[hannob]

I'm always baffled by such statements.

Can you explain in which way solar is not a "near-infinite source of energy"? I mean... there are without doubt technical challenges and all that (but arguably less technical challenges than to do the same with nuclear), but there really is no relevant limit to the deployment of solar cells if you include things like large-scale installations in the desert.

[chrisco255]

Solar depends on weather, location and battery storage. Solar cells also require massive amounts of physical area to produce the same amount of energy as a nuclear power plant. And you can't compare a "2 gigawatt" solar installation to an equivalent nuclear installation because nuclear will produce power 24/7 at peak capacity, rain or shine. A solar plant sees a huge amount of variability and only hits peak efficiency for a brief part of the day on clear days.

[aplummer]

Solar power in the desert produces power 24/7 by keeping the molten sand hot overnight. It’s also always sunny

[Accujack]

That technology is far more expensive than photovoltaic panels.... for example, the solar thermal Ivanpah project is now obsolete for that exact reason.

Additionally, The storage density of molten salt is far lower than the generation capacity of a reactor.

[hajile]

Solar panels may be cheap to produce, but they are terrible for the environment because of the complex manufacturing process. Parabolic reflectors can be melted down and reformed without huge additional environmental costs. If you're interested in the environment, this is the real benefit.

Cutting-edge solar panels have about 23% theoretical efficiency. Stirling dish systems have about a 30% theoretical efficiency and about a 25% real-world efficiency.

[ZeroGravitas]

Solar plus battery near the equator can be sized for 24/7 power with relative ease.

But no one would do that, because we don't need power at the same rate all the time. Near the equator, where most people on the planet live, our need for energy is correlated with when the sun is shining and air con is running and people are awake.

This is why solar is better even at the mythical "baseload" than nuclear is.

[Accujack]

>Near the equator, where most people on the planet live

Nope.

In fact, a minority of people live near the equator... for good reason:

https://www.datagraver.com/case/world-population-distributio...

Also, the base load most of us are talking about isn't created by people for the most part... it's created by industry, without which life on the equator or anywhere else would be rather primitive.

In any case, the equator is going to become unlivable in the next few decades to the point where populations in equatorial areas will drop drastically.

[reitzensteinm]

Do you have any data on power consumption near the equator, or where does this assertion come from?

Anecdotally, it doesn't ring true to me from my time in Thailand and Malaysia, where inefficient air con would be left on in poorly insulated houses overnight to help people sleep. I couldn't find any graphs like you can trivially find for power grids in the west.

But I did find this article[1] which indicates the record power consumption occurred at 9:35pm, beating the previous record which occurred at 10:28pm a few years prior, and both of these are times where it's all going to be coming from batteries.

But this isn't necessarily representative. Even if your reference is a book I'd be happy to purchase it, I find solar penetration in developing countries particularly interesting.

[1] https://www.thaipbsworld.com/power-consumption-in-bangkok-su...

[chrisco255]

You are hand waving the complexity, cost, feasibility and trade-offs of doing this.

[chrisco255]

I hate to break it to you but night time hits the desert as well. They don't magically escape earth's rotational spin in the desert.

[threeseed]

Especially if there are advancements in power distribution e.g. high temperature superconductors.

This would be a game changer for the major continents like Europe, US, Africa where you could have power coming from hydro, thermal, solar, wind etc and being shipped to where it is needed.

[posix_me_less]

Loss of power during distribution is not a problem that needs solving, power losses due to transmission in conventional grid are mere 5%.

[1] https://en.wikipedia.org/wiki/Electric_power_transmission#Lo...

Considering how costly and inflexible all superconductors are, I don't see why they would help.

[chrisco255]

Those losses are on a per 100 mile basis. 2-5% per 100 miles of line (not as the crow flies mind you). Superconductors would make a huge difference if they could build a room temperature superconductor.

[Already__Taken]

Exactly, when people mention losses saved by superconductors they don't mean to improve the current grid. It's to route power from the always sunny side of the planet.

[xorfish]

HVDC is already below 3% per 1'000km. So connecting Europe to the Sahara is around 5% with current technology

[chrisco255]

No. Sorry the Mediterranean Sea separates Europe from Sahara (as well as several countries) and you can't do this practically by any means. Europe doesn't own the Sahara.

