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Total Surface Area Required to Fuel the World With Solar



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According to the US Department of Energy (Energy Information Administration), the world consumption of energy in all of its forms (barrels of petroleum, cubic meters of natural gas, watts of hydro power, etc.) is projected to reach 678 quadrillion Btu (or 7.15 exajoules) by 2030 – a 44% increase over 2008 levels (levels for 1980 were 283 quadrillion Btu and we stand at around 500 quadrillion Btu today).

I wonder what surface area would be required and what type of infrastructural investment would be required to supply that amount of power by using only solar panels. To create fuel that can be used in vehicles and equipment I am assuming that some of the electricity generated would be used to create hydrogen. We should all start wondering about these things since we will have really no other choice* by the turn of the next century.

So to find this out we start with the big number 678,000,000,000,000,000 Btu.

Converting this to KW•h [1 Btu = .0002931 kW•h (kilowatt hours)] makes 198,721,800,000,000 kW•h (199,721 TW•h). This is for an entire year. As a comparison, the average household uses approximately 18,000 kW•h per year (1/11 billion of the total world usage).

We can figure a capacity of .2KW per SM of land (an efficiency of 20% of the 1000 watts that strikes the surface in each SM of land).

So now we know the capacity of each square meter and what our goal is. We have our capacity in KW so in order to figure out how much area we’ll need, we have to multiply it by the number of hours that we can expect each of those square meters of photovoltaic panel to be outputting the .2KW capacity (kilowatts x hours = kW•h).

Using 70% as the average sunshine days per year (large parts of the world like upper Africa and the Arabian peninsula see 90-95% – so this number is more than fair), we can say that there will be 250 sun days per year at 8 hours of daylight on average. That’s 2,000 hours per year of direct sunlight.

Therefore, we can multiply each square meter by 2,000 to arrive at a yearly kW•h capacity per square meter of 400 kW•h.

Dividing the global yearly demand by 400 kW•h per square meter (198,721,800,000,000 / 400) and we arrive at 496,804,500,000 square meters or 496,805 square kilometers (191,817 square miles) as the area required to power the world with solar panels. This is roughly equal to the area of Spain. At first that sounds like a lot and it is. But we should put this in perspective.

If divided into 5,000 super-site installations around the world (average of 25 per country), it would measure less than 10km a side for each. The UAE has plans to construct 1,500MW of capacity by 2020 which will require a space of 3 km per side. If the UAE constructed the other 7 km per side of that area, it would be able to power itself as a nation completely with solar energy. The USA would require a much larger area and approximately 1,000 of these super-sites.

According to the United Nations 170,000 square kilometers of forest is destroyed each year. If we constructed solar farms at the same rate, we would be finished in 3 years.

There are 1.2 million square kilometers of farmland in China. This is 2 1/2 times the area of solar farm required to power the world in 2030.

Compare it to the Saharan Desert:

The Saharan Desert is 9,064,958 square kilometers, or 18 times the total required area to fuel the world.

By another measure, “the unpopulated area of the Sahara desert is over 9 million km², which if covered with solar panels would provide 630 terawatts total power. The Earth’s current energy consumption rate is around 13.5 TW at any given moment (including oil, gas, coal, nuclear, and hydroelectric).” This measure arrives at a multiplier of 46 times the area needed and shows that my numbers are very conservative.

Compare it to highways:

At a density ratio of 800km per 1000 square kilometers and a total length of 75,440km, the overall area of the US interstate highway system (constructed entirely between 1956 and 1991 – 35 years) is 94,000 square kilometers, or 20% of the overall required area for the world. The US also consumes about 20% of the world’s energy. (if the efficiency of conversion from solar to electricity was 100%, the area of USA highway would be equal to exactly that required to run the world). Indeed if every nation were to embark on a state program of the scale of the US highway system we could be finished with the required infrastructure in 20-40 years.

