This solar farm has to switch off every second day due to negative prices

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https://reneweconomy.com.au/this-solar-farm-has-to-switch-off-every-second-day-due-to-negative-prices-63529/

Some thoughts:
- This could be a great tool to penalize the non-green sources (coal, gas) that can't switch off on the cheap, and end up getting hit by the negative prices.
- OTOH these agreements are confidential, and since the non-renewable sources can provide stable and weather independent supply they could easily negotiate a lot better conditions, meaning no negative prices, so without sufficient "hydro batteries" I doubt the pressure is meaningful on non-renewable sources

[Marco]

Time to mine and refine more aluminium.

[bdunham7]

There's nothing surprising or wrong about this.  Obviously with a zero incremental cost, the solar plant would like to sell all of the electricity it can produce, but there will never be an exact match between capacity and demand.  When the price of the commodity goes below the cost of production, you turn the system off.  Since the only way you can have sufficient production all or most of the time is to have surplus capacity, it seems obvious that at times some capacity will not be needed.  When solar was a small part of it, other non-zero incremental cost producers would drop offline first. As solar and wind become larger, curtailment will become the normal process for managing the grid.  At least it is easy and quick to turn on and off!

[T3sl4co1l]

Time to mine and refine more aluminium.

It would be interesting actually to put it into an aluminum battery of some sort.  Unfortunately the Hall process demands continuous operation at scale; indeed, it's usually run on hydro.

Aluminum electroplated out of some kind of organic carbonate solution (analogous to getting lithium metal out of an overcharged ion cell) would be interesting, though I wonder if it could end up anywhere near economical anyway.  (And in any case, energy storage is better with alkali metals, no need to try and sell an already quite cheap industrial metal out of it, etc. etc... )

Tim

[Syntax Error]

Any engineers know of a way of converting CO₂ into a solid? This would be a rather green way of using the over capacity by directly or indirectly removing atmospheric CO₂ and then, selling this carbon capture on the global carbon trading market. Yes New South Wales, you can tax that. Maybe even make hydrogen for fuel cells? Or just mine Bitcoins on 'negative' electricity days? Otherwise it's a tragic waist of sunlight.

[coppice]

Time to mine and refine more aluminium.

It would be interesting actually to put it into an aluminum battery of some sort.  Unfortunately the Hall process demands continuous operation at scale; indeed, it's usually run on hydro.

Most aluminium used to be produced in countries with surplus hydro power. Look at the global production figures now, and you'll find most aluminium is produced in China, where there is a massive shortfall in renewable power. They are the world's biggest installer of renewables, but they have a long way to go to wean aluminium production off fossil fuels.

[ejeffrey]

Any engineers know of a way of converting CO₂ into a solid? This would be a rather green way of using the over capacity by directly or indirectly removing atmospheric CO₂ and then, selling this carbon capture on the global carbon trading market. Yes New South Wales, you can tax that. Maybe even make hydrogen for fuel cells? Or just mine Bitcoins on 'negative' electricity days? Otherwise it's a tragic waist of sunlight.

It is pretty hard and energy inefficient to remove CO2 from the atmosphere as the concentration is so low.  For the forseable future it is much more advantageous to remove it from waste streams where the concentration is much higher.

In terms of fixing CO2, there are basically two options: 1) carbonate minerals.  This is attractive because it doesn't require massive energy input.  This is how geological carbon sequestration works. The downside is that you have to mine a ton of uncarbonated minerals.  We actually mine carbonated minerals (calcium carbonate) and extract the CO2 in order to produce quicklime.  2) hydrocarbons.  This doesn't require any particular mining, but again we currently mine hydrocarbons and burn them, so this doesn't make a huge amount of sense to do the reverse process.

[daqq]

Any engineers know of a way of converting CO2 into a solid? This would be a rather green way of using the over capacity by directly or indirectly removing atmospheric CO2 and then, selling this carbon capture on the global carbon trading market. Yes New South Wales, you can tax that. Maybe even make hydrogen for fuel cells? Or just mine Bitcoins on 'negative' electricity days? Otherwise it's a tragic waist of sunlight.

