Fusion Power is 5 years away! (Really?)

[Lord Torath]

From The Guardian: World’s largest nuclear fusion project begins assembly in France (https://www.theguardian.com/environment/2020/jul/28/worlds-largest-nuclear-fusion-project-under-assembly-in-france).

They expect to have it running in 5 years.

I haven't heard anything lately from Lockheed-Martin's Compact Fusion project, which, I think, stated in 2013 that they planned to have a working prototype in five years.

[sihnfahl]

I haven't heard anything lately from Lockheed-Martin's Compact Fusion project, which, I think, stated in 2013 that they planned to have a working prototype in five years.
That's because they ran into some design issues and had to head back to the drawing board.

They're still stuck on the 4th reactor level, IIRC. They're having trouble getting that stable before they can scale again.

[Vinyadan]

Is this really better than harnessing the (fusion) power of the Sun? I'm not against the research per se, but this has to be a lot of money, and I wonder if investing in photovoltaic research would achieve similar results. Although I guess that anyone could invest in solar panels, while this kind of mega-project requires supranational collaboration.

[Strigon]

Is this really better than harnessing the (fusion) power of the Sun? I'm not against the research per se, but this has to be a lot of money, and I wonder if investing in photovoltaic research would achieve similar results. Although I guess that anyone could invest in solar panels, while this kind of mega-project requires supranational collaboration.

The source of the power doesn't matter at all. All that matters is the power density, cost per unit of energy, waste product, reliability, scalability, and construction times, cost, and complexity. In each and every one of those, fusion power and solar power are drastically different.
Fusion power would be far, far more compact, and would have the significant benefit of not shutting down every night and every time it's cloudy outside. You need acres of solar farms to produce a significant amount of power, and then you need even more in battery storage to make it reliable. On the other hand, solar panels are a lot simpler to maintain, needing no input and far less maintenance.

Saying solar power and fusion reactors are similar because they both rely on fusion in the end is like saying beef and milk are the same because they both come from a cow.

[Yora]

To be nitpicky, burning fossil fuel is really just accessing energy from sunlight too.

ITER being five years from completion (allegedly) doesn't mean fusion power will power any industrial or consumer devices. It's still more a proof of concept than a prototype. Once it's up and running, and assuming it does work the way it's supposed to, it will be followed by many years of collecting and analysing data, which can be used to make adjustments and eventually form the basis for designing a commercially viable reactor model. Which then still needs to be build and broken in before it can be connected to the power grid.

I'm pretty sure fusion power as a significant source of global energy production will still happen in my lifetime. But 20 to 40 years until that point still sounds pretty plausible.

The good thing about fusion research is that even though the expected timeline gets extended constantly, the ultimate goal is not getting further away from us. We're still seeing constant progress and getting closer, but the speed for the next major step is always much slower than expected. But we're getting there. Eventually.

[monomer]

Research reactors are already able to produce fusion power, but they are all net negative, in that it takes more electricity to run the reactor than it can produce. For example, the Joint European Torus (https://en.wikipedia.org/wiki/Joint_European_Torus) was able to produce 16 MW but required 24 MW just to get the fuel to operating temperature. This also doesn't include the electricity to power the rest of the system, such as the electro-magnets which control the plasma flow. Note that this was achieved in 1997 and is still the record for fusion production.

So even if they finish construction of Iter in 2025, I doubt that they will be able to show net positive energy production any time soon after commissioning. While Iter was designed to be able to produce 500 MW on 50 MW of input, it will likely take some time before it gets to a point where it is actually making more energy than it consumes, if it is ever able to do so.

[Lord Torath]

Is this really better than harnessing the (fusion) power of the Sun? I'm not against the research per se, but this has to be a lot of money, and I wonder if investing in photovoltaic research would achieve similar results. Although I guess that anyone could invest in solar panels, while this kind of mega-project requires supranational collaboration.
Sunlight gives us about 1360 watts per meter2, which translates to roughly 1.8 horsepower per square meter, assuming 100% efficient conversion. I think current solar panels top out at about 15% efficiency, so 0.27 HP/m2. If you plaster the top of a full-length shipping container (12.05m x 2.35m) with solar panels, you get about 5.8 kw (7.6 HP). Compare that with Lockheed-Martin's proposed 100 Mw for a similarly sized reactor, and you get a good idea of the reason why fusion is attractive.

