Solar-powered flight around the world

[Wilber]

Given that the aircraft in question was able to carry a pilot around at a speed of up to 80 km/h, it could have applications for personal air travel / recreation.

Recreation maybe but I notice the next project these guys are doing is an unmanned aircraft which is probably where any potential for solar powered flight really lies.

80 KPH into a 30 KPH headwind means a ground speed of 50 KPH. Not really practical for personal transportation at those speeds. If you notice, the round the world flight was done in a easterly direction because the prevaiing winds are westerly in the northern hemisphere.

Edited July 27, 2016 by Wilber

[poochy]

Given that the aircraft in question was able to carry a pilot around at a speed of up to 80 km/h, it could have applications for personal air travel / recreation.

http://i.cbc.ca/1.3694879.1469494893!/cpImage/httpImage/image.jpg_gen/derivatives/16x9_780/mideast-solar-plane.jpg

There is a reason it has to be comically large, doesn't look very convenient for recreation, but no worry, if we can magically improve solar cell technology by another, even 10% (in reality that is a HUGE amount) you might be able to park it in a hangar big enough for a 737.

[Guest]

Facebook will use autonomous solar planes to act as atmospheric satellites, streaming internet to millions, in remote regions. The AI controlled planes are already passing flight tests. When fully operational they will soar autonomously for months at a time.

If Facebook has operational, autonomous, solar planes that will connect people to the internet, I'm fairly sure the US military has tested options fitted with cameras, sensing equipment and bombs.

[Wilber]

Again, a very specialized use. The aircraft needs to be very large but can carry very little. It will need to fly at very high altitudes to stay out of the jet stream, otherwise it won't be able to keep its station.

Cameras and sensing equipment maybe but I don think the US military would have much use for aircraft that can only do 80 KPH and can't carry much more than a bucket of hand grenades.

[?Impact]

The primary advantage of nuclear powered aircraft would have been in their ability to stay in the air for months at a time, but this ability was deemed not necessary for the purposes of the day.

What possible need would we ever have for a manned aircraft to stay aloft for more than the few hours to get from point A to point B?

New reserves of fossil fuels are still being discovered faster than existing ones are consumed.

Not true, new technology has enabled us to extract what was previously impractical.

[?Impact]

Some people believe there is some sort of magic silver bullet to replace fossil fuels.

Fossil fuels are solar energy that takes 100's of millions of years to be packaged. Can we find a more efficient method of harnessing solar energy, and preferably one with fewer harmful byproducts per joule.

[TimG]

Fossil fuels are solar energy that takes 100's of millions of years to be packaged. Can we find a more efficient method of harnessing solar energy, and preferably one with fewer harmful byproducts per joule.

We have had the technology for a long time to make gasoline from scratch (google blue diesel). The trouble is the energy needed to create it far exceeds the eventual energy output. When we use fossil fuels we are benefiting from the energy that 100 million years of natural processes added for free. The only way to produce energy more efficiently than fossil fuels is nuclear. Any less efficient process will result is many more byproducts than fossil fuels when deployed at a large enough scale to match the energy currently provided by fossil fuels. Edited July 30, 2016 by TimG

[Wilber]

Fossil fuels are solar energy that takes 100's of millions of years to be packaged. Can we find a more efficient method of harnessing solar energy, and preferably one with fewer harmful byproducts per joule.

Using those terms, all energy is solar energy.

[Bonam]

Using those terms, all energy is solar energy.

Except nuclear. The fissile isotopes found in the Earth's crust did not come from the Sun, though they did come from other stars.

[Wilber]

Except nuclear. The fissile isotopes found in the Earth's crust did not come from the Sun, though they did come from other stars.

Other stars are suns.

[Bonam]

Other stars are suns.

Other way around, the Sun is a star. Other stars are not Suns (the definition of "Sun" is the star around which the Earth orbits). Anyway, irrelevant to the topic at hand here. All energy is stellar energy

Except fusion... most of the hydrogen that exists in the universe was created in the big bang, not in stars.

[Wilber]

Other way around, the Sun is a star. Other stars are not Suns (the definition of "Sun" is the star around which the Earth orbits). Anyway, irrelevant to the topic at hand here. All energy is stellar energy

Except fusion... most of the hydrogen that exists in the universe was created in the big bang, not in stars.

