Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

A near 100% renewables grid is well within reach, and with little storage

reneweconomy.com.au

Post reply on HN
Print view View original

171–180 of 365 posts

Re: A near 100% renewables grid is well within reach, and with little storage

#171

Post by fulafel »

sokoloff wrote: post #147
ktzar wrote: post #140

I wonder how would the results vary if for every MW of renewables there was 100kWh of storage (using flywheels, lipo, thermal rock, gravity, etc...). I really believe a future with 100% renewables is very, very close. Will happen in the 2030s.

That’s only 6 minutes of peak load worth of storage (assuming it’s rated on output kWh, perhaps only 5 minutes otherwise). If you have three different types of renewables, all equally sized, and uncorrelated, it’s 18/15 minutes against a single type of renewable being offline. That doesn’t seem like enough for a 100% renewables grid to be 3 9’s reliable.

Demand can be regulated to meet supply using various ways (eg pricing, quotas, etc).

Re: A near 100% renewables grid is well within reach, and with little storage

#172

Post by idiotsecant »

Retric wrote: post #115
ZeroGravitas wrote: post #105

Earlier quoted context omitted.

Yeah, but that renewable hydro is unlikely to grow much in the USA, while wind and solar will be growing exponentially. Hydro is cool, and works well with solar/wind/nuclear to help match supply and demand, but ... If you look at global renewable output, the big chunk of hydro production that's been flat for decades, somewhat obscures the recent sudden rise of solar and wind.

Swapping hydro from 24/7 power to a backup for wind and solar goes a long way to eliminate the need for storage. We don’t need more total kWh per year of hydro we need to be able to more flexibility get those kWh.

I am an engineer that works on hydro control systems - It's worth noting that a hydro turbine, depending on it's construction, has a certain turndown ratio - That ratio of it's full scale output to it's minimum output. At the turn of the century designers of these turbines did not particularly care about operating at a lot of different power output levels, they cared about maximizing power output at a particular point, and importantly, maximizing efficiency at that point. These units typically have a turndown ratio very close to one. Consequently many hydro turbines are capable of a relatively narrow operating range, and are not suitable for fast grid support of the type that would be required as the primary source of solar backup. They're on-off type resources in many cases. These turbines can be retrofitted to variable geometry style turbines with much wider operating bands but these upgrades are slow and expensive.

Long story short - hydro is good as a 'base load' but we desperately need storage. Pumped storage, battery storage, compression storage. And we need massive transmission system upgrades (in the US at least). Nothing else will lead to a reliable grid based on renewables in the US.

Re: A near 100% renewables grid is well within reach, and with little storage

#173

Post by olddustytrail »

thrown_22 wrote: post #125
thayne wrote: post #57

"in Australia" is an important qualification here. Australia has a very high ratio of available solar and wind energy to population. Not that getting Australia fully on renewables wouldn't be exciting. But it is definitely an easier target than say the US.

Australian energy prices doubled in the last 6 months. I'm not sure who would ever use the Australian market as a model, other than "under no circumstances follow suit".

The reason for that is because of high natural gas prices. And the reason that increases overall prices is because they are treated as a single purchase so renewable sources (who are obviously well aware of gas prices) push their prices up to match.

This is so obviously a bad idea that even the CEO of a major energy firm has suggested the purchase market be split between renewable and fossil, so there are effectively two markets, and everyone can take advantage of cheap renewable prices.

You should learn about this stuff rather than parroting the nuclear fanbook.

Re: A near 100% renewables grid is well within reach, and with little storage

#174

Post by throwaway894345 »

epistasis wrote: post #139
throwaway894345 wrote: post #127

Earlier quoted context omitted.

The problem is that electrification of fossil fuel applications is going to significantly increase the demand on our grid. So it’s not enough to get to parity in renewables, but we have to go far beyond our current capacity in order to accommodate a world in which almost every car is electric (whether electric hybrid or green hydrogen) and almost every home uses electric rather than natural gas for heating (not to me…

It's going to increase the amount of energy flowing through the grid, but there's plenty of excess grid capacity to accommodate that. The grid is a technological marvel, but one weakness about it is that it has never included storage except small amount of hydro (which I've heard some claim is because nuclear needed it so that the reactor could stay always on, but I have my doubts on that origin story) Without storag…

That's an interesting point I hadn't considered before. That said, I would think the net effect is still increased demand on the grid. If everyone buys an EV, I can't imagine that constitutes a net reduction in demand on the grid even if everyone charges off-peak (unless utilities can pull storage from those car batteries during peak hours, and I doubt car owners will want that kind of wear on their batteries). Do you know of any publications which try to estimate the effect of electrification on capacity?

