At the control centre of the New England Independent System Operator in Holyoke, Massachusetts, where the entire wall glows with system schematics, the signals are sent out every four seconds. More power. Less. Turn it up here. Turn it down there. The signals go out over the internet, and computers use those signals to control generators supplying power to the grid, directly and indirectly.
This is how the system operators balance supply and demand in what’s been called the most complicated machine on Earth – the North American power grid – where the draw from all the computers and air conditioners in city centres must match the output from all the spinning turbines tens or hundreds of miles away to within a small fraction. If the mismatch deviates by more than a few percent then CPUs fry and motors burn out. To keep the two sides in close balance as the day goes on requires constant management. Major resources are dedicated to the maintenance of reliable and smooth power supply and as a result, if new technology can help keep the system in balance, it can be worth big dollars.
A key challenge is that the primary means of maintaining balance at present is to ramp generation up or down to match load. Existing regulatory requirements, both under the US Federal Energy Regulatory Commission, and in the Ontario system, stipulate a five-minute window for that to happen. Grid frequency will vary on a considerably shorter time scale than that. As Beacon Power’s Gene Hunt puts it, by the time a generator has brought power up on a particular line by ten megawatts, the ISO may well have told it 50 or more times to bring it down again. Even the nimble gas turbine seems tortoise-like compared to that timescale. But Beacon’s high-speed flywheel energy storage system will respond within that original four-second signal interval, dumping needed power out one moment and storing surplus power the next, significantly improving the IESO’s ability to smooth power flows to within hundredths of a percent, and to keep variations in frequency within a precision-engineered range.
A 1MW-capacity flywheel energy storage system installed by Beacon Power has been responding to those every-four-second control signals from the New England ISO control centre since November. With a 1,300-kilogram carbon-fiber composite flywheel, balanced to the shadow of a hair and spinning at 16,000 rpm, the installation can provide up to 15 minutes of supply or absorb 15 minutes of excess on a moment’s notice. The flywheel is connected to a generator that is also a motor, depending on whether it’s putting power out or taking it in, seemingly the essence of adaptability. The overall energy storage capacity can be increased if the installation is scaled up beyond pilot size, potentially providing even more system regulation needs, Hunt says.
Gene Hunt emphasizes that the kind of service this system is designed to provide – frequency regulation – is completely different from bulk storage. Bulk storage is hard to justify financially in the current market and currently exists only in a few forms like pumped hydro storage or compressed air in underground caverns, and involves quantities of power two orders of magnitude larger. Although smaller perhaps than the potential market for bulk storage, the market for frequency regulation in the deregulated (i.e. open) markets in the US is more than 2,000 MW – in other words, substantial. The total value of such regulation services in the United States is about US$1 billion per year, about 1% of total bulk power, and can be expected to increase as the proportion of power supplied by intermittent renewables like wind increases.
When its first 20 MW plant is built (planned for Stephentown, New York), Beacon will bid that amount of regulation service into the market every day, in competition with other generators. It will be paid by the ISO on a capacity basis.
Important funding, in the form of a loan guarantee, for that 20 MW plant, the first such utility-scale installation anywhere, has been in the works for 2 years with the US Department of Energy. At the time of writing their decision is expected soon. The financial support program, being energy efficiency and greenhouse gas-related, pre-dates the Obama administration and its recently announced smart grid stimulus package, which also has funding for energy storage / frequency regulation. “When they provide everyone with the details of how to apply for that, we will,” says Hunt.
The 1 MW New England pilot will be followed by the 20MW installation for the New York ISO. Cost of the first 20MW plant will be US$ 50-60 million; the 3rd or 4th plant should be half that, Beacon estimates.
Kim Warren, Director of class=en10>Planning and Assessments at the Independent Electricity System Operator (IESO), is familiar with the Beacon Power facilities, and confirms that the picture in Ontario is very like that in New England, even to the maximum allowable deviation of 130 MW between supply and demand (the two systems are very comparable in size).
At this point, the IESO is actively engaged in an awareness campaign around new technologies and the system-regulating services they can provide, Warren says.
“In order to carry out our duties we have to be aware of changes in the industry,” he says. “As people bring new products forward, it’s our responsibility to be aware of their capabilities, and then determine how they can best be utilized in Ontario. In our last Reliability Outlook we talked about the need for storage in Ontario. With our nuclear base, and the considerable move to renewables, we’re a natural candidate for storage – especially when you superimpose things like smart meters and time-of-use rates. So storage starts to look quite attractive. It could be used to support load-following, operating reserve, in shifting or flattening demand itself.”
The IESO has realigned a small department called Operational Analysis and Readiness, Warren said, which is looking for new technologies and capabilities, and trying to determine what our operation and our control room looks like in the future. IESO personnel have had discussions with some of the LDCs about where some of these devices could be located – on the high voltage system or the distribution system. The response from LDCs has been positive, he said.
“Existing, aging facilities that are being retired – what you could call the intermediate fleet – have provided system services of this type that have been almost taken for granted in the past,” Warren continued. “For example there has been no industry standard on governor response (frequency control). The North American Electricity Reliability Corporation (NERC) is looking at it now. There are certain basic parameters, but no one standard. It’s likely that this is going to be required in the future, with the growing move to renewables, and smaller generators that typically don’t provide that service.”
Some developments are underway on the rules and regulations that will be needed to operationalize the new services. The IESO is holding a stakeholdering initiative, next June 16, on embedded and renewable generators, and one aspect of this undertaking is looking at the potential need for new standards there. But NERC has also created an Integrated Variable Generation Task Force, which addresses the need for potential new industry standards for areas like load following, governor response, inertia standards — areas that the industry has been taking for granted. “We’re hoping they move swiftly, so that Ontario and others don’t have to develop them in isolation,” Warren said.