The Remarkable Progress of Renewable Energy

[ZiprHead]

What about using the excess to charge batteries to use for controlled cutbacks to generator output? Seems like it might save money in the long run.

 

[bilby]

What about using the excess to charge batteries to use for controlled cutbacks to generator output? Seems like it might save money in the long run.

Again, it sounds like a great idea, if you have no grasp whatsoever of the scale of what you are trying to achieve.

There literally are not enough batteries in the world, by several orders of magnitude; And if it were somehow possible to build so much battery capacity, it would cost vastly more than the cost of the entire existing grid infrastructure, generators, cables, transformers and all.

The world's largest battery storage system has a capacity of less than 4GWh, and a discharge power rating of 1.3GW (I can't find data for the peak charge-up rate, but it would typically be lower than the peak discharge rate).

Germany generates an average of 57GW. The worlds largest battery could store about 4.2 minutes of Germany's grid power. To store the excess power from a day or so of high solar and wind output, you are going to need maybe a hundred of these. Each costs around 2.4 billion US dollars.

And you probably need to store at least a weeks worth of power to cover for typical long German nights under a winter anticyclone with light winds.

You won't get much change from two trillion bucks. That's trillion with a "T". Germany's GDP is about 4.7 trillion per annum.

 

[steve_bank]

An intro to battery specs.

Understanding Battery Amp Hours

Knowing how many amp hours your battery provides is the key to getting a battery that will support you through your daily routine. To learn more, read here.

www.mkbattery.com

In brief, most of the modern light water nuclear reactors are capable (by design) to operate in a load following mode, i.e. to change their power level once or twice per day in the range of 100% to 50% (or even lower) of the rated power, with a ramp rate of up to 5% (or even more) of rated power per minute.

https://www.oecd-nea.org/upload/docs/application/pdf/2021-12/technical_and_economic_aspects_of_load_following_with_nuclear_power_plants.pdf

Load following for any generator or power supply can be a problem. For rotating senators there can be stability and regulation problems that are load dependent. For rotating generators here are curves of load versus frequency and voltage.

In switching power supplies an old solution was to add a resistor across the output toto set minimum load, at the expense of a loss in efficiency.

Excess hydro power is used to pump water up to a lake. Excess nuclear power could do the same.

 

[Loren Pechtel]

Can't one avoid shutting down or shedding all load by simply routing the current through an appropriate large resistor? (Or would such a resistor (heat sink) need to be very large and well-designed for safety?)

A tiny fraction of the output of a large powerplant is capable of operating an arc furnace that can melt large quantities of any metal you care to name.

From what would this hypothetical "large resistor" be made? No material can soak up a GW of power for very long without melting (and then vaporising if you persist in adding energy to it).

You can shed a few kW in the manner you describe; But not a few million kW.

Boil sea water.

 

[bilby]

Can't one avoid shutting down or shedding all load by simply routing the current through an appropriate large resistor? (Or would such a resistor (heat sink) need to be very large and well-designed for safety?)

A tiny fraction of the output of a large powerplant is capable of operating an arc furnace that can melt large quantities of any metal you care to name.

From what would this hypothetical "large resistor" be made? No material can soak up a GW of power for very long without melting (and then vaporising if you persist in adding energy to it).

You can shed a few kW in the manner you describe; But not a few million kW.

Boil sea water.

That's going to be great for the fish. Good luck getting past a German environmental impact study with that one.

 

[Loren Pechtel]

Ooops! But my unthinking suggestion wasn't COMPLETELY absurd:

(Or would such a resistor (heat sink) need to be very large and well-designed for safety?)

should have been

(Or would such a resistor (heat sink) need to be very large and very expensive as well as very well-designed for safety?)

OTOH, this seems to be an argument in favor of wind and solar. They have little or no problem when load is reduced, right?
And anyway why don't the best-when-cheapest applications (pumping, excavation(?), hydrogen production, EV charging, bitcoin mining ha ha ha) show up when the wholesale electricity price is near zero?

They're the problem. You're proposing to dig deeper into the hole.

And of course this discussion just reinforces the importance of batteries and other energy storage methods.

If we had good storage options the issue would be moot.

 

[Elixir]

If we had good storage options the issue would be moot.

What are the attributes of a “good storage system” that are lacking from those mention?

 

[Loren Pechtel]

My question was technical. The briefest skim of the thread would suffice for anyone to know your views on intermittent renewables.

BTW, what about geothermal? Not intermittent, right?

Not very much of it available.

And, locally, we have objection to geothermal development because people are afraid it will destroy the hot springs.

 

[Loren Pechtel]

What about using the excess to charge batteries to use for controlled cutbacks to generator output? Seems like it might save money in the long run.

This isn't Factorio with a 7 minute day and only 42 seconds/day of full darkness and nothing ever wears out. Grid scale batteries simply don't exist by some orders of magnitude.

The only technology that could presently be deployed at grid scale is using hydrogen as your storage medium. Round trip efficiency isn't too good and whether we have enough of the required materials to even build that much capacity is questionable. And note that doing so would end up being the majority of the cost of electricity.