Not sure about solid, but carbon capture is a thing. Don't know how efficient it is.
http://www.climeworks.com/our-technology/

[Retep]

Any engineers know of a way of converting CO₂ into a solid?

Grow a tree?

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Grow a tree?

Isn't photosynthesis clever? This might work as a concept if the excess electric is used to power pumps to irrigate crops or even a forest. But then where does all the water come from in a desert where solar farms are often located?

Not sure about solid, but carbon capture is a thing. Don't know how efficient it is.

Sucking air through carbon eating filters might work, but I doubt there are economies of scale when you calculate how much C0₂ is produced making the fans in China or India. Idea for a Kickstarter/Snakeoil project; fit carbon eating filters on all kinds of extraction fans around the home. A million dollar$ please.

It is pretty hard and energy inefficient to remove CO2 from the atmosphere as the concentration is so low.  For the forseable future it is much more advantageous to remove it from waste streams where the concentration is much higher.
--etc--

Agreed. I wonder if they'll ever worry about the levels of CO₂ on Mars?

It's a crying shame that all of his sunlight goes to waste, but that's just the "the market" for you. Expecting governments, state administrators, industry and private venture capital to use joined-up-thinking to mitigate climate issues is not going to happen anytime this century.

[chickenHeadKnob]

The other chemical pathway for energy storage is Ammonia. Ammonia can be burned, or put through a fuel cell or sold as fertilizer in liquified anhydrous form. Farms could be made entirely self powered.

[NiHaoMike]

A reasonable way to make use of the "extra" energy is to pass through the savings to customers. A large part would be to leverage existing thermal mass as storage, e.g. set water heaters to a higher temperature, run HVAC equipment more, set freezers to minimum temperature.

[chickenHeadKnob]

A reasonable way to make use of the "extra" energy is to pass through the savings to customers. A large part would be to leverage existing thermal mass as storage, e.g. set water heaters to a higher temperature, run HVAC equipment more, set freezers to minimum temperature.

In Canada I think this already being tried in a small way, I heard Nova Scotia or PEI has some kind of smart water heater program but I live on the opposite coast so not sure.. It is easily implemented with an IOT controller that checks in with the power utility  and requires very low incremental infrastructure costs. Easy win.

[DenzilPenberthy]

I don't know about using excess power to remove CO₂ directly but there are plants using excess power to generate hydrogen which is then fed in to the gas grid.

https://en.wikipedia.org/wiki/Power-to-gas

[Marco]

Unfortunately the Hall process demands continuous operation at scale

Everything needs to be kept molten, but that can probably be done with far less power than electrolysis itself. The plants weren't designed with as hugely varying power costs as we have nowadays, there is obviously huge inertia given the capital and R&D investments involved but I expect intermittent plants at some point. Even if none of the alternative reduction methods bear out.

It's solidified electricity, if you can make it and even get paid for the electricity you're consuming you're golden.

[Someone]

A reasonable way to make use of the "extra" energy is to pass through the savings to customers. A large part would be to leverage existing thermal mass as storage, e.g. set water heaters to a higher temperature, run HVAC equipment more, set freezers to minimum temperature.

This is significant "low hanging fruit" in the possible ways to develop demand responsive grids. Various sources claim HVAC alone is a significant part of the total energy demand so its not like the well funded yet minimally effective efforts to change to high efficiency lighting. Sadly very few customers are exposed to the wholesale market so many efforts so far have been by pooling resources through a wholesale market participant, who acts as a middle man and takes all the profit.

More encouragingly energy for heating is dominated in "developed" countries by low temperature demand which is easier to deliver/store or simply produce at low cost from renewables. Long term storage is still more expensive than oversizing the generation capacity there, so market fluctuations with negative cost periods are probably a healthy sign.

[Marco]

Easier to store, yes. Easier to deliver, hell no. Only a small subset of houses have district heating, they pretty much all have electricity.

[Someone]

Easier to store, yes. Easier to deliver, hell no. Only a small subset of houses have district heating, they pretty much all have electricity.

Note the conjunction:

More encouragingly energy for heating is dominated in "developed" countries by low temperature demand which is easier to deliver/store or simply produce at low cost from renewables.