Compare it to golf courses:

The typical golf course covers about a square kilometer. We have 40,000 of them around the world being meticulously maintained. If the same could be said for solar farms we would be almost 10% of the way there.

Also remember that we are working here with a worst case scenario based on projections for the year 2030 that assume a lot about growth. What could we do to lower the overall Btu load? And what other sources of clean energy could contribute to lower the area needed for solar panels?

Wave:

World wave energy potential = 2,100,000,000,000 KW•h (2,100 TW•h) or 1% of the required load.

Wind:

A 5 MW turbine can be expected to produce 17 GWh per year (they are 40% effective from their peak rated capacity – 5 MW x 365 x 24 = 43.8 GWh). Therefore, it would require 11,748,294 of the 5 MW capacity turbines to create the same yearly output. There are 500 million cars in the world so it’s not like that’s an unattainable goal from a manufacturing standpoint. And each 5 MW turbine is a 30 year lifespan money making machine for whoever buys it. The same can not be said for my car. But if we can build 90,000 Cape Wind size installations, we would be there on wind alone. Based on that installation, each turbine requires 1/2 square mile of area for offshore sites. This would require 5.85 million square kilometers for 2030 world energy needs.

Here is a graphic for wind based on the notes above. The area in the North Sea is taken directly from the OMA proposal by Rem Koolhaas the pdf of which can be seen here.


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Existing Hydroelectric:

I say existing hydroelectric because it would be damaging to the environment to construct more dams on rivers. Such designs have been shown conclusively to have a deleterious effects on the ecosystems of the watersheds that are fed by the existing river.

As of 2004, hydroelectric power accounted for 6% of the energy production in the world. A conversion of this percentage into energy capacity makes 28 quadrillion Btu (492 quadrillion Btu x 6%). As a percentage of 2030 levels and accounting, this would be more like 4% and accounting for a hopeful decommissioning of existing dams, let’s assume 2%.

So these other sources together have the potential to reduce the area required by 5% – 25% based on the amount of wind power we tap into. Solar panels are really going to have to do the vast majority of the work but a sustainable solution is going to require a great mix of solutions that are diversified as much as possible.

The technologies are improving and the efficiencies are getting greater. We must make it our goal to by the end of this century construct the area required by at the same time reducing our demand and by starting the necessary infrastructure projects today everywhere around the world. Otherwise the consequences are unthinkable.

*As for nuclear power, it currently produces 2.5% of the world’s energy or 10 quadrillion Btu per year. In 2008, the International Atomic Energy Agency (IAEA) predicted that nuclear power capacity could double by 2030, though that would not be enough to increase nuclear’s share of electricity generation. As for the non-renewable resource of uranium, according to the nuclear industry’s own estimation:

Current usage is about 65,000 tU/yr. Thus the world’s present measured resources of uranium (5.5 Mt) in the cost category somewhat below present spot prices and used only in conventional reactors, are enough to last for over 80 years.

80 years does not equal sustainable. And this is only assuming current use rates (the 5% of world energy needs).

An average plant puts out 3 cubic meters of spent fuel each year. Assuming 1000 plants operating around the world (there are 500 today), that would makes 3,000 cubic meters per year. Over those 80 years this would create a volume of 240,000 cubic meters or a cube of 60 meters on each side (bigger than the Pantheon and roughly equivalent to the volume of the Gol Gumbaz Mausoleum. What do we do with that amount of dangerous radioactive material that has a half life of 2 million years?

Update 1: some comments being posted here:
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Update 2: Many comments have to do with the distribution of energy. I reiterate that I am in favor of a maximizing of diversity of clean energy technologies and of points of generation. For example, if we use the figure of 6 billion people in the world, and if over the course of each person’s lifetime they would be responsible for creating a panel to use their equal share of the worldwide demand (never mind the non-equal distribution) then we would each be in for a 9m x 9m square, or something that gives off 33,000 kW•h per year. With a typical home roof installation that assumes 15 kW capacity. Obviously this extreme localization is also not ideal — what is needed is a plan that captures the best balance of centralized/localized and best mix of renewable and clean resources.

