How solvable is storage for a grid supply?

[741]

There are lots of good ideas about; I think the solution will be from a wide variety of solutions.

Eg, Tesla cars suggest eventually car batteries on overnight charge could smooth the load, also supply-load redistribution over large geographic areas.

At present though, is storage a major problem? To what extent do there already exist non-green reserve diesel generators etc specifically there to compensate for the intermittant nature of wind, tide and so on?

[Someone]

Depends who you talk to, short term peaking power is typically produced in gas turbines but diesel generators are in the mix as well, along with hydro power. These can all deliver power for when its needed with varying costs, and hydro is the largest base of installed energy storage with growing demand to increase its capacity. You can look at the load factors for the different power plant types but it doesn't say if the peaking is done on a seasonal or daily basis just that there was unused capacity, the UK has seen a big increase in the load factor of its gas plants recently while coal has fallen off but that doesn't mean the coal has been used for short term peaking:
https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/632604/DUKES_5.10.xls

Storage isn't a major problem at the moment but it might be able to reduce electricity prices in the future if there is increased volatility in pricing (from low marginal cost producers such as wind and solar).

[Kleinstein]

There is already quite some storage in the grid. The largest part is hydroelectric - either with extra pumps to pump up water and thus really take electricity from the grid, but also the flexible hydroelectric plants that change power to follow the demand. So the cross over from storage to flexible production is kind of fluid.

The very short time (e.g. a few seconds) storage is via the large generators working as a kind of fly-weel. With less of these large synchronous generators this part of storage is more like going down.
There are projects to add new storage, but much is still at an prototype state.
With increasing contribution of fluctuating renewable sources (wind and PV) there will be more demand for storage. In Germany we already have times, when the production from wind and PV is so high and not enough storage to take all the power - so they sometimes shut down PV and wind because of too much possible production.  Currently in Germany it is more like flexible other power stations, not real storage to do the balance. However this must change if more wind and PV is to be used effectively.

It depends on the region if more storage is needed or wanted. In areas with a lot of wind power or PV more storage would be nice. The grid capacity is limited and thus it is not just a global balance, but also a kind of local balance of production and consumption. A stronger grid can reduce the local requirements. So a stronger grid can to a certain point replace storage. Hydroelectric storage is also kind of concentrated in some areas - so plenty of it in Norway, but not much in Denmark or the Netherlands.

[IanMacdonald]

Much harder and massively more costly than to develop thorium energy. Or even fusion.

A quick cost analysis

What's worse is that windfarm contracts are being signed on the strength of claims that battery backup WILL be available.
Even though it hasn't been invented yet.  Shades of kickstarter vapourware? 

[Jeroen3]

To what extent do there already exist non-green reserve diesel generators etc specifically there to compensate for the intermittant nature of wind, tide and so on?

Co-generation heating plants are sometimes programmed to act based on energy price. These are natural gas generators.
Expensive kWh? Export power.
Cheap kWh? Import power.

Most of the time they are on a simple schedule though, based on day and night tariff.

[nctnico]

Much harder and massively more costly than to develop thorium energy. Or even fusion.

Unfortunately these are decades away from being practical. Thanks to Greenpeace et al investments in safe nuclear energy have been minimal. As a bonus we got stuck with antiquated time bombs.

[f4eru]

Thorium is dangerous. Or put it that way: practical thorium application have very very dangerous side effects.
Anyway, thermal nuclear is not capable of supplying fluctuating loads  either, so it has nothing to do with storage.

Concerning storage, there can be many technologies. In bold the ones that have scaled to grid level:
- potential energy (gravity) :
a) Water pumping
b) Trains climbing mountains (not realized yet)

- Direct Electrochemical energy:
c) Lithium Batteries
d) Pb Batteries ?
e) Molten salt batteries
f) Flow batteries
....

-Indirect (electro)chemical
g) Fuel cell + hydrogen storage + electrolysis
h)  electrolysis + H2 injection into natural gas
i) Fuel production from electricity
j) Carbon capture to fuel from thermal fossil burning plants
....

