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Edit: A bounty was offered; Later, I answered my question - see below the looong math answer. I accepted it, because it's the only one to calculate the outcome with all the parameters included. I'll award the bounty manually to the answer that best addresses the question (except mine).

This is the second, updated version of The Project Sahara my grandfather made with me:

The European countries in cooperation with USA, Japan, and other economically strong states will give money and brains to build and manage this project. On the western African coast, close to the equator, where the rocky Sahara desert is, giant fields of solar panels and thermosiphons (water heaters/boilers) will be built.

Nowadays solar panels have an efficiency of about 5%, that is a power of cca 70W/m^2, and water heaters have an efficiency of cca 30%, that is 400W/m^2 from the Sun (not in electricity this time). If we had 1000 square km with 50% water heaters, we would get a power of 235GW - that is 1020TJ (terajoules; 1 terajoul is 1000000000000 joules) of energy every day (12 hours). Without using any otherwise usable land.

The energy would be used to do this:

  • boil seawater using the water heaters to get (distilled) water and salt

  • sell the salt (salt prices fall down; From about $0.2/kg to about 0.05/kg, then the other salt-selling companies fall, and the salt prices go up again)

  • export some of the water across Africa

  • export some of the electricity across Africa

  • using the electricity it will break down water into oxygen and hydrogen, and using CO2 from the air and the hydrogen, produce methane (CH4)

  • export methane as a fuel for cars, etc., instead of petrol - it will be exported using pipes, as petrol is - petrol prices fall, and the states and companies selling it will suffer a crisis; ISIS goes short of money.

  • sell some of the oxygen to whoever wants it, and release the rest into the atmosphere - it's an unwanted product.

This project has many advantages:

  • methane is easy to store, especially long-term; Hydrogen isn't, and electricity isn't at all

  • logistics: it will be transported as easily as petrol, maybe easier

  • burning methane... well, burning methane will produce again the CO2 used to make it - no change overall

  • a lot (thousands, actually) of working spaces created. This could literally employ a whole slum city to maintain the panels/heaters - sweeping panels and guarding entrances doesn't need qualified workers. This would update the economical and political situation in whole Africa

  • new technologies. New technologies would be invented along this project - like it was during NASA's moon-conquering program

  • no more Russia and Saudi Arabia dictating fuel prices

  • no need to push away the locals - there are no locals, instead, people will be encouraged to come

Is such a giant project achievable? I know it will never happen in reality, but that's because if the political situation, but I'm asking about the technical side of this.

Is this feasible?

And importantly, how can I improve this project?

Also, thanks to @TrEs-2b for his interest and support of this project: What are the political outcomes of the Sahara Project?

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    $\begingroup$ @RudolfL.Jelínek, you're saying there's a 0% loss for using electricity to hydrolyze water and produce methane?(Not to mention likely conversion of methane back into electricity once it reaches Europe) $\endgroup$ – Salmoncrusher Sep 23 '16 at 18:09
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    $\begingroup$ @RudolfL.Jelínek The efficiency of the methane production is not really good (not to mention capturing the CO2!!!), plus there are quite some costs in pressurising the pipes and pumping the gas, not to mention maintenance for pipes compared to maintenance for cables. $\endgroup$ – Karl Sep 23 '16 at 20:01
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    $\begingroup$ that was close. ;-) $\endgroup$ – Karl Sep 23 '16 at 20:05
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    $\begingroup$ You don't think that maybe ISIS (or some other, closer terrorist organization) would set up shop on the outskirts of the desert and hijack control of Project Sahara? Or at least attempt to destroy it? The world is putting its energy supply in one neat little area in the middle of Africa for you... it's too enticing a situation to pass up by any terrorist organization that has it out for the US or Western nations, or that just wants more power. $\endgroup$ – TylerH Sep 26 '16 at 17:32
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    $\begingroup$ Or worse, that the nation(s) in which the thing is built would claim sovereignty and spark an international incident/conflict? Or fund rebels secretly to blow up or sabotage pipelines? $\endgroup$ – TylerH Sep 26 '16 at 17:32
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First you should read this:

http://www.forbes.com/sites/quora/2014/07/02/why-dont-we-put-solar-panels-in-the-sahara-desert-as-a-source-of-electricity/#67ca233213d7

How much is this worth?

