[hannasanarion]

No it wouldn't, because nuclear isn't reactive enough to produce energy to match the extreme afternoon demand curves when solar capacity drops and demand jumps.

To account for those rapid jumps in non-renewable demand, you need an energy source that can ramp up really fast on short notice, like hydrocarbon fire.

[lostapathy]

Apparently this is less true for newer reactors, or older reactors with upgrades. I'm not an expert, but https://www.powermag.com/flexible-operation-of-nuclear-power...

Even if reactors aren't as fast to react as a gas peaking plant is, perhaps batteries will soon be able to bridge that gap. The economics of batteries change greatly if you only need them to carry the load for tens of minutes for reactors to ramp up, vs needing to carry the load until the sun shines again.

[nerpderp82]

The power supply and the energy supply will not have a single solution. It is analogous to the levels of caching in a Von Neumann cpu. L1 will capacitors, L2 batteries, bulk storage is pumped hydro and other GWh energy stores.

The duck curve is a smoke screen and should only exist for a region that doesn't have solar to the west of it. Those solar farms in CA should be feeding users a timezone over to the east.

Any source can then feed into those stores, wind, solar, hydro.

If your power solution is involves hydrocarbons, it should be a closed cycle.

[audunw]

> like hydrocarbon fire.

Or batteries and other storage methods. It looks like battery solutions could get cheap enough in the next 10-20 years to smooth things out and take care of storage for a few hours (see for instance http://news.mit.edu/2018/metal-mesh-membrane-rechargeable-ba... .. Donald Sadoway has some good talks on YouTube)

But yeah, for days that happen to have less wind/solar, I think the best thing is just keep gas power plants around. The CO2 impact for that will be minimal, the power plants are already built, and over time you could replace the fuel with synthetic gas made from renewables, which would basically be another energy storage mechanism. Cheaper renewable gas is something we need to make the world sustainable anyway.

The only unsolved problem is seasonal variations in colder climates. But those areas could import more trash and burn it (for both electricity and heat), like Sweden does. Norway has a ton of hydroelectric power, and is building more HVDC power lines to other areas of Northern Europe which will help with that area. Not sure what the solution for North America is though. But it's not nuclear. Having a nuclear power plant idle for half a year is the exact opposite of what you want. The plant is expensive and the fuel is cheap - if you build it you want it to run 24/7.

[akvadrako]

No, the battery solution is currently about 10000x too expensive. Even building a 1 day battery for each geographical region would be thousands of trillions of dollars.

Only some unexpected breakthrough could make it feasible.

[femto]

AGL in Australia is looking to turn disused coal mines into pumped storage.

https://www.agl.com.au/about-agl/media-centre/asx-and-media-...

[NullPrefix]

> the extreme afternoon demand curves when solar capacity drops and demand jumps

Does the hourly schedule variate day by day or can it be predicted?

If you can predict when and how much power you will need to produce then it can be ramped up slowly, I assume.

[hannasanarion]

"ramping up slowly" isn't an option when the demand curve is changing quickly, because there's nowhere for that extra energy to go. Energy storage isn't really feasible, so all the electrical grids in the world need to match supply to demand 1:1 in real time.

There are electrical dispatchers who are monitoring grid supply 24/7 and instruct plants on how much they are responsible for generating on a minute-by-minute basis.

[dredmorbius]

An alternative to storage is dispatchable demand. This would require high-load activities or uses which can be rapidly cycled.

Storage batteries, pumped storage, and CAES are examples of this, though simple raw thermal banking (hot water heating, typically) is an excellent way to suck up excess Joules or GWh.

1 GWh is roughly the energy required to heat a pool of water 1 hectare * 1 m by 86 degrees Celsius. This scales to multiple GWh by increasing area, depth, or both. Conversion to steam is also possible, though that requires more engineering (pressure is A Thing). Substrates such as molten salt have a lower heat capacity per unit mass, but can be heated to far greater temperatures.

Storage at the scale of entire US generating capacity for multiple weeks using molten salt thermal storage, even accounting for Carnot cycle efficiency losses (about 20-50% depending on specifics, 30% is a good ballpark) is actually a tractable-scale concept. Existing petroleum storage facilities are roughly comperable in size, though molten salt would require somewhat more robust facilities and insulation.

Whilst it doesn't have the net efficiencies of pumped hydro (exceeding 90% round-trip storage efficiency), pumped hydro lacks sufficient developable sites, and has significant environmental impacts.

[nerpderp82]

> Energy storage isn't really feasible

You couldn't be more Dam wrong.

[dredmorbius]

Doesn't scale. Not enough sites.

Mind, where it does work, it's phenomenally effective, efficient, and responsive.

There are a few sites at which seawater-based systems might be possible, in which the ocean forms the "lower reservoir". These are dependent on suitable terrain. Matching terrain to consumption patterns is difficult: the Netherlands and much of Britain are sorely lacking. Some of the best potential sites are along the Balkan coast in Serbia and Croatia. Chile's Atacama Desert, along the Pacific coastline, is nearly ideal geographically, but is far from most use (North America, Europe, Asia). Portions of the US West Coast might be suitable, though would all but certainly face major political resistance for environmental impacts.

And: working with seawater is complex from an engineering standpoint: it's corrosive and sea life has a pronounced tendency to foul large-scale water-handling systems, though this may be tractable. There've been several pilot projects, though those have since been decomissioned, excepting Rance in France, designed as a tidal power plant, though capable of working as a pumped-hydro facility.

[keanzu]

> Doesn't scale. Not enough sites.

Terrible energy density, massive land use.

