Looking at current cost VRE trends, when variable sources contribute up to 4% of world energy, and surrounded by massive amounts of cheap but high-carbon natural gas, and assuming that the trends will just continue exponentially downward without serious complication, is optimistic.
Cost of integration of variable sources plus batteries is expected in many studies and somewhat intuitively to skyrocket as market penetration increases. When you have enough VRE to cover 100% including the big evening peak with batteries during a clear summer day, the extra generation you build to fill the other gaps gets curtailed. But you have to fill daily and then seasonal gaps, worldwide, including heat in winter and worldwide transportation (not just electricity). Buying that battery that is only even needed at all every third day is 3x the price, yet we prefer if the power doesn't brownout with this frequency. This is difficult. Already we're seeing NIBMYism in large solar installations in california and with transmissions lines. That gets worse with scale.
Nuclear today is a hedge against the possibility that deeply carbonizing with variable renewables + storage at world scale will be harder than we all think and hope it will be.
That said, nuclear certainly needs to drop capital and O&M cost dramatically if it wants to play the game. And security is indeed a big factor in this. Its competition in the small-footprint dispatchable world is natural gas with full CCS, which is also looking pretty cheap.
IMHO 5X cost reduction is basically a done deal even just applying simple economies of scale. You can argue whether this happens in five or ten years maybe but arguing it isn't happening seems futile. Beyond that, 10x is extremely likely to happen as well. There's a lot of research happening that would need to be a complete failure/waste of time for that to not happen. At worst it will happen slower that I might like. Maybe this happens over the next decade. Or two. Or three even. From there, 20x might be quite possible as well.
Beyond that we're indeed talking rapidly diminishing returns. 10X would mean 0.2 cent/kwh. 20x would cut that to about 0.1 cent. This indeed gets you in to territory where metering it becomes more expensive than is worth the trouble. The average household uses about 15000 kwh per year, or about 150$ worth of energy at these prices; much less outside the US. Much of that is going to be produced on people's roofs or in their back yards. At that point it turns into a fixed cost.
Historically the same sources producing the studies you are referencing have been off by magnitudes predicting current adoption and prices for both solar and wind. So, I'd consider that the pessimist glass half empty point of view. Not to dismiss it entirely but arguing cost increases seems a bit far fetched in light of current trends in the market.
>Not to dismiss it entirely but arguing cost increases seems a bit far fetched in light of current trends in the market.
I think what the parent was saying is that because solar and wind don't reliably produce energy, we will need redundancy. As the market share of solar and wind grows we will need to increase the amount of storage and power generation far beyond what we normally need to operate.
Let's say you have a city that uses 1 GWh of electricity per day. If you were to generate all the electricity with natural gas then you need to have 1 GWh plus some extra for redundancy to fulfill the needs of the city. If you generate 5% with solar and the rest with natural gas then nothing really changes. If the weather is bad then the natural gas plant will step in.
As the share of your solar power generation grows toil need more and more redundant storage and solar power generation. If you rely 100% on solar power generation and the weather can be bad for a week in a row over the city, then you'll need storage that will last for more than that entire week. Not only that, you'll also need extra power generation capability to be able to fill and maintain that storage.
Just to put this into perspective: the US uses about 10 TWh of electricity per day.
They are good enough. Low efficiency just means we have to buy more of them. Obviously we'd need solar plants (and maybe wind parks and other clean sources) to also power those with limited access to roof surface.
Of course, bad weather doesn't mean solar stops working; it just reduces the output. The effect is typically very local as well. So, all that means is that you need a bit extra capacity to cover for that or import energy from somewhere else where the weather isn't miserable.
When (not if) the price for solar and wind drops 10x, you'll be able to buy 10x more than what you need and still beat coal/gas/nuclear on price. 10x is an insane safety margin that would mean you produce more than you need even on the most cold, dark, and miserable day imaginable. And of course solar is not the only source of clean cheap energy. Wind would be another popular option.
Further south in Germany, Netherlands, etc. Solar is usable throughout the year and quite common. Obviously output in the summer is going to be much better than during the winter.
We are well past the point where tracking the sun was desirable. The apparatus that allows solar panels to track the sun is now much more expensive, especially when you consider the maintenance costs, than just using more static panels.