What is you maximum revenue?

This analysis makes a number of favorable assumptions this is the best case.

All of the things that you describe are harder to ship than electricity, so for the moment assume that you could ship what ever it is as electicity to the consumer convert it and sell it.

How much is this worth?

All the conversion process could just as easily be done at the end point so the fact that we aren't doing them regularly in the rest of the world implies the value of the final product is less than or equal to the price of the electricity.

What is the value of the electricity: about 8 - 18 cents per KWH according to npr.org.

Your site produces $1020 × 10^{12}$ Joules = $283 × 10^9$ Watt Hours. Assuming 12 cents per kilo watt hour it's $3,400,000 per day.

How much do your 1000 km^2 of water heaters cost? Well a 15 × 20 heater costs $497 on ebay.

This is not a great reference point but that is 4.166 ft^2 for 497 dollars. So $1.0764 × 10^7$ ft^2 to 1 km^2 so $258 * 10^7 is an estimate for your cost or 2.58 Billion dollars.

So the cells have to run for about 2 years to pay for themselves assuming not additional costs to ship you products from the Sahara to the rest of the world.

Caveats

  • you will probably have to pay a lot for shipping to get anything out of the Sahara (say 1/2 - 3/4 of the value of the product spent shipping it) which moves break even out from 2 years to 4 or 6, let's say 4.

  • The heaters will need to be replaced or repaired (assume they last for 10 years) so on average you spend $\frac{2.58}{8}$ Billion dollars a year to maintain them. This drops you annual income from 1.241 billion to $(\frac{1.241}{2}) - (\frac{2.5}{8}) = 0.298$ Billion Dollars. So then it takes 8.6 years to break even.

  • You need to buy the land. 1000 km^2 is a lot of land, twice the area of Rhode island, especially if you want it on the coast, this could easily be another 2 billion dollars and another 8 years.

  • You are locking away 4.5 Billion dollars for 16 years, if you just invested that money at 5 percent you would have another 9 Billion at the end, the plant is not profitable enough.

  • There is risk in waiting those 16 years to break even. The local government may change and start taxing you or seize your very expensive plant.

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  • $\begingroup$ Good answer because you provided links and numbers. But yiu will get more upvotes (and more general admiration) if you format the links into the text rather than just dumping the URLs into the sentence, proof for format-code mistakes (it's clear you didn't look at what you wrote!), etc. $\endgroup$ – JDługosz Sep 24 '16 at 7:57
  • $\begingroup$ Great detailed answer! +1. Just it assumes that 1) We will buy solar panels and water heaters from ebay and 2) unoccupied dessert land will cost a lot to buy. :) $\endgroup$ – RudolfJelin Sep 24 '16 at 8:23
  • $\begingroup$ 16 years... that's less that I hoped for. Plus the taxes, let's say, 20 years... $\endgroup$ – RudolfJelin Sep 24 '16 at 8:25
  • $\begingroup$ This looks like a collection of random numbers, assembled to make the idea look bad. $\endgroup$ – Karl Sep 25 '16 at 16:49
  • $\begingroup$ @RudolfL.Jelínek This is a lot of land the state of Rhode island is 484 KM ^2 this is 1000, buying 2 states worth of land on the coast will be expensive, though I admit the 2 billion number is pulled out of thin air. as I said in the answer about the ebay price "This is not a great reference point " if you have a more reliable price I'll use it. $\endgroup$ – sdrawkcabdear Sep 26 '16 at 17:18
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Its not the political situation, its the economic situation that makes it unfeasible. All those things you are generating are valuable, but how long will you have to sell your products in order to break even on the money spent on solar panels?

Selling water seems like a great idea, but its really hard to move a lot of water. Its heavy, has a low price per volume or weight, and needs to be sent in tanks or it will evaporate.

Solar electricity can be exported, but you'd be exporting a ton during the day, and none at night. If people need power at night (they do) they will look at more reliable local power solutions and the competition will cut into your profit margins. Also, Africa is surprisingly big and long distance power lines are expensive and go through politically unstable places (thanks Boko Haram!).