- Electrical charge
k) Supercapacitors (not enough energy density yet)

- Thermal energy
l) solar-thermal storage with molten salt
m) Seasonal thermal energy storage for aircon -> direct use as thermal energy

-compressed gas storage
n)compressed air storage

- kinetic energy
o)Flywheel

Do you know other ones ?

One alternative to storage would be extended worldwide extreme range distribution to smooth out for daily variation.
This would use HVDC links at a new scale :
https://www.researchgate.net/publication/283526924_Application_research_on_UHVDC_technology_in_asia-europe_power_transmission_planning
https://spectrum.ieee.org/energy/the-smarter-grid/lets-build-a-global-power-grid

[tszaboo]

It is not a problem, it is an opportunity.
All the people nagging about the lack of grid scale power storage:
Please tell me, how much money did we invest into grid storage. And how much money did we invest into nuclear power. Well, there a 3-4-5 magnitude difference, isnt there? So suddenly storage solutions should be the same power capability as a nuclear power plant, but you only give 1 /1000 the money for it. Well isn't that silly?

Power to gas (methane) has probably the best feasibility, since storing massive amount of gas is a solved technical problem, it makes a lot of heating systems greener without investment at spot.

Also concentrated solar in countries, like Spain could be huge.

[Kleinstein]

There is one more variation of gravitational energy storage, based on lifting a kind of large piston up with pressurized water. Some claim it could be a big deal, but some have doubt.

The List of batteries should include sodium/sulfur based one, that usually run hot. They are already in use at some scale.

There are some experiments with magnetic storage in large superconducting magnets. This is not my favorite - maybe for the very short time, like a fly-weel.

A rather big factor could also be to adapt the energy usage to actual production. It is not actual storage, but has a similar effect on the grid. This could be something like part in the chemical industry, production of compressed/liquid gases. This is already done with cold houses and heat pumps. It will add to investment cost, but this is offset by lower energy costs.

Power to gas has a rather low efficiency. So it likely would not be a good solution for shorter time scales (e.g. less than a week), but it is a good option for the longer timescale. Battery storage might be combined with PV, and this way could use the same DC/AC converter.

[NiHaoMike]

Far easier is to vary "flexible" loads to match supply. It helps that the top 3 energy users in most homes - hot water, HVAC, and refrigeration - are of that nature. Simply put, thermal mass is far cheaper than batteries and never wears out.

Programs like Ohmconnect are a step in the right direction.

[coppice]

Far easier is to vary "flexible" loads to match supply. It helps that the top 3 energy users in most homes - hot water, HVAC, and refrigeration - are of that nature. Simply put, thermal mass is far cheaper than batteries and never wears out.

Flexible loads are good for smoothing out the 24 hour cycles, but not so good for dealing with the multi-day problems - e.g. extended becalmed periods for wind generation. If we only had to deal with the 24 hour cycle issues the storage problems for renewable sources of energy would be a lot easier than they are.

[CatalinaWOW]

Power to gas (methane) has probably the best feasibility, since storing massive amount of gas is a solved technical problem, it makes a lot of heating systems greener without investment at spot.

Storing massive amount of gas is solved problem?  There are three methods I am aware of.   One is large tanks with floating lids.  They don't hold that much gas per euro or dollar or whatever financial unit you like.  Maybe suitable for diurnal power fluctuations but very dicey for seasonal storage as required with wind.    Pressurized tankage is another.  Same issues as with the floating lid tanks.  The other method is injection into old mines.  Has had lots of problems with leaks and depends on existence of the mines.  Where a suitable mine is available it is a cheap method.  But the supply of sealable abandoned mines is very finite.

[coppice]

Power to gas (methane) has probably the best feasibility, since storing massive amount of gas is a solved technical problem, it makes a lot of heating systems greener without investment at spot.

Storing massive amount of gas is solved problem?  There are three methods I am aware of.   One is large tanks with floating lids.  They don't hold that much gas per euro or dollar or whatever financial unit you like.  Maybe suitable for diurnal power fluctuations but very dicey for seasonal storage as required with wind.    Pressurized tankage is another.  Same issues as with the floating lid tanks.  The other method is injection into old mines.  Has had lots of problems with leaks and depends on existence of the mines.  Where a suitable mine is available it is a cheap method.  But the supply of sealable abandoned mines is very finite.