Re: A near 100% renewables grid is well within reach, and with little storage

#175

Post by megaman821 »

eldaisfish wrote: post #117
ZeroGravitas wrote: post #99

Earlier quoted context omitted.

No, because there never is such an issue. Renewables can turn themselves off and on so fast that this won't ever be a problem. The current Australian model we're discussing has about 15% 'overgeneration' because that's economically efficient, there's no problems caused by that.

What you have in mind requires someone to do the coordination. that is currently the system operator and they operate at a data rate measured in minutes or 4 s for the fastest changes (e.g. PJM). Meanwhile, solar output can go from 100% to 10% in three seconds. How is this not a problem?

Well, you need a 30 minute battery buffer to get gas peakers online. Whether those gas peakers are running natural gas or green hydrogen depends on how much excess solar capacity there is and how much hydrogen plants cost.

Also, medium term storage is a very, very young industry. Things like redox batteries, flow batteries, molten salt, compressed air, and many others are on the horizon. The better these work the more gas peakers are solely used as backup.

Re: A near 100% renewables grid is well within reach, and with little storage

#176

Post by ZeroGravitas »

erie wrote: post #170
JumpCrisscross wrote: post #152

Earlier quoted context omitted.

> US intends to hit this target (i.e. 95% carbon-free generation) in 8 years I think, with 100% and wider electrification of current fossil fuel uses in 2035 This seems ambitious. Source?

And the big elephant in the room? getting the US military on board is going to be tough. Every year, US armed forces consume more than 100 million barrels of oil to power ships, vehicles, aircraft, and ground operations

The US military spends more on renewables each year than most countries. They were on board long before the wider US Government felt it was politically safe.

https://www.reuters.com/article/us-usa-military-green-energy...

> The military’s push into alternative energy started under Republican President George W. Bush in 2007, when he signed a law requiring the Pentagon to get 25 percent of the electricity for its buildings from renewable energy by 2025.

Re: A near 100% renewables grid is well within reach, and with little storage

#177

Post by fallingknife »

fulafel wrote: post #171
sokoloff wrote: post #147

Earlier quoted context omitted.

That’s only 6 minutes of peak load worth of storage (assuming it’s rated on output kWh, perhaps only 5 minutes otherwise). If you have three different types of renewables, all equally sized, and uncorrelated, it’s 18/15 minutes against a single type of renewable being offline. That doesn’t seem like enough for a 100% renewables grid to be 3 9’s reliable.

Demand can be regulated to meet supply using various ways (eg pricing, quotas, etc).

Pricing is a poor tool as the signal doesn't propagate quickly enough. Quotas just means blackouts, and that isn't ever going to fly politically.

Re: A near 100% renewables grid is well within reach, and with little storage

#178

Post by JumpCrisscross »

ZeroGravitas wrote: post #168
jlmorton wrote: post #161

Earlier quoted context omitted.

Getting to 100% carbon-free generation is a goal of the President's Long Term Strategy [1]: > DECARBONIZE ELECTRICITY. Electricity delivers > diverse services to all sectors of the American > economy. The transition to a clean electricity > system has been accelerating in recent years— > driven by plummeting costs for solar and wind > technologies, federal and subnational policies, > and consumer demand. Building on…

I think the latter is talking about procurement of energy by the government, not generation. Which obviously helps and is something the government has more control over, but is a slightly different thing. The 100% by 2035 is fairly widely communicated, but there's definately a document that talks about aiming for 95% in 2030 and then focusing on electrification of other sectors as the diminishing returns start to hit…

> the latter is talking about procurement of energy by the government, not generation

Cute how they don’t link to the order nor mention its number. Here it is [1].

It exempts the GAO and independent agencies as well as anything not “an executive agency as defined in section 105 of title 5, United States Code” (§ 603.b). So no military, which is reasonable.

[1] https://www.whitehouse.gov/briefing-room/presidential-action...

Re: A near 100% renewables grid is well within reach, and with little storage

#180

Post by theluketaylor »

anonporridge wrote: post #130
ZeroGravitas wrote: post #99

Earlier quoted context omitted.

No, because there never is such an issue. Renewables can turn themselves off and on so fast that this won't ever be a problem. The current Australian model we're discussing has about 15% 'overgeneration' because that's economically efficient, there's no problems caused by that.

It's not a technical issue, but an economic one. If you have so much wind and solar generation that they spend too much of their lifespans sitting idle and not generating income, they potentially never even pay for their initial build cost and basic maintenance, let alone be a better investment than just buying a treasury note yielding 1%. That's a recipe for long term stagnation and depression.

If whole solar or wind farms find themselves sitting idle someone will drop off some containers nearby to split water into hydrogen or run a data center or something else that drinks power and skip the grid middle-man. Over-idle is not going to be a real issue; someone will always find a way to use of excess power.
Post reply on HN