[Rockphed]

So how much fusion power would we need before we started noticing a drop in the Earth's ocean levels?

[Strigon]

So how much fusion power would we need before we started noticing a drop in the Earth's ocean levels?

Well, that depends on your measuring equipment, doesn't it?

To be a bit less obtuse, are you asking because you're concerned it may be a legitimate issue if we switch to fusion, or out of curiosity?
If it's the former, the answer is "more than we could possibly know what to do with for the forseeable future of mankind."
If it's the latter, (or if it's the former and you aren't content with my answer,) here's a pretty good answer. (https://dothemath.ucsd.edu/2012/01/nuclear-fusion/)

[Rockphed]

Well, that depends on your measuring equipment, doesn't it?

To be a bit less obtuse, are you asking because you're concerned it may be a legitimate issue if we switch to fusion, or out of curiosity?
If it's the former, the answer is "more than we could possibly know what to do with for the forseeable future of mankind."
If it's the latter, (or if it's the former and you aren't content with my answer,) here's a pretty good answer. (https://dothemath.ucsd.edu/2012/01/nuclear-fusion/)

I was thinking how much loss of hydrogen if we powered the earth with 0-energy input fusion compared to how quickly we lose hydrogen to space. Also there was a book where people had settled mars and Earth had decided to stop allowing them to take water for fuel and to terraform mars.

[Yora]

I would say it's literally undetectable, even over tens of thousands of years. The great thing (among many) about fusion power is that the amount of energy per mass is just staggering. It's on a completely different order of magnitude from hydrocarbons, and the energy gained from hydrogen fusion is many times greater than from uranium fission.

Hydrocarbon fuels get you about 30-50 megajoules per kilo.
Deuterium (Hyydrogen-2) gets you 579,000,000!

Uranium still gets you about a seventh the amount of energy as hydrogen, but uranium is a very rare element, while hydrogen absolutely is not.

With current technology (and quite possibly) ordinary Hydrogen-1 isn't going to be a good fuel. The more rare Hydrogen-2 makes a much better fusion fuel. There is 6400 times more Hydrogen-1 than Hydrogen-2, but given the ludicrous amounts of water on Earth, that's still quite a lot. Though many people seriously believe that in the long term it will be much easier to just get Hydrogen-2 from the Moon, where it's much more accessible than trying to extract it from water.

Current global energy consumption is about 567,000,000,000,000 megajoules. So with hyper-efficient fusion reactors, it would take 1,000 tons of deuterium to cover global energy needs (though if we had that capability, we certainly would find ways to consume much more.)
After extracting the heavy water (with deuterium atoms in it) from regular water (with boring Hydrogen-1), you need 9,000 tons of water to get your 1,000 tons of deuterium and release 8,000 tons of oxygen into the air. (Somewhat rounded, I know deuterium is heavier than Hydrogen-1.)
There's about 1,260,000,000,000,000,000 tons of water on Earth. So if you were to consume 9,000 tons of water each year, it would take over a million years to use up even one billionth of the water on Earth. Increase the future energy consumption by a hundred times, and it still would take 10,000 years to consume this tiny fraction of global water.

Let's roughly say that 2% of the Earth's water is currently in the form of ice. That's 20 million more times than that hypothetical one-billionth I made up. Grossly simplifying my model even more to make the oceans a simple cube instead of a sphere with uneven depth, consuming all this water and releasing oxygen and helium (the exhaust of deuterium fusion) would lead to a sea level drop of 0,003 milimeters.

TLDR back of the envelope: At current energy consumption levels and with very efficient fusion reactors, getting your fusion fuel from sea water would drop the ocean levels by 1 milimeter over the next 3 billion years.
Since the increasing brightness of the sun will have evaporated all water on Earth in a billion years anyway, we wouldn't even ever get there.