 

[Loren Pechtel]

Can't one avoid shutting down or shedding all load by simply routing the current through an appropriate large resistor? (Or would such a resistor (heat sink) need to be very large and well-designed for safety?)

A tiny fraction of the output of a large powerplant is capable of operating an arc furnace that can melt large quantities of any metal you care to name.

From what would this hypothetical "large resistor" be made? No material can soak up a GW of power for very long without melting (and then vaporising if you persist in adding energy to it).

You can shed a few kW in the manner you describe; But not a few million kW.

Boil sea water.

That's going to be great for the fish. Good luck getting past a German environmental impact study with that one.

You pump the water into an evaporator, you don't stick your coils into the water. Pump the brine into someplace like Great Salt Lake.

(Yeah, I'm not saying it's efficient, I'm saying if you truly needed to dump power you could.)

 

[Swammerdami]

You pump the water into an evaporator, you don't stick your coils into the water. Pump the brine into someplace like Great Salt Lake.

(Yeah, I'm not saying it's efficient, I'm saying if you truly needed to dump power you could.)

Since the goal was to discard the energy as a better alternative than selling it for a NEGATIVE price, I don't think efficiency is an issue!
Although if you ARE heating water, that hot water can be an energy storage method.

Calling intermittent renewables the PROBLEM is misleading in terms of the particular subthread about negative energy prices, ASSUMING that their energy is sold at the market price. I think we all might agree that it is misguided for governments to enforce a high price for electricity at times when the market price is zero or less. (Though I guess the price doesn't get THAT low without the subsidies.)

As Loren mentions, hydrogen can be produced when electricity is cheap. There are other applications where the power consumer can choose WHEN to buy electricity. For example, IIUC electricity is a bigger expense than hardware for data centers! Does Google have redundant centers in different parts of the world (daylight zones), quiescing each at night when electricity is expensive there?

(We don't need to hear again that nuclear is better, better, better. The topic is HOW to use intermittents if that's what we got.)

 

[bilby]

If we had good storage options the issue would be moot.

What are the attributes of a “good storage system” that are lacking from those mention?

Energy density.

The best (ie highest energy density) batteries are rapidly approaching the limits of what can be done by manipulating free electrons.

You can get higher energy densities by playing with the electrons involved in molecular bonding, but then you aren't using batteries anymore, you're using fuels.

You can get higher energy densities still by using nuclear forces, but then you are using nuclear power.

The other option is to abandon energy density and instead use sheer volume of something incredibly cheap - that's how pumped hydro works. You need a massive amount of water, but water doesn't cost much. If you can build a battery out of materials that are cheaper than water, and find enough cheap land to put your unobtanium batteries on, you are on to a winner.

Energy density is inextricably linked to technology - a high tech process is one that uses high energy densities.

For a clear example, look at ships - they progress from low energy density (sailing), through steam, to internal combustion, and finally to nuclear power. Each step more effective at getting stuff across an ocean quickly than the last. Each requiring less fuel than the last (sailing ship fuel is free and abundant; But if you measure how much air is needed, it adds up to a lot).

Industry shows the same progression, from windmills, waterwheels, and greenhouses, through steam engines and internal combustion, to nuclear power. As energy density goes up, so does wealth.

Going back to wind and solar power is as practical as a return to the age of sail. Sailing vessels have lots of niche applications, but a push for all (or even very much) modern shipping to go back to wind power would be stupid and disastrous, just on energy density grounds (though there are, of course, other problems too, not least wind's unreliability).

 

[bilby]

Calling intermittent renewables the PROBLEM is misleading in terms of the particular subthread about negative energy prices, ASSUMING that their energy is sold at the market price.

Their energy is NOT sold at the market price, and if it were, the problem would indeed go away, along with the windmills and solar panels which could no longer pay for themselves in their own lifetimes.

The assumption that electricity markets are in any sense free and fair is laughably naïve.

 

[Elixir]

The other option is to abandon energy density and instead use sheer volume of something incredibly cheap - that's how pumped hydro works. You need a massive amount of water, but water doesn't cost much. If you can build a battery out of materials that are cheaper than water, and find enough cheap land to put your unobtanium batteries on, you are on to a winner.

Yeah, that. It’s what I was thinking.
Unobtanium is so energy dense that you don’t need cheap land - the size of a ping pong table can power the globe indefinitely.
But unobtanium being in such short supply, I think water fills the role quite well. Why should “energy density” have anything to do with it, other than portability?

 

[bilby]

The other option is to abandon energy density and instead use sheer volume of something incredibly cheap - that's how pumped hydro works. You need a massive amount of water, but water doesn't cost much. If you can build a battery out of materials that are cheaper than water, and find enough cheap land to put your unobtanium batteries on, you are on to a winner.

Yeah, that. It’s what I was thinking.
Unobtanium is so energy dense that you don’t need cheap land - the size of a ping pong table can power the globe indefinitely.
But unobtanium being in such short supply, I think water fills the role quite well. Why should “energy density” have anything to do with it, other than portability?

