Photo courtesy of Cajon Valley Union School District
In collaboration with partners and communities, WRI’s Electric School Bus Initiative aims to build unstoppable momentum toward an equitable transition of the U.S. school bus fleet to electric by 2030, bringing health, climate and economic benefits to children and families across the country and normalizing electric mobility for an entire generation. The Electric School Bus Series shows how superintendents and fleet managers across the United States have pursued school bus electrification in their own communities. This edition covers Cajon Valley Union School District in California, which has worked with its electric utility and technology partners to build out its electric school bus fleet while participating in a vehicle-to-grid pilot program and discharging energy back to the electric grid.
Located in southern California, the Cajon Valley Union School District (Cajon Valley) has recently made news headlines for successfully discharging energy from its electric school buses’ (ESBs) batteries back to the electricity grid via vehicle-to-grid (V2G) technology. This is an exciting, developing technology that may accelerate transportation electrification, particularly for ESBs.
Serving over 60 square miles of San Diego’s East County, Cajon Valley educates almost 16,000 students and provides transportation services to around 800 students, about half of whom are students with disabilities. Seven of the district’s 49 school buses are V2G capable electric school buses manufactured by the Lion Electric Company, meaning they can charge via a bidirectional charger and later be directed to send energy stored in the bus batteries back to the electric grid.
Sending energy from the vehicle to the grid (V2G) is one of several use cases of a broader array of vehicle-to-everything (V2X) opportunities, which also includes discharging energy to power a building (V2B) or some other connected load (V2L), such as an appliance like a coffee maker. V2X may further incentivize ESB adoption via its ability to bolster resiliency, strengthen the grid and lower energy bills.
The school district’s Transportation Director, Tysen Brodwolf, provided WRI with an insider's perspective on how Cajon Valley found itself participating in one of the nation’s first operating V2G ESB projects. Cajon Valley’s ESB program faced numerous obstacles including significant capital costs and charging reliability problems, but the program has overcome these and other challenges thanks to the frequent collaboration and unshakeable optimism of Brodwolf and her colleagues. Brodwolf is encouraged by the project’s status and hopes to continue procuring additional ESBs.
Motivation & co-benefits
Before purchasing ESBs, Cajon Valley was already known as a forward-thinking school district, having pioneered energy efficiency upgrades and investments in rooftop solar. When the school district was considering how best to build a sustainable bus fleet, ESBs were a new technology with ample funding available to help purchase the vehicles and install charging infrastructure. The school district determined procuring ESBs would help achieve its sustainability goals and would reduce student exposure to harmful pollutants created by diesel buses.
In 2019, after hearing a presentation from the local electric utility, San Diego Gas & Electric (SDG&E), about developing a V2G ESB pilot project, Cajon Valley connected with the utility about the opportunity. As part of the project, SDG&E would help Cajon Valley obtain federal and state grant funding to purchase the vehicles. The utility would also pay for the charging infrastructure, including the V2G system and necessary bidirectional chargers and any required electrical infrastructure upgrades. Once the V2G pilot was operational, Cajon Valley would provide SDG&E with essential data regarding charging, discharging and impacts on the ESBs and charging infrastructure so the utility and others could learn from the pilot.
Several partners collaborated on this trailblazing ESB V2G implementation.
SDG&E has been a crucial partner to Cajon Valley. Beyond helping Cajon Valley cover vehicle and infrastructure costs, SDG&E appointed a dedicated project manager who worked with the school district throughout the process. SDG&E held monthly meetings with Cajon Valley and other industry stakeholders and school districts to discuss updates on the project’s status, developing technologies and different clean transportation grant opportunities.
Nuvve, a private sector provider of V2G technologies, has worked with SDG&E and Cajon Valley to implement the V2G component of the pilot project. Nuvve’s software for the charging stations allows a remote operator, like SDG&E, to trigger a discharging event to the grid. Nuvve provided Cajon Valley with a digital charging and energy dashboard, which can set parameters around the charging and discharging of the vehicles to ensure there is no disruption of transportation operations.