[duckymcduckface]

The 5% is quoted further in the article for overall grid waste. The per mile basis is purely there to compare why higher voltages for the Samer power lead to less waste.

[The_Double]

Not every country has access to a desert to deploy large scale solar. Most of the EU, Russia for instance, and those places do not want to be dependent on other countries.

[Accujack]

It's probably also worth noting that photovoltaics have to be exposed to the sun to work... which means that they can't be protected by armor or bunkers, which means that they're terrifically vulnerable to terrorist or other attack.

[lhopki01]

The terrorist attack that is going to take out 1000s of square kilometres of solar panels? Surely they'd just attack a city if they had that amount of firepower? Or in the more likely case that they don't it's easier to attack power transmission than generation.

[Accujack]

Assuming there are that many panels, it is in fact quite easy for any industrialized country to design a weapon that can destroy a square mile of panels or more with a single warhead. They're thin sheets of silicon covered in glass.

[kragen]

A square mile is 2.6 square km. You are replying to someone who said it would be hard to destroy thousands of square km of panels. It would seem that your reply, that "it is…easy…to…destroy a square mile of panels or more with a single warhead", is not to the point.

However, by coincidence, your position is right, for two reasons:

1. Single nuclear warheads routinely have blast radii of tens of km rather than, as you suggest, hundreds of meters. So in fact a single warhead can indeed destroy thousands of square km.

2. 1000km² of solar panels would be 1000 GWp; at a low-cost module price of €0.19/W (the average for 2019) that's €190 billion. Currently solar plants are not built that large, nor nearly so.

[lhopki01]

I was replying to a comment that said solar panels are vulnerable to terrorists.

If terrorists have a nuclear warhead they are going to use it against a city not solar panels. Similarly if terrorists have a weapon that can take out thousands of square km of panels it can easily take out existing powerplants (which btw are not armored or in bunkers - apart from some limited shield on nuclear powerplant cores.

The point here is that solar panels are not more vulnerable to terrorists than the existing infrastructure and are probably less vulnerable due to size and how distributed they are.

[friendlybus]

Most militaries rely on oil and dirty fuel to run campaigns. There's mandatory fuel stockpiling. The event of a power station going down would be seen as an act of war and suddenly there's much bigger problems for everyone involved to worry about.

[bra4you]

Me too. But lets not forget, we are dealing with 16 years old kiddies here.

But for you: https://dothemath.ucsd.edu/2011/07/galactic-scale-energy/

[belorn]

What I have heard, you do loose energy in transmitting power over large distances. There exist low loss transmission cables, but I don't know how effective that is over very great distance. There is also the question of how to redesign a distributed power grid into a centralized version where all the power comes from a single sources in desert areas.

On top of that there are political challenges. I have a hard time imagine Europe in current climate being happy to rely exclusively on power from the Sahara.

[hannob]

The Sahara thing is ultimately just to illustrate that there's no real limit to solar energy (because the upper commenter claimed that nuclear is the only energy that is practically limitless). But of course in practice you'd do the easy things first - that is, build solar on every rooftop. No country is anywhere close to that.

I guess in the future we'll use imported solar for hard to solve problems, e.g. turn it into hydrogen or synthetic fuels (which also makes the transmission loss problem much smaller), while our electricity needs will be served mostly by local wind and solar.

[chrisco255]

There's no solar energy in the Sahara at night. And then as people mentioned, there is energy lost in transmission through resistance in power lines. There's also the fact that not too many of the world's 8 billion people live within serviceable range of the Sahara, assuming you can get past the geopolitical instability in that region to construct and maintain such things. The solar cells would need constant cleaning from dust storms to keep them running at high efficiency.

No, running solar on rooftops isn't the most practical use either. Depending on latitude, weather, cost of solar installation and battery installation, orientation and layout of roof to the sun, the problems with snow, rain, and hail, the lack of solar at night, the fact that none of this generates enough power for those times when you need it most like in the middle of winter in northern climates, etc. Solar and wind will never meet the growing needs of modern economy. Period. It's a pipe dream.

They are great supplemental sources of electricity. They cannot power a first world economy.

[eloff]

Every thread in HN is filled with pessimistic people pointing out how things can't work. It's tiring to read.

