My first impression:<p>This idea sounds great ... until you need to hop in your car and drive somewhere midday and learn that the battery is mostly drained because it's a hot day and everyone's turned their A/C on full blast.<p>I'm sure the engineers have thought about that scenario and maybe only allow 20% of the battery to be used for the purpose of grid maintenance, but I imagine it will be difficult to sell the average car owner on the idea, because people are always thinking about worst cases.<p>I mean, think of it in terms of a conventional car. How would you like to never know with certainty whether you have a full tank or not when you get in your car?
The biggest obstacle, in my opinion, to vehicle-to-grid (V2G) applications is distribution utilities. All utilities have comprehensive procedures for studying and approving connection of distribution generation resources to their networks (rooftop PV, small CCGT, etc.). These take in account the maximum possible output of the generation asset as well as how they will behave under fault conditions.<p>They're already quite stingy about approving customer-owned DGs (because there is little or no financial benefit to the utility) - I can only imagine how they'll feel about people connecting a generator they don't control, at locations and times they can't predict, with the ability to disconnect them arbitrarily and drive away.<p>In order for V2G to become a reality, utilities will need far more advanced software and metering infrastructure to perform real-time load-flow analysis of their systems and determine if/how to dispatch connected EVs. At present few utilities even have the metering infrastructure to enable that kind of intelligent control, let alone the supervisory control software.
This "Vehicle to Grid" idea has been around for a while. The article cites some progress (a trial program in SoCal).<p>It's noted that using one's car to contribute to grid stability may void current battery warranties, about which the article notes:<p>"Innovators in the field are gradually convincing car manufacturers of the potential to create a "value proposition for the car owner" and thus boost sales, Gage said. Ultimately, however, carmakers may be put at ease by experiments being conducted by the military."
Recently there have been quite a few debates on the subject of solar/alternative-energy users feeding power back onto the grid .. and the latest story seems to be that power companies are attempting to fight off the impending doom of self-powered individuals by stating that 'it costs too much to update the grid to allow everyone to push to it, so these alternative-energy users should pay a hefty fee to upgrade the grid'.<p>Well, this story seems to point to the solution: put batteries in all the things! If its going to cost more to feed power back to the grid, then why not just make everything in your home store its own local power supply ..<p>To some extent, I'm already doing this - pretty much every electronic device in my house uses rechargeable batteries. So maybe the campaign by the utilities against feeding power to the grid is going to have the effect of pushing everyone to localise their power needs even further, and instead of pushing excess to an ageing, antiquated monopoly, us alternative-energy freaks are instead going to foster the creation of a heftier market for battery-protected devices. (I'd be quite happy to run my TV on battery power, if it only had one in it, like my laptops and cell phones and toothbrushes do ..)
I would imagine that the best batteries would be reservoirs. Take two spaces that hold water. One at high ground and one at low ground. Pump the water from low ground to high ground when energy is plentiful and let it run through generators when you need energy. Yeah, there is going to be energy loss, but this approach should scale to the quantity of energy necessary to provide the same amount of energy as a power plant for 12-24 hours.
It'll be interesting how the energy landscape gets defined in the near future. Of note, there's a funded kickstarter that stores energy in residential flywheels that appears to be another promising solution: <a href="http://www.kickstarter.com/projects/1340066560/velkess-energy-storage/posts" rel="nofollow">http://www.kickstarter.com/projects/1340066560/velkess-energ...</a>