Energetics, a clean energy technology and management consulting firm, has developed the software for the buses to ensure SDG&E could collect its desired data and has coordinated with the school district, Nuvve and the electric utility to address software challenges.
Brodwolf was appreciative of the support partners in the pilot project have given her when addressing mechanical and software issues. She said, “The great thing about [our partners] is that they have been extraordinarily consistent on trying to work through and fix the problems...I am very pleased, and I am very fortunate to have the relationship that I do with them.”
In 2019, Cajon Valley bought five Type C Lion ESBs using a Diesel Emissions Reduction Act (DERA) grant from the Environmental Protection Agency (EPA). These ESBs came with 132 kWh battery packs and could travel around 100 miles on a full charge. Each ESB cost about $380,000, but, thanks to its grant funding, Cajon Valley only spent about $50,000 in total. The funding specified use of the buses within communities with poor air quality and high diesel emissions.
In 2021, the school district bought two additional Type C Lion Electric ESBs, funded by grants from the Carl Moyer Program through the California Air Resources Board (CARB). These buses came equipped with 169 kWh battery packs capable of 120 miles of range, and they cost the school district about the same as the first round of ESBs.
SDG&E and Nuvve installed six 60 kW bidirectional fast chargers that were manufactured by Rhombus Energy Solutions. The utility covered over $1 million in electrical infrastructure upgrades at the school district’s bus depot, none of which had to be paid for by Cajon Valley. Brodwolf plans to expand to over a dozen V2G-capable fast chargers in the near future to power the fleet. Additionally, several Level 2 (L2) wall chargers were installed for resiliency purposes in case any of the V2G-capable chargers went offline.
Unlike the charging infrastructure, the ESBs were not originally V2G-capable and required upgrades to participate in the pilot project. These retrofits were delayed due to the COVID-19 pandemic, but they were finally made in June 2022, with the first successful discharge back to the grid undertaken at the end of the month. The hardware and software upgrades to the buses and chargers were part of pre-arranged agreements, so the school district did not need to pay for these upgrades.
Cajon Valley’s seven V2G-enabled ESBs can simultaneously discharge to the grid through their chargers. The original five buses are reportedly discharging 24 or 28 kW of power back to the grid, depending on the bus model, while the newer two buses are discharging 45 kW of power. To maximize benefits for the grid, the buses are engaged in managed charging and will charge outside of peak hours when not in use (off-peak hours for SDG&E being from 6 a.m. to 4 p.m. and 9 p.m. to 12 a.m. and super off-peak being 12 a.m. to 6 a.m.), but additional charging may be necessary between routes.
Currently, with the V2G infrastructure upgrades completed, the pilot project is just beginning and will operate for the next five years. In late July, Nuvve announced that Cajon Valley’s ESBs would be able to participate in SDG&E’s Emergency Load Reduction Program (ELRP), which pays participants $2/kWh for energy sent back to the grid or reduced energy load during emergencies that occur from May through October. For the school district, this program is currently the only revenue mechanism for battery discharging, but other mechanisms may be created at the state level in the future. The ELRP participation should not disrupt Cajon Valley’s bus services, as the requests will occur between 4 and 9 p.m., most of that period being outside of the regularly scheduled school bus operations. Additionally, the school district is not obligated to participate during an ELRP event and can choose whether to discharge to the grid. Participants will be asked to participate no more than 60 hours per year.
Commenting on Cajon Valley’s long-term plans, Brodwolf said, “We are going to be all V2G. That is the goal of this district… to be able to support the grid and send the energy back to the grid on demand with the vehicles that we have right now.”
Thus far, Cajon Valley has received some revenues from the ERLP program for discharges to the grid, directing those funds into the school district’s general fund. Additionally, managed charging of the vehicles is pushing down its electricity costs since the school district is avoiding high peak electricity prices. SDG&E is also restructuring the depot’s billing, putting the V2G charging on a separate meter.