Try looking up how much CNG is on the high seas and in the storage facilities at each end of the major sea routes at any moment.

[Someone]

Power to gas (methane) has probably the best feasibility, since storing massive amount of gas is a solved technical problem, it makes a lot of heating systems greener without investment at spot.

Storing massive amount of gas is solved problem?  There are three methods I am aware of.   One is large tanks with floating lids.  They don't hold that much gas per euro or dollar or whatever financial unit you like.  Maybe suitable for diurnal power fluctuations but very dicey for seasonal storage as required with wind.    Pressurized tankage is another.  Same issues as with the floating lid tanks.  The other method is injection into old mines.  Has had lots of problems with leaks and depends on existence of the mines.  Where a suitable mine is available it is a cheap method.  But the supply of sealable abandoned mines is very finite.

Germany has quite some storage in underground systems:
http://www.catalyticengineering.com/terawatt-hour-energy-storage-power-to-gas/
https://uk.reuters.com/article/germany-gas-storage/german-gas-storage-full-but-operators-seen-as-weak-idUKL6N0RU3L820140929
some of which are salt caverns:
https://corporate.vattenfall.com/about-vattenfall/our-operations/market-transparency/gas-storage/

And combining the forms of US storage they're holding onto huge reserve capacity:
http://naturalgas.org/naturalgas/storage/
Which is mostly in depleted wells. Not quite 1PWh of energy, but a mere 800TWh at peak storage:
https://ycharts.com/indicators/reports/weekly_natural_gas_storage
Enough to cover the total energy demand of the US for more than a week?

[tszaboo]

Power to gas (methane) has probably the best feasibility, since storing massive amount of gas is a solved technical problem, it makes a lot of heating systems greener without investment at spot.

Storing massive amount of gas is solved problem?  There are three methods I am aware of.   One is large tanks with floating lids.  They don't hold that much gas per euro or dollar or whatever financial unit you like.  Maybe suitable for diurnal power fluctuations but very dicey for seasonal storage as required with wind.    Pressurized tankage is another.  Same issues as with the floating lid tanks.  The other method is injection into old mines.  Has had lots of problems with leaks and depends on existence of the mines.  Where a suitable mine is available it is a cheap method.  But the supply of sealable abandoned mines is very finite.

Since Russia proved to be an unavailable source of gas, Hungary built a strategic storage facilities for 4 billion cubic meter of gas, enough to cover 2 months of winter for 10 million people. Underground, hidden, most of it is stored in limestone.

[cdev]

This planet likely should be devoting a lot more energy to finding better ways to generate energy that don't cause massive problems.

I've always thought that compression of air has a lot going for it as an energy storage solution.

We should be transitioning away from the kind of grid we have today because its vulnerable to solar storms and nuclear EMP as well.

Every decade there is a one in eight chance of a devastating solar storm like the one in 1859 that if it happened today, would cause massive problems, and perhaps even a major disaster in the form of multiple nuclear meltdowns like the ones at Fukushima, all around the globe.

Thats because the solar storm could wipe out the grid so severely that power might go out over large areas, in such a devastating way that it could not be restored for a long time.

See

https://www.nap.edu/catalog/12507/severe-space-weather-events-understanding-societal-and-economic-impacts-a

Some nuclear power plants would be left without power and without adequate means of cooling their spent fuel, a problem called "Loss of the ultimate heat sink".

This and the vulnerability of transformers to solar storm generated EMP are engineering problems we need to address.

 The whole concept of an energy grid based on AC is showing its age.

But especially we should transition away the use of transformers, and move towards a more store and forward based system that generates most of its energy as close to where its used as possible.

Its possible we might be able to use superconductivity as a means of sending power long distances with minimal loss.

We should transition away from nuclear fission. None of the forms of fission we've currently seen proposed as solutions are, they all have the spent fuel problem.

I think there are serious issues with human governance of things like nuclear power plants. We've shown we're unable to handle those kinds of responsibilities in a manner that puts the interests of all people above profit.

Aging nuclear power plants and their spent fuel pools are disasters waiting to happen.