To store the energy contained in 1 gallon of gasoline requires over 55,000 gallons to be pumped up 726 feet (CCST 2012). [1]

Itaipu Dam has 14,000 MW installed power, 1,350 square kilometres (520 sq mi) were flooded. [2]

[1] http://energyskeptic.com/2015/hydropower-has-a-very-low-ener...

[2] https://en.wikipedia.org/wiki/Itaipu_Dam

[dredmorbius]

Itaipu (or comparable impoundages such as Three Gorges) provide both capacity, indicated as installed GWe of generating capability, a measure of power, and storage, indicated as GWH of energy generation. These are equivalent to the capabilities of an automobile's engine (power) and fuel tank (storage).

Hydroelectric projects also virtually always provide additional services such as flood control, irrigation water, recreation, and waterways management (ensuring water flows, etc.), which also account for design elements including scale, etc.

Pumped hydro should provide a sufficient level of both capacity and storage, though in general the storage requirements are far smaller than traditional hydroelectric dams aimed at generation. There are quite small pumped hydro facilities, the compensation being that water levels can rise or fall considerably, often many metres in a single day's storage/generation cycle.

Gravity is in general a weak force, but water is relatively massive, largely non-toxic, and can be utilised through large-scale pump-generator units (~800 MW per generator IIRC), which is a scale few other options can match. Again, on balance, pumped hydro is a good solution, there's just not enough of it to go around.

[nerpderp82]

Pumped hydro is 70-80% efficient at storing energy. [1]

Converting to sensible units gives

mass = 55e3 * 3.79kg/gallon ~ 208450kg

height = 221 meters

mass * height * 9.8m/s^2 ~ 452043210 joules (watt-seconds)

or 125KwH, 70% of that is 87KwH. What does gasoline have to do with energy storage on the grid? Furthermore, a gallon of gas has 33KwH [2].

What does the Itaipu Dam's installed power have to do with stored energy?

[1] https://en.wikipedia.org/wiki/Pumped-storage_hydroelectricit...

[2] https://en.wikipedia.org/wiki/Gasoline_gallon_equivalent

[nerpderp82]

Does it have to scale? What does scaling mean? Could the existing 2400 dams in the United States be used for PSH? [1]

How many sites do we need? Why would the Netherlands need pumped hydro, isn't the European grid interconnected?

See my comment below.

https://www.energy.gov/sites/prod/files/2018/04/f51/Hydropow...

[dredmorbius]

I'm going to suggest you think through what I've written, the general problem of power grids, generation, and storage, energy uses, and consequences of power outages. The answer may reveal itself to you.

Likewise, you seem to have failed to grasp what I'd hoped would be a rather evident reason for mentioning the Netherlands in the context of pumped hydro and terrain.

[dredmorbius]

The demand can be generally predicted for at least several days in advance based on weather. This affects both generating capacity (incident solar, wind) and loads (hours of daylight, heating or cooling load). The process isn't perefect, but converges on experience the closer to present you are. Factors such as predictable human activities (workday, workweek, and seasonal factors) also enter in.

The events you may have noted in news of "negative energy prices" are often failures of prediction -- unexpectedly high availability (more sun or wind), and unexpectedly low demand. Though "pay to take my power" sounds good, it's actually a sign of mismanaged resources.

There are occasional incidental factors -- sudden demand, or more often, equipment or transmission failures which require bringing additional capacity online, or shedding load to prevent under-voltage (and hence: over-amperage), or underfrequency. Grid power frequency is generally 60Hz in the US, 50Hz in the UK, and just for grins, both in Japan, on separate and noninterdependent grids, which made generation capacity loss following the Tohoku earthquake/tsunami and Fukushima incident all the more critical. Loss of synchronisation or deviation by more than a very small fraction from the nominal frequency is considered a Very Bad Thing. Viz the recent UK blackouts.

[tofflos]

The Nordic system operators are in the early stages of transitioning from a reactive to a predictive process. The schedule does vary from day to day but there isn't anyone there that doesn't believe it can't be predicted with an accuracy that is more safe, and economical, than the current reactive process.

You can read more about it at http://nordicbalancingmodel.net.

[ianai]

So make a big enough nuclear plant for those peaks.

[NullPrefix]

Too expensive. Bigger capacity means bigger costs up front and runtime.

[ianai]

How much more expensive? How much more capacity?

I’d rather have way too much nuclear power than rely on any fossil fuels. If anything, energy demand seems posed to always increase.

[namibj]

AFAIK it's about Xenon poisoning.

[NullPrefix]

Xenon

[FullyFunctional]

Or deploy storage to make the curve smoother

[Scoundreller]

You mean I can “bank” A/C in the form of ice???

[namibj]

Well, ammonia coolers offer cheap storage in the form of liquid ammonia. This applies to both absorption and compressor coolers.

[mprovost]

...or hydro.

[The_rationalist]

Source for the latency of nuclear concerning spikes in electrical demand? > 70% of France electricity is made from nuclear and they don't seem to have the issue you claim.

[bryanlarsen]

Half of that 30% are natural gas peaker plants.

[08-15]

You're a victim of a common misconception. Nuclear reactors can ramp up and down as quickly as the control rods move. Check out the Borax experiments (from shutdown to full power in seconds) and the TRIGA reactor (from shutdown to gigawatts and back to shutdown in milliseconds).

What can't ramp quickly is the steam turbine connected to the reactor, but that's more of a design decision than a technical limitation. The German nuclear plants ("Konvoi" series) can in fact ramp faster than the German gas turbine plants, because that was a design requirement.