I know all that, I was responding the statement that fossil fuels are solar energy. The fact is, except for a bomb we are not capable of producing fusion for power generation and must use conventional energy sources to extract hydrogen to use as a fuel.

Edited July 31, 2016 by Wilber

[?Impact]

As I have stated in another thread, all energy we use is one of three: solar, nuclear, and tidal. Theoretically we also have chemical energy, but most of what we can exploit is derived from solar. I am unaware of any practical method to exploit non-solar derived chemical energy (ie. energy out being greater than energy in).

Not sure why Wilber has singled out fusion energy, we have successfully exploited fission energy for power generation.

TimG, yes we are using those 100`s of millions of solar energy, but we are using it in a few 100 years. You might consider it `free`, but future générations won`t appreciate your interpretation.

Edited August 1, 2016 by ?Impact

[TimG]

TimG, yes we are using those 100`s of millions of solar energy, but we are using it in a few 100 years. You might consider it `free`, but future générations won`t appreciate your interpretation.

You are the one who used the word 'efficient'. Efficiency is measured by energy input vs. energy output. Whether you like it or not some variant of nuclear will have to be the mainstay of our energy sources once fossil fuels run out. For now that is not an issue. Solar and wind even with battery backup does not produce an EROI large enough to keep our society running. (see http://festkoerper-kernphysik.de/Weissbach_EROI_preprint.pdf). EROI is a better measure of how efficient an energy source is. Edited August 1, 2016 by TimG

[dre]

You are the one who used the word 'efficient'. Efficiency is measured by energy input vs. energy output. Whether you like it or not some variant of nuclear will have to be the mainstay of our energy sources once fossil fuels run out. For now that is not an issue. Solar and wind even with battery backup does not produce an EROI large enough to keep our society running. (see http://festkoerper-kernphysik.de/Weissbach_EROI_preprint.pdf). EROI is a better measure of how efficient an energy source is.

This is rather wishful thinking on your part. A solar powered world is definitely possible. Enough energy in the form of sunlight hits the earth every hour than humans use in an entire year. Using 20% efficiency PV the total area needed to be covered by panels would only be about the size of Spain. No small task, but certainly not impossible.

And use is increasing fast... Fossil fuels are increasing in price, and the cost of nuclear plants has increased to the point where no private company can even build one.

Storage is a problem, but by the time fossil fuels become cost prohibitive there will probably be solutions in the scale that's required.. Even now pretty much any area with contours in the last and changes in elevation could use pumped storage.

[Wilber]

Back to the OP, solar is not a viable alternative in aviation except in very specialized applications.

[TimG]

A solar powered world is definitely possible.

Power that is only available when the sun shines has limited use so it makes no difference how much 'potential' exists. If you add storage you have to consider the energy required to create the storage and subtract that from energy produced by the solar panels. When people do this calculation they find that solar and wind barely break even which means they are useless as primary energy sources for a complex industrial society. Whether you like it or not nuclear and fossil fuels will be an essential part of the energy mix for the foreseeable future. Edited August 2, 2016 by TimG

[dre]

Power that is only available when the sun shines has limited use so it makes no difference how much 'potential' exists. If you add storage you have to consider the energy required to create the storage and subtract that from energy produced by the solar panels. When people do this calculation they find that solar and wind barely break even which means they are useless as primary energy sources for a complex industrial society. Whether you like it or not nuclear and fossil fuels will be an essential part of the energy mix for the foreseeable future.

Nuclear needs a lot of development to become a viable source of energy without huge subsidization. The cost of building modern plants is insane, and the west is broke and lost its appetite for mega-projects. There's still plenty of oil in the ground, but the price has tripled in the last couple of decades. If it triples again over the next couple its use will become cost prohibitive... even if there's still lots in the ground.

The most likely path forward is that we will use cleaner coal and gas plants. There's coal and gas plant designs with extremely low emissions that will start construction over the next couple of decades. These energy sources will bridge the gap, and replace all the nuclear plants built in the 60's and 70's which are near end of life, and need to be decommissioned (at huge expense to the public, since the decom fund kept by the nuclear industry is only large enough to pay for a fraction of shutting these things down).

My guess is we move along like that for about another 40-70 years with the use of renewables growing consistently. While this is happening people will be working on storage, thorium, and all kinds of other things.

Id like to see some kind of small thorium appliance that could be manufactured in huge scale like TV sets on some offshore assembly line, that could power homes and small businesses.

