Another step for distributed storage

Phil Carson | Feb 17, 2010


Yesterday's column took off from an astute reader's remarks and parallel points made in that day's news media -- a pleasing coincidence some call "synchronicity."

That tells me our discussion of smart grid-related issues is far from insular; rather, the general public and mainstream media are paying attention. (And thank goodness for a break from metering uproars.)

Today I want to look at a distributed storage project based on batteries, which appears to offer one method for utilities to buffer demand at the distribution level. And I'll finish by noting some of the really solid points readers made yesterday on electric vehicles (henceforth, EVs).

Storage, of course, is one of the industry's Holy Grails and an integral aspect of the smart grid. Just 12 hours of storage, enough to shift loads between peak and off-peak, could work wonders to balance the supply-and-demand equation. Efficient, utility-scale storage is an area I need to get up-to-speed on. But distributed storage is being investigated at a scale I can more easily grasp.

Short-term, local storage strengthens the value proposition of distributed generation to both homeowner and utility. Storage could help alleviate uncertainties over electricity costs facing the American consumer. I understand that a lot of very smart people are working on this goal.

Thus it should come as no surprise that nearly 50 related projects -- battery technology, manufacturing and recycling, EVs, charging infrastructure, educational programs -- won stimulus funding under the American Recovery and Reinvestment Act. (I'd like to hear of such projects that didn't get funded, and whether they got shelved or are moving ahead.) 

One such demonstration project involves American Electric Power in Ohio (AEP Ohio), which is putting in place multiple elements of a smart grid in northeast central Ohio that includes 110,000 consumers in parts of Columbus and nearby communities. This is a $150 million project AEP Ohio dubs "gridSMART."

In what AEP Ohio calls community energy storage (CES), the utility has recently selected S&C Electric Co. to help it integrate small-scale, battery storage at the distribution level. International Battery's prismatic lithium-ion batteries won the contract for this demonstration project.  

(In contrast, we've recently discussed in some detail an example of large-scale, distributed thermal storage innovations by Ice Energy, now being deployed by Southern California Public Power. Here are recent articles by colleagues Kate Rowland, Warren Causey and me.)

AEP Ohio's CES project involves putting a module of batteries between the distribution transformer and the meters on four to six homes. The first CESs will go from lab testing to the field about a year from now and are expected to produce 25 kW for one hour. An average home uses about 1.2 kW/hr, according to Jim Sember, vice president for power quality products at S&C. At that rate, the CES can run six homes for up to three and a half hours.

"Most reliability problems occur at the substation and transformer near your home," Sember told me recently. "A small battery system can address that challenge."

International Battery's prismatic lithium-ion batteries are large-format cells designed for "energy applications" -- that is, constant power output over several hours. "That's 'grid-friendly,'" Sember said. CES can also take the kinks out of frequency variations in electricity passing through the distribution system.

AEP Ohio will need four to five years to get sufficient data on performance and cost to determine whether CES fulfills its vision, and can do so at scale, according to Almgren. "The concept of 'community energy storage' makes a lot of sense," he said. "Our technology is a good fit. I'm humble about the challenges."

I'll close with a few thoughts posted by readers of yesterday's column on EVs' challenge to utilities, particularly their recharging load at the distribution level.

One reader asked if anyone has data on the aggregate load represented by all the cars and trucks on the road today -- what is the magnitude of the potential fuel shift? If any readers know of such calculations, please write in.

EVs need to avoid charging during peak hours and, thus, battery swapping during peak hours may be an excellent business model -- not incidentally, one that has garnered hundreds of millions of dollars in funding for Better Place, a start-up that is implementing that idea.

Meanwhile, readers encouraged utilities to be involved up front.

"PG&E is right to be looking at this seriously and I hope others utilities are considering it as well," one reader said. "The cars are coming. The clock is ticking. We will not have a smart grid implemented before they get here so some action needs to be taken."

Phil Carson
Intelligent Utility Daily

Related Topics



Quoting from the article, "An average home uses about 1.2 kW/hr, according to Jim Sember, vice president for power quality products at S&C. At that rate, the CES can run six homes for up to three and a half hours."