Update 3: SES technology would bring down the solar area required to 315,000 square kilometers (based on the 629 kW•h per square meter listed on the site sourced as from Southern California Edison and Sandia National Laboratories). This is a 40% reduction just on efficiency of the capturing device. The technology will continue to get better and better…

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  1. IT IS INDEED WITH GREAT PLEAURE AND INTEREST, I HAVE CAREFULLY READ THE AFORESAID LINES WHEREIN YOU HAVE TAKEN GREAT EFFORT TO ENLIGHTEN THE WORLD OVER ABOUT THE IMPORTANCE OF HARVESTING THE ABOUNDANTLY AVAILABLE SOLAR ENERGY BY THE MANKIND FROM NOW ONWARDS. WE ARE REEALLY ON THE BRINK OF SEVERE ENERGY STRINGENCY AND RECESSION IT IS ALMOST AT THE DOOR STEP OF EVERY HOME AND DWELLING PLACES.IT IS NEEDLESS TO STRESS AT THIS CRITICAL JUNCTURE TO THINK UNILATERALLY AND SYNCHRONOUSLY BY ALL CLASS OF PEOPLE IRESPECTIVE OF CAST, CREED,AND GENERATION ARCHITECTURE.

    IT IS HIGH TIME NOW, TO IMMEDIATELY IMPLEMENT THE SOLAR HARVESTING BY MEANS OF APPROPRIATE SOLAR PHOTOVOLTAIC MODULES OF GREATER EFFICIENCY.

    THE ALMIGHTY GOD THE UBIQUITIOUS OMNIPOTENT HAS PROVIDED US THE INEXHAUSTIBLE FORM OF ENERGY THROUGH THIS HELIOCENTRIC UNIVERSE WHILE, WE EVEN NOW DO NOT REALIZE THIS ENERGY GIFT BY GOD INSTEAD WE ARE ALWAYS ACT IN EXTRAVAGANT ENERGY UTILIZATION BY ALL CLASS OF PEOPLE THROUGHOUT THE WORLD.

    IN WHATEVER POSITION-STATE, WE ALL ARE, WE ARE REALLY NEGLETING THIS ASPEFCT AND MOST PROBABLY WE ALL HAVE TO GREATLY THIRST FOR ENERGY OF ALL TYPES-WATER.

    WHAT WE ALL SHOULD THINK OF IS THE COST ASPECT OF SOLAR PHOTOVOLTAICS IN ODER TO PROMOTE THIS AT A FASTER RATE.

    AT ANY COST, HYBRID SYSTEM(WIND+SOLAR) AT APPROPRIATE GENERATION RATIO ACCORDING GEOGRAPHICAL STATUS OF THE EARTH SURFACE ALSO OF GREAT IMPORTANT TO BE THOUGHT AT THIS INSTANT.

    MAY I SOLICIT YOUR VALUAABLE INFORMATION IN THIS REGARD SO AS TO ENABLE TO PROPAGATE THIS TO THE YOUNGER GENERATION IN A PHASED MANNER.

    WITH WARM REGARDS AND GLITTERING X’MAS GREETINGS AND PROSPEROUS NEW YEAR 2K12 WISHES FROM THRISSUR THE CULTURAL CAPITAL OF KERALA, SOUTH INDIA.

    C.A.JOHN(CHAZHOOR ANTONY JOHN)

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  2. Last I checked, average capacity factor for wind turbines was around 20 %, not 40 %, at least in Germany/Finland/Sweden (although offshore might be somewhat more efficient and some individual WPPs in optimal locations might get near 40 %).

    Also, 80 years of uranium for nuclear power plants assumes:
    1. “in the cost category somewhat below present spot prices” 2. “used only in conventional reactors”
    3. No new reserves are found and unconventional reserves are not used.