Something like this... It could use steam to run a small turbine for electricity, and then after passing through the turbine it could be routed in a network of pex tubes to get radiant heating and domestic hot water. Something about the size of a 40 gallon electric hot water tank. If they manufactured a few hundred million of them, the price would probably come down to the point where you can pick one up at Home Depot for 600 bucks.

Edited August 2, 2016 by dre

[Bonam]

Id like to see some kind of small thorium appliance that could be manufactured in huge scale like TV sets on some offshore assembly line, that could power homes and small businesses.

Something like this... It could use steam to run a small turbine for electricity, and then after passing through the turbine it could be routed in a network of pex tubes to get radiant heating and domestic hot water. Something about the size of a 40 gallon electric hot water tank. If they manufactured a few hundred million of them, the price would probably come down to the point where you can pick one up at Home Depot for 600 bucks.

There are plenty of conceptual/prototype/researchy reactors that are small like what you are talking about. The same issue that prevents larger scale nuclear from being developed is what is keeping these from being commercialized: cost. The cost is not inherent to nuclear technology but is to a large extent result of the regulatory regimes and politics around nuclear technology.

My guess is we move along like that for about another 40-70 years with the use of renewables growing consistently. While this is happening people will be working on storage, thorium, and all kinds of other things.

If you look at the deployment rate of solar technology, it has been following an exponential for ~20 years. It's literally the only energy technology that has followed the same pattern as Moore's Law, because it's the only energy technology that is based on printing semiconductors:

https://upload.wikimedia.org/wikipedia/commons/7/77/PV_cume_semi_log_chart_2014_estimate.svg

I think solar will become the predominant energy source faster than most people suspect. Electric grids span large enough distances in the developed world that pumped storage is applicable just about everywhere in developed countries. And in developing countries which are still undergoing electrification, having electricity some of the time (when the Sun is shining) is such a major advantage over not having electricity at all, that it will still be deployed there too. And, it's much easier in these countries for individuals and businesses to deploy their own small scale solar power to meet their needs than to rely on corrupt and remote and ineffectual governments to try to coordinate large centralized power plants.

That linked graph shows deployed solar capacity increasing by a factor of ~10 every ~7 years. World energy use is ~12 TW while the solar currently deployed can provide about 120 GW (1%). A factor of 100 increase to meet the majority of the world's needs should only take 14 years if the present trend continues.

[TimG]

If you look at the deployment rate of solar technology, it has been following an exponential for ~20 years.

When a process starts from zero it is very easy to produce an exponential. The growth has been driven by government subsidies not only in developed countries but also in China which has been subsidizing its panel makers to corner the market on the technology (subsidies which include zero cost dumping of toxic waste). Past performance is no guarantee of future growth.

The premise of the paper I linked about is that every energy source requires energy to produce energy. It goes without saying that energy sources which take more energy than it ultimately produces are of limited use (e.g. possibly useful for specialized applications but not as a general source of power). The paper looks at the EROI for solar with and without storage (including loses from storing and recovering the power) and found the EROI is much lower when storage is added to the mix. How much lower depends on the assumptions. If storage is too costly (in terms of losses and the cost of creating the storage) the EROI drops below what could be considered enough to sustain a modern society. That I why I don't see storage of renewable as a silver bullet. We will need gas turbines, clean coal and nuclear to provide baseload with a high EROI even if solar gets to the point where people use without massive government subsidies.

Edited August 2, 2016 by TimG

[Bonam]

When a process starts from zero it is very easy to produce an exponential. The growth has been driven by government subsidies not only in developed countries but also in China which has been subsidizing its panel makers to corner the market on the technology (subsidies which include zero cost dumping of toxic waste). Past performance is no guarantee of future growth.

The premise of the paper I linked about is that every energy source requires energy to produce energy. It goes without saying that energy sources which take more energy than it ultimately produces are of limited use (e.g. possibly useful for specialized applications but not as a general source of power). The paper looks at the EROI for solar with and without storage (including loses from storing and recovering the power) and found the EROI is much lower when storage is added to the mix. How much lower depends on the assumptions. If storage is too costly (in terms of losses and the cost of creating the storage) the EROI drops below what could be considered enough to sustain a modern society. That I why I don't see storage of renewable as a silver bullet. We will need gas turbines, clean coal and nuclear to provide baseload with a high EROI even if solar gets to the point where people use without massive government subsidies.

