Plug In Autos (PHEV) Grid Hero or Terror?

I saw this article about the New York Independent System Operator reporting that PHEVs won't cause a strain on the grid "as long as owners plug-in overnight". Funny, I keep hearing that PHEVs will be the savior of renewable energy, allowing for storage of wind and solar from the grid and from the home, transporting power to the workplace where they can be plugged in to run the office building on wind power stored from the grid at night, etc.. Now I see a statement about a potential strain on the grid?

Here's the problem: The typical home probably will not use more than 5 kW at any time during the day. Most of the time much less, with the peak demand around dinner time when everyone comes home and turns on the TV, the electric stove for dinner, the air conditioning during summer or the lights in winter. This causes a peak on the entire system, and the grid operator has to make sure there are enough generators - and enough distribution and transmission wires - to handle the load.

Now, it takes much more energy to move a car down the road then it does to light up a house. Most 8 cylinder cars will generate around 35 kw of power! If your PHEV has a 5 - 10 kW demand, and you plug it in when you get home - BAM - you just doubled or tripled your load on the grid!

"If vehicle batteries are charged during high-demand daytime hours, particularly in the summer, it could strain the grid and cause the need for costly new power plants, the report showed."

So the plan is to encourage millions of new battery powered cars or hybrids, and also set up a system that encourages consumers to act in ways that don't melt the grid.

Random question: How many folks want a plug-in electric car or hybrid? Now, how many of those people park their car in the garage? Oops - "there are only about 54 million garages for the 247 million registered passenger vehicles in the United States today." (pg 20 of the December 2008 report by the Electricity Advisory Committee). And of those 54 million garages - how many have room for a car? Better buy stock in extension cord companies.

Now here's an interesting dilemma - do the utilities install enough wires, generators and infrastructure to handle a potential peak from many PHEVs plugged in at one time - or do they hope that the incentives, etc., prevent that from happening?

Interesting irony - one solution to this dilemma, and many other potential grid issues, is to install large energy storage systems - like the VRB-ESS - on the local distribution circuit. This would increase capacity to handle a worst case scenario, without the need for more transmission wires, and allow for generation shifting from off-peak to peak.

The limits of energy storage technology | Bulletin of the Atomic Scientists

This obviously brilliant atomic scientist wrote a long and well researched article on the potential energy densities of energy storage v. hydrocarbon. He points out that there is much more energy per volume in hydrocarbon fuels then there can be in batteries or other forms of advanced storage.

"The maximum theoretical potential of advanced lithium-ion batteries that haven't yet been demonstrated to work is still only about 6 percent of crude oil."

However, he apparently ignores the fact that advanced storage technologies; like lithium ion, flywheels and the vanadium redox flow battery (VRB-ESS), can be used over and over! Storing wind, which is free and non-polluting energy, in energy storage that can be recycled - an unlimited number of times in the case of the VRB-ESS - should easily beat the hydrocarbons on energy v. volume, since the fossil fuel can only be used once! And, if the energy storage facility is in an area where space is not an issue - like a PV or Wind farm - then the discussion loses even more relevance.

His points may be more aimed at vehicles than grid connected storage. There's no opportunity to comment on his column where it was published, so I have to comment here.

The limits of energy storage technology | Bulletin of the Atomic Scientists

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Utility-Scale (Grid) Energy Storage Development – Increased Demand Results in Industry Innovation

Fairly extensive presentation on the market opportunities and suppliers for large grid connected energy storage. Plenty of opportunity for many technologies.

Utility-Scale (Grid) Energy Storage Development – Increased Demand Results in Industry Innovation

View more Microsoft Word documents from Frost Sullivan.

Duke Energy Smart Grid Demonstration Uses Storage

Someone said that a smart grid without storage is like a computer without a hard drive. Duke Energy seems to agree.

While much of the discussion about the the smart grid has focused on cool demand side gadgets to control thermostats, air conditioning and refrigerators - and the software and incentives (or forced compliance) to control them, the most effective "smart" appliance is an energy storage system. Energy storage on a distribution grid allows for the most efficient use of renewable energy - like PV systems on residences - and peak demand that occurs from air conditioning (and future hybrid plug-in cars) without intrusive monitoring of residential power use. What a concept - one robust and dispatchable grid connected battery - like the VRB-ESS - instead of multitudes of residential controllers, software and regulations.

Duke Energy plans to demonstrate such a common sense approach. Their system will utilize an advanced flow battery to balance PV, shift generation to cover peak, and provide power quality. Residential customers will be given the option to change power consumption by providing them with information and incentives - not by forcing remotely monitored / controlled motion sensors (to turn lights and power off and on) and thermostats on customers.



The advanced energy storage system (battery) allows Duke to work cooperatively with their customers without forcing compliance or intruding into their privacy. Customers can chose to respond to price signals or other data provided by Duke. However, the battery fills in any gaps and provides a truly "smart" addition to the grid.

Storage Technology of Renewable and Green Energy Act of 2009

U.S. Senator Ron Wyden (D-Ore.) has proposed legislation to provide tax incentives for energy storage. This is a first - providing energy storage with incentives similar to renewable energy, demand response and energy efficiency.

Press Release:
"In an effort to increase infrastructure supporting renewable fuels, the STORAGE Act provides investment tax credits for energy storage facilities and equipment that temporarily store energy for delivery or use at a later time. Currently tax incentives are only available for the generation of renewable energy, but output from wind, solar, and wave and tidal energy projects literally rises and falls with natural conditions. Storage technologies can help harness the output of renewable energy sources and allow them to be used when they are most needed. The bill encourages innovation by providing tax credits for a broad range of storage technologies, from water reservoirs to flywheels to hydrogen production to batteries when connected to the nation’s electricity transmission and distribution system and when installed in homes, businesses, and factories."

Although mentioning flywheels and hydrogen production, the language of the bill seems to be more oriented to advanced batteries like the VRB-ESS.

For example, the definition of ‘qualified energy storage property’ includes a minimum requirement to store at least 2 megawatt hours of energy, and output 500 kilowatts of electricity for 4 hours. On the face of it, this 4:1 storage v. capacity ratio would seem to rule out a flywheel that only has 15 minutes of storage. However, a flywheel system could provide 4 hours of electricity at 500 kW if the storage was oversized to 8 MWHrs. The conceptual grid-connected flywheel system, like that of Beacon Power, as well as the lithium ion systems, like Altairnano (see anuual shareholders presentation), are planned to provide short pulses of energy for grid stability, not sustained electricity delivery of more than 4 hours. So, a large flywheel/li-ion system could qualify, but it would seem to go against the conceptual definition in the bill. Looks like a loophole that Senator Wyden may want to tighten.

Also, the bill requires the energy storage to store and deliver electricity. For hydrogen production to qualify, a system would have to be designed to use electricity to generate hydrogen - say through electrolysis of water - and then convert the hydrogen to electricity - perhaps through a fuel cell. The problem is that this wastes a tremendous amount of energy. Taking 100 units of electricity through this cycle only returns about 20 - 30 units of delivered power. By comparison, storing electricity in the VRB-ESS is about 75% efficient. This may be another area for Senator Wyden to be more specific. Does he want to incentivize grossly inefficient electric storage systems?

We'll continue to follow this bill and comment.