New energy-storage options emerging in New England; ISO-NE publishes primer and makes FERC filing on market participation

June 22 update: Information added on ISO-NE’s May FERC filing. Proposed project megawatts (MW) were also updated to reflect the withdrawal of 50 MW of battery storage to have been included as part of a proposed new natural-gas-fired generator.

For the first time, grid-scale (or utility-scale) battery storage projects are seeking to join New England’s regional power system. Late last year, three projects with a combined 94 megawatts (MW) in nameplate capacity applied for interconnection in Maine, with one planning to go live by the end of 2016 and the other two in 2019.*

Emerging energy-storage technologies hold great potential for helping to balance the weather-dependent output from wind- and solar-powered resources.

Emerging energy-storage technologies hold great potential for helping to balance the weather-dependent output from the growing number of wind- and solar-powered resources in New England. In light of growing interest in energy storage from project developers, policymakers, and other stakeholders, the ISO released “How Energy Storage Can Participate in New England’s Wholesale Electricity Markets” in January, with updates to reflect stakeholder feedback in March. The paper describes various types of existing and emerging storage technologies and provides an overview of how both large- and small-scale resources can compete for compensation in the markets.

Interested parties should also see the ISO’s May 16 filing to the Federal Energy Regulatory Commission (FERC) in response to FERC’s data request to grid operators on the participation of electric storage resources in wholesale markets. Among other things, the filing details how the technology-neutral regional markets have evolved over time to better enable storage resources to participate and provides eligibility and performance requirements for participation.

Energy storage in New England

New England has a long history of operating the power system with pumped-storage hydropower—a type of large-scale energy storage. These resources can respond very quickly to system needs and for a sustained period, making them particularly valuable for helping to ensure a reliable supply of electricity. However, development of new pumped-storage projects is unlikely because of environmental concerns and high development costs. Emerging energy-storage technologies, on the other hand, could offer the region similar benefits, though their run time may be more limited.

Here are some examples of energy-storage resources that exist or are emerging in New England. A unique characteristic of these resources is that they act as both demand and generation: they draw electricity from the power system as energy is “stockpiled,” then add electricity back when that stored energy is released. The specific way that each type of storage resource is configured and operates determines which markets the resource can participate in or ancillary services it can provide. See the ISO paper for details.

• Pumped-storage hydro—These facilities pump water into a reservoir for storage, then release the water to create electricity when needed. New England has two such facilities built in the 1970s, which can supply almost 2,000 MW of capacity within 10 minutes. These resources were initially developed to provide fast-response capability in the event that a nuclear power plant tripped off line.
• Flywheels—These devices use a motor to quickly spin a wheel. The kinetic energy from that rotation can then be used to produce electricity. A flywheel system providing regulation was part of the ISO’s 2008–2015 pilot program to encourage alternative technologies to participate in wholesale electricity markets. That program helped set the stage for the ISO’s redesign of its Regulation Market.
• Batteries—Electricity is used to charge batteries, which can then supply power when needed.
• Electric vehicles—The batteries of electric and plug-in vehicles can provide power to the grid when not in operation.
• Compressed air—Air is compressed and stored in tanks or underground. This pressurized air can then be used to drive a generator.

*Not all projects proposed in the queue are built. Historically, there’s an attrition rate of about 70% of the megawatts proposed. See the current ISO Interconnection Request Queue.