I might have a few mistakes and my estimated could be a thousand or a million times to small. But even then, there wouldn't be any noticable impact on the amount of water on Earth before liquid water will already become impossible on Earth. :smallamused:

[Tvtyrant]

I was going to say, if we get Cold Fusion going we will just collect some comets to make up for lost matter in the long run. It's kind of a lynch pin tech, if we don't get it we probably aren't making it around the river bend so to speak.

[Grey_Wolf_c]

I'm pretty sure fusion power as a significant source of global energy production will still happen in my lifetime. But 20 to 40 years until that point still sounds pretty plausible.

Ah, the optimism of youth. As someone that doesn't have 40 years of life left (actuarially), I'd love it that was true, but I wouldn't expect to see it happen.

GW

[factotum]

With current technology (and quite possibly) ordinary Hydrogen-1 isn't going to be a good fuel.

It's not just a matter of technology, it's a matter of physics. Regular hydrogen is really, really difficult to fuse, mainly because the primary product of such an event is Helium-2, which is horrifically unstable; the only way it will hang around long enough for the energy release from the fusion to be useful is if it almost immediately decays via beta decay into deuterium, rather than just splitting apart into its constituent protons and absorbing the energy again. It's actually rather good that this is the case, since it's the main reason why the Sun can live so long--it's fusing such a tiny fraction of its available hydrogen that the supply will last billions of years.

[Azuresun]

I think fusion power has been 5-10 years away for the last forty-odd years.

[tyckspoon]

I think fusion power has been 5-10 years away for the last forty-odd years.

Fusion researchers: "Give us unlimited resources and don't yank it away at the first failed experiment, and we'll give you fusion in five years."
People who can fund fusion researchers: "Ok, ok, that sounds good, how about we give you 1/100th of what you want, just for a trial run, you know, and it better work the first time."
Fusion researchers: "Fusion is fifty years away and always will be."

[Tvtyrant]

I think fusion power has been 5-10 years away for the last forty-odd years.

Finding longitude was once compared to perpetual motion in its impossibility. I'm not saying we will get cold fusion (personally I think the system will crash before that) but I wouldn't write it off just because it is taking us a long time.

[Rockphed]

Finding longitude was once compared to perpetual motion in its impossibility. I'm not saying we will get cold fusion (personally I think the system will crash before that) but I wouldn't write it off just because it is taking us a long time.

I could swear that Fleishman and Ponns were responsible for "cold fusion" being written off as impossible.

[Tvtyrant]

I could swear that Fleishman and Ponns were responsible for "cold fusion" being written off as impossible.

Well, if by responsible you mean they hyped up the subject and then people got cold feet looking at the bill. The amount of money actually spent at any point was tiny, I believe less than $100 million worldwide.

[Rockphed]

Well, if by responsible you mean they hyped up the subject and then people got cold feet looking at the bill. The amount of money actually spent at any point was tiny, I believe less than $100 million worldwide.

I haven't looked at it closely, but while their positive results were all fraudulent I vaguely remember hearing that when people looked at the real results they concluded that what was being chased was impossible.

[Vinyadan]

Fusion researchers: "Give us unlimited resources and don't yank it away at the first failed experiment, and we'll give you fusion in five years."
People who can fund fusion researchers: "Ok, ok, that sounds good, how about we give you 1/100th of what you want, just for a trial run, you know, and it better work the first time."
Fusion researchers: "Fusion is fifty years away and always will be."
That sounds like a terrible pitch, though.

[Tvtyrant]

That sounds like a terrible pitch, though.

I think it is more about the steady failure of R&D and infrastructure in the West than anything. There has been a creeping reduction in blue sky projects in favor of more immediately profitable projects since the 1950s, which is fair in light of man extremely expensive and pointless projects like Canadian Flying Tanks but also cuts into NASA, transportation, etc.

[Lord Torath]

I haven't looked at it closely, but while their positive results were all fraudulent I vaguely remember hearing that when people looked at the real results they concluded that what was being chased was impossible.That particular type of Cold Fusion has been pretty thoroughly disproven. Google's been looking into it for a few years, and not found anything.