Thousands of jobs isn't a big deal in a continent closing on a billion people.

Here in the key deal-breaker: The sabatier reaction is very energy expensive. You need a LOT of solar panels to power it. The return on selling methane will take decades to pay off your solar panels...at which point you might need to replace the panels. No one really knows how long these new super-efficient panels last since none of them are more than a couple years old. My biggest life lesson from working in an industrial environment is to never underestimate machinery's capacity for sudden catastrophic failure...and electronics are even worse!

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  • $\begingroup$ Water can be transported via pipelines, and giant pumps used to deliver it inland, but the cost of the infrastructure and the fact it will be passing through politically unstable regions means much of the water might never be delivered, and the cost of the project will never be offset by the revenues collected by selling water. For an equally unfeasible project, look at this: up-ship.com/blog/?p=4440 and up-ship.com/blog/?p=12881 $\endgroup$ – Thucydides Sep 21 '16 at 15:53
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    $\begingroup$ Hogwash. Energy is valueable, just not today, because the near east despots we've been feeding so generously for fourly years are flooding the market with oil. Thanks to ... no i'm not saying. You all know who asked for it. $\endgroup$ – Karl Sep 23 '16 at 20:13
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It seems to me that this is over-engineered. We already have a method for taking carbon dioxide from the atmosphere that requires water and sunlight and produces oxygen and hydrocarbons as a side effect. Why add extra steps?

  • Evaporate saltwater to make fresh water. Possibly with a saltwater greenhouse. Not in the Sahara, but in places like Florida, Texas, California, Mexico, Columbia, Brazil, Spain, Greece, Italy, Saudi Arabia, India, and Japan.
  • Use the water for irrigation of plants. They will draw carbon dioxide from the atmosphere and release oxygen.
  • Extract something useful, e.g. grain from the plants.
  • Use the remainder of the plant in a cogeneration facility. This will produce heat (evaporate more saltwater?), electricity, fuel, and fertilizer.

There's also an alternative version that grows kelp instead of land plants. That saves the evaporation and irrigation steps.

The point of water in the Sahara would be less to produce fuel and more to increase the amount of biomass. We'd want to pull the carbon dioxide from the atmosphere and trap the carbon in plants. We wouldn't want to send it back to the atmosphere after burning it as fuel. The Sahara Forest project is an example of a plan to do this.

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I'd like to pitch a few ideas.

  1. To boil the seawater - why go through 5% efficiency when you can directly have near 100%? Also keep in mind that the salt will require raffination if it is intended for human consumption (energy intensive). Likely you will end up with mountains of salt which you will need to treat as poisonous waste. Also condensing the water takes some extra cooling likely making it quite expensive. If you are after cheap drinking water reverse osmosis is the way to go nowadays. Either way it would make way more sense to build such plants coastal not in the desert.
  2. Using methane. Using modern technology it would make way more sense to convert to methanol/ethanol. Hear me out on this. It would have all the benefits of methane (ok stores slightly less energy). But is even easier to store and handle since it is liquid - no need for pressure containers, plain tanks and bottles suffice. Also with a few chemical addtives it could be used as fuel for current era cars (it's the same as biofuel). Also keep in mind compared to current petrol or methanol - ethanol has very low toxicity or environmental danger and it's not even explosive - so it might even be possible to save money as it requires less safety.
  3. nothing in this project benefits from doing this in massive scale. Why not plan for many small size plants?
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Yes but you'll have to do it like all big things do things

"Oh Tres, what ever do you mean?" I hear you ask, well when man started building, did they start with the Burj Khalifa? No, they started with grass and mud huts. When we went to the sky did we start with a rocket? No, we built balloons. I could go on, but my point is clear, for every project that exists, you start small and get bigger.

Start with a small plot of land, a couple dozen square meters, then slowly expand. eventually you will reach the size you want of hundreds of square kilometers and then, as other answers point out, the project becomes efficient and feasible.

