Clean Power

Published on February 9th, 2013 | by Zachary Shahan


Fun With Numbers…

February 9th, 2013 by  

Here’s some number fun from one of our readers that we thought was worth sharing. The topic is: “how much land we would need for a massive wind program to power 40% of the US.

Wind turbine in meadow via Shutterstock

The footprint of a wind turbine is typically around 0.25 acres. This includes the tower foundation, roads, and support structures.

In 2010, the US used 4,143 TWh of electricity (or 11,300,000 MWh per day).

Since we’re just guessing what our future grid would look like, let’s assume we get 40% of our electricity from wind; 40% from solar; and 20% from hydro, geothermal, tidal, etc.

4,143 TWh / 365 * 40% = 4,540 MWh per day from wind.

The average wind turbine is around 3 MW and median capacity is now 43%.

3 x 24 hours x 0.43 = 30.1 MWh per day

4,520,000 / 30.1 = 150,166 3MW turbines.

150,166 x 0.25 = 36,040 acres required.

So, a massive wind power program would require 2.4 Manhattan Islands, 1.4 Disney Worlds, or 0.0015% of the US.

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About the Author

is tryin' to help society help itself (and other species) with the power of the typed word. He spends most of his time here on CleanTechnica as its director and chief editor, but he's also the president of Important Media and the director/founder of EV Obsession, Solar Love, and Bikocity. Zach is recognized globally as a solar energy, electric car, and energy storage expert. Zach has long-term investments in TSLA, FSLR, SPWR, SEDG, & ABB — after years of covering solar and EVs, he simply has a lot of faith in these particular companies and feels like they are good cleantech companies to invest in.

  • Pieter Siegers

    Hello Zachary, your intention is obviously a very good one and I can
    see you want a dream come true just like me and many others, but writing
    down calculations you should take a bit more care… for example:

    “In 2010, the US[A] used 4,143 TWh of electricity (or 11,300,000 MWh per day).”
    It should be (11,350 MWh per day), of course.

    The other example:
    “4,143 TWh / 365 = 4,520,000 MWh per day from wind.”
    This should actually be:
    “4,143 TWh / 365 * 40% = 4,540 MWh per day from wind.”

    So ultimately you now can recalculate the are needed; I’ll leave it up to
    you to correct your article, but it shows a factor of about a 1000 less
    area is needed… think about it!

    Apart from those details and assuming the amounts you mention are appr. correct, it does show us how easy it should be to phase over to non-fossil energy sources. It would be a lot of fun making that a reality… much more than thinking about
    it. And of course really stopping the climate changes we’re living today from getting worse.

    Another point of interest (and fun) should be energy efficiency. This would allow for population growth and at the same time using less energy per citizen so the total energy use shrinks.

    Finally, moving to renewables should allow for less (energy) wars, a lot more
    green jobs and hold a much brighter future for our children and theirs and so on.

    Ultimately, energy should not be a problem of this world and I think it is very well possible. The one thing that shouldn’t be allowed to interfere is commercial interest while creating basic public sustainable energy sources.

    By the way, thanks for maintaining such an important news feed! 🙂

    Regards, Pieter

    • Bob_Wallace

      From –

      In 2010 the US generated 4,125,060 Thousand Megawatt hours

      That’s 4,125,060,000 MWh (Megawattt hours)

      Or 11,301,534 MWh per Day

      One of us is wrong. I haven’t had my morning coffee, so it could be me. But I did let a spreadsheet do the math….

      • Pieter Siegers

        Hi Bob, I recalculated wrong, I just had my coffee and saw my error. 🙂

        Anyways the area needed is tiny even with factor 1000 so there’s nothing to be worried about.

        • Bob_Wallace

          Thanks. I was a bit worried.

          I’m not used to working with numbers larger than my net worth. And that doesn’t even get me to the MWh per day level.

    • Hello Pieter,

      I didn’t write the post (as noted at the top of the article).

      Looks like the numbers are correct (from what I’m gathering from the rest of this comment thread), right?

      As far as US vs USA — in the US, we tend to just write “US.” Is that confusing to foreigners? For me, it looks weird to write USA. The bulk of our audience is in the US, but we do have a significant non-US audience, so we’ve been trying to use international language and such.