Solar and wind absolutely can produce all the energy the world currently needs, using only a tiny fraction of available land area. You could power the whole of the US by 100 square miles of solar panels in the southwest, backed with one square mile of batteries [1]. Clearly it's a hard problem and there are many obstacles to overcome, but just as clearly it's not fundamentally unsolvable.

Long-distance electrical transmission is actually pretty efficient nowadays, so that's not a showstopper either.

Bottom line, optimists are responsible for progress and while many people on HN are content to write comments about how it can't be done, somewhere there's an entrepreneur working hard to make it happen - and the smart money is on them, collectively, over the long-term - and thank goodness for that!

[1] http://www.digitaljournal.com/tech-and-science/technology/we...

[belorn]

You can absolutely power the whole of the US by 100 square miles of solar panels in the southwest. The cost would be to build the solar panels, the square mile of batteries, replace all the power lines in the US with cables that can handle very high voltage (twice or more than what current power transmission cables can handle) needed for long-distance, and replace all the power stations connected to those so that can take that high voltage.

It not impossible at all, we have the technology, it just money. Replacing 200,000 miles of cables, with a price tag of a few millions per mile is a project the US could undertake. Replacing all the power station to handle the very high voltage is similarly possible.

When choosing between the many alternatives it is something which should be calculated next to the cost of building nuclear plants in a distrusted pattern, and the long term cost of nuclear waste that such plan would entail. If entrepreneurs could invent power transmission cables and power stations that can manage millions of volts and cost a fraction of existing methods to install would make a centralized place for power generation a much more attractive option.

[cameldrv]

It's a lot more than 100 square miles. Here's an NREL report on this exact question: https://www.nrel.gov/docs/fy13osti/56290.pdf If you extrapolate (see analysis here: https://www.freeingenergy.com/how-much-solar-would-it-take-t...), you get 21,250 square miles. Elon musk says 100 miles x 100 miles, which is 10,000 square miles. Both of those figures are just for current electricity demand, so if we electrified all transportation and industry, we're looking at maybe 60,000 square miles.

60,000 square miles is half of Arizona. Now suppose we want to scale up energy consumption in the U.S. by a factor of 100. At that point, you're at twice the land area of the U.S. Even at current consumption, the amount of ecological damage you're causing by covering half of Arizona with solar panels is huge.

On the other hand, if you wanted to replace all U.S. energy production with nuclear, you'd need about 7-10x more than we have today, or about 1000 reactors. The land area for these reactors is about 700 square miles, or about 25x25 miles. If we wanted to scale it up by a factor of 100, we'd be looking at half of Arizona again.

[roenxi]

The solar panels do have to be fabricated. That probably doesn't have the same scaling potential as nuclear given how much power/m2 nuclear can reach.

Also, at a guess the energy in solar panels drop with the square of distance to the sun. It is unlikely to be a good choice for interstellar travel if 'advance[ing] as a species' heads in the more fantastic directions.

[epistasis]

If we are getting to the point where W/m2 is an important win for nuclear, we are going to start to have serious problems with the rejected heat.

A fundamental limitation of thermal steam engines is that they can only ever be 50% efficient, and you have to dump that waste heat in order to maintain power.

Already, heat mitigation systems for some existing nuclear plants are starting to fail during heat waves as the climate warms. And these are expensive systems: at Diablo Canyon in California, it's cheaper to replace an entire, functioning reactor with renewables than it is to simply build a new cooling system.

Which is all to say that nuclear won't scale tremendously well unless we 1) figure out fusion, and 2) figure out direct conversion of energy to electricity rather than using steam turbines to mechanically drive a generator.

For the ultimate goal that many people have for nuclear, as a power source when not on earth, these sorts of advancements are also likely also necessary. Cooling in space is not a trivial matter.

[erulabs]

Solar power is simply indirect nuclear power anyhow. If we can do what’s happening in the sun in a bottle - then no need to produce panels. If there is material in stars to produce solar power, then there is more potential nuclear power. I’m for both, and solar seems distributed in a way that makes me think it’s better for human society, but since stars are made of fissable materials - by definition there is more “potential energy” in fission than solar, since solar is simply a subset of fission at a distance.

