Like for aluminum smelting which apparently needs ~10x the energy that steel needs https://theconversation.com/the-trouble-with-aluminium-7245
Crypto-mining may be one alternative, you are converting energy into currency is the most straight forward fashion. Could be the way, who knows.
I am not questioning the utility of Aluminium here.
I have a suspicion that this is being used by Germany to feed them a disguised subsidy.
Photovoltaics are cheap, but the diurnal variation makes them singularly inappropriate for aluminum smelting.
Friends who used to work at aluminum plants were surprisingly happy when the plant was snowed in: it was more economical to keep workers onsite running rotating understaffed shifts at triple pay for the duration than to let the pots solidify.
From the Wikipedia page on aluminum smelting:
An aluminium smelter consists of a large number of cells (pots) in which the electrolysis takes place. [...] Smelting is run as a batch process, with the aluminium metal deposited at the bottom of the pots and periodically siphoned off. [...] However power must not be interrupted for more than 4-5 hours, since the pots have to be repaired at significant cost if the liquid metal solidifies.
In addition to Wikipedia, there’s a surprisingly good explanation here:
I'd love to see some napkin math on this.
But that's still half the energy density of gas. Instead of buying 12 gallons of gas every week or two, you're now buying 720 kg of aluminum every few months. All the gas tanker trucks you see on the road right now? They're replaced with twice as many aluminum-air battery carrying trucks. All the pipelines, supertankers, rail cars, etc? Replaced with aluminum carriers. And on top of all that, gas turns into CO2 and water, disappearing into the atmosphere. With this plan, you have to ship these aluminum batteries back to the manufacturer for rebuilding!
You'd have to build thousands of mostly automated battery reconditioning plants and scatter them across the country for that to work.
If not I'd assume Tesla would be well positioned there, but I wonder if even it could scale that far.
Here's the frame I'd suggest: batteries, demand-response (to which efficiency contributes), grid management, and rate schedules are mutually supporting tools which allow us to continually improve our use of power along several axes, including GHG emissions, efficiency, end-user price, and reliability. There isn't one accurate and stable perspective from which to consider the "value" or "viability" of, say, compressed-air storage. Instead we have a web of complex local, regional, and global situations and concerns, and varying sets of goals to pursue within those situations.
The Bath County Pumped hydro station stores about 35-40 GWh of power (35,000 MWh), cost $1.6 billion in 1977-1985 or so (so inflation-adjusted about $100-150/kWh).
Compare to the largest ever battery storage project, the Tesla 129MWh installation in Australia is "guaranteed" for $250/kWh, but that doesn't include a lot of extras (the storage facility has a pretty high discharge rate, able to dump its storage in roughly 1.3 hours vs like 4-8 hours for better battery life and lower secondary costs).
So in terms of cost and scale, pumped storage steal beats the best battery installation by a factor of 2 (not counting likely longer service life before replacement, although that depends strongly on how hard you cycle the lithium batteries), and scale-wise beats it by a crazy factor of 300.
Pumped hydro does have some geographical constraints, but there's a lot more opportunity to build them than many detractors suggest. (Obviously, the sweetest places to build them are by definition limited, but you can also build pumped hydro with a very low head, like on some of the Great Lakes projects, or with a very large head requiring very little water.... you don't need a nice canyon feature for pumped storage, a big round concrete reservoir on top of a hill works just fine, too. And with enough volume of water, you don't even need a hill.)
And I say this as a firm believer in the potential (heh) of the lithium battery and in Elon Musk. Pumped hydro should not be ignored.
Regardless, I don't disagree that pumped hydro can still a viable choice in some places when it comes to large scale, I think South Australia made the best choice going with battery storage, even if driven from mostly political reasons.