Greatest challenge in setting up the pilot
Since the purchase of the ESBs, Cajon Valley has had to overcome recurring charging issues between the buses and charging stations. Brodwolf reported that the buses have stopped charging in the middle of the night, and the chargers have sometimes drained the batteries of connected buses. In the past, software updates have shut down chargers, and there have been issues with the power cabinets and display screens.
Brodwolf says that although the ESBs have performed consistently, their operational limitations have created some of the biggest challenges. Despite the quoted range of 100 miles for the first five buses and 120 miles for the second two buses, the school district realistically sees between 70 and 100 miles of range from the respective buses due to the passenger load and use of onboard systems like A/C or the heater. With some of their bus routes being 70-80 miles, the school district only deploys their ESBs on short bus routes where they do not have to be as concerned about battery charge. This has been a major problem because the grant funding for the two most recent buses stipulated that they be used within disadvantaged communities (DACs), which are on higher mileage routes. With additional assistance from Nuvve to determine how to deploy the buses along the required routes, using a detailed charging projection and battery analysis, Cajon Valley has been able to satisfy its grant requirements.
Moving forward, Brodwolf says she is worried about the availability of future funding and whether the school district will be able to afford further expansion of its ESB fleet. With the ongoing supply chain issues, Cajon Valley has been waiting since 2021 for a Lion Type D bus to be manufactured and delivered, and during that time, the ESB’s price has increased about 10%. The California Energy Commission has extended their ESB grant to Cajon Valley while they wait for the bus to be ready for purchase, but Brodwolf says that future grants will be harder to obtain due to their eligibility and equity requirements. Many grants require scrapping older buses, and they prioritize electrifying school buses that operate within disadvantaged communities; however, Cajon Valley has already replaced most of their older buses, and they have already assigned ESBs to their DAC regions.
Brodwolf did express optimism that the ESB market is growing and becoming more competitive, so school districts have more options. With the recently released Clean School Bus Program funding from the EPA awarded to school districts across the country, Brodwolf is hopeful there will be downward pressure on rising ESB prices.
Advice for other school districts
Despite all the challenges Cajon Valley has faced, Brodwolf remains enthusiastic about this important work. Brodwolf said, “It is a pilot project. We all must keep that in mind, that before we get to that big success, there's going be a lot of failures.”
When asked about what advice she would give to other school districts, Brodwolf said that planning ahead is essential when undertaking the massive investments for electrifying a school bus fleet. School districts should think about what they want their fleets to look like in the future and ensure that investments made now are ready to meet future needs. This could include considering where buses are going to be parked, where chargers need to be installed, what the future impacts of a V2X system will be, etc.
She also emphasized that when coordinating with the utility on the placement and operation of chargers and other equipment, it is important that the school district applies its knowledge of vehicle operations and reminds the utility that ESBs are vehicles first and grid assets second. This dialogue will ensure that the infrastructure necessary for ESBs and V2X are placed and used appropriately without compromising the school district’s ability to efficiently operate a school bus fleet.
Brodwolf is hopeful the lessons learned from her district can help other school districts who are purchasing ESBs and those who are considering integrating V2X with their ESB fleet, and she is encouraged by the project’s status and hopes to continue procuring additional ESBs. Brodwolf recognizes that many other transportation directors are going through the same challenges she did in the past, which is why being a leader on transportation electrification is so important.
- All About Managed Charging and “Vehicle-to-Everything” or V2X | Electric School Bus Initiative
- Emergency Load Reduction Program (ca.gov)
- Current V2G Projects | San Diego Gas & Electric (sdge.com)
- Behind the Wheel of Electric School Buses: Driving Green Instead of Yellow - Generation180
Want to learn more from the Electric School Bus Series? Explore more stories here.”