    1: “It is estimated that for every doubling of price, that the supply of uranium that can be econimicaly mined is increased 2.5 times.” (keep in mind that fuel is around 9 % of the costs of NPP)

    2: Breeder reactors and thorium reactors could give thousands of years of nuclear power.

    3: NEA estimated 10,5 million metric tons of undiscovered uranium, compared to 5,5 million in reserves at 59$/lb. Also, around 22 million metric tons in phosphate deposits at around current price point. And finally there are 4 gigatonnes in seawater (current tech/econ allows “mining” at ~$300/lb) which would mean billions of years with breeder reactors.

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  3. I think more than anything, this just shows that we can’t simply rely on one source… Also, was your calculations for area based on area of the panel or area required for each panel… having a 2 x2 m panel doesn’t mean it only takes up 4 square meters…

    This just shows how unfeasible complete switch would entail, remember that there would need to be mass storage facilities that would be equally or greater in expense. You are also looking at 20% efficiency, 5% above what is normal. As well as the fact you forgot to consider decreasing efficiency with each year, so either extend the area of the panels, or replace panels….

    I think solar will play a role in our energy independence, but not a complete role, no energy source will do that (exception of fusion perhaps)

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  4. Hi there, I discovered your blog by means of Google whilst searching for a similar subject, your site got here up, it appears great. I have bookmarked it in my google bookmarks.

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  5. If we can build millions of miles of roads, millions of buildings, millions of factories, billions of motor vehicles; then we can build the massive infrastructure required to supply our energy needs through renewable, and mostly non-polluting, sources.

    This undertaking will provide millions of jobs, a new and vibrant world economy, and a better life for everyone on this planet.

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  6. I appreciate the time and effort you went through to post these numbers and all of the information you provided.
    I would like to offer a global solution to the solar issue, given the numbers you have provided that would be needed for such a venture.
    Instead of thinking of the this as such a big problem it may be simpler to tackle it one small step at a time. I’ve been planning on electroplating a dish (that any satellite cable service can readily provide) to create a reflective parabolic dish, to which I am going to attach a 10 cm^2 photovoltaic and system to provide electricity and heat my water at the same time.
    Walking around any neighborhood in the US you can see it is very acceptable to install this type of dish on your home… what if we put one on every house? Not only on houses, but on telephone poles also? There are somewhere around 175 million telephone poles in the US… that is roughly 17.5 million m^2 of solar panels on telephone poles by themselves. Since concentrated solar is about 40% more efficient, a reasonable number equivalent would be around 20 million m^2 of solar. Let’s say there are 100 million houses and half would be willing to put these up… 25 million m^2 of solar in the US, would that be enough for the country?
    This way would also be able to take advantage of our already established (outdated) grid system while creating 1000′s of installation, maintenance and clerical jobs all over the country. Global, too.
    Government/big business will never allow energy to be “free”, though.
    My own idea would be to directly turn the solar into hydrogen that could be transported from the creation point to the use point with almost no loss of energy across the distance from point to point, while pumping clean O2 into the atmosphere.
    In less fortunate places on the planet this would also provide much needed clean water… and replenish the Earth’s clean water supply at the same time.
    Clean air, clean water and electricity from the sun… what a dream.

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  7. Unless I missed it you missed geothermal energy and in particular enhanced geothermal energy. Several years ago the Geological Survey of Canada produced a report called “Geothermal Energy Resource Potential of Canada” do a web search for GEOLOGICAL SURVEY OF CANADA
    OPEN FILE 6914 – it’s a 54MB pdf file. 100 enhanced geothermal stations across Canada wouls produce all the energy needed for all of North America.

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  8. Certainly, but we all need to realize that adding Solar to their house is an asset which could raise the actual worth of their house if / when they come to a decision to sell. With the environment the way it is going we simply cannot disregard any system that presents 100 % free power at no cost to both the buyer and more notably the environment!