[neuronic]

Solar is fusion and not fission [1]. If you can't even get that right, why should anyone take these weird pro-fission arguments seriously in 2020?

The solution is to keep using existing nuclear power and develop renewables for replacement. Nuclear fission plants take at the very least 10 years (!!) to go online from the day construction begins. And that leaves out years of planning and dealing with contracts.

It's too expensive, dangerous and redundant in the face of emerging renewable tech which is becoming cheaper and more efficient by the month.

[1] https://www.energy.gov/ne/articles/fission-and-fusion-what-d...

[belorn]

Renewables are not a replacement for existing nuclear power unless you either add fossil fuels or batteries to the mix. Countries which currently are replacing nuclear power do so with a combination of renewables and fossil fuels, with fossil fuels burning when renewables are not producing.

Batteries, usually reverse hydro power, is an interesting future technology. Some argue it is significant more developed than fusion. The bigger question is if its economically competitive compared to fission. There is costs and energy loss in every single step of producing electricity from renewables, transmitting it to the battery, converting it into potential, recreate the electricity, and finnally transmitting it to the end users. With fission you go directly from the power plant to the end user. Reverse hydro power plants also take a long time to build and either use a lot of land or coast. If you build it on land it also release a lot of methane as top layer of the land decompose.

[cygx]

Countries which currently are replacing nuclear power do so with a combination of renewables and fossil fuels

Which countries? Germany for example isn't - yet. We're still in a place where we can reduce usage of both fossil fuels and nuclear, though that won't last unless we figure out effective means of energy storage.

[belorn]

As an example, Sweden. People will use fossil fueled energy when the choice is between people freezing in their home or burning fossil fuels. Sweden rely on a mix between hydro and nuclear, but it is not feasible to extend hydro beyond current capacity. The nuclear plants however is getting older, and politically people want to shut them down. Something has to produce the energy, and during the winter it is imported fossil fuels energy when the wind is not blowing.

Germany as an example illustrate the issue quite nice, as can be seen live at electricitymap.org. When the wind is blowing the country goes green with around 70% of energy being produced by wind. Very sunny days you get around 20% solar. Days like today that is a bit rainy and not very windy, and you have 60% fossil fuels. The constant is nuclear around 10%, so remove that and the above numbers will go up depending on weather conditions.

[renaudg]

German anti-nuclear activists like to tout the percentage figure of renewables in the country, but that's not the right metric to look at : the coal+gas baseline is so bad in terms of CO2 emissions, that even in ideal conditions when wind production is 70%, German electricity's carbon intensity is still way higher than in France, Sweden or Iceland (

Coal causes 35.000 premature deaths in Europe every year, and 7 of the 10 most polluting industry sites on the continent are German lignite power plants.

The hypocrisy and constant lecturing from Die Grüne needs to stop.

[cygx]

Sure. But that doesn't make Germany an example of replacing nuclear with fossil fuels. From 2002 to 2019, percentage wise, fossil fuels went down by 1/3 (from ~60% to ~40%) and nuclear by 1/2 (from ~30% to ~15%).

[renaudg]

Germany absolutely is relying on coal and (Russian) gas to afford its ideological decision to prematurely sunset nuclear plants, at the worst possible time in history : just as climate change becomes an emergency.

The cold hard truth is that it's impossible to operate a grid with solar & wind energy alone, unless and until a hypothetical battery storage breakthrough lands in the next decades.

I've just checked the realtime figures and as I write this, German electricity is 5 times more carbon intensive than in France (72% nuclear) : https://www.electricitymap.org/

[Brometheus]

For nuclear you still need to have peaker plants. ALso nuclear is really expensive.

[renaudg]

Pretty sure it's actually cheapest per kWh

[Reason077]

New-build nuclear is far more expensive, per kWh, than renewables. In Europe, even off-shore wind - one of the most expensive renewables - is now coming in much cheaper than nuclear projects.

In the US, even many old nuclear plants are struggling to compete without subsidies against renewables and natural gas.

[pasttense01]

No. If it were cheapest companies would be building nuclear. Right now in the U.S. the cheapest are wind, natural gas and solar.

[Reason077]

> "Nuclear fission plants take at the very least 10 years (!!) to go online from the day construction begins."