Store and deliver, as in deliverable. Delivering low temperature deltas is much easier, particularly from local thermal storage.

[Simon]

I was paid to use electricity last weekend.

[Kleinstein]

Industrial, larger consumers already see the variable costs and some cases they already make a good use of it (e.g. large scale cooling). It may need extra investments to get the production more flexible. To some degree this may also work with aluminum production, though this may not be the most efficient case. There are also some facilities that shut down in times of high demand (e.g. during winter or heat waves in other areas) and thus lower the need for storage this way. This could probably also be done with aluminum production - shut down for those months were the supply is usually short - this would replace long term (e.g. summer to winter) storage.

With many small users (like private freezers) there is the problem of how to control it reliably. Such a control system showing glitches could bring down the grid, if it is doing the wrong thing. So it is not an easy thing.

For storing carbon there is the option to use plant growth and make some kind of char coal, that can be stored in stead of getting burned. So kind of coal mining in reverse. So probably stop coal mining first.  At least the plants could be used to get concentrated CO2, when pants are burned to produce energy.

[David Hess]

- This could be a great tool to penalize the non-green sources (coal, gas) that can't switch off on the cheap, and end up getting hit by the negative prices.

The Sierra Club actually had that as an bonus when enacting renewable energy laws in California a couple decades ago.  Keep in mind that it affects nuclear also.

If you penalized dispatchable energy sources enough, then they will not be available when you need them, as California is discovering.  These laws are specifically intended to lower the capacity factor of dispatchable energy sources, especially nuclear, making them less economical.  California and countries like Germany have ended up exporting their dispatchable energy demand to neighboring states and countries.

And if you think batteries will solve that, they cost as much as a nuclear power plant with the same capacity but provide less capacity factor as California also discovered which is why they did not purchase battery capacity commensurate with their renewable energy capacity.

You have to wonder about a political process which creates incentives to make money by installing megawatt scale toaster ovens.

https://slate.com/business/2015/09/texas-electricity-goes-negative-wind-power-was-so-plentiful-one-night-that-producers-paid-the-state-to-take-it.html

[NiHaoMike]

If you penalized dispatchable energy sources enough, then they will not be available when you need them, as California is discovering.  These laws are specifically intended to lower the capacity factor of dispatchable energy sources, especially nuclear, making them less economical.  California and countries like Germany have ended up exporting their dispatchable energy demand to neighboring states and countries.

And if you think batteries will solve that, they cost as much as a nuclear power plant with the same capacity but provide less capacity factor as California also discovered which is why they did not purchase battery capacity commensurate with their renewable energy capacity.

The current California energy crisis is due to aging/neglected/unsafe infrastructure. That might shift things in favor of batteries, as in perhaps it would be more economical to convert houses to off grid or neighborhoods to microgrids than it would be to build new, safe transmission lines? With the current situation already getting the ball rolling on residential storage, it's only cutting into the funds utilities would have to rebuild with, and any attempt they might try to recover that will further push investment in residential storage+solar.

[David Hess]

The current California energy crisis is due to aging/neglected/unsafe infrastructure. That might shift things in favor of batteries, as in perhaps it would be more economical to convert houses to off grid or neighborhoods to microgrids than it would be to build new, safe transmission lines? With the current situation already getting the ball rolling on residential storage, it's only cutting into the funds utilities would have to rebuild with, and any attempt they might try to recover that will further push investment in residential storage+solar.

California is disfunctional in may ways but shutting down power plants so that they had to transmit power over longer distances did not help the situation.  This is the state which legislated fixed wholesale but variable retail power prices and then blamed deregulation.  The legislature knew exactly what it was doing when it created the Enron fiasco.

[grifftech]

solid CO2= dry ice

[Red Squirrel]

Wonder how feasible it is to store dry ice for long periods of time (days or even weeks).  Could be interesting to store it, then use thermo electric generators in addition to the pressure it creates in a tight vessel to generate power.  Would be a way to store excess energy to use it later.   This would not be very efficient, but if you are using spare free green energy that would be wasted anyway, efficiency is less critical.