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  • $\begingroup$ True answer, +1. But I think we have enough techno and finances to start immediatley at a few tens of square km. $\endgroup$ – RudolfJelin Sep 23 '16 at 17:46
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    $\begingroup$ "Oh Tres, what ever do you mean?" I SEE you ask, (...) $\endgroup$ – RudolfJelin Sep 23 '16 at 17:48
  • $\begingroup$ @RudolfL.Jelínek True, but buying the land would be expensive and you need to start somewhere $\endgroup$ – TrEs-2b Sep 23 '16 at 17:53
  • $\begingroup$ I get your point, but I don't think so. - the West Sahara coast has a population density of about 10ppl/km^2, and the desert has... about 0ppl/km^2. You could cheaply buy free land from the state for almost nothing at all - the state would anyways get A LOT of money from taxes later. $\endgroup$ – RudolfJelin Sep 23 '16 at 18:03
  • $\begingroup$ @RudolfL.Jelínek Yes, but the politics are the problem. Canada could just sell Devon island, but we don't because it's our land. Africa will feel the same way $\endgroup$ – TrEs-2b Sep 23 '16 at 18:07
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So, let's do some maths. This is hard science, people! (Skip to the TL;DR at the end, or plunge waist-deep through maths):

We get about 235GW of power. That is 1020TJ ($1020 × 10^{12}$) of energy generated every day (assuming the Sun shines at 100% exactly 12 hours a day) Let's round that down, what if: 1PJ ($10^{15}$) of energy. Every day.

What the project does:

  1. Sells some of the electricity. Let's assume $\frac{1}{10}$ of all the electricity produced is sold.

    • That leaves us with $\frac{9}{10} × 10^{15}J = 9 × 10^{14}$ Joules to work with on the next steps.

    • One kWh (3600000 Joules) of energy is sold for about \$0.14 in Africa - that gives us about $\frac{0.14}{3600000} × 10^{14} = 3880000$$ per day. If you kick the prices down, you get about 3M dollars every day from this

  2. Distills water and sells the salt.

    • if we assume we get 30°C water from the sea, we need to heat it another 70°C to make it boil. Water's specific heat capacity is $\frac{4200J}{kg × t}$, that is, to heat 1 kilogram of water by 1 degree, we need 4200J. To boil $m_1$ kilograms of water, we need $\frac{4200J}{kg × t} × m_1 × 70°C = 294000 × m_1$ Joules.
  3. Sells some of the water.

    • From what the Wikipedia says, the water could be sold for about $1/cubic meter.

    • Let's assume $\frac{1}{10}$ of the water is sold. We get $\frac{m_1}{10} × 1$$ of money.

    • Also, let's assume that 1$/m^3 is the final money we get, after substracting all the losses - no energy spent.

    • We are left with $m_2 = \frac{9 × m_1}{10}$ of water.

  4. Divide water into hydrogen and oxygen

    • According to Wikipedia,

      Practical electrolysis (using a rotating electrolyser at 15 bar pressure) may consume 180 MJ/kg

    • So this uses up another $180 × 10^6 × m_2$ Joules of energy.

  5. Use the Sabbatier reaction to convert the H2 to CH4 using CO2

    • The Wikipedia describes this as a exothermic reaction:

    CO2 + 4 H2 → CH4 + 2 H2O + energy
    ∆H = −165.0 kJ/mol
    (some initial energy/heat is required to start the reaction)

    • That means that we don't need any energy for this, since the reaction will be running itself once it's started.

    • We get water from this. If we resend it again and again, we just get the same result, just without the H2O.

    • One kilo of water has 890 grams of oxygen and 110 grams of hydrogen inside. One kilo of CO2 has 270 grams of carbon and 730 grams of oxygen inside. One kilo of CH4 has 750 grams of carbon and 250 grams of hydrogen inside. That means, that for each 1 kilogram of water that is converted, we get $\frac{110}{250} = 440g$ of CH4, using $\frac{330}{270} = 1222g$ of CO2. Additionally, we get $890 + (0.73 × 1222) = 1782$ grams of oxygen for each 1kg of methane is produced.