This is where reality meets theory: I defy anyone to satisfy the needs of the "average home" with a 1.2kW supply...which cannot possibly accomodate the demand of air conditioning, electric heating or for that matter, concurrently running the TV and a hair dryer. If you first disable these devices using your fancy-schmancy "smart meter" aren't you in fact defeating the whole purpose?

Folks....credibility is something you build out of realistic facts and proven performance. Wishing won't make it so. If I wanted a 12-hour UPS for my fridge, I'd already have one.

I'll allow that the author may not have inluded all of the details necessary for a fair assessment. Still, the consequences of a neighborhood quasi-UPS battery system (again, for what purpose?) seem at great odds with the competing ideals of Greenies everywhere (batteries, until proven different, are not exactly eco-friently).

As much as I admire forward-thinking, I question the motives of vendors (and utilities) that fabricate "needs" to fit the availability of products.

Small Scale Pumped Storage

One concept I read about on one of the Energy Central Sites a few years back was the idea of using hydraulics in conjunction with a parking structure to create an urban pumped storage facility to manage peak loads. I recall at the time there was a proposed test project to be built I Houston, but I’ve never seen anything further on it.

A structure like this would literally kill two birds with one stone, parking and power in a downtown location. The structure could be lifted over an 8 hour period at night while mostly empty then in the morning cars would add additional potential energy to the system as they parked.  Finally when the midday peak came the structure could be allowed to slowly drop back down, turning the pumps and motors in reverse to feed back into the distribution system. Given the limitations of battery storage and the possibility of greater then 100% energy return from the perspective of the facility owner (all the “free” energy added to the system as cars drive themselves up the ramp) I can’t see why this idea hasn’t caught on.


V2G for energy storage

ACPROPULSION.COM has already shown vehicle to GRID with it's Electric Vehicles. The storage is massive depending on how many vehicles and the battery capacity of each. So far they use 50 Kw in the eBox and Delaware has a study and rates established like net-metering for solar to cover these great vehicles.

We can continue to import 60% of our oil each day, at $37 Billion or more each year and create TONS of pollution or drive pollution free, charge on excess power in the GRID Off Peak and Sell On Peak . It helps the economy and environment while you make money.

  Most vehicles sit 20-24 hours a day, mostly at night and can power America. A really great book on this is V2G-101. It's one of the best books on EVs and V2G I have ever read.


EV batteries as storage

The idea of using batteries as distribution storage has one major drawback - batteries have a limited number of charge-discharge cycles.  If I were an owner of an EV, there is no way I would willing tie my vehicle to a system that would likely reduce the life of my batteries without being heavily compensated for the battery maintenance expense.


It's easy enough to prove V2G works with a few vehicles.  Getting the idea to work  cost-effectively work with hundreds of thousands of vehicles is a more complex task, even without the challenges of compensating owners for charge/discharge cycles.  For one thing, every V2G scheme I'm aware of assumes the grid operator (utility or ISO) will control charging much as they dispatch power plants.  Even if consumers allowed it, the cost and complexity of centrally managing that many end-use devices without emptying a customer's "fuel tank" make the idea impractical.  The fact that most vehicles are idle at any given point in time does not mean they will be idle for the duration of the charge/discharge event, which introduces another element of complexity.

Implementing V2G using distributed decision-making (the vehicle, with some programming by its owner, decides whether and how to inject or withdraw energy), might work if the necessary elements were in place and grid operators would allow it.

Excellent exchange


Do I understand correctly that the batteries in EVs are one of the most expensive components? If so, your point is very valid.

But someone must be thinking about this, given the value of EVs' storage as possible buffer for the grid's reliability and to store off-peak, intermittent wind power generation.

Perhaps Better Place has thinking on this, as one of their ideas -- and I haven't delved yet -- is that they "sell miles, not power." You get to your car's mileage limit and swap out the battery, rather than wait for charging. Somehow, they'll have to take into account the number of charge/discharge cycles to ensure equitable value in the swaps.

The other idea I've heard mentioned is that discharging to the grid would be compensated, both for the electricity and, presumably, for the loss of value to the battery from repeated charge/discharge cycles.

I'd be open to anyone who can point us to current thinking (and by whom) on this.

Regards, Phil Carson