Yes, but that's what the small modular reactors being proposed by Rolls-Royce, and others, intend to solve. If successful, they would greatly reduce the construction time, risk, and cost of nuclear projects.

[neuronic]

It's a great project for the technology alone but isn't the projected time frame too late? Where will we be 10 years from now with renewables?

Also, if Rolls-Royce projects 2029 it doesn't mean it's done by 2029 and most certainly not wide scale deployed/operable. So what kind of renewable infrastructure and tech will be deployed 15-20 years from now?

That's what you have to compare it with.

[Reason077]

> "It's a great project for the technology alone but isn't the projected time frame too late? Where will we be 10 years from now with renewables?"

It's not a question of nuclear or renewables - we absolutely need renewables, and right now renewables are much cheaper, and can be delivered faster, than nuclear.

But there are regions of the world that may struggle to decarbonise completely without nuclear in the mix. Especially if you consider additional demands in the future from electrification of transport, building heat, etc.

[renaudg]

> Where will we be 10 years from now with renewables?

If the electricity storage problem doesn't get solved (which is a pretty small "if", since it requires a very uncertain breakthrough in physics) : nowhere.

In 10 years the climate emergency will be even more salient, but one of coal/gas/nuclear/hydro will still be required in the mix.

Countries that can't have hydro for geography reasons, and have shut down nuclear early for political reasons will be a liability to the rest of the world.

[Accujack]

Most likely in that time frame we'll be trying to get by on a mix of renewables and non carbon neutral generation from coal or similar, and we'll also have implemented limits on carbon generation that will effectively be crippling various industries and increasing the cost of various necessities worldwide.

We won't have a choice... it'll be down to either everyone accepting reduced quality of life or nuclear... at which point nuclear starts to look very good.

[Accujack]

>Solar is fusion and not fission [1]. If you can't even get that right, why should anyone take these weird pro-fission arguments seriously in 2020?

To nitpick a bit, he didn't say the sun was powered by fusion, he said fissionable elements are present in the sun. Which is entirely true.

[aguyfromnb]

>It's too expensive, dangerous and redundant in the face of emerging renewable tech which is becoming cheaper and more efficient by the month.

Why are you comparing the state of nuclear energy today with the potential scientific breakthroughs of renewable energy in the future?

If you compare nuclear of today with renewables of today, then the winner is clear. If you compare the two accounting for potential scientific breakthroughs..who knows?

[lorenzhs]

Stars are fusion reactors, not fission. They're mostly made of hydrogen and helium, which account for 98% of its mass: http://hyperphysics.phy-astr.gsu.edu/hbase/Tables/suncomp.ht.... You're going to have a hard time building a fission reactor running on hydrogen and helium.

[logfromblammo]

Stellar fusion like that which occurs in our sun is effectively aneutronic, but is also relatively slow, because the limiting step is the combination of two protons into a proton-neutron pair.

You need to keep a lot of hydrogen at plasma-hot temperatures and very high pressures for a long time. So you can't really do it with masses smaller than Jupiter, because smaller bodies can radiate the energy away faster, and produce fewer events from the lesser mass.

So the only technologically effective way to leverage solar is to deconstruct larger stars into red dwarfs between 0.08 and 0.35 solar mass, perhaps with a ferro-platosmiridium core to increase the overall density and make the reactions viable at lower overall mass. Then surround the whole thing with a Dyson shell and Shkadov/Caplan thruster.

It's a bit beyond our means right now.

[cuspycode]

Aneutronic reactors are good of course, but the Sun still puts out lots of other dangerous radiation. In particular, ultraviolet electromagnetic radiation from the Sun causes tens of thousands of cancer deaths every year. I have no problem accepting a few percent of that mortality from man-made radiation sources if that helps solving the CO2 emission crisis.

[logfromblammo]

Good. For the foreseeable future, the limit of energy available from solar will be the total surface area of the Earth divided by two.

And that includes hydro from evaporation-rainfall cycling, photosynthesis, and wind. Which basically leaves as alternate energy sources tidal, from the sun and moon dragging the oceans around, energy stored from long periods of solar absorption in ages past, residual geothermal, and nuclear.

A little neutron-activated waste is indeed a small price to pay.

[erulabs]

Edit: subset of nuclear at a distance. Yes the sun is powered by fusion, not fission, but the point still stands.