      Good additional points. Energy efficiency certainly deserves some space at the table, so to speak. And great points on jobs, war, etc.

      • Pieter Siegers

        Yeah , you didn’t write it but your bio appears under the message…

        I know now that Bob Wallace wrote it since he responded when I pointed him to the “errors”.

        Anyways, the numbers are correct, my fault. But the second formula was not complete, that still stands.

        About US or USA, for foreigners USA or even America (for Europe) is the correct name. Just so that you know, I am European (Netherlands) but already live in Mexico for 18 years now.

        Actually, officially Mexico is also a ‘US’, just check it’s official name… (Estados Unidos de México).

        Having said all this, I guess that it is not easy to write for an international audience.

        And thanks for the other comments.

        Also, keep up the good work, and please if you can, expand your audience because we are going to face a very difficult time if we’re continuing with our current lifestyle.

        For example, please help to block the Keystone XL Pipeline. I sometimes read articles (on your or related sites that come in the digest of Alternative Energy News that I daily review) that still seem to encourage that stupid project. It is key for our future to stop the project and you with your momentum can really help. I hope Obama will keep his word and honour in this case.

        Thanks for listening!


        • Bob_Wallace

          The original got chewed up in the editorial process….

          “4,143 TWh / 365 * 40% = 4,540 MWh per day”

          Some people ding us when we call our selves “America”. They think that word should be used for everything from Canada down to the tip of South America.

          So we call ourselves “The United States” and other people get critical.

          It’s kind of a no-win. Perhaps we should change our name to Sam. Or Sally.

          On a more serious note, I doubt the Keystone is blockable. The oil industry simply has too much power and too many voters will react harshly if they think the cost of fuel at the pump will increase if it is blocked. Which is how it will be spun.

          We’ve got to give people cheaper alternatives to driving ICEVs. There’s no way to cut off the fuel supply and make them walk.

          We need more PHEV models so that there is more competition.

          And we need to crank up the subsidy in order to get manufacturing volumes up which will bring prices down.

          If we move people to PHEVs (and some to EVs) we could cut our oil usage to the point at which it would not make sense to extract tar sands oil.

          • Pieter Siegers

            Hi Bob!

            You wrote

            “On a more serious note, I doubt the Keystone is blockable.”

            IMO it IS very blockable, and it should be done for one simple reason: what do you do when you find a product you depend on is not available anymore or its impact on your environment is too big, or simply it gets too pricy? You simply change to another product. You will find your way through if your attitude is positive.

            For Obama to not betray his own words he can’t allow accepting the project to continue. Yes Big Dirty Oil will fight back but they will loose that fight on the long run. Because alternative energies are here and growing stronger and stronger. This new clean energy will be as cheap as it can get. Just look at Germany (solar). Look at Spain (wind). Let’s face it, fossil fuels can’t compete with that. Four years can do a lot of change if you really want it.

            But there must be a driving force that will make the (excellent) wishes you describe come true.

            It is just my hope that we can move away from fossil fuels using the evolutional model. It seems that the process goes way too slow. The pipeline will make that transition slower. People will think “Now we are good!!” seeing prices at the pump stabilize, and that’s NOT good. Because world pollution ppm keeps going up and they won’t notice. Future clean up costs would be immense if not irreversable.

            So I put every bit of hope and positivism in believing Obama will stop the project and put it in the trashcan and so Big Dirty Oil momentum will loose power.

            IMO we simply just cannot afford anymore these type of projects.

            For the rest I agree with you, of course. We should all drive 100% Solar Powered EVs by now! 🙂

            Regards, Pieter

          • Bob_Wallace

            “For Obama to not betray his own words he can’t allow accepting the project to continue.”

            What words are you referring to?

            I don’t agree that we can cut the supply of oil in order to make it more expensive. Most voters would not tolerate that.

            If we have personal energy to spend I think it best to use it to further EVs and PHEVs, get their price down. As soon as people have a reasonable alternative to oil they will switch over.

            What we need right now is more people buying EVs and PHEVs so that their prices come down.

          • I have to say, if could get all the people together it has gotten to oppose the Keystone XL, and then use those people to educate the public more about EVs, and to actually push EV adoption and such, that would be a big help. A tremendous amount of time and money has gone into blocking this pipeline. What if that were used to promote the alternatives? Unfortunately, it’s often easier to get people together to fight something than it is to get them together to promote something.