    • For 1 kg of water, we get 440g of CH4. So for $m_2$ kilo of water, we get $m_3 = 0.44 × m_2$ = 0.44 × 0.9 × m_1 kg of CH4 and $m_o = 1.782 × m_2 = 1.604 × m_1$ kg of O2

  6. Sell the fuel.

    • Actual fuel prices are about \$1 - \$1.5 per litre (kg). So if methane would be sold for \$1/kg, we would get $\frac{m_1}{2.52}$ dollars every day.
  7. Sell the oxygen.

    • nowadays oxygen prices are about \$0.2 per kg. Here, it could be sold for \$0.1.

    • For each kilogram of water converted, we get 1.604kg of oxygen. That is $1.604 × m_1 × 0.1 = 0.1604 × m_1$ dollars every day.

Now, let's calculate, how much water to convert can we afford:

Each day, can use $9 × 10^{14}$J to convert water to methane. For each kilogram, we need $294000 + (180 × 10^6 × 0.9) = 162294000$J. With $9 × 10^{14}$ J every day, we get $\frac{9 × 10^{14}}{162294000} = 55455000$kg of water converted every day. That is also a 194000kg load of salt.

  • salt will be sold for about 0.05 dollars/kg. That is $9700/day

  • we get $0.44 × 5545500 = 244000$ kg of methane and $1.604 × 5545500 = 889500$kg of oxygen.

  • oxygen will be sold for 0.1\$/day, as mentioned above, so we get \$889500 for selling oxygen daily

  • for methane you'll get \$1 per kg, that is 244000\$ per day. It's rather low, but the prices can go up again later :)

  • for the electricity, you'll get 3000000\$ per day.

  • for water, we get $\frac{m_1}{10} × 1$ = 554550$ every day.

So, altogether, we get $$9700 + 244000 + 889500 + 3000000 + 554550 = 4700000$ $$ Every day.

That is $4700000 × 365 = 1715000000$ \$ a year.

How much does the project cost?

What is needed to buy:

  • Land. 1000 square kilometers of rocky land in the dessert is "almost free". Let's count with the worst scenario: \$ 10000000 for the land.

  • Solar panels. 500km^2. That is 500000000m^2 of solar panels. According to this site, normal solar panels can be as cheap as 10000\$ for 40kW. This project uses only 5% efficiency panels and will most probably have it's own factory, so the price could go down to cca. 3000\$ for 40 kW. Also, solar panels "need" about \$3000/life last (cca. 20yrs) for maintenance - but from pro's. This project uses normal people with a bit of schooling, glad for their work. So let's say \$100 per year and per 40kW.

    • We have 235GW of power, from which 11,25GW comes from solar panels. That's $\frac{112500000000}{40000} × 2000 = 97 × 10^8$ dollars, and $\frac{112500000000}{40000} × 60 = 28 × 10^7$ dollars yearly for maintenance of the panels and everything around them.
  • Water heaters. The same like at the solar panels, just the prices are (cca.) 20x smaller. Lets count that with the previous step - by adding 5%

  • let's count another 50% more for yearly costs - this covers all infrastructure, development, additional maintenance, reserve money, fees, lawyers, etc.

  • also, you would need a lot of nickel for the Sabbatier reaction - that is another cca. 1 billion dollars.

Altogether, we got

  • $9700000000 + 10000000 + 1000000000 = 10710000000$ dollars initial investment,

  • and $28000000 × 1.5 × 1.05 = 441000000$ dollars yearly cost.

That leaves us with $1715000000 - 441000000 = 1274000000$ $ yearly profit.

  • $\frac{10700000000}{1274000000} = 8.3$ years refund time, let's round to 10.

TL;DR: It would take 10 YEARS only to refund this project.

With a \$224M input, nobody will really do this, but it's possible! Of course, that doesn't mean that it will happen.