There's another type of Cold Fusion, but it's not useful for generating power: Minute Phsysics: Cold Fusion (https://www.youtube.com/watch?v=aDfB3gnxRhc)

[LibraryOgre]

Ah, the optimism of youth. As someone that doesn't have 40 years of life left (actuarially), I'd love it that was true, but I wouldn't expect to see it happen.


Ugh, you had to word it that way. I feel age deep in my bones, now.

[Tvtyrant]

One of the questions I had years back is why hydrogen fuel cells never took off. Getting the hydrogen is extremely easy, you just split the water at a dam using the energy from the dam and then ship the hydrogen. So much energy leaks from the lines it wouldn't be much less efficient then what we do now.

I think mostly new energy just isn't interesting to the countries that can afford to explore it, and too expensive to the ones that can't.

[Lord Torath]

I recall it had something to do with Energy Density. Gasoline has a pretty high energy density in terms of joules / volume. Hydrogen has a lot of potential chemical energy per unit of mass, but not per unit volume.

[LibraryOgre]

https://xkcd.com/1162/

[Rockphed]

One of the questions I had years back is why hydrogen fuel cells never took off. Getting the hydrogen is extremely easy, you just split the water at a dam using the energy from the dam and then ship the hydrogen. So much energy leaks from the lines it wouldn't be much less efficient then what we do now.

I think mostly new energy just isn't interesting to the countries that can afford to explore it, and too expensive to the ones that can't.

If you could transport hydrogen without losses you could probably be more efficient in a lot of cases than current electrical transmission. That is actually the hard sell. Also, gasoline is a liquid at close to atmospheric conditions while hydrogen is a gas without high pressure and low temperature, so not only is hydrogen harder to contain because it leaks more easily, but it is harder to contain because you need high-pressure vessels to transport it.

[tyckspoon]

One of the questions I had years back is why hydrogen fuel cells never took off. Getting the hydrogen is extremely easy, you just split the water at a dam using the energy from the dam and then ship the hydrogen. So much energy leaks from the lines it wouldn't be much less efficient then what we do now.


Hydrogen is difficult to store - it has very small molecules, which means it can escape from containers that can securely store larger compounds and elements. It's reactive with basically everything, so there's an issue with it destroying gaskets, seals, and components of the systems that interact with it. And it takes a lot of it to get a useful amount of energy, which is generally dealt with by either keeping it under very high pressure or by liquifying it in order to store the amount required in a manageable volume.. which means you have the issues going along with safely handling high-pressure vessels and/or ultra low temperature vessels. None of this is impossible to deal with, of course, but it does mean long-distance storage and transport of hydrogen is a pretty expensive prospect, and so far nobody has really found it worthwhile to build the infrastructure that would be needed to make it a large-scale alternative form of energy storage. It is already in use in places where businesses find it makes sense - it's just not likely to become the main method of energy storage for personal transport or home use due to the issues with handling hydrogen.

[Tvtyrant]

Okay, storage and density make sense. I'm frequently shocked by how wasteful we are with dams, like shipping electricity to an aluminum plant hundreds of miles away instead of putting them right on top of each other.

[Rockphed]

Okay, storage and density make sense. I'm frequently shocked by how wasteful we are with dams, like shipping electricity to an aluminum plant hundreds of miles away instead of putting them right on top of each other.

Where Dams go is pretty hard to change. While you lose some power in transmission, I'm not sure how much it actually is. Per this site (https://info.siteselectiongroup.com/blog/power-in-the-data-center-and-its-costs-across-the-united-states), electricity in the US costs between 4.5 and 22 cents per kilowatt-hour. Assuming you aren't running your aluminum foundry in one of the high rate states, you are probably paying about 7.5 cents per kWh. It takes about 17,000 kWh to make a ton of aluminum, so if it costs more than $170 per cent saved in per kWh rate to ship the aluminum ore to the new smelter site and ship the aluminum from the smelter site, then it is better to not ship it. Even if you would save on costs that way, you might have other reasons for where you site your smelter, such as ease of transport, proximity to labor or major customers, or simply that you already own the land and have buildings built.

[UtopiaNext]

They expect to have it running in 5 years.

