November 02, 2016 Categories: California Clean Energy Climate Change Fossil Fuels Low-Carbon Fuel

How Electric School Buses Can Drive to a Cleaner, Safer Future

The yellow school bus is an ubiquitous sight across America. Nearly 500,000 of these predominantly diesel-powered vehicles shuttle kids to and from school 180 days of the year. But as the wheels of these buses go round (and round), their tailpipes and diesel-fueled engines are belching out dangerous soot, sulfur, and carbon – and America’s next generation of climate heroes and their young lungs are right in the line of fire. Luckily, there is a promising solution – transition our diesel-powered school bus fleet to 100% electric.

The Environmental and Health Impacts of School Busses

Diesel-powered school busses travel almost 6 billion miles per year, primarily through residential neighborhoods, with an average fuel economy of just 7 miles per gallon. That means our nation’s school bus fleet (despite only operating for a few hours a day, 180 days a year) emits 8.4 million metric tons of carbon pollution every year. This is roughly equivalent to the combined annual emissions of 1.4 million passenger cars.

In addition to the climate toll of diesel school busses, there are also devastating health impacts. There is no known safe exposure level to diesel exhaust.

Diesel fumes contain high levels of fine particles and a variety of air toxins that can interfere with our DNA and cause mutations that may lead to cancer or other health problems. Even at relatively low levels, these toxins are known to cause and exacerbate asthma, bronchitis, and pneumonia – especially in children. Retrofitting school busses to lower emissions will reduce children’s hospital visits for serious respiratory illnesses. But with modern electrical vehicle technology, we don’t need to settle for just reducing these dangerous emissions –we can eliminate them altogether.

The Solution

It is time to make school busses 100% electric. In addition to avoiding tailpipe emissions and dramatically reducing children’s exposure to dangerous particulate matter and carcinogens, switching to electric buses can provide additional benefits to the electrical grid as a form of energy storage, all while saving school districts money.

Grid Balancing

As we transition away from fossil fuels and to renewable sources of energy, we need flexible power sources that are able to respond to variability in electric supply and demand in real time. Advanced energy storage technologies and a smarter, more-integrated electric grid are needed.

Utilities across the country are beginning to recognize the need for energy storage, especially in states like California, where 26% of electricity generation already comes from non-hydroelectric renewables like wind and solar power, with a target of at least 50% renewable generation by 2030. To help facilitate higher levels of renewable generation, California has mandated the state’s three largest utilities to add at least 1.3 GW of energy storage to the grid by the end of the decade.

Enter the all-electric, yellow school bus.

For the majority of a school bus’s life, it sits idle. During the middle of the day, on weekends, and during the summer school buses just sit there, waiting to be put to use. But if each school bus had an electric battery, instead of a dirty diesel-powered engine, these busses could be put to productive use during their downtime. They can charge in the middle of the night when energy demand is low or in the middle of the day when solar energy supply is high. Then, they can reverse the flow of energy and give their power back to the grid when demand is high. In the summer months, when energy demand reaches peak capacity and school buses are least in use, the combined energy storage of a fleet of electric school busses would help balance supply and demand on our electrical grid.

If the State of California, for example, transitions its 24,000 school busses to a 100% electric fleet, each with a 70 kWh battery (good for over 50 miles of range), that would add 1.7 GW of energy storage to the grid – significantly more than the state’s energy storage mandate. With 100 kWh batteries, California would add 2.4 GW of storage to the grid. On a national scale, transforming our fleet could yield between 34 and 48 GW of energy storage, all from unused yellow school buses sitting in a parking lots.

There is also a societal benefit of having a large, mobile energy supply in the case of emergencies. Electric school buses could potentially be used to power individual buildings like hospitals or shelters during natural disasters or when there are extended local power outages.

Big Benefits, Lower Price.

There are a variety of factors that contribute to the cost of an electric school bus. Is it a new bus, or a retrofit? What is the desired range and what size battery makes that range possible? Is there a bidirectional inverter installed, allowing power to flow from the bus to the grid? There have been an array of pilot projects designed to show how transitioning to electric school busses can actually save school districts money, and we are starting to see results.

A financial model from the Clinton Global Initiative shows that, given an average 15-year lifespan for school buses, schools can save money by going electric, despite higher upfront cost. When you factor in savings from reduced fueling costs, reduced maintenance costs (electric vehicles have no transmission, no radiator and fewer moving parts over all)  and revenue from utilizing the bus for energy storage, those additional upfront costs are more than offset after about 13 years. By financing buses through low-interest bonds paid back over the lifetime of the bus, schools can start to see this savings in the very first year, and state or federal incentives can help to increase these savings even further.

These savings don’t account for any of the public health benefits to the children or the neighborhoods the school busses travel through every day. Counting these benefits makes electric buses even clearer winners.

As  more school districts and states recognize that electric school buses are worthwhile investments, demand will rise, and prices will continue to fall. The best way to jump-start this market, and the transition to an all electric school bus fleet, is through a large federal grant to the states, as part of a broader push to a 100% clean transportation system. Investing here could deploy tens of thousands of electric school buses across America and create the demand necessary to bring this market to scale. This will improve the health of our climate, the health of our children, and the health of our electrical grid – it’s a win-win-win.

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