Californians love their cars and have a reputation for being environmentally conscious, so it is no surprise that the state leads the nation in green vehicle purchases. According to the Detroit News, roughly 50,000 electric vehicles (EVs) were sold in the U.S. in 2012. California accounted for just under one-third of those sales. In 2013, a total of 96,000 electric vehicles were sold in the U.S., just shy of double the previous year’s figure. As of 2012, ‘California’s viable goal is to make a total of 1.5 million EV sales by the year 2025’ (CAISO). Over the next decade, California will adopt measures and build infrastructure to entice more people to buy emission-free electric vehicles by making charging stations more accessible and offering rebates of up to $2500 on the purchase or lease of a new, eligible zero-emission or plug-in hybrid electric vehicle.
The proposed upsurge in sales of EVs over the next few years leaves me wondering if California’s, and indeed the rest of the United States’, power grids can handle this additional fleet of plug-in cars. Californian utilities constantly worry about spikes in demand at the end of each day; these spikes will only be enhanced when more EV owners begin charging their cars upon returning home from work in the evening. The state as a whole has enough capacity to deal with the additional demand generated by more EVs through power plants and transmission lines, but distribution problems become more pronounced when attempting to distribute power on a neighborhood-by-neighborhood basis. In most residential areas, one EV can easily be accepted into the charging infrastructure; however, as soon as a cluster of EVs charge in one area, additional pressures on the power bridge can cause unexpected power outages.
How Electric Vehicles Might Impact the Grid
The impact of charging an EV depends on where it is on the grid. According to SFGate, EV sales in California are the most prominent in the San Francisco Bay Area, the San Joaquin Valley, the Los Angeles basin, and San Diego County. Unevenly distributed EV sales puts further pressure on the grid. According to the EIA, Los Angeles and San Diego use the most amount of electricity in the state. As such, the addition of EVs in these areas poses challenges for the operation of the regional transmission grid.
Recent transmission upgrades along with capacity additions fueled by thermal, imported, and renewable sources have been implemented to help strengthen the Californian grid. Figure 1 below shows electricity generation by type in California (January 2011–January 2014).
Most of the electricity used in California continues to come from in-state generators fueled by thermal energy and imports from a variety of generation sources in other portions of the western interconnection. Renewable generation has been increasing in the past several years, while nuclear generation has dropped considerably since the shutdown of the two-unit San Onofre Nuclear Generating Station (SONGS) in January 2012 (EIA). However, with the influx of EVs on the grid over the next decade, a more reliable source of electricity such as nuclear may be required to balance the load.
California’s Renewables Portfolio Standard (RPS) is one of the most ambitious renewable energy standards in the United States. The RPS program requires all retail sellers of electricity to serve 33% of their load with renewable energy by 2020. As such, it will become more and more difficult to accommodate EVs under a status quo grid.
Fast-charging stations are not positioned to impact residential transformers or transmission lines. Instead, they are part of commercial grids that have supplementary transformers to accommodate large loads during business hours. However, if fast charging stations are ever connected to substations within residential areas that experience peak demand, there will be an even greater strain on the grid.
Further issues become apparent when EV owners install proposed EV charging circuits in their homes. Depending on the home and the EV, one EV’s demand is the equivalent of putting one to three houses on the grid, which can be a significant additional burden.
Californian Electricity Prices Are on the Rise
Given the history of electricity prices in the state, California still experiences extremely volatile electricity prices to this day. It’s very difficult to balance the grid when prices are so unstable. Figure 2 below illustrates the electricity prices of Southern California (January 2012–January 2014).
After the shutdown of SONGS in early 2012, the relatively inexpensive nuclear generation produced by SONGS had to be replaced with power from more expensive sources. Consequently, since April 2012 Southern Californian power prices have increased considerably. Furthermore, the closure of SONGS put pressure on CAISO, to adjust both power generation and transmission in order to meet summer demands for electricity–demands attributable to the surge in air conditioning use during this period (EIA). Grid unreliability will become more prominent and prices will continue to rise with the addition of EV use in the state over the next number of years.
CAISO Rolls Out Roadmap for Electric Vehicle-Grid Integration
The California Independent System Operator Corporation (ISO) has come up with a solution for integrating EVs into the grid, outlined in the Vehicle-Grid Integration Roadmap. The roadmap proposes potential solutions that will balance grid resources while meeting EV owners’ charging needs.
CAISO’s Vehicle-Grid Integration Roadmap was developed to advance the state’s 2025 EV goal. The blueprint is expected to lead to EV charging behavior that is beneficial or at least not adverse to grid reliability (CAISO).
The integration of EVs into the grid presents an opportunity for EV owners to develop charging strategies that support reliable management of the electricity grid. This will ensure that EVs do not increase peak load and require additional generation or expanded capacity. According to CAISO, “charging should be coordinated with grid conditions and the ability for aggregation of EVs to respond to grid operator signals is the obvious solution”.
Power generators end up producing surplus power at night due to decreased electricity demand, consequently, when EVs are plugged in at night, there is often surplus power waiting for them, and the electricity grid will also have some power-handling capacity available, due to that same decreased demand. Therefore, if ISOs create the right incentive price signals for EV owners, EV owners will be more likely to charge their vehicles during non-peak hours in order to reduce household electricity bills.
CAISO’s goal is to utilize EVs to help stabilize the reliability of the grid. Although the time to charge EVs is determined by the vehicle’s owner, most owners will choose to charge their vehicles at night to save money on their bills.
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