[cdev]

Are you sure the US still has a reserve? I heard some time ago that the US wanted to get rid of it.

Let the free market decide and all.


Remember Enron ?

Companies like that trade energy. Gaming the gradients, so to speak.

Those huge natural gas tanks are definietely capable of storing it but I worry about terrorism. They are not so great in that respect. Underground is far better if its not near an aquifer. But how do we know for sure? Also, methane leaking from natural gas operations is such a serious problem natural gas may be worse than coal for GHG. Recent evidence points in that direction. Methane from natural gas is a very powerful GHG.

See:
A bridge to nowhere: methane emissions and the greenhouse gas footprint of natural gas - Howarth 2014

http://www.sierraclub.org/sites/www.sierraclub.org/files/sce/connecticut-chapter/Howarth%202014.pdf

So then the whole argument about it being eco-friendly falls apart.  Also, substantial amounts of methane are being released from the continental shelf and melting permafrost so we really have to solve this one quickly and stop futzing around.

Storage of energy from solar during the summer months for the winter would require such a huge investment in new electricity infrastructure. The current system has the capacity if we had more storage at the end user. Then we could send the energy to the users at night.

We should keep the natural gas as a backup and try to use it much less.

Power to gas (methane) has probably the best feasibility, since storing massive amount of gas is a solved technical problem, it makes a lot of heating systems greener without investment at spot.

Storing massive amount of gas is solved problem?  There are three methods I am aware of.   One is large tanks with floating lids.  They don't hold that much gas per euro or dollar or whatever financial unit you like.  Maybe suitable for diurnal power fluctuations but very dicey for seasonal storage as required with wind.    Pressurized tankage is another.  Same issues as with the floating lid tanks.  The other method is injection into old mines.  Has had lots of problems with leaks and depends on existence of the mines.  Where a suitable mine is available it is a cheap method.  But the supply of sealable abandoned mines is very finite.

Germany has quite some storage in underground systems:
http://www.catalyticengineering.com/terawatt-hour-energy-storage-power-to-gas/
https://uk.reuters.com/article/germany-gas-storage/german-gas-storage-full-but-operators-seen-as-weak-idUKL6N0RU3L820140929
some of which are salt caverns:
https://corporate.vattenfall.com/about-vattenfall/our-operations/market-transparency/gas-storage/

And combining the forms of US storage they're holding onto huge reserve capacity:
http://naturalgas.org/naturalgas/storage/
Which is mostly in depleted wells. Not quite 1PWh of energy, but a mere 800TWh at peak storage:
https://ycharts.com/indicators/reports/weekly_natural_gas_storage
Enough to cover the total energy demand of the US for more than a week?

[cdev]

The worst case scenario is a volcanic eruption that put significant amounts of ash into the high stratosphere, which would change the albedo of the planet. The increase in reflectivity would cool the earth, reducing its entropy, it would also reduce the magnitude of the winds and cause much less energy to fall on solar panels. Also, it would become hard to grow food because of year round danger of frost. Also sulphuric acid causes crops to wither and die.

This has happened as recently as the 1780s, when Benjamin Franklin, one of the founders of the United States and also a pioneer in the history of electricity, wrote about its effects from France.
https://earthobservatory.nasa.gov/Features/Franklin/franklin_2.php

also: "How an Icelandic volcano helped spark the French Revolution: Profound effects of eight-month eruption in 1783 caused chaos from US to Egypt, say experts"

https://www.theguardian.com/world/2010/apr/15/iceland-volcano-weather-french-revolution

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

Huge volcanic eruptions which happen unpredictably every few (thousand? hundred?)  years are extremely bad things for humanity and we should plan on how to deal with them as best as we can. We could lose our ability to generate enough energy from renewable sources temporaily due to an eruption, which dramatically reduces the solar energy striking the Earth, so it also reduces the power available to the winds and to evaporate water. So everything that depends on that heat is likely to be impacted. It could be a huge global disaster. So we should try to plan for more resilience, and flexibility.

Far easier is to vary "flexible" loads to match supply. It helps that the top 3 energy users in most homes - hot water, HVAC, and refrigeration - are of that nature. Simply put, thermal mass is far cheaper than batteries and never wears out.