I haven't heard anything lately from Lockheed-Martin's Compact Fusion project, which, I think, stated in 2013 that they planned to have a working prototype in five years.

From what I understand, this is going to be a running experiment that is intended to "bridge" between the fusion experiments that have gone on so far and an actual productive fusion reactor. IIRC by 2035 they want to be ready for the next step, so everything before that is going to be trying to achieve the 50 mw in / 500 mw out figure they stated.

My general impression is that they don't really know exactly how this will pan out but figure that the effort will at least be useful. Odds are, I think, whatever they figure out should be added to the other fusion projects present and planned, so if we're lucky we might be able to actually make useful fusion reactors by 2035?

[Sigako]

If I learned anything about nuclear fusion in my life, it's a knowledge that fusion reactor is always 5 years away. It's called half-wait period (or something like that, I heard the term in Russian).

[monomer]

One of the questions I had years back is why hydrogen fuel cells never took off. Getting the hydrogen is extremely easy, you just split the water at a dam using the energy from the dam and then ship the hydrogen. So much energy leaks from the lines it wouldn't be much less efficient then what we do now.

I think mostly new energy just isn't interesting to the countries that can afford to explore it, and too expensive to the ones that can't.

Power transmission over long distances in the United Sates has losses of up to around 5% (http://insideenergy.org/2015/11/06/lost-in-transmission-how-much-electricity-disappears-between-a-power-plant-and-your-plug/). Distribution adds up to another 5% (though you wouldn't be too worried about that if you are a major customer with dedicated high-voltage line), so in all you are generally looking at around 10% total losses.

Conversion of water to hydrogen via electrolysis is up to 80% efficient at an industrial plant (https://en.wikipedia.org/wiki/Electrolysis_of_water#Efficiency), and around 70% at a smaller plant, so you are already starting at a disadvantage just from making the hydrogen.

For the end-user, in a smaller application like a car, low temperature proton-exchange membrane fuel cells are roughly 60% efficient at converting the hydrogen back to electricity (https://en.wikipedia.org/wiki/Fuel_cell#Efficiency_of_leading_fuel_cell_types), while larger / hotter industrial fuel cells are up to about 85% efficient with heat reclamation.

So all in all, you have about 10% loss from electricity distribution, while just the conversion from electricity>>hydrogen>>electricity you have at least a 32% loss, which doesn't even take into account the energy required for compression and transportation of the hydrogen.

[factotum]

So all in all, you have about 10% loss from electricity distribution, while just the conversion from electricity>>hydrogen>>electricity you have at least a 32% loss, which doesn't even take into account the energy required for compression and transportation of the hydrogen.

Efficiency isn't a major deciding factor for this sort of usage, though. For instance, the internal combustion engine in a regular car is maybe 25-30% efficient--burning that fuel in a car is by far and away the worst thing you could be doing with it, since burning it in a power plant would be a far more efficient use. However, a tankful of fuel has such a high energy density that it's still advantageous to do that compared to using batteries and an electric motor--even the longest range electric vehicles can't hope to match the range between top-ups that an ICE car can do. If you're using fuel cells in a mobile application it's for the advantages of range and (relatively) quick and easy refuelling, not because of the efficiency.

[Chronos]

Practical fusion has never been claimed to be five years away. The usual claim is 30, with steady and continuing funding and support (which it's never gotten). Without funding and support, the only possible prediction is and always has been "never".

Impractical fusion is here now, and has been for a very long time. The guy who invented television also made a device that fits on a tabletop and which produces fusion. You could build a fusion reactor in any reasonably well-stocked workshop.

Cold fusion is a hoax, and is irrelevant anyway. Even if what Pons and Fleischmann claimed were true, their device wasn't practical, either. And even if there is some real way to produce cold fusion, there's no reason whatsoever to believe it would be any more practical than hot fusion.

