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Durango, Colorado’s 9-R school district will soon be the owner of a brand-new, all-electric Bluebird bus. Thanks to a grant from the Regional Air Quality Council’s ALT Fuels Colorado program and southwest Colorado’s La Plata Electric Association (LPEA), the school district is getting the bus entirely for free. This was made possible by the state grant funding, which covered much of the $210,000 difference between the cost of a diesel vs electric bus, but also by LPEA’s initiative in penciling out how both they and the school district could benefit from nascent vehicle-to-grid (V2G) technology.

It will be the first use of V2G technology with a school bus in the state of Colorado. LPEA aims to demonstrate how electric school buses can provide benefits and savings to everyone in their service area. I spoke with Dominic May, LPEA’s Energy Resource Program Architect, to learn more about the bus, V2G and the benefits.

V2G gives LPEA a return on their investment

LPEA contributed about $150,000 to cover the remainder of the cost of the bus and to install a 60 kW bidirectional charger at the school district’s bus barn. Bidirectional chargers are at the heart of V2G technology. They take the AC power provided by LPEA’s electrical grid and turn it into DC power which fills the bus battery. They can also go the other way and change the DC power in the bus battery into AC power, which can then be sent back into LPEA’s electric grid.

The bus and the bidirectional charger are now owned by the school district, but they have an operational agreement with LPEA which allows LPEA control of the battery for the coop’s benefit.

V2G is the big reason I got interested, in addition to finding a project that could be entirely free for the school.

Dominic May, Energy Resource Program Architect

How can the school district and LPEA both use the same bus?

We have an operational agreement that we will run the battery to perform energy arbitrage in the background. The school district will never notice we’re doing it but will always charge at our cheapest off peak rate.

Dominic May, LPEA Energy Resource Program Architect

The bus battery holds about 175 kWh of energy. It will charge overnight and during mid-day when the bus is back at the bus barn. On the commercial time-of-use rate LPEA provides, these are the cheapest times of day to use electricity.

After it returns from its morning route at about 9 AM, the bus will need about 3 hours to refill the battery. It arrives back from its afternoon route at 4:30 or 5:00 PM. LPEA’s evening peaks usually occur at about 6:30 or 7:00 PM. They will recharge the battery up until the evening energy use peak starts ramping up. As the peak 15-minute period approaches, LPEA will signal the bus battery to push 60 kW onto the grid. (60 kW is the maximum rate the bidirectional charger can discharge at.) When the peak is passed and peak rate time is over, the bus will continue recharging into the night.

What’s in it for LPEA?

LPEA’s supplier, Tri-State Generation and Transmission Association, charges LPEA a monthly demand charge based on their peak monthly usage. For every kilowatt LPEA uses during their peak 15 minutes in each month, Tri-State charges $20/kW. By reducing their peak with the bus battery, LPEA realizes 60 kW x $20/kW = $1,200 savings a month. Says May, 60 kW of demand “that’s like a dozen houses or more coming off the grid during the peak hour.”

Just selling that off-peak energy, we don’t make much more than $0.02 per kWh and it would’ve been close to a 400 year payback period, but doing demand managing with the V2G system turns it into about a five to eight year payback period.

Dominic May, LPEA Energy Resource Program Architect

After that, the savings will accrue to LPEA’s membership.

The bus is free to the school district, but is it cheap?

The electric fuel for the bus will be one sixth the cost of diesel. The electric motor and drive train require much less maintenance than gas or diesel buses. No oil or coolant changes, no air filters, no tune-ups. LPEA’s use of the battery doesn’t require any changes to the regular schedule the bus would run. They only use it when it would be sitting at the bus barn anyway.

A diesel bus will have to be sacrificed as a condition of the state grant dollars. The school district’s oldest bus must have its axles broken or its engine cored to ensure it is permanently disabled. The intent of the state grant is to reduce air pollution by taking old diesels, which have very dirty exhaust, off the road.

What else can you do with a school bus full of cheap energy and V2G technology?

Provide mobile electricity sources during blackouts.

Any school or other buildings designated as emergency shelters would need to be outfitted with a bidirectional charger, and the electrical infrastructure to support it, to be able to receive the energy in the event of a blackout. Once installed, these chargers could also be used as fast chargers for any electric vehicle in non-emergency circumstances.

They definitely can serve as an emergency generator. One of the cooler things they could do is come up and power something like a FEMA shelter. However, the caveat is the places have to be wired up to receive this and infrastructure will need to be built to support it.

Dominic May, LPEA Energy Resource Program Architect

Demand Management

Demand management is getting bigger and bigger, especially as renewables come on the grid. You have this extremely cheap and clean energy, but it’s intermittent. So, anything you can do for storage is really what this is all about. That’s the dream of V2G – that we would multi-purpose this giant fleet of batteries that are out there to make the grid cheaper, cleaner, and more resilient.

Dominic May, LPEA Energy Resource Program Architect

Does the electric school bus help decrease greenhouse gas emissions?

On some grids, the power used at peak times is dirtier than at other times. For example, on a grid which has solar generation, and uses natural gas “peaker” plants to provide energy during the peak evening hours just as solar is waning, energy used at peak times will have higher carbon dioxide emissions per kilowatt. By decreasing the amount of kW used at peak times, those higher emissions are avoided.

On our current fuel mix, the school bus will reduce carbon emissions by about 2 ½ times its weight in carbon dioxide every year.”

Dominic May, LPEA Energy Resource Program Architect

When greenhouse gas emissions are decreased, the other pollutants associated with burning petroleum are also decreased. Diesel engines emit particulate matter, nitrogen oxides, carbon monoxide and numerous toxic volatile organic compounds.

The bus is expected to arrive in Durango by the end of October 2021. It’s now at its final stop, getting outfitted by a company on the front range to the school district’s specifications.