It doesn't. But 'portability', in the broadst sense, is no trivial thing to handwave away.

There are VERY few places where hydropower is practical, and most of them already have it.

How do you set up pumped hydro storage in Kansas? You need deep valleys, ideally two of them, one well above the other (but not too far above, or too far away); And you need to not mind flooding them both (which can be problematic if somebody has built a city in one or both of them); And you need them to have adequate water to begin with.

And that's where energy density comes back to bite us. Gravity is utterly shit as a force. So while a big hydroelectric scheme may be fairly cheap, it's really not that BIG.That is, it occupies a lot of space, but it doesn't store a lot of power per unit volume, so to soak up a lot of power you need to flood an absolute shitload of valleys. There are simply not enough valleys (and the ones we have are often in inconvenient locations).

 

[Elixir]

How do you set up pumped hydro storage in Kansas?

You could ship it from Colorado via existing grid.

But you’re probably right that energy density is a fundamentally prohibitive factor, at least for large scale energy storage.

 

[TV and credit cards]

My question was technical. The briefest skim of the thread would suffice for anyone to know your views on intermittent renewables.

BTW, what about geothermal? Not intermittent, right?

Right. And can be easily throttled. I posted up a number of stories on today's "geothermal" utilizing fracking tech both here and/or in the Climate Changed thread. There's oodles of it available with today's technology. They are currently going for the low hanging fruit in Utah but geological survey maps show this is viable over about a third of the US. And it has nothing to do with hot springs.

Not very much of it available.
And, locally, we have objection to geothermal development because people are afraid it will destroy the hot springs.

 

[Loren Pechtel]

If we had good storage options the issue would be moot.

What are the attributes of a “good storage system” that are lacking from those mention?

Energy density.

Disagree. Energy density is important when you're hauling it with you but you're not hauling around grid scale storage systems. Thus density is almost irrelevant. At grid scale you care about $ per joule stored, $ per watt it can deliver, and round trip efficiency. Density is only relevant if it's so low that where to put it becomes an issue. (Pumped hydro--the only way you get a remotely decent $ per joule is if nature did most of the building for you and you only need to dam one narrow spot.)

The best (ie highest energy density) batteries are rapidly approaching the limits of what can be done by manipulating free electrons.

Approaching? What reaction could be more energetic on a per-pound basis than lithium?

You can get higher energy densities by playing with the electrons involved in molecular bonding, but then you aren't using batteries anymore, you're using fuels.

Disagree. Look at your car--that battery under the hood. When you start your car you are oxidizing lead.

The difference between rechargeable batteries and fuels is that the battery reaction can be reversed by the application of power. Fuels are not directly reversible. (Not that they are inherently reversible--crack water, store the components. Recombine, you get power. But the generator and the cracker are separate pieces of equipment.)

The other option is to abandon energy density and instead use sheer volume of something incredibly cheap - that's how pumped hydro works. You need a massive amount of water, but water doesn't cost much. If you can build a battery out of materials that are cheaper than water, and find enough cheap land to put your unobtanium batteries on, you are on to a winner.

The problem with pumped hydro is the cost of the container.

Going back to wind and solar power is as practical as a return to the age of sail. Sailing vessels have lots of niche applications, but a push for all (or even very much) modern shipping to go back to wind power would be stupid and disastrous, just on energy density grounds (though there are, of course, other problems too, not least wind's unreliability).

Ships are a case where you're hauling power around.

 

[Elixir]

The problem with pumped hydro is the cost of the container.

That’s the geographic constraint. Where I disagreed with Bilby is about whether pumped hydro storage has already been fully deployed. I think it could be downscaled, not necessarily to portability, but to improving life in places with zero infrastructure but lots of sun, serving small populations in small villages, providing a little power for after dark. I’m sure smaller locations that are close to ready-made, are more plentiful than large ones.

 

[bilby]

improving life in places with zero infrastructure but lots of sun, serving small populations in small villages, providing a little power for after dark.

Sounds great. It's a shame that we mostly stopped living like that at the end of the Middle Ages.

Most people live in big cities. Set up all the small villages in the world with a nice local power system, and the majority of humans would not benefit at all from your project.

Even the people who do still live in small villages are completely dependant on cities; Many villagers are commuters, and work in a nearby urban centre. Those who aren't depend on urban factories (often in another country) for almost everything. Their energy needs are modest, in large part because their vehicles, tools, homes, furniture, appliances, cookware, etc., etc., are made in energy hungry factories elsewhere.

Domestic lighting, heating, and airconditioning are a fairly small fraction of world electricity consumption, and an even smaller fraction of world energy consumption. Fixing these obvious in-your-face power demands barely scratches the surface of the global energy problem - how do we power ALL of modern society, 24x7x365, without destroying our environment, and/or suffering blackouts, energy rationing, or other forms of energy poverty?

That's a huge and thorny problem, exacerbated by politicians who think that domestic lighting is the main (or even a major) source of demand for electricity.

"Keep the lights on" is an idiom, not a problem specification.