[snowblizz]

Where Dams go is pretty hard to change.
Even if you would save on costs that way, you might have other reasons for where you site your smelter, such as ease of transport, proximity to labor or major customers, or simply that you already own the land and have buildings built.
Not to mention the places good for dams are unlikely to be ideal for large industrial sites and transportation networks. Basically you can build the transmission lines almost over any terrain. But try building the road or rail need to ship bulky bauxite ore. A dam can run with a lean staff compared to an aluminium smelting-plant.

With the low cost of "free" electricity the other costs of the equation matter a lot in how it shakes out. So e.g. it makes sense to ship ore to Iceland to smelt it.

Sometimes other whacky considerations like environment and such actually matter too.


One of the questions I had years back is why hydrogen fuel cells never took off. Getting the hydrogen is extremely easy, you just split the water at a dam using the energy from the dam and then ship the hydrogen. So much energy leaks from the lines it wouldn't be much less efficient then what we do now.

I think mostly new energy just isn't interesting to the countries that can afford to explore it, and too expensive to the ones that can't.

I think the main problem stems from needing a completely new secondary infrastructure to support hydrogen fuelcells. And as others have noted it is much more inconvenient to store. Or put a bit hyperbolically do we want every car, every truck and every gas-station be a potential Hindenburg? In comparison take that power you didn't use to create motive bombs and put it into electric cars where you can actually even refuse existing infrastructure, and probably 90-95% of what you need already exists.
Basically, all vehicles need to be replaced already. But do we also need to completely replace all logistics and transportation infrastructure too? Hydrogen fuel-cells suffer from massive bootstrap problem the alternatives doesn't quite have.

[Rockphed]

I think the main problem stems from needing a completely new secondary infrastructure to support hydrogen fuelcells. And as others have noted it is much more inconvenient to store. Or put a bit hyperbolically do we want every car, every truck and every gas-station be a potential Hindenburg? In comparison take that power you didn't use to create motive bombs and put it into electric cars where you can actually even refuse existing infrastructure, and probably 90-95% of what you need already exists.
Basically, all vehicles need to be replaced already. But do we also need to completely replace all logistics and transportation infrastructure too? Hydrogen fuel-cells suffer from massive bootstrap problem the alternatives doesn't quite have.

I suspect that even running a bioreactor to produce gasoline or diesel under artificial light would work better than using fuel cells due to hydrogen's really hard storage requirements.

One fuel technology that hasn't happened and I wonder why is cars using liquified natural gas. I hear about cities using it for their garbage trucks, but haven't seen anything about cars running it. Is it just a different enough engine and tank design that cars can't, or is it that nobody sells the stuff?

[Lord Torath]

Cold fusion is a hoax, and is irrelevant anyway. Even if what Pons and Fleischmann claimed were true, their device wasn't practical, either. And even if there is some real way to produce cold fusion, there's no reason whatsoever to believe it would be any more practical than hot fusion.
There's another type of Cold Fusion, but it's not useful for generating power: Minute Phsysics: Cold Fusion (https://www.youtube.com/watch?v=aDfB3gnxRhc)Not a hoax. Just not useful for generating power, as you only get out about 1/2 the power you put in, assuming 100% transfer/collection efficiency.

[snowblizz]

I suspect that even running a bioreactor to produce gasoline or diesel under artificial light would work better than using fuel cells due to hydrogen's really hard storage requirements.

One fuel technology that hasn't happened and I wonder why is cars using liquified natural gas. I hear about cities using it for their garbage trucks, but haven't seen anything about cars running it. Is it just a different enough engine and tank design that cars can't, or is it that nobody sells the stuff?

A bit column A, bit B I think. Infrastructure's a female dog. They couple years ago commissioned a cruiseliner using LNG and it required a new everything (including crew). Including a pipeline to a refueling plant. LNG is I think easier than hydrogen to store but not by a lot. They wanted a refuelling infrastructure on the other end of it's trip too but that got a firm NIMBY response. You still need the new infrastructure but just switched to a less flexible fossil fuel. Without looking it up I think simply put LNG works better at scale. Like why coal powered ship and train works but not really a car.

[factotum]

You can get cars converted to run on LPG. I believe there are a few cold start issues with such an engine, but the major problem is obviously that LPG is just another fraction distilled from crude oil and therefore isn't a solution to the problem of running out of fossil fuels, so nobody's really pushed hard to replace existing petrol and diesel infrastructure with it.

