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Flow Batteries[1]!

They work (as in: are being used in Africa & South America to power mobile networks). Also my (office) building is powered by one.

They don't cost much more than lead-acid

They last much, much longer than lead-acid or lithium*

There is no limit to the number of power cycles(!!) and they can be deep-discharged.

They do have disadvantages - they aren't suitable for cars, and are currently fairly noisy when cycling, and have lower power density than lithium* batteries. They also need to be periodically complete discharged (although most have software to make sure each individual cell does this as part of the normal use)

Disclaimer: An investor in Redflow owns my building (hence the power source)[2]

[1] https://en.wikipedia.org/wiki/Flow_battery

[2] http://redflow.com/

167 Wh/l = 167kWh per cubic metre, say 16 hours of no sun, 16kW output at night, seems reasonable

167Wh/l is a relatively recent prototype, Redflow uses the older zinc-bromide which is only around 70Wh/l.

Yep. Next time someone claims base load means renewables don't work do that math. Also point to the experience in developing countries where they don't have reliable base load, yet have similar uptime.

Wind provides base load anyway, always windy somewhere

That's a bad argument. Arbitrary energy transportation is not a solved problem. Power grids are designed to deliver from power plants to the consumers.

Interesting, haven't heard about such batteries being commercially sold. Any idea who sells those for private consumers in Europe?

Not sure about the private consumer part in Europe, but following seems to be in Austria:

http://www.bluesky-energy.eu/project/redflow-zinc-bromide-ba...

I believe Redflow will have a consumer offering this year, (under another brand). Not sure about European availability.

> Flow Batteries[1]!

From the wikipedia article, it appears that typical flow batteries only reach 10% to 20% of lithium polymer's power density.

That means that it would take a flow battery that weights 5 to 10 times as the standard lithium polymer batteries that equip a Tesla/Nissan Leaf/whatever electric car you imagine to deliver the same power.

Energy STORAGE is a huge bottleneck issue for anyone that follows renewable energy news as well

Very true, but, interestingly, large-scale electric vehicle adoption may help this: http://thinkprogress.org/climate/2016/05/09/3775606/used-sec... as lightly used car batteries may cease being attractive for use in cars but be very attractive in terms of base-load storage.

Absolutely. It's all about the $/kWh stored. A "worn out" electric car battery might have only 70% of its cycle depth/capacity remaining compared to when it was new, but if the battery packs can be acquired for very cheap, that doesn't matter so much.

There is a guy with videos on youtube who has purchased battery packs from crashed Tesla Model S and retrofitted an old volkswagon bus for 100+ mile EV range.

I would like to know more! Is this the incident in question?

http://insideevs.com/diy-project-salvaged-tesla-model-s-to-u...

"Joe’s “donor” Model S will be brought back to life by Otmar in the form of a stretched Volkswagen Vanagon called Strechla.

The Vanagon will exist only on the outside. On the inside, underside and everywhere in between, you’ll find Model S."

edit: added more words

it's this guy:

https://www.youtube.com/user/jehugarcia/videos

scroll down a bit into the older videos and you will see the VW.

Yes. He also had some packs made from salvaged battery cells.

And a battery trailer, inspected by the DMV.

The problem is that current batteries wear down on every charge cycle. This means that by charging and dis-charging a battery, it loses value, which means that there is a cost for each charge cycle.

I am too lazy to put numbers on this, but this cost is currently much too high to make it economically viable to use car batteries for energy storage.

That is a true statement. However, you should not compare car batteries (usually LiFePo, LiMn or whatever it is Tesla uses) with standard laptop batteries.

Electric car batteries can endure thousands of full cycles before their useful capacity drops down to 80%. That figure can be as high as tens of thousands, depending on who you ask.

Suprisingly, for LiMn, temperature and age have a much greater effect on lifetime than cycles.

2,000 cycles sounds great, but at just once per day that's only 5.5 years. Grid storage needs to be really cheap AND last for 20-50 years. Which is why capacitors and pumped hydro are both used. Capacitors can discharge 1,000's of times a day to maintain the proper wave form and hydro can discharge 1-3 times a day to handle changing demand.

PS: The real advantage of hydro is you can invest in capacity or peak load as more or less separate things.

2,000 cycles sounds great, but at just once per day that's only 5.5 years. Grid storage needs to be really cheap AND last for 20-50 years.

5.5 years is about the lifespan of servers in a datacenter. What's wrong with managing energy storage the way we manage datacenters? We don't expect servers to last 20-50 years. And no doubt, as battery tech improves, the lifespan will improve too. But the infrastructure to get good storage needs to start somewhere. Run them as datacenters for now while waiting for battery tech to get better.