There is also only so much more efficient the panels can get per sq m. Right now we are approaching 20% efficiency, so the idea that they are going to get 10* cheaper with complete ease seems to be pushing it.
Regardless solar and wind have a lot of externalities that aren't really priced into these 2c/kWh PPA prices. If you need to build a fleet of natural gas plants that are only operational 10% of the time and therefore cost 50c/kWh to take up the slack from low solar days it needs to be priced in somehow.
It's amusing to see "permitting costs" being presented as a barrier, when at the same time "get rid of regulations" is spouted as the panacea for reducing nuclear's costs.
But such is not the nature of the logistic function, which is usually a more accurate model of how technologies penetrate. (yes, in the beginning it looks like an exponential)
- The prospect of every household having a battery backup big enough to smooth over spikes and dips is ludicrously wasteful. We are already struggling just mining enough to make batteries for cars and phones.
- the sheer scale of the wind and solar farms will leave major environmental impact to wildlife. Look at how massive area solar farms need, and know the area has to be cleared and desolate of life.
The wild life impact of solar is relatively minor compared to burning coal, intensive farming, and all the other things we do. We'd need to only cover a relatively small amount of land with solar to produce what we need. And ironically some of the most suitable land for this would be deserts that have relatively little wild life to begin with. Of course the impact of wiping out coal, gas, and petrol usage would be enormously positive.
Windmills do indeed kill some birds. Yet, these things seem to have barely any impact on e.g. the seagull populations in places like Denmark that have a ridiculous amount of wind mills.
Molten salt reactor is a stepping stone for fusion reactors. We need to master liquid and gaseous reactors before going plasma. Our civilization should aim for larger goals. We need some form of nuclear power to terraform other planets and spread earth's precious life and conciousness everywhere.
In space (actual space, not a planetary surface), it's difficult for nuclear to dissipate its prodigious amounts of waste heat. Solar, in contrast, can be made much lighter than on Earth, as there isn't wind and rain to deal with. And of course in general the Sun is available 100% of the time in space, further improving the economics.
But in any case, the argument wasn't that solar was necessarily better, it was that nuclear wasn't necessary. Solar can provide energy basically anywhere, with power beaming, even out into interstellar space.
MSR and many other fluid-fuel reactors run hot and it makes radiators small: https://www.flickr.com/photos/oakridgelab/31537153147/
Stefan–Boltzmann law: Radiation heat transfer is proportional to 4th power of temperature.
This does not rule out use of solar energy.
> During interstallar journey there is time delay in communication, so it may take hours to adjust the power beam when spacecraft moves a little bit
The vehicle tracks the beam, not vice versa.
> Fusion is like solar energy just near to us and MSR will be eventually replaced by fusion reactors.
Fusion is ridiculous when examined closely. It's like fission, only far worse from an engineering and cost perspective.
> Stefan–Boltzmann law: Radiation heat transfer is proportional to 4th power of temperature.
Which means waste heat from a reactor in space has to be radiated at higher temperature than for a reactor here on Earth, which means nuclear is worse off there than here. In contrast, solar works better in space, as I argued upthread.
You can place the nuclear generators in police stations, military bases, other locations that are already protected, there is no need to have a small nuclear generator in each electronic device like in Fallout.
The security aspect would make this a lot more expensive than it already is and cost is already on the high side even before you consider that. This is a problem with traditional reactors as well but they have the advantage that they are huge facilities and that there are only a handful of them; so securing them is relatively easy.
People are suggesting this as complementing renewables but the cold hard truth is that renewables are already dirt cheap and on track to continue to drop in price by magnitudes for the next decades. That includes battery storage as well. Already quite cheap, also dropping in price, and typically already factored into e.g. new solar bids that are killing competing bids for coal and gas plants (or in some cases shutting them down prematurely).
Even at the current prices, that's a problem for any kind of nuclear solutions being contemplated right now. At the low end of the spectrum, we are talking 2 cents per kwh currently. Imagine this dropping to something like half a cent or even less. At those prices, the security alone would make nuclear too expensive probably. A 1 mw facility would have basically be generating only about 500-2000$ worth of energy per hour but only at peak demand. There's no guarantee prices won't drop way below that either. Any kind of operational overhead would be a problem. Needing 24x7 intense security would be very undesirable.