Comment by bell-cot | Hacker News Reader

Comment by bell-cot | Hacker News Reader

The reality is much more complex than "batteries replace gas" -

> Developers can no longer use financial modelling that assumes gas power plants are used constantly throughout their 20-year-plus lifetime, analysts said.

> Instead, modellers need to predict how much gas generation is needed during times of peak demand and to compensate for the intermittency of renewable sources that are hard to anticipate.

> "It does become more complex," Nigel Scott, head of structured trade and commodity finance at Sumitomo Mitsui Banking Corporation, said.

> Investors are putting increased scrutiny on the modelling, he added.

- so basically, maintaining a large-scale grid is an optimization problem. And batteries merely shift the answer to "how much of which each type of equipment should we have?" around some. Kinda like someone architecting a DC-scale system has to understand trade-offs between L1 cache / L2 cache / L3 cache / local-to-core RAM / more-distant RAM / SSD / HD / Tape - vs. what equipment is actually available - at what prices, lead times, configuration limitations, ...

A major problem here is that intermittency isn't consistent.

Okay, solar doesn't generate at night, so you would need to charge some batteries during the day and discharge them at night. Maybe that's fine.

But solar also generates less in winter. If we want to transition heating from oil and gas to electric, we need a lot of generation in the winter. If we build some more solar to do that, now there's way more than enough in the summer, so anything that can make up the shortfall in winter is only going to be used in winter. Duty cycle for whatever that is just got cut in half or worse.

Then sometimes it's cloudy for a week. Having enough battery capacity to make it through the night is very different than having enough to make it a whole week, or two. By the second or third day you need enough traditional generating capacity to run the whole grid at night -- but that capacity only gets used one week out of the year.

Now you want to say that gas is too expensive if it can only amortize its costs in those limited circumstances. But what do you want to do instead? You need something that can run the whole grid the week that it's cloudy, none of the options for that are cheap, but the alternative is everybody loses power that week.

But the capacity needed to top up that battery on a cloudy week is still less than having a gas plant having to meet peak demand.

Kinda like the BMW i3 with Rex. You charge it at home (solar), but when it gets low the on-board generator (gasoline 2 cylinder) can trickle charge your battery until you get home (where you have solar again).

That works in a car because a car's energy demands are bursty. The power to accelerate the car from a stop comes from the battery and then the car's energy requirements drop by 95% and the tiny engine can eek out a little more than the 5% needed to maintain cruising speed and use the rest to slowly recharge the battery.

The power grid doesn't work like that. The base load is around half of the peak load. It never drops to 5%.

That doesn't mean the batteries can't be useful. If the average load is 150GW but that's because it's 100GW at night and 200GW during the day, the batteries let you get away with having only 150GW of average generating capacity instead of 200GW, because during the times when the generation exceeds the demand you can put the surplus in the batteries.

But you still need to maintain an average of 150GW of generating capacity or the batteries will get empty and the power goes out.

I must say I fail to see how any of this is all that new. Winter affects how much air conditioning and heating is needed - and probably even when people go to work and return. You had to take that into account before solar issues. Now both consumption and production are affected by the season, sure, but that's still a known mechanism. Same for cloudiness vs air conditioning (and heating and lighting).

But wait, in most places hydroelectricity availability has always been a factor. And THAT was already variable depending on the season (and anomalous seasons). So anyway, both production and consumption have always been seasonal and weather-dependent.

With sometimes chaotic results when a winter is exceptionally mild like last winter in Europe, or strong. Not new either.

And then on top of that, in places like the American West, the prices to import electricity from neighboring regions or states have sometimes been chaotic. Also something that had to be taken into account for peaking gas-powered generation.

nobody is saying it is new in concept, but it is new in magnitude and impact.

> I must say I fail to see how any of this is all that new.

The difference is the scale. Traditionally you had a particular amount of base load that would run all the time. Nuclear and coal. The load never dropped below their generation capacity so they never had to stop generating and making money to recover their construction costs.

Then you would have natural gas peaker plants that only ran for part of the day, but they still ran pretty much every day. And these would also allow you to shut down base load plants for maintenance during the lower demand season. So they still got plenty of use.

Now you want to have solar and batteries which can satisfy the demand 98% of the time -- meaning some backup system has to recover its costs out of the remaining 2% of the time. But that backup system doesn't just have to pick up the extra 10% load because it's extra hot today. If it's cloudy long enough for the batteries to run down and it's night, your output from that system is now zero, but you still have the entire load of the power grid to satisfy. Where does it come from? An entirely parallel generating system that only gets used 2% of the time?