It's just a question of cost. If it's cheap and lasts for 50 years, great. If it's 1/8 the cost and lasts for 5.5 years that also works. But battery's are still a long way from cheap let alone 1/8th of cheap.

Don't forget computer investment has long operated under the assumption of rapidly declining prices. With that slowing data centers may go to a 10+ year cycle.

Controlling for state of charge, temperature and less deep cycles, it is likely that we can achieve your figures given current tech. The question is the price. If you are not fully using them, then you need more batteries. At which point it becomes economical requires some guesses and heavy number crunching.

I agree with you on hydro, gravitational storage is relatively simple to do. But it takes space. Batteries could make more sense for microgrids.

That's fine, though. If your car that used to do 300 miles on a charge can only do 200, you'll probably replace it.

That 200 mile charge may still be perfectly usable in a house, particularly given you can fit a couple cars worth into your basement without issues. The resulting battery cluster doesn't have to be particularly compact or light-weight.

Car applications care about kilograms per kWh stored, and cubic volume per kWh stored. Stationary batteries, not so much.

Not as much, yes, but it's still important. Space is quite valuable even in a normal household.

Space is only at a premium because it costs more to have more space.

The real question is "how much space are you willing to sacrifice for energy self-sufficiency?"

In the UK, electric bills hover around $1200 a year for electric/gas households and $2000 a year for full electric.

Renewable households will have a HUGE potential market.

U.K. Residential market is 26 million houses. Theoretical price point of $1500 dollars (one years energy cost) = 39 billion dollar market not including the massive combined secondary services in maintenance, installation training providers, parts, etc.

USA residential would be 6 times that and the provision of renewables to corporates is almost incalculable.

It's an entirely new economic ecosystem divorced from petrochemical.

It a price point higher than $3000 dollars we are getting into a market cap of many trillions worldwide.

IF you can get a solar system and batteries for £1k, then that starts to look feasible. But that's a big if.

I had a 3.8kW solar system put in for £5k last year and have yet to really run the numbers on savings; the payback period is 10 years of feed-in tariff cheques. If I went off-grid that would be reduced. I don't really see why I'd want to go off-grid for its own sake, I'd rather better explore the possibilities of net metering and sharing power with the rest of the city.

If you continue to cycle the batteries as deeply as you were in the car this might be true but if you're willing to charge and discharge slower as well as cycle shallower the gain in life for a Li-ion battery is quite remarkable. Obviously you need more batteries but in general energy storage is just less harsh to batteries than use in cars.

> but you need to use many of your 1200-1400 kWh/month at night

As air conditioning, but there are other solutions! Ice has neigh-infinite charge/discharge cycles and big institutions have been doing this for years. If your "campus" is more than a few hundred tons of AC it's probably cooled by ice.

It's not been terribly economical to do this at a small scale but as solar gets cheaper and batteries don't there are people working on the problem.

https://www.ice-energy.com/technology/

Roughly the same dynamics that relate cloud apps vs self hosted apps to reliability relates solar power and grid power to reliability. The grid is - for now - the cheapest battery there is, and it gives you immediate redundancy. It will be far more reliable than anything you install on your roof and in your basement on a per-case basis, even if a grid outage takes down your whole neighborhood, town, or even country.

Batteries, at whatever price you pay for them are a really in-efficient way to store and retrieve energy compared to the grid.

The thing is, the grid from the perspective of an average residential user is actually not that reliable. In many places in the Pacific Northwest where trees fall on power lines in winter storms the grid does not meet five nines reliability (52 minutes or less outage per year). A properly implemented whole-building off grid battery system and a few inverters running in parallel can be much more reliable than this. The grid is subject to all sorts of failure modes from trees, landslides, flooded vaults and things involving the environment, while a PV system has no moving parts (perhaps except from a ventilation fan in an inverter), and a larger set up can be run with several inverters in parallel providing AC for a building.

If you're still using above ground power lines for local distribution then that definitely would make a difference when it comes to reliability. Just like in Northern Ontario where our solar/wind homebrew solution was a lot more reliable than the local grid. Even so, in a developed country that's a choice, not a necessity.

Isn't it really cloudy in the Pacific Northwest during winter?

How do the LiFePo batteries used in current electric cars change the equation? Not so great energy density, but can withstand an immense number of cycles.

Conversion losses and cost / KWh are the problem nowadays, not the number of cycles, that's getting to the point where it is still a factor but not the factor.

we have two options here: We either improve the power grid all around the world, so whenever it's dark in one side of the planet, the other side, sunny, feeds the darker part; or we start investing heavier on other renewable sources not depending on the sun, to provide the required energy for those nights and cold evenings in the the winter months.

This is one of the most optimistic and best things I have read in weeks.

+1