[Mastikator]

I was thinking how much loss of hydrogen if we powered the earth with 0-energy input fusion compared to how quickly we lose hydrogen to space. Also there was a book where people had settled mars and Earth had decided to stop allowing them to take water for fuel and to terraform mars.

Even if we somehow replaced literally all energy sources with fusion that uses oceanic water the sea level would continue to rise for the next thousand years or so. The CO2 in the atmosphere is incredibly high and the global temperature is slowly catching up.

If you really want to lower the sea level then you have to drop a gigantic ice cube into the ocean. Thus solving the problem once and for all!

[Telok]

One fuel technology that hasn't happened and I wonder why is cars using liquified natural gas. I hear about cities using it for their garbage trucks, but haven't seen anything about cars running it. Is it just a different enough engine and tank design that cars can't, or is it that nobody sells the stuff?

The first and last LNG car I saw/used was almost 30 years ago on a US military base. It was a rental car in Oklahoma City. I recall that it turned out there was exactly one LNG fuel station in the entire state, on the military base.

I suppose it could have been worth it if they had a problem with lots of people running off with rental cars. At the time it just seemed weird.

[Chronos]

You can get a car that runs on liquid propane, but I'm not sure why you would. It's only slightly better than gasoline on the greenhouse gas front, but significantly worse on all of the other pollutants, costs more, and requires a more difficult fuel tank that takes longer to refill, with fewer filling stations available. You might be able to get tax credits or the like for an "alternative fuel vehicle", depending on jurisdiction, but if so, that's just a sign of poorly-worded laws.

Liquefied methane (natural gas) requires an even more difficult fuel tank and takes similarly long to refill, but since many houses already have natural gas piped in, you can install a home fueling station. It also has nonzero but significantly less greenhouse gas emissions (as long as you don't have any leaks; methane itself is a much worse GHG than carbon dioxide), and also less emissions of all of the other pollutants. Currently it's mostly only practical for large centralized fleets like city garbage trucks or city buses, but (if you value the clean air), it is practical for those.

[snowblizz]

Liquefied methane (natural gas) requires an even more difficult fuel tank and takes similarly long to refill, but since many houses already have natural gas piped in, you can install a home fueling station. It also has nonzero but significantly less greenhouse gas emissions (as long as you don't have any leaks; methane itself is a much worse GHG than carbon dioxide), and also less emissions of all of the other pollutants. Currently it's mostly only practical for large centralized fleets like city garbage trucks or city buses, but (if you value the clean air), it is practical for those.

The irony is that the large centralised fleet is one the applications electric vehicles are best at. Even less emissions at point of use, and you can then limited the infrastructure to a centralised plant that just makes electricity.

[tyckspoon]

Liquefied methane (natural gas) requires an even more difficult fuel tank and takes similarly long to refill, but since many houses already have natural gas piped in, you can install a home fueling station. It also has nonzero but significantly less greenhouse gas emissions (as long as you don't have any leaks; methane itself is a much worse GHG than carbon dioxide), and also less emissions of all of the other pollutants. Currently it's mostly only practical for large centralized fleets like city garbage trucks or city buses, but (if you value the clean air), it is practical for those.

The best argument for using LNG is probably just that it provides a market for the stuff, which means gas and oil producers have a reason to collect it, refine it if needed, and transport it.. instead of just burning it off in the field. A lot of natural gas is pumped as a byproduct of drilling and pumping for oil, and if there's no monetary value to it it often just gets flared off on-site as a waste product. If it goes into vehicles, power plants, or even home usage, then it can be usefully burnt to provide energy and have its combustion products run through filters and converters to clean them up some.

[Xyril]

Is this really better than harnessing the (fusion) power of the Sun? I'm not against the research per se, but this has to be a lot of money, and I wonder if investing in photovoltaic research would achieve similar results. Although I guess that anyone could invest in solar panels, while this kind of mega-project requires supranational collaboration.

Define "better."