Flexible loads are good for smoothing out the 24 hour cycles, but not so good for dealing with the multi-day problems - e.g. extended becalmed periods for wind generation. If we only had to deal with the 24 hour cycle issues the storage problems for renewable sources of energy would be a lot easier than they are.

[CatalinaWOW]

Try looking up how much CNG is on the high seas and in the storage facilities at each end of the major sea routes at any moment.

The quantity is huge.  But a little thought shows that that it is roughly equal to the consumption during a round trip for the tanker.   The typical tanker operates at around 15-17 knots (See the archaic unit thread). Translates to roughly 30 km/hr.   Stage lengths vary widely from across the Mediterranean Sea to across the (narrower parts) of the Pacific.   Using 10,000 km as a generous average this gives a round trip time of about 700 hours.  About a month.

So it is plenty for diurnal uses and possibly even for some seasonal purposes.  Assuming you are willing to build another significant fraction of the tanker fleet for diurnal load leveling.  Or duplicate multiples of the entire fleet to handle seasonal fluctuations.  And build the infrastructure to make methane from excess energy. 

All technically possible.  Not clear if the economics work out. 

[coppice]

Try looking up how much CNG is on the high seas and in the storage facilities at each end of the major sea routes at any moment.

The quantity is huge.  But a little thought shows that that it is roughly equal to the consumption during a round trip for the tanker.   The typical tanker operates at around 15-17 knots (See the archaic unit thread). Translates to roughly 30 km/hr.   Stage lengths vary widely from across the Mediterranean Sea to across the (narrower parts) of the Pacific.   Using 10,000 km as a generous average this gives a round trip time of about 700 hours.  About a month.

So it is plenty for diurnal uses and possibly even for some seasonal purposes.  Assuming you are willing to build another significant fraction of the tanker fleet for diurnal load leveling.  Or duplicate multiples of the entire fleet to handle seasonal fluctuations.  And build the infrastructure to make methane from excess energy. 

All technically possible.  Not clear if the economics work out.

To allow for political and military instability they have somewhat more capacity at the terminals in Europe than that. The existing capacity was not a stretch for anyone to build, whether you look at the land resources, safety or cost. Something considerably larger would not be a problem.

When you look at how much trouble oil storage facilities all over the world have had with ground pollution from leaks, it can be quite surprising to see how much gas is stored with low levels of leakage and waste.

[schmitt trigger]

I've seen kinetic energy storage first hand. Used as a short term UPS, providing at most a minute or so of energy while the backup diesel engine starts and gets up to speed.

No exotic materials, just a humongous steel flywheel.

[cdev]

The New York Times did a series a few years ago about how the estimates of natural gas that were being bandied around by natural gas companies were quite substantially overestimated, and that the real reserves were quite a bit lower.

See http://www.nytimes.com/interactive/us/DRILLING_DOWN_SERIES.html

Also http://www.nytimes.com/2011/06/26/us/26gas.html  and http://www.nytimes.com/interactive/us/natural-gas-drilling-down-documents-5.html

As you can see, many wells have run out or are running out so the extraction of natural gas is too costly to be profitable.

Now they are basically going to reserves they had written off as too difficult in the past..

They must use extreme measures (such as hydrofracturing) that extract the last remaining natural gas but considering the quite substantial environmental risks (which include radiation, the waste water and slurry from large portions of the Marcellus shale zone contains high levels of radiation, see  http://ehp.niehs.nih.gov/122-a50/ - a toxic byproduct of fracking which must be disposed of properly, but it isn't being, instead it has even been discovered being spread on roads as a substitute for salt in the winter )


as well as a growing body of evidence that these methods of natural gas extraction cause a huge amount of methane to be released into he atmosphere, giving it a greenhouse gas impact that's arguably as bad as that of coal..
http://www.eeb.cornell.edu/howarth/publications/Howarth_2014_ESE_methane_emissions.pdf

Also, there is a risk of polluting precious aquifers, in an era where droughts and desertification are very real risks..

its just way too costly to the communities and the planet to justify it.