lung cancer.”
There are so many other costs to coal not accounted for here.
Here’s the point.
Sometimes, things are so big that they’re easy to overlook.
Sometimes, things become so “normal” that you don’t see how “not normal” they are.
I’m sure the people working at the Black Thunder Coal Mine are good people. They are very likely hardworking, honest, decent people who do what they do because they provide for themselves and their families. The work they do is important to keeping the *current* world moving. (They’re also likely underpaid. If coal is able to be delivered for $36/ton to utilities, I don’t know how these workers could be getting paid what they deserve. But I haven’t really looked into that… it’s just speculation.)
None of this is a reflection on them or the work they do. The Black Thunder mine just happens to be the example I chose.
There are lots of other mines, and this is the way things have been done for the past 50-150 years.
And many industries (not just coal) are causing health issues and planetary destruction.
But the point is this:
I got a message from someone basically calling me crazy for proposing a solution which makes good sense:
- economically
- from a health perspective
- from a planetary perspective
- from a growth perspective
- from a *solving real changes today* perspective
Ripping coal from the earth to power our electricity desires is so big globally that it looks normal to the vast majority of our entire human species.
And we’ve overlooked how not normal even that is.
It’s so big that we don’t even see the alternatives as possibilities, even when they make much greater sense from all perspectives.
China builds two new coal plants every month, while an Australian company has been trying to get funding to build a solar updraft tower since 2001.
Why? It makes NO sense.
The sun comes to the planet every day. The only reason a solar updraft tower looks weird or seems like a strange concept is because we’ve been doing strange things for so long that they now look normal, and things that should be normal look strange.
Normal = sun comes to earth and converts into usable energy in the form of wind, light, and heat.
Coal takes millions of years to form, and weeks, months, years to extract from the earth, and days, weeks, or months to convert into electricity.
Arthur Schopenhauer is credited with having said:
All truth passes through three stages. First, it is ridiculed. Second, it is violently opposed. Third, it is accepted as being self-evident.
How do we get from ridiculed to self-evident more quickly on something like this? This post is my attempt at it. Can you think of ways we can be testing these concepts in our own backyards?
It’s really important.
Maybe we can fix this? We really need to.
I’ve spent a lot of time pulling figures for this post, and I’m open to suggestions, thoughts, feedback, and/or criticism. Please use the comments below.
About Carrie Kraft
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25 Responses to “Open Pit Mines (coal) vs. Solar Updraft Towers”
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Lee Mazengarb says:
Sounds like a very futuristic idea and I can see why it is so violently opposed. So many leeching blood sucking companies with government backing are existing and gouging people of money using the old energy way. Like the electric car.
Can u imagine cheap energy if real could ever be made available???
The company in question should have got funding by now, what with all the greenery ways the government has been pushing. The company should have put their money where their mouth is and started developing it and putting forward a motion or offers of electricity supply to the main grid. Sydney and Wollongong and other major cities have had short supply of electricity and energy companies have whinged about needs for better electricity, even the NSW state government has tried and whinged about needing an electricity overhaul and vast improvements…so if its credible then it should get some funding if only to prove it will work. -
Shawn Donovan says:
This is great.
Sign me up if you start build towers. -
sabir says:
ok, i have been analysing this all articles about solar updraft plants, i totaly agree with you , that they are more feasible than a coal mine, and economicaly cheaper ( at long terms)
i am even thinking in building one small , for test purposes on my own backyard, if you have any schematics could you sen me please? ( ogrande2@msn.com)
but there is a cacht, imagine that all of your calculations are correct, there still one major problem, energy consumption its higher at night for ilumination, its higher when weather conditions are not good, its higher in winter, but our solar power plant, its dependent on good whether and good sunshine, so the air can war up, and cause a nice air streem to move the turbine, so its thet, where the coal beat solar, its avaliable as a power source independently of the wheater,time of year or day, at sufisant quantities! please feel free to argue!-
Going Green says:
Hi Sabir, Sorry for not replying on this sooner as I missed your comment. Yes, it is possible for a solar updraft tower to work at night. The builder can put rings of oil under the canopy which heat during the day, and continue to provide heat while they cool off at night, Providing electricity the majority of the day and night. I’m sure this issue could be handled through greater storage capacity as well, which is only a better/bigger battery away, for times of peak demand and low production. It’s been more than 2 years since you posted your original comment. How is your backyard tower coming along?