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  9. Haven’t read it all, but did you also take into account that the area of a solar farm is not covered 100% with solar panels? There’s roads, some space between every panel and so on. I guess that would amount to quite a factor of more area required?

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    1. Thanks! We’re assuming that all the installations would be spread our anyway, not lumped together. This is just to make the graphic readable. Most of the installations will probably end up on roof tops.

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      1. Julian is right! Most of the installations can’t end up on the rooftops, because in most of the metropolitan areas there is no “rooftop” space. So, at least 80% of the installed solar panels will end up in the big solar fields and therefore at least 2x factor is in order for all of your calculations.

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        1. “…in most of the metropolitan areas there is no ‘rooftop’ space.” There isn’t? What keeps the rain out of the buildings? Of course there’s rooftop space. Look at an aerial picture of a city and you’ll see lots of rooftop space. It’s true that some urban roofs are unsuited for solar panels because they are overshadowed by taller neighbors, but there are many others that could take PV panels just fine.

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  10. Great research and calculations. Thanks.
    I was wondering about your source for the wave energy calculation, a new study available at: http://www.oceanor.no/related/59149/paper_OMAW_2010_20473_final.pdf
    puts the world wave resource at about 4 TWh per h.

    Also if you could comment of this, since sea water has a density of about 800 times that of air (wind) how do the wave and wind systems compare, it seems to me there is a great deal of torgue in the waves compared to wind, yet waves can theoretically supply only a small percentage compared to wind. Thanks.

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  11. Actually, PV panels are icrbidnley cheap right now.The only reason they appear expensive is when compared agaist fossil fuels, like oil, which are already becoming MUCH more expensive, and which will continue to do so for many, many year.Buy PV now, or kick yourself for not doing so later.

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  12. I see the calculations for solar panels required to meet global energy demand presuppose the existence of a superconducting global smart grid so that we don’t have to pay big transmission loss penalties sending electricity generated in the Sahara, or from a small number of big solar farms, all over the world. Otherwise, we’ll need more solar panels than these calculations suggest – either to cover the transmission losses or to compensate for the fact that we’ll have to move our solar panels much closer to home, to places where our panels will start their service lives generating more like 175-350 kW/m^2/yr instead of 400 kW/m^2/yr. We’re also assuming that our hundreds of thousands of km^2 of solar panels are all new, so they’re all getting their listed 20% efficiency rating and not the ~20-(3+.5(# yrs after 1st year)% efficiency they’ll get during their service lifetime. We’re also assuming all of them are completely clean all the time, which would be quite an impressive statistic if they’re operating in environments with lots pollen, dust and damaging wind-blown sand, because the power output of a dirty solar panel can easily fall 40-70% or more. And we’re assuming that it’s good enough for the total energy output from all our solar panels to be equal to the globe’s total energy demand, and that we can ignore any mismatch between energy produced by our solar panels and energy demanded at any given moment. Even though that little detail happens to matter immensely. Well, under those assumptions, solar power looks incredibly expensive, and there are certainly much cheaper ways to achieve a decarbonised energy portfolio, but I suppose it is technically doable.

    I think when you run through the calculations a bit more, it becomes clear that solar power, and even solar and wind power together, are only going to play a globally relatively minor role (though they may be major players in certain regions) in a clean energy future.

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  13. “…so they’re all getting their listed 20% efficiency rating and not the ~20-(3+.5(# yrs after 1st year)% efficiency they’ll get during their service lifetime.”

    Sorry, make that ~20(.97x_1-.5x_n)% efficiency they’ll get over the course of their service lifetime.

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  14. Professor Einstein once said “for every action there is an opposite and equal reaction”!

    A question on the pushing power of reflective energy. Considering the oceans etc. are already reflecting sunlight, How many square miles of reflecting solar panels would it take for the reflective “push” of the sun to push the earth out of orbit?
    They are now using this reflective sun power to push spacecraft that can attain incredible speed, however if “spaceship Earth” gets pushed even slightly out of orbit, We all perish!

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