The alternative is to keep something like nuclear as e.g. 40% of the grid, and have it generate all the time as it does now. At which point that 40% of the generating capacity is more like 80% of the nighttime load and you're in much better shape to have to make up the last 20% than the entire 100%.

I think the article is not so much about how more difficult it is to price the energy of a gas peaking plant but instead about changing strategies by developers of such plants. There is the temptation to switch to battery plants now rather than later. There is the change in the equation that such plants used to be mostly priced by the energy provided (in contracted amounts) and that now they are more charging for contingency / continuity service. That is they are charging for a different service: not paid by the kW/hr but by the capability to produce on demand. And then subsidies, permitting, environmental concerns also are changing: easier to build batteries, hard to build gas. And lenders having to follow in the change in profitability mechanism.

> There is the temptation to switch to battery plants now rather than later.

But this is the problem, right? They don't serve the same purpose.

The battery plant allows you to store surplus solar generation during the day and use it at night. That's useful, but it's not the same thing -- because if it's cloudy for an extended period of time, you don't have surplus solar generation during the day, and your batteries are empty. What then?

Batteries can store energy from any source, with solar, wind, nuclear and hydro being top candidates as all might produce in excess of demand.

The source isn't really the point. If you normally have 200GW of solar generation but it's cloudy so now you have 10% of that, you don't have surplus generation of any kind. The remaining power plants can't even cover the current load, the batteries are being discharged rather than charged and when they run out, what do you do?

I think most people are delusional about this, including the operators talked about in the article. I believe this is mostly posturing and people trying to find ways to get some of that sweet subvention money flowing for renewable tech and associated. In other words, there are some profits to be made and for this they need to pretend that they don't know better. Because as you said, this is not sustainable. The numbers don't work, if we only build battery with renewables someone has to lose power somewhere some of the time.

I worked around a small model with rather optimistic assumptions with zero concern for cost and a focus on efficient consumption to determine what would be required to make a single 1–2-person habitation completely sustainable off grid but with most of the modern confort. I used past weather data and sunshine/wind values. It doesn't work. The number of batteries you need is ridiculous and unrealistic when you scale up the model, that's before considering costs that are just insane.

I think renewables are a good technology especially because we can use the peaks to our advantage and work/organise society around that. In particular car battery charging and air conditioning are 2 very good candidates. Realistically we still need reliable technology to ensure baseload at all times, especially at night. Personally, I think nuclear is just that but just saying that word is so political that people lose all rationality it seems, so we get sucks in meaningless debates and projections...

In a weird twist, most pro-renewables are also anti electric car, I swear ideological people are really unbelievable. I think the world became too political in general (a feminine way of "solving" problems) but in particular the field of energy is overrun by politics; which is kind of funny when you consider that the core skill to make everything work is rationality.

But I guess when we will get grid shut down like in South Africa they will agree that batteries don't work. It will be too late though...

If that's the situation, then you have just demonstrated that you can't do it like that. Solar plus battery. That's fine. You look for something else. For example you get a contract to fund a gas-powered humongous plant from the companies whose mandate it is to not run out of power. (but you probably can't get gas for that plant on a one-off basis - you'll have to store.)

The point is to do that use case planning (and fund a plant based on the results.)

Hopefully nobody is really getting themselves in that situation.

I like that analogy.

Batteries are kind of the RAM/cache in the system: - Big merchant batteries like Hornsdale are kind of like more distant ram RAM - Batteries co-located with renewables are kind of the local to core ram - UPS and similar are cache - Pumped hydro is probably Tape ;)

It feels like we might still be lacking a good/widely deployed HD/SSD equivalent in this space, hopefully new/emerging technologies (maybe the sodium chemistries others are mentioning) will be able to fill that in.

I think in terms of the energy grid batteries are currently more like your L1 cache or similar. I.e. very expensive to have, and has specific requirements so you have little of it.

Hydro would be more like your RAM.

Superb analogy indeed as this is the same approach I use in my next pursuit in breaking through to those from a technology background. The cache sources can be anything providing energy to be stored in the rapid response system while the cache system itself is modular in design allowing ingress and egress simultaneously based on inputs and outputs of demand. The fun part is designing and writing the software to control all the "cache" hardware. I have no idea what I am talking about though but I did stay in a Holiday Inn last night... or was it a Motel 6. :)

For those with their ear on the track when that sound resonates they will see the light, everyone else will be in the dark without energy storage. Costs are spiking everywhere and the U.S. government is having meetings near weekly exactly about this coming fun. Those meetings reflect frank direct statements about coming derailments and the grid has not changed since its inception and remains to be centralized to this very day. There are enough smart technologists here that can put together exactly what I infer, significant opportunity.