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Andrew says:
Contrary to the opinion listed above the Solar Tower is a viable prospect for the production of long term power generation. After EnviroMission acquired the rights to the Technology extensive research and subsequent investment was made improving the technology to create a commercially viable generation plant. The new concept has a total of 32 turbines at the base of the tower and would only need to be 750 m tall to generate a capacity of 200 MW. Having said that it is one of the only renewable technologies out there to date that can be tailored to meet ‘Site Specific’ needs. This means not only does it have the capacity to generate 200MW of power (keeping in mind many improvements can be made to the Technology in future such as geared turbines etc) it can be redesigned to meet a 50 MW capacity or a 100 MW capacity with feasibility studies and thermal flow designs already completed. I’m positive that once the first one is constructed on a commercial scale it will be at the forefront of renewable energy. Lastly I think Victor Hugo said it best “All the forces in the world are not so powerful as an idea whose time has come”
For further information go to http://www.enviromission.com.au-
Hi Andrew,
thanks for your comment on this 2 years ago. What’s the status on towers now? Could we do an interview with you for GreenJoyment?
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Bryan says:
In response to Sabir :
If you check out the video these actually do work at night wich is why they are so facinating , the ground under the canopy is still hotter than the outside air at night so the air continues to flows up the center tube to turn the turbine.
way cool , Bryan -
staypuftman says:
What about the open pit rock mine that will supply the concrete ingredients (one of which is often and ironically flash ash from coal power plants)? Not to mention the energy required to make concrete is the #2 global warming pollutant itself after coal.
There is no free lunch here. -
Hey staypuftman,
Great points you make here for sure. My points in rebuttal would be:
The rocks that need to be pulverized to make concrete (and the flash ash from coal sometimes used in making concrete) wouldn’t necessarily be the only material that these towers could be made from.
But, even if that were the case, wouldn’t it make sense to have the one-time “expense” of the electricity and fuel for pulverizing the rock and mining the coal to turn it into something that would generate electricity for at least the next 50 years?
I agree that there is no free lunch, but when we currently are harvesting coal and burning it, that’s a huge one-time expense for a one-time use, and creates huge damage to the ground where the coal has to be stripped from. Rock quarries are significantly less invasive than coal operations.
Would be interested in your thoughts here.
Warmest,
Jonathan -
Anonymous says:
I live on a small holding in Springs, Gauteng, South Africa. A company has submitted a proposal to mine ( open pit mining operation) clay and coal close to our property.. We have a wetland in our area too . They want us to object following which they will take it that we accept. Please can you tell me what health and environmental risks their are in them starting this project. Their are farms with vegetables and cattle/horses/chikens and a bird santurary in this area which they are wanting to mine. I am not exited, and feel they are going to destroy our invironment. Dust and cracking of structures (homes)? Please help. I need some advise. URGENT !!!!
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Bill Bishop says:
There is a serious flaw in your (Jonathan’s) financial/energy calculations. The cost of generating capacity should be in units of dollars per kilowatt, not dollars per kilowatt-hour. A coal plant would cost on the order of $1300/kW to build, and a $750 million, 200 MW solar updraft plant (as EnviroMission proposes) would cost $3750/kW. The solar updraft capital cost is comparable to CSP (trough) solar plants, a more mature technology that doesn’t require tall towers to be built.
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Franz says:
Anonymous: GET OUT WHILE YOU STILL CAN!!!! POLITICIANS ARE CROOKED AND SO ARE THE DEVELOPERS!!
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BreathontheWind says:
A great analysis even with the 2 errors already mentioned. To the response comparing the solar updraft tower cost to a solar trough technology there are two points of difference. The first is the ability of the updraft tower to store energy for 24/7 electrical production. The solar trough requires a separate system of hot salts that presently give 5 to 7 hours of additional electrical production.
The second factor is the amount of water that is used by each technology. Both can take advantage of increased solar insolation in deserts, but the trough technology requires water to keep the reflectors clean. The canopy of the updraft tower is a collector and is less affected by dirt and dust. I have seen some reports that the updraft tower does not require a constant supply of water for cleaning or cooling of what essentially becomes a conventional thermal power production facility in the trough design.
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Right… The only things that need cleaning in the tower design are the inside of the tower (not necessary except maybe once every 20 years), the plastic/glass covering over the ground space (maybe 1x/year), and maybe the turbines (maybe 1x/20 years). Compare this with troughs which stop working optimally as soon as any dust begins to accumulate. I’m for solar troughs as well… I just don’t know what the impediments are to putting up towers in addition. Especially when desert land can be converted into arable quality farmland which holds both moisture and heat, and allows the tower to work at peak efficiency most of the year, 24 hours/day, regardless of the external climate conditions or dust over the ground space. Any additional thoughts on why we’re not building these? The concrete required is already being used in commercial construction of buildings… Just don’t understand why we’re not building these yet.