The SA govt needed to show the federal govt they were capable of holding their own on their renewable policy, against the federal line of the Snowy Mountain 2.0 pumped hydro. Having something up and going in ~100 days with very few unknown factors (pour concrete, install batteries, hook up to grid), opposed to waiting 5-10 years for a solution from the federal government that hasn't even finished a feasibility study yet, and has so much more risk (geological survey, environmental survey, new transmission lines  etc)
The other advantage of battery storage I see is that it is immensely flexible for a rapidly changing market. Underprovision? Just buy more. Overprovision? Truck them somewhere else, lease them to a business with peaky loads, plenty of other options.
Alternatively, there was a German experiment to use underwater concrete pump storage to provide storage close to production for offshore windfarms. Not sure where the project is at, but these ideas could well supplement batteries.
Lithium-ion batteries are the "hot" energy storage. Efficient, powerful, and very light, but also expensive great for a laptop or a car, not so great for massive-scale "cold" storage.
Simpler things like flywheels, compressed air, reverse hydro, other cheaper battery types all seem like more plausible options.
Is an example - from Donald sadoway at MIT who presents easily my top 5 TED talks on the idea as well (molten salt storage)
But we already have good examples of electricity storage by pumping water uphill to reservoirs in Scandinavia etc
Storage is probaly not a problem - mobile storage might be
Also, big maglev centrifuges are being looked at, and of course pumped storage, which is pretty old-fashioned.
2011 goals targetting 2020:
$0.09 per kilowatt hour for residential photovoltaics (PV)
$0.07 per kilowatt hour for commercial PV
$0.06 per kilowatt hour for utility-scale PV
2016 goals for 2030:
$0.05 per kilowatt hour for residential PV
$0.04 per kilowatt hour for commercial PV
$0.03 per kilowatt hour for utility-scale PV
This slightly older piece from 2015 make some projections based on a 16% learning rate and suggests various large orgs have estimated similar levels:
I would also like to see rooftop solar become widespread in the near future. But I think for most people to get on board, they'll need to be able to break even on the investment within something like 3 years.
I don't think most solar installations are designed to operate without a grid connection though, and even not all powerwall installations can run off grid.
Though I'm not sure that they beat a generator (diesel or connected to your gas line) if you really anticipate regular grid outages and probably won't for a while.
You mean the car that is parked during the day in your office parking lot a few tens miles away and the laptop and phone that you are carrying with you?
Seriously, without some form of (efficient) storage system, the whole thing depends on exchanges on the grid.
Off grid - as I see it - is a very nice solution (still with some minimal storage) for a hut in the woods, where everything is specifically designed for low power (and where you don't have a dishwasher, a washer, etc.), replacing - in a more environment friendly way - the noisy generator, but still it remains something good for youe being there on - say - every other weekend.
Having an el-cheapo (diesel or gasoline) small generator for emergencies is handy, but only for those hopefully very rare emergencies, the cost for a good quality (suitable to run often and in several hours stretches) generator and for the fuel is not competitive with solar (though of course the initial cost of solar is still higher).
In the normal run of things though, I agree, the correct and sensible thing is to be grid connected, and have sane regulations that ensure that excess from generating customers gets redirected to their neighbours and that everyone gets compensated fairly for their contribution to a well running grid so that incentives are correctly aligned.
This value will in most cases be more than utilities would be prepared to pay if left to choose a number themselves and they will unfortunately generate propaganda to make solar installations seem like free riders rather than go by actual studies of how much they reduce the peak demand. In both Australia and the USA studies have found Billions (with a B!) in savings thanks to solar installations.
I have the same thing here, up in Maine. I live in one of the windiest places around and it hasn't been a problem. It gets flipped for blizzards, mostly.
The idea in my previous post was:
>the whole thing depends on exchanges on the grid.
and anyway we were talking of off-grid setups.
I guess this was one of the first: http://www.smainverted.com/how-to-explain-secure-power-suppl...
At $500 additional cost, calling it a design issue is probably the correct thing.
Of course an auxiliary plug is way less convenient than whole house power, but a couple thousand watts is way more convenient than no electricity.