          • Pieter Siegers

            Hi Bob, here’s what I’m referring to, this article link contains some of the words of President Obama on the topic you’re asking me for, and very well describes what should be done:


            I think you will agree that the message is clear. And the action plan is clear.

            We all know that consumers have the power to change the way products are being made. So here’s the power to the people.

            But also governments should be brave enough to withstand the power of the upper elite. They won’t stand a chance if we all deny further exploitation of fossil fuels.

            If the consumers wait for things to change it will take too much time. We need to take action now, and everybody has to do their part. So let’s move now we still can.

            Besides the pipeline will be there only to transport a dangerous liquid to Texas and then (I suspect) it will mostly be sold to other countries. Is that what you’re waiting for? I don’t think so.

          • Bob_Wallace

            Pieter, I just don’t agree.

            I do not think that it is politically possible to lower CO2 emissions by causing people to drive less via doing things which increase fuel prices. I think that is a losing strategy.

            I think we can lower CO2 emissions by increasing MPG requirements (which PBO has done), by improving public transportation(which PBO has facilitated), and by assisting development of non-fossil fuel transportation (which PBO has done). Even improving the condition of our roads helps. And PBO used stimulus money to improve roads.

            If people want to do something I think they should be putting their energy behind better public transportation and bike lanes. And increasing EVs and PHEV sales. We need sales numbers to increase in order to bring battery prices down.

            If people could buy a EV or PHEV and recover the price difference in 2-3 years, then start saving money I think we’d see very large decreases in the sales of ICEVs.

            That’s how we make Canadian tar sand oil stop flowing. We lower demand and those low EROEI sources like tar sands go out of business.

        • ah, i was supposed to correct that line (Bob caught that at some point) — my bad.

          interesting point on Mexico.

          as Bob notes, “America” isn’t politically correct within the US. i remember when i first came to Europe (lived in the NL for 5 months — Groningen) and heard everyone saying America. initially, i explained to people why that wasn’t politically correct, but i eventually gave up and have even used the term a couple times.

          but yeah, basically, seems like every option is going to seem wrong or odd for someone. perhaps we should stick with U.S. — i personally prefer the British version without the decimals, but if it helps clarify, i can get over it. 😀

          Keystone XL: the citizen effort against it is tremendous. but the political spaghetti around it is intricate. i’m not sure where it will go, but with climate hawk John Kerry being in charge of the decision, i think that it will be blocked if we ever had any chance of that. but really not sure.

          As Bob notes, i think the key is to price tar sands oil (and all oil) out of the market with EVs. think that’s our best bet. that and putting a strong price on GHG anywhere we can.

          But we will continue to post on the Keystone XL a bit.

          Thanks for the input. 😀

  • hi

    median capacity factor for wind power is 43% OFFSHORE

    • Bob_Wallace

      No, onshore.

      Go here…

      Click on the Capacity Factor tab.

      Hover your cursor over the middle of the Onshore bar.

      You’ll see median 38%, Q3 43% and max 50.4%. At least half the turbines in that sample are older, some as old as 30 years. It’s reasonable to assume that they are the bottom half for the most part. Years of improvements.

      That makes the median of turbines yet to be installed around 43%. Technology is improving as are siting skills. We’re now seeing turbines designed for different wind conditions. Even lower wind sites are returning 40+% performance.

  • jimmydimmy

    I heard that geothermal capacity alone would power the US 500 times over. How wind, geothermal and solar are growing, I wouldn’t doubt that very soon we will be getting a renewables power grid. Of course, energy storage to meet demand would remain our biggest challenge, except for East Coast cities power by offshore wind.

    • Bob_Wallace

      It’s possible.

      First we have to figure out how to affordably use enhanced/dry rock geothermal. This is where we drill down to very hot rock and, basically, pour water on it to make steam. The water goes down one hole, flows through cracked (fracked) rock and steam comes up from one or more other holes.

      A couple companies made good progress on this technology in 2012. One was able to frack using CO2. Another was able to frack at multiple levels which greatly increased the number of cracked rocks available. They used a biodegradable fracking compound.

      We’ve got a lot of wet rock geothermal in the US but it’s limited to parts of the far West.

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