For those further interested check out YT: "Environment Hearing: Clean Power Plan 2.0 Will Jeopardize Reliable and Affordable Energy". As with anything making significant revenues however those threatened with revenue loss will play the dirtiest games to preserve their position, this includes increasing the pollution output that is making that revenue.

Stay Healthy!

Complexoty causes high system costs at scale for energy grids with a large amount of intermittent renewables. Adding more stable adjustable sources like nuclear, hydro or geothermal will become more attractive than creating wildly intricate "smart grid" architecture. Just produce more power when needed instead of costly redistribution and storage.

It is probably smart to keep around a certain capacity of nonrenewables to provide at least some base load. Long periods of low sunshine and slow winds could deplete batteries to a critical level. Also, the turbines of big powerplants act as grid frequency stabilizer. Do grid-scale batteries use alternators or might they run flywheels?

It's quite likely that in the future electricity sellers will need to pay a tariff to cover the operation of flywheels.

Not sure why the cost would be borne by sellers. More likely consumers will pay for it as part of the grid infrastructure in my opinion.

Well, currently the sellers are the ones directly paying for the grid infrastructure.

It makes much more sense. They are the ones that can choose what part of the grid they plug on, and they are the ones choosing if they provide the service or not.

I dont think I agree.

Typically electric companies pay for the grid infrastructure and operation currently. Electricity producers like solar plants out in the desert is not paying to maintain the poles to your house.

Retail electricity companies pay only for their own grid. They aren't paying for the link between your city and the plant out in the desert.

maybe we have a difference in terminology. The interconnects between the grid and primary producers are often owned an managed by the retail company. Who pays for them is often a sticking point and can go both ways.

What I think is indisputable is that it is the retail electric company who manages and maintains their grid, and manages it's demand and stability.

>sellers are the ones directly paying for the grid infrastructure.

This is absolutely not the case for the vast majority of that infrastructure. You just mentioned small connections. If you look at the grid, it is basically all retail companies[1]

https://www.researchgate.net/figure/California-electric-grid...

You're using American-centric terminology that doesn't translate well to other countries, most of which have one national grid company that manages the transmission grid (which extends up to the generation facilities) and where 'retail companies' refers to local distributors who may operate their own distribution networks or who may just handle billing etc.

I believe they just switch on and off fast enough.

Tesla power wall does that.

Yes, but the rest of the grid can not, except for some forms of hydro, flywheels, superconducting coils and grid scale batteries. They hydro has a fastest rate of change of about 1 minute from zero to full load and a bit slower to go back again and batteries can more-or-less match renewables for rate of change. The superconductor solution is the fastest but also the most expensive per KWh of storage.

In the time before renewables all of the rate-of-change limitations came from sudden increases or decreases in consumption, never from the supply side and this has subtle implications for the structure of the power grid and how much power companies can do to control the match between the two.

Think of it as a person walking across a rope with a balancing pole: you can overbalance for a short while because you can correct for that with the mass of the pole. But if the overbalance is too large for the mass of the pole then you will inevitably fall (brownout, blackout).

"Superconductor solution": did you mean "supercapacitor solution"?

No, superconductor. Effectively an electronic version of the flywheel.

There is a company in the United States that has been making these for almost 20 years now, they are used for ride-through in hospitals and for windfarm output stabilization.

https://en.wikipedia.org/wiki/Superconducting_magnetic_energ...

https://www.amsc.com/gridtec/renewable-interconnectivity-sol...

Enjoy the read. It's interesting stuff.

It is indeed, but the refrigeration needed would seem cumbersome for most applications.

Not really, I've seen these units in the middle of the mountains sitting right next to a windfarm. About as inaccessible as it gets and yet they were there and humming along. Note that there is plenty of energy available for the refrigeration and that those units run for years unattended. Occasionally you need to top off the refrigeration gear but that's once every two years or so, a bit more involved than your average HVAC setup but not that much more involved.

Yes but we will get much more grid scale batteries anyway

One of the biggest challenges with renewable energy in energy grids is something called inertia.

Her's a nice article:

https://www.fingridlehti.fi/en/what-is-inertia/

Batteries can and are used for frequency stabilization, yes.

https://www.pv-magazine.com/2022/07/27/tesla-big-battery-beg...

Superconducting coils as well. Those are popular near windfarms due to their fast response time, both on the uptake as the release.

Inverters have come a long way in the past few years. They are at the point where they are (subjectively) better than giant flywheels.

It doesn't necessarily need to be non-renewables through. There just has to be spare capacity that the grid could count on being there. There just needs to be a way for the grid to pay for the capacity that's going to go unused a lot of times, whether it's batteries, extra water and turbine in a dam, or standby power plants.

Yes, what type of equipment do you want. And do you want to favor fossil fuels or renewable. If the latter, deploy batteries.

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