Having already taken some substantive steps to clean their power generation portfolios, each of the three Pacific states have now begun to target emissions from the transportation sector, which has become the lead sector in emissions in each state (for California, see [3]; for Washington, see [4]; for Oregon, see [5]). Toward this end, Electric Vehicles (EVs) are not the only solution being pursued, but they play a significant role in each state’s climate action plans. However, while these states (along with many of their larger cities and electric utilities) are developing and promoting policies meant to increase their constituents’ adoption of EVs, there are issues that must be addressed to maintain reliability and cost-effective services in light of the increasing likelihood of a scenario that will see rapid and significant market adoption of EVs over the coming decades.
From a utility (or even transmission operator) perspective, the nightmare scenario of EV penetration involves the specter of uncoordinated charging. In particular, there is concern that if all EV owners charge their vehicles at the end of a work-day, the aggregate demand could dramatically increase evening peak loads. Ultimately, uncoordinated charging introduces a dual threat of higher costs (to build more peak-serving generation) and diminished reliability of the grid (at overtaxed portions within distribution systems) [6].
1.1.Objective
This research project endeavored to shed some light on what utilities might (or should) do to effectively integrate EVs into the grid in ways that reduce market barriers (for EV adoption) and maintain reliability at the lowest cost to ratepayers. As the project team began disaggregating the range of issues and decision-making factors informing the business challenge posed to utilities, it became obvious that two tiers of decisionmaking needed addressing.
The first decision point is defined by the current state of the market and utility strategy needs. The EV market adoption is already underway, but options for Vehicle-to-Grid (V2G) tactics are limited by the lack of commercial availability of bidirectional charging equipment. Specifically, outside of pilot projects, most consumers only have cost-effective access to unidirectional charging equipment; they cannot export power from their vehicles to the grid yet. This means that utilities witnessing significant EV growth in their distribution territories are limited to grid-support tactics that rely more on behavior change. Until bi-directional chargers become widely available, utilities must find ways to incentivize their customers to avoid charging during summer peak hours, especially during heat waves. At present, there is a viable solution: dynamic pricing tariffs that vary the cost for power during peak and offpeak hours, respectively. Today, utilities in twenty states (including Oregon and California) have made dynamic pricing programs available to customers with EVs.
Having determined that applying the hierarchical decisionmaking methodology would be unnecessary to address the first decision-point, this research team decided to focus its efforts on supporting a near-future decision point that will emerge with the commercial availability of bi-directional chargers. Additionally, while there are many potential services that could be provided through V2G approaches, our team focused on one use case: the summer peak grid support.
1.2.Problem definition
Research problem: What are the most opportune behind-the-meter transportation technologies/products to use for future summer peak V2G programs in California, Oregon and/or Washington?
To explore this question, we investigated a range of potential EV applications (see Table 1) and challenged ourselves to view the availability of these options over time (as they might emerge in the market place as viable resources for future V2G programs). For this evaluation, we defined summer peak periods as those generally experienced in Washington, Oregon and California, that is, from 1 June to 30 September, between 4 pm and 9 pm. Of course, while there is a daily evening peak, there are typically only about 20 days per year where utilities need additional resources to successfully serve peak loads (most often during summer heat waves or days of highest summer temperatures).
Table 1.Potential V2G applications.
Note: An “X” means that the technology/product is not a good fit; a “
1.3.Gap analysis
Following brainstorming potential options, the research team identified a total of eleven EV products/technologies that could potentially provide exports to distribution grids during periods of summer peak stress. The initial eleven options identified included eight fleet options and three non-fleet options. Municipal buses, municipal non-bus vehicles, school buses, police vehicles, taxis, military vehicles, garbage vehicles and delivery vehicles made up the fleet options, while individual electric vehicles, off-road vehicles and Electrical Vehicle Supply Equipment (EVSE) comprised the non-fleet options.
As pointed out, these technologies/products were considered with the assumption that bi-directional charging equipment will become available to EV owners in the near-future. With this first enabling capability in mind, the next task required us to evaluate those options to determine which option, if any, would likely be available and capable enough to participate in a summer peak V2G program. Key gaps that needed to be filled, included: availability during summer peak periods, commercial availability, the likelihood of having sufficient export capability (determined by the State of Charge (SoC) available in the battery system during peak hours) and the capability of the EV owners (that is, their ability to participate without negatively impacting their primary use requirements/needs). Table 1 summarizes our findings; the prioritized options are shaded.
1.4.Perspectives and criteria
The Transportation Technology Assessment conducted for this report considered three overarching perspectives: Availability, Readiness Status, and the Likelihood of Owner Participation. These three perspectives are important for analyzing the adoption rate of Vehicle Grid Integration (VGI) technology in the near future. Each perspective includes criteria that inform the decision-making model and the options it provides.
1.Availability essentially considers potential EV types as options based on time and power. There are three criterions that build out this perspective:
i.The likelihood of being connected to a charger during the summer peak. Certain types of EVs, such as those that are individually owned, may be used more during peak times than others, e.g., garbage truck fleets.
ii.Whether the existing SoC is high enough to provide exportable power during peak hours, which depends on an EV’s charging load and speed. The key factor is whether an EV can be charged fast enough during prepeak or current peak times, so that it can export power to help support the grid during such peak times.
iii.Whether EVs are capable of being scheduled for precharging prior to peak times. Some EVs, such as school buses, are not constantly in use and may be scheduled more easily than other EVs that are regularly in use, such as