We need to decentralize energy generation (solar) AND cellphone signals (mesh networking).
Here I expound on it at length:
???? That's a 33% discount rate. Kind of insane expectations... I put solar on my house in 2014, after doing a bunch of analysis showing the breakeven point was 8-12 years. After having it and checking the utility bills, it looks like it's going to be 10-11 years. Maybe less if they raise their rates.
These exist nowadays 
Most are so focused on reliability they are quite resistant to pushing the limits. There must have been some cost savings such as avoiding building or upgrading a substation
The power grid in the US is way more unreliable than any other country I've experienced, and I can only think that it's because the utilities are so profit-focused that they put lowering infrastructure costs above losing a little revenue due to power outages here and there. After all, the real societal costs due to unreliable power are completely externalized onto their customers.
The utilities are fine talking about reliability when it comes to newfangled competitors like solar, but that's mostly because they're a threat to their bottom line, not because they actually care about reliability.
whatever your connection fee on your monthly bill is (mine is $10 CAD), would you like it to be 4x higher?
There is more that goes into transmission line engineering than cost. "Agility" is important, and it is a lot harder to tap underground transmission lines than overhead lines. Outages, while less likely for underground, are actually, on average, longer than overhead line outages.
and Pacific Gas & Electric
green mountain power appears to be a retailer of electricity and not a distribution company; they don't own any power lines. The distribution co. will have to be on board to safely accept power flowing in the opposite direction (from the load), and for the most part they have no incentive for this so don't really care.
Green Mountain Power (GMP), a subsidiary of Gaz Métro, is the largest electricity distributor in Vermont, serving over 70% of the market and more than 260,000 customers. GMP’s core business includes the distribution, transportation, generation, purchase and sale of electricity in Vermont and, to a lesser degree, electricity transportation in New Hampshire and electricity generation in the states of New York, Maine and Connecticut.
The GMP network comprises over 1,500 km of overhead transmission lines, 18,000 km of overhead distribution lines and 1,600 km of underground distribution lines, located mainly in Vermont but also extending to New Hampshire and New York.
You may be confusing them with Green Mountain Energy, which got spun off and bought by someone else:
>All told, the Edison Electric Institute estimates (pdf) that some 18 percent of the country's distribution lines are buried. For the transmission system, only about 0.5 percent of lines sit beneath the surface. "Undergrounding an entire power system," says EIA, "is considered cost prohibitive." Instead, most utilities will just try to bury a few key lines.
Repairing underground lines takes longer than overhead lines.
Here's a respected centrist think tank's take:
"Nevertheless, by the end of 2015,
regulators in at least 10 states had conducted studies to develop methodologies to value distributed generation and net metering, while other states conducted less formal inquiries, ranging from direct rate design or net-metering policy changes to general education of decisionmakers and the public. And there is a degree of consensus. What do the commission-sponsored analyses show? A growing number show that net metering benefits all utility customers"
So it's not a subsidy.
The structure of how power plants generate electricity and are paid for it are idiosyncratic to their particular operating and economic conditions. It would make no sense to try to force something completely unlike that in to their regime.
Thus the many efforts that are designing a "value of solar" regime that encompasses the important aspects of solar, so that equitable and efficient cost schemes can be designed.
I don't think they're impact resistant ?
Generators already have the inverter built in. "Storage" is your tank of gasoline or whatever fuel it uses.
Generators are cheaper and more reliable for emergency situations right now.
Actually, please get ready to fight these tooth & nail.
It was also pretty clearly done at the behest of the fossil fuel industry and "greenwashed" by pretending to be done to protect US solar jobs. US solar manufacturing (as opposed to installation) is a pretty tiny industry with no political muscle.
The justifications were cringeworthy too. I took a glance at the US trade dept documents accusing China of protectionism and the first one I saw made accusations of "free advertising" because Chinese local government promoted a local solar company on its website.
It suddenly makes a few $20 billion storm cleanups pale by comparison.