The first fundamental limit of solar energy is power flux. We can keep making strides in improving efficiency by improving conversion efficiency per area of solar panel, and panel utilization per area of space, and in that regard, there's still a lot of gains to be made, but at some point the only way we can meaningfully scale up is by thinking beyond terrestrial solar panels.


I'm actually in favor of this, since it synergizes well with developing space travel, but from an investment standpoint, developing and deploying space-based solar solutions is probably on the same order of magnitude as developing practical fusion power.


Right now, practical solar panels are about 20% efficient. We can probably get a bit higher by further optimizing the engineering solutions (i.e., finding ways to further reduce parasitic losses without drastically increasing production costs), but the fundamental source of inefficiency comes from the initial capture of light. The first step in a solar panel is the absorption of the photon--when light hits the semiconductor, excites an electron, and hopefully we're able to direct that electron somewhere that it can do useful work before the whole thing returns to an unexcited state. The efficiency of this process--what percentage of electrons get absorbed and excite something, rather than passing through without interacting, and what percentage of those excited electrons do something useful before returning to a low energy state--is largely a material property of semiconductors.

We can tweak these properties by doping--adding impurities--which is why we can get so much interesting behavior out of devices that are 99% silicon, but in terms of tweaking them to be more efficient light absorbers, we've pretty much hit a wall with silicon. This is important because silicon's pretty much the cheapest bulk semiconductor material we have available. They've actually gotten much higher efficiencies using other semiconductors--I want to say indium-gallium was one of the more promising ones--but these materials are currently more expensive to process and to integrate into working cells.

I absolutely believe there is a way forward in terms of improving solar, but the point is that we're at the point where we have to characterize and experiment with new materials, and eventually find a way to integrate these new materials with manufacturing processes, and to hopefully scale up without drastically increasing costs. In other words, we're getting very close to having the same situation as with fusion--where the fundamental science is novel enough that we really can't predict how much money and effort we'll have to sink in to get results, or that we'll even get significant progress within a certain time frame.

And even if we do, we don't know for sure what our energy needs will be in a few decades. It's possible that solar cells at 30-40% efficiency will meet all of our needs, without having to cram the Earth so full of them that we start disrupting the biologically or meteorological processes that also depend on solar energy. However, it's also possible that our power needs will grow so much that only a compact solution--something like fusion, fission--will be viable. What if, for example, we manage to exhaust our supply of ground water? Desalination is often the thing that turns a green boat into one that has to rely on gas generators for long voyages.

[snowblizz]

And even if we do, we don't know for sure what our energy needs will be in a few decades. It's possible that solar cells at 30-40% efficiency will meet all of our needs, without having to cram the Earth so full of them that we start disrupting the biologically or meteorological processes that also depend on solar energy.
I'm going out on the limb and say it never will. Because large parts of the planet does not get enough sunlight all the time. And at some point we hit limits on storing and transferring solar power from places that do.

And there are other issues, am told in some places in Germany where they got a lot of solarpower in towns on the roofs a local cloudformation can disrupt the grid as it shields a significant portion of local power. We get all of these kinds of issues with only one or even few numbers of means of producing. Every time I consider a solar and wind only world e.g. I wonder what we will do a sunny day in early February when it's still. The sun may shine but it only produces a tiny fraction of energy compared to other parts of the year. There's a stagnant highpressure so no wind either. And it'll be -20 C because sunny means cold in February.

That's when you need something else.


However, it's also possible that our power needs will grow so much that only a compact solution--something like fusion, fission--will be viable.
We are likely going to be growing our use of power to match our ability to produce it for a long time still. Fusion and fission provides something that wind and solar can't easily do, which is built in redundancy where you ramp up production for peaks. There's nothing that powergrids hate as much as power that fluctuates. The problem lies in providing constant effect for the grid, how exactly the input is made doens't matter as much as that the input can be controlled or predicted.

The optimum solution probably lies somewhere in setup where fusion plants run at 30-40% capacity and the rest is covered by solar and wind (and others) but where fusion can cover 100% of the need if it has to. If we run fusion on a rare isotope, even though there migth be quite a lot of it, makes sense not to "waste" it and use as much "free" power as we can.