Slashdot Mirror
Why Our Antiquated Power Grid Needs Battery Storage
Lucas123 writes: Last year, renewable energy sources accounted for half of new installed electric-generation capacity (natural gas units made up most of the remainder). As more photovoltaic panels are installed on rooftops around the nation, an antiquated power grid is being overburdened by a bidirectional load its was never engineered to handle. The Hawaiian Electric Company, for example, said it's struggling with electricity "backflow" that could destabilize its system. Batteries for distributed renewable power has the potential to mitigate the load on the national grid by allowing a redistribution of power during peak hours. Because of this, Tesla, which is expected to announce batteries for homes and utilities on Thursday, and others are targeting a market estimated to be worth $1.2B by 2019. Along with taking up some of the load during peak load, battery capacity can be used when power isn't being generated by renewable systems, such as at night and during inclement weather. That also reduces grid demand.
There are other -- probably cheaper -- solutions for local storage than batteries.
A couple of off-the-cuff examples: lifting a very large weight with your excess electricity, then running a generator with it during peak loads or periods. (Did I say VERY large weight?)
Another would be pumped hydro storage. Build a -- yet again very large -- tank at a height. During excess generation periods, use the electricity to pump water into the tank. During peak periods, use the water to turn a generator and reclaim the electricity.
All such systems have inefficiencies, even batteries. But pumped storage and other such solutions are used on a very large scale today... and should be quite workable for the small scale as well. Another advantage of pumped storage is that you now have a nice, big, full water tank with gravity feed in case of zombie apocalypse or whatever.
There are many ways to 'store' electricity. Batteries are just one.
I rather like this one, a thermal storage solution. Putting air into and out of bladders under deep water is a very simple method, as is moving water up and down hills. Then there are flywheels and fixed volume compressed air storage. (The air bladders above are fixed pressure compressed air storage.) There other thermal storage possibilities, but getting good round trip efficiency is tricky.
There are non-traditional battery techniques too: flow batteries (liquid electrolytes in tanks, adding storage capacity is as easy as adding tanks full of electrolyte) and molten metal batteries (take the idea of aluminium smelting and make it reversible).
All the non-battery alternatives I can think of work at industrial scale, so if you're looking for a household/small business solution, I think that at least for now batteries are it.
Quattuor res in hoc mundo sanctae sunt: libri, liberi, libertas et liberalitas.
Trouble is you need very large tanks of water, or to seperate them a long way. For instance a house might use 2 kWh overnight, that's about 7 MJ.
Round trip efficiency for pumped hydro system is around 88%, call it 100, and call g 10. So you need a tower or hill 350m high with 2 tons of water in it, or if you prefer, a swimming pool, 2*5*10m suspended 6 metres above your current pool. So, that's a fair bit of unlikely, just to power one house.
Most sensible big hydro locations have already been gobbled up, they made sense decades ago.
Most sensible big hydro locations have already been gobbled up, they made sense decades ago.
The other issue , at least in the U.S. is that it has been near impossible to deal with the permitting process for large water projects. Look at California, if you need an example of just how much damage people are willing to do when it comes to stopping these projects.
Don't forget that adding solar panels is a virtuous cycle with respect to HVAC. You're not only capturing energy, but you're also not dumping that solar load onto your roof and attic. Here in Albuquerque, some of my friends that have put panels up found that even before the panels went live, their electric bills dropped 20+% just due to the panels providing shade for a portion of the roof. Then they found that their solar panels were oversized since they hadn't expected that reduction, and exceeded house demand essentially from 8am to 6pm. Most of them are providing above 90% total load month to month, even in the winter (natural gas heating). Another panel or two and some energy storage and they'd be there.
I have personally found that if you mount normal panels (as opposed to the flexible panels that you tape/glue in place directly on the surface), you create some clearance under the panels that air circulates under, insulating the roof from the sun.
To me, solar is a "why not" item. Not just for saving on electric bills, but providing electricity in areas where it isn't worth the hassle to run code-compliant wiring to, especially if all one is needed is basic lighting or a place to charge cordless drill batteries. For RV-ing, solar goes without saying, because it keeps house batteries topped off and helps minimize engine or generator use. Even for a plain old house, one can use a set of panels, storage battery, and inverter as a UPS so one can move all the parasitic draw devices (set top boxes, consoles, USB chargers) to that circuit, where they get clean power... and are not on the electric bill.