PS. If you see I made a mistake, please tell me (but don't try to find a mistake, please :) )

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    $\begingroup$ Not to put too fine a point on it, but this is completely wrong. This is a classic example of applying abstract math to a practical problem without correct assumptions. The Sabatier process is catalyzed by a nickel catalyst. That means you need a VERY large surface area of nickel in order to produce methane at the rate you suggest. You have completely disregarded the cost of the catalyst, the equipment necessary to run your reactants through the catalyst (pumps cost money to install and operate), and the operations expenses of the industrial plant. $\endgroup$ – kingledion Sep 27 '16 at 16:29
  • $\begingroup$ You have also completely neglected the transport costs of your various products. Oxygen and methane must be put into tanks, water into tanks or pipes, electricity distributed through transmission lines, etc. All of these things have initial capital costs, and long-term operating costs. $\endgroup$ – kingledion Sep 27 '16 at 16:31
  • $\begingroup$ @kingledion I did not. The costs are counted into the let's count another 50% more for yearly costs - this covers all infrastructure, development, additional maintenance, reserve money, fees, lawyers, etc. part... $\endgroup$ – RudolfJelin Sep 27 '16 at 16:37
  • $\begingroup$ You're missing the point. You have to enumerate those costs to find out how many billions they add up to. Try to estimate the costs of storing and transporting 900 metric tons of oxygen a day. $\endgroup$ – kingledion Sep 27 '16 at 16:42
  • $\begingroup$ @kingledion Didn't mean to be offensive towards you... but a downvote for such an answer... If you want write an answer yourself :) $\endgroup$ – RudolfJelin Sep 27 '16 at 16:43
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Technically feasible? Probably. But do we want to?

We could stop all communicable human-to-human disease. All it takes is that we all go into voluntary and solitary quarantine and stay there until the incubation period of all diseases have passed.

We could stop all airplane accidents, right now. All it takes is that we instantly ban air travel.

We could stop anthropological global warming dead in its tracks. All it takes is that we stop using fossil fuels, and stop eating meat, right now.

We could all be rich, because all it takes it to start extracting the 20 000 000 000 kg of gold — that is more than 2kg per person on Earth — that is in plain sea water.

The question is not if these projects are technically feasible — they are — but whether we want to go through with them, considering the cost and the hassle they cause.

In the end your project comes down to measuring outcome vs cost; time spent building it until there are results; the use of scarce resources vs the gain we get when it is completed.

And when you have all of those numbers, you need to put those in contrast to using other methods to achieve the same things that your project is meant to deliver.

Yes your project is all fine on paper when not considering these things. But if we are to spend something that is more than a fortune on this project; if there is uncertainty as to the amount of time before it delivers; if other projects have to stand back in order that money and resources be made available for this one... then it is quite likely that people will say "Oh screw it... there are better options".

So the question is not: is it technically feasible? Because the answer is a plain: yes, it probably is. The question is if we want to do it when we consider the harsh realities of things such as cost, the use of scarce resources, and time... especially compared to competing technologies.

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    $\begingroup$ He? It is not only 100% feasible, it would also be highly economical, were it not for the political "costs" of a large number of today higly influencial people loosing their present (corrupt) business lines. $\endgroup$ – Karl Sep 23 '16 at 20:10
  • $\begingroup$ @Karl roll eyes Sorry, cannot hear you because I am busy cashing my checks from Big Energy, Big Pharma and Big Everything. Take any such rants on suitable forums. SE is not one of them. $\endgroup$ – MichaelK Sep 23 '16 at 20:12
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    $\begingroup$ I'm not complaining. It's an inevitable fact that new, esp. LARGE business ideas like this one invalidate the currently profitable investments of last year, and thus are not welcomed by everyone. Ignoring that is the typical leftist stupidity. Your rant however is the orthodox capitalist nearly religious prevarication, that an idea that is not immediately profitable must be stupid. I say, boil your own head. No offence intended. :-) $\endgroup$ – Karl Sep 23 '16 at 20:24
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    $\begingroup$ And, pray tell: What are those alternatives? Nuclear power? Right, but politically impossible. $\endgroup$ – Karl Sep 25 '16 at 9:37
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    $\begingroup$ Well, sorry. Your statement was "Possible, but there are better alternatives", but you gave none, and also did not point out any factual problem. Instead some sarcastic comment about airplane crashes and gold mining. That made me suspect you having some ideological policy. $\endgroup$ – Karl Sep 25 '16 at 10:23

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