I've skimmed through the paper. One thing worth noting for the way he calculates solar is that he assumes you need to store 10 days worth of energy. This seems like a really large amount of storage. I would think 1 day worth of storage would enable solar to be used for a much larger % of the energy contribution of the total grid than now, while requiring 10x less storage infrastructure.

Additionally, the headline number he lists (4.0) is for locations in Germany with low sunlight and he explicitly mentions that in southern Europe you'd get a factor of 1.7x higher EROI, which is 6.8, very close to your threshold of 7.

I suspect that with further advances in manufacturing/performance/longevity of solar cells combined with using them in areas where there is more ample sunlight and considering more reasonable storage timeframes, and you'll see the EROI well over 7 within one decade of today.

Edited August 3, 2016 by Bonam

[TimG]

One thing worth noting for the way he calculates solar is that he assumes you need to store 10 days worth of energy.

I noticed that which is why I said the EROI depends on assumptions. 10 days is reasonable worst case if you assume no backup from any other power source. If renewables are only a supplement to regular baseload then 1 day would be enough.

Additionally, the headline number he lists (4.0) is for locations in Germany with low sunlight and he explicitly mentions that in southern Europe you'd get a factor of 1.7x higher EROI, which is 6.8, very close to your threshold of 7.

The threshold itself is arbitrary but the fact that renewables end up at the lower end of EROI range in some locales once storage is include means we have to be very careful doing proper engineering analysis before investing heavily in any given technology and any given location. Unfortunately, the current political environment tends to favor expansion of nameplate capacity over all else and that will mean a lot of projects will not provide a net benefit to society.

[Bonam]

The threshold itself is arbitrary but the fact that renewables end up at the lower end of EROI range in some locales once storage is include means we have to be very careful doing proper engineering analysis before investing heavily in any given technology and any given location. Unfortunately, the current political environment tends to favor expansion of nameplate capacity over all else and that will mean a lot of projects will not provide a net benefit to society.

That's all true but is a much weaker assertion than some of your previous statements which claim that solar's EROI is simply too low. Of course analysis should be done to determine when and where solar makes sense to install. But, the economics and energetics of solar energy are changing faster than for any other power source and I suspect that within 20 years it will seem foolish to build anything else in any part of the world that has reliable sunlight within a few thousand kilometers.

[TimG]

That's all true but is a much weaker assertion than some of your previous statements which claim that solar's EROI is simply too low.

Well, context is important. If we are talking about a hypothetical renewable only world then the 10 day backup assumption is reasonable because large scale weather patterns can disrupt supplies which means the EROIs are bad and renewables are not viable. If we are talking about renewables as a supplement to traditional base load with a few hours of load shifting then the EROI could be reasonable.

I suspect that within 20 years it will seem foolish to build anything else in any part of the world that has reliable sunlight within a few thousand kilometers.

Reliable sunlight is not the only question. Political reliability is a bigger question. For example, the Sahara might be able to power all of Europe but Europeans would have to be insane to leave themselves vulnerable to political instability in North Africa. I don't think we will see large scale transport of solar over more than a few 100 kms.

A more likely scenario is adopters of grid scale solar will continue to be burned with excessive electrical prices caused by poor planning, inefficient subsidies and the baked in cost of low EROI. Countries which choose to rely on nuclear and or gas for base-load will enjoy lower prices and more reliability.

I also don't share your techno-optimism on the ability of future developments to future lower EROI because no curve increase exponentially forever. There will be a wall and the question is when it will be hit.

If solar takes off it will have to come from panels that provide power to private homes and businesses that are competitive without subsidies. If that happens we will see a very fast revolution.

[Bonam]

If solar takes off it will have to come from panels that provide power to private homes and businesses that are competitive without subsidies. If that happens we will see a very fast revolution.

Of course. I am no more a fan of government subsidies than you are. When solar is the obvious choice, it will be deployed very rapidly, just like when coal/oil/hydro were the obvious choice in their time they too were deployed very rapidly.

I also don't share your techno-optimism on the ability of future developments to future lower EROI because no curve increase exponentially forever. There will be a wall and the question is when it will be hit.

Clearly there are physical limits. But I don't see any evidence to suggest we will hit such physical limits before solar energy improves another factor of 2 in terms of its EROI.