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Enviromission has the rights to the design. They are proceeding on a project in Arizona very slowly. Funding seems to be the primary issue. Economies of scale are very significant here. Bigger is definitely better in the math of how it works. But a far cheaper tower might be had using a lighter than air structure or a vortex air columb. Some hybrid tower might be best. From a backers perspective why invest in a technological marvel when proven CSP designs are giving a more risk free return.
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I think the tourism potential alone (once built) could pay off a tower in the first 10 years of it’s existence. What do you think about the Arizona project? Do you think it will move forward or get hung up like previous plans have in Australia?
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The tourism factor is only mentioned by EnviroMission as they are focused on marketing rather than technology. They continue to seek funding and it is understandable that they add up every potential source (carbon capture, manufacture under the canopy…) I am troubled by the lack of progress in over 10 years of repeated attempts at varioius locations. I am troubled by the vast amount of confusion in names sometimes seemingly pormoted by Enviromission. It seems to make so much sense that a working model would make funding so much easier, yet Enviromission seems to take an all or nothing position. The Chineese seem to have forced their hand a bit with their project. Beyond this I would prefer not to speculate as I have just written an article on Updraft towers ( http://cleantechnica.com/2011/08/01/giant-arizona-solar-tower-high-energy-with-hot-air/ ) and referenced this site. I hope it does get built. Once it is built there will be many insights and a whole new world of energy possibilities. That also has value.
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Frank says:
“In 27 years, 907 million tons came out of the Black Thunder mine. They say that met about 10% of the nation’s energy needs. If that number is accurate, this means that in 25 years, the US used about 10 billion tons of coal. If energy consumption remained the same (which it won’t because consumption is increasing, but it’s easy for purposes of the example), the US would use 20 Billion tons of coal in 50 years.”
In 2004, Black Thunder produced roughly 10% of the nation’s energy needs. This is not true over the 27 year period stated above. The US consumed 24.3 billion tons of coal from 1978-2004.
– Source EIA“According to APPVoices, a traditional coal power plant costs approximately $1,300 per kilowatt hour of generation capacity. Therefore, a 500 megawatt plant costs about $650 million. (Integrated Gasification Combined Cycle plants and Fluidized Bed plants are more expensive at more than $1,400 per kilowatt hour, or more than $700 million for a 500 megawatt plant.)
We’re going to use the lower number of those numbers, $1,300 per kilowatt hour of generation capacity. This means that (in 50 years) 20 billion tons of coal produced around 40 trillion kilowatt hours of electricity. 40 trillion kilowatt hours * $1300/kilowatt hour, is a a total cost (just in production of electricity from coal) of 520 trillion dollars (over 50 years).”$1,300 per KWh of generation capacity means that to build a coal-fired power plant it costs $1,300 per KWh of capacity. We are talking about capital costs here. This is a single cost referring to the construction of the plant. The actual delivered cost of power from a coal-fired power plant is about 5 cents per KWh. That is a big difference from the $1,300 per KWh you used in your forward looking calculation. The $520 trillion calculated above changes to $2 trillion dollars.
In my opinion as an engineer in the power field, the best way to determine the effective delivered cost of power over time would be to spread the capital cost over the life of the power producing plant while also considering the annual operating cost. Combining these two numbers and then putting that new number in terms of cents per KWh delivered would tell the true story.
All the construction details of the tower aside, what will be the final cost of power delivered from one of these towers in terms of $/KWh?
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Hi Frank,
Thanks for your comment. I’m not sure I understand your question:
All the construction details of the tower aside, what will be the final cost of power delivered from one of these towers in terms of $/KWh?
The cost would be determined by the company that built them, or the utility which delivered the power, which (if I’m thinking about this correctly) would be based on their construction cost, operational cost, and desired profit margin…
Maybe I didn’t understand your question?
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Exactly, you got it right. If a company were to undertake this project what would be the final delivered cost of power from this generating center?
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In addition to my last post, a 500MW coal-fired power plant might cost $1 Billion to build and will typically deliver 3.5 Billion KWh per year.
The capital cost per KWh is a bit lower than you stated!! Roughly 30 cents per KWh compared to the $1,300 you used.
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Michael Hertel says:
HI, I would like to build not a concrete tower but a sloped updraft tower on the surface of the earth. Have a mountain slope sun facing and cover with greenhouse, turbines at the top or bottom, greenhouse supported mostly with cables but with occasional towers supporting them.
Use the area under the inside the green house for crops, and other things. Send me email if interested; mghertel(at) exexpc.com note clearly (at) should be @
Just a note on the radius of the towers Jon.
That is a 1.5 mile radius – You use 1.5 mile diameter. Because the relationship is exponential You could only built 4 towers in the foot print of the mine.
From the other data it is still feasible though as it would rid the US of all other types of polluters including nuclear – if you powered 100% by this means.