by Bob Shively, Enerdynamics President and Lead Facilitator

Some key regions around the world – New York, California, and Germany among others – are amidst a major transformation from an electric grid driven by centralized generation to a grid powered by distributed energy resources (DER). New York is currently revising its method of regulating electric utilities to foster use of DER when they are more economic than traditional generation resources. As Audrey Zibelman, Chair of the New York Public Services Commission, wrote recently in IEEE Power and Energy Magazine:

“It is time to recognize that the demand side of the grid can be a more-valuable resource than we could have imagined 30 years ago. Rooftop solar, energy storage (from household batteries to electric vehicles), smart energy management technology, and the aggregation of demand are all areas where demand, rather than generation, can become the state’s primary energy resource.”[1]

As this transformation is occurring, it is important for those in the energy industry to understand the services that DER must provide if they are to become a primary energy resource. It takes much more than just kilowatt-hours to run a grid reliably. As shown in the table below, necessary services can be divided into energy-related services and network-related services[2].

Below is a closer look at energy-related services and what they entail. Next week we’ll continue with a deeper look at network-related services.

Energy-related Services

• Energy (kWh): Load-serving entities (LSEs) must ensure that sufficient kilowatt-hours (kWh) of supply are provided to the grid to match their customers’ loads plus system losses. Energy acquired by LSEs may be purchased forward (for a period in the future beyond tomorrow), day-ahead (for delivery tomorrow), hour-ahead (for delivery in the next operating hour), or in real-time (for immediate delivery). Depending on the type of DER, energy can be made contractually available for some or all of these timeframes. 
• Firm capacity (kW): System operators must ensure that enough supply capacity is available to provide energy upon request during future timeframes. Capacity planning occurs over long-term periods (three or more years) as well as seasonally and monthly, and capacity is planned to meet the forecast peak demand during that time period plus a reserve margin. DER that can reliably provide energy during the peak can provide capacity services.
• Fast ramp capacity (kW): In regions with significant variable renewable resources (wind and solar) system operators must ensure capacity to provide kWh upon request during a specified period with the capability to move from one level of output to another level of output quickly (measured in kW or MW per minute). DER with the capability of ramping quickly can provide fast ramp capacity.
• Operating reserves: Going in to each operating hour, the system operator must have available sufficient capacity to provide kWh as needed to balance the system during an operating hour. This reserve capacity is needed to respond to both normal supply and demand fluctuations and fluctuations due to contingencies such as unexpected loss of generation or transmission.  Various operating reserves are required including regulating reserves, spinning reserves, non-spinning reserves, and supplemental reserves. Certain DERs can provide some or all of these services.
• Black start: System operators must have availability of units that can start-up to put energy on the grid without first drawing power from the grid.  This is necessary to recover from grid outages. Certain DERs can provide this service.

Next week we’ll continue with a breakdown of network-related services.

Footnotes:

[1] Audrey Zibelman, REVing Up the Energy Vision in New York, IEEE Power and Energy, Volume 14, Number 3, May/June 2016

[2] This table has been adapted from figure 3 in the article by Ignacio J. Pérez-Arriaga, The Transmission of the Future, IEEE Power and Energy, Volume 14, Number 4, July/August 2016.