Executive Summary
This report documents a practical demonstration of Vehicle-to-Grid power, providing real-time frequency regulation from an electric car. Vehicle-to-Grid (V2G) presents a mechanism to meet key requirements of the electric power system, using electric vehicles when they are parked and underutilized. While V2G is expected to have several applications, the most economic entry for this green innovation is the market for ancillary services (A/S). The highest value A/S is frequency regulation (in many ISOs, including PJM, this service is simply called “regulation” and we will use that term subsequently). In areas with deregulated electricity markets, regulation can have average values of $30-$45/MW per hour, with hourly rates fluctuating widely around that average.
A second market of interest is spinning reserves, or synchronous reserves, with values in the range of $10/MW per hour, but much less frequent dispatch. The primary revenue in both of these markets is for capacity rather than energy, and both markets are well suited for batteries as a storage resource because they require quick response times yet low total energy demand. Additionally, V2G can provide distribution system support when there is a concentration of parked V2G cars, along overload elements in the distribution system.
A later application, when parked V2G-capable cars are connected and aggregated in large numbers, would be to use them as dispersed energy storage for intermittent but renewable resources such as wind and solar. The results of the study show that V2G, in addition to providing valuable grid servies, could also prove to be a prominent application in the global transition to the emerging green and sustainable energy economy.
A fully functional, freeway-capable electric vehicle was used in this study. Its power electronics are designed to both drive the vehicle and allow for high-power exchange with the electric grid. We modified this vehicle by adding controls and logic to make it respond to the PJM real-time signal for regulation.
The data and resulting graphs show the ability of the car to provide regulation in addition to zero emission local commute driving. This is a technology proof of concept with a single vehicle. Current work is directed toward developing dispatch of about a half-dozen vehicles. To move from a technology demonstration to commercial application, the next step would be a business model development at the scale of 100 to 300 vehicles.
The report is comprised of six sections. Section I provides an introduction of the research initiative. Section II covers the infrastructural background concepts involved in V2G application for regulation. Section III calculates the commercial value of V2G as demonstrated by the existing ancillary service markets. Section IV reviews distribution issues, including service drop and distribution transformer power capacity. Section V describes the methodology used in the study. In Section VI, we present the experimental results of the test. Finally, in Section VII, we provide concluding remarks and the proposed future work that will be needed to make this green, sustainable and energy security/independence innovation a reality.
Section I: Introduction
With the increasing cost of petroleum and growing acceptance of global climate change as a critical environmental problem, policy makers, engineers and business leaders are searching for alternative energy solutions. Re-electrification of automobile transportation and enhancement of the existing power system grid is one such solution.
The electric power system is a complex and critical infrastructural system, yet it lacks energy storage capacity, so electricity must be simultaneously produced and consumed.1 Automobiles contain distributed energy storage; today, that storage is in the form of liquid fuel but we, and much of the industry, anticipate a shift to electricity.2 Both the power system and automobiles are designed to meet peak demands – peak electric use for the power system and the power to accelerate to full speed for the automobile. The actual level of utilization of both assets is far less than 100% most of the time, especially for local commute vehicles for individual urban families.
Although the electric power system industry has undergone restructuring, the fundamental engineering aspects of the system remain the same. The load and the generation in the system must be balanced at all times. To accomplish this real time balancing, several functions have been established to manage the system effectively.
With restructuring, some of the balancing functions, such as spinning reserve and regulation, have become marketed services. Other functions, such as voltage control and reactive power management, are at the distribution level and remain the responsibility of the local load-serving entity. Spinning reserve and regulation are termed ancillary services, abbreviated A/S, in well- established power markets such as PJM and other Regional Transmission Organizations (RTOs) or Independent System Operators (ISOs).
The biggest challenge with electric vehicles has been the battery that stores the energy needed to drive the vehicle, with challenges of both cost and lifetime. There has been significant research to improve both variables and it is anticipated that if adequate public policy is implemented, both costs will become competitive within four to seven years.* Now is the time to establish the business models for electric vehicle interaction with the grid, so that the business is developed and ready for rapid expansion as electric vehicles enter the market place in the coming years.
AC Propulsion of California has designed an electric drive system using mass-produced 18650 lithium-ion batteries and a patented power electronics unit that is ideally suited for Vehicle-to- Grid (V2G). They have also created electric and plug-in hybrid vehicles by converting existing gasoline vehicles. Other manufacturers, including global auto manufacturers such as Renault/Nissan, Mitsubishi Motors, and BMW, are producing all-electric vehicles for some markets and have announced full-scale production plans for all-electric vehicles.
Results from an Industry-University Research Partnership
Willett Kempton,* Victor Udo,✝ Ken Huber,§ Kevin Komara,§ Steve Letendre,¶ Scott Baker,* Doug Brunner,* & Nat Pearre*
