Riding on Electrons


Guest blog post by Mehak Vashisth and Ian Gray

Seventy-five years ago, Pittsburgh became a leader in the movement for clean air and water. Today, the city can and should be a leader for electric transportation. Rapid Substitution presents an ideal model for the Pittsburgh Port Authority (now Pittsburgh Regional Transit) to electrify and save money. Let’s explore how this works.

The transportation sector in the United States has been the largest sector by greenhouse gas (GHG) emissions for years. In 2020, these emissions decreased by thirteen percent (13%) due to the COVID-19 pandemic’s impact on travel – a perfect example of the positive environmental impacts of Rapid Substitution

Even with this decrease, the transportation sector remained the largest source of GHG emissions. According to the Environmental Protection Agency (EPA), the transportation sector contributes twenty-seven percent (27%) to the total US GHG emissions; the second highest economic sector is electricity generation at twenty-five percent (25%). The electrical grid continues to get cleaner, as zero carbon renewables accounted for eighty-one percent (81%) of new electricity generating capacity in 2021. 

We need to ensure the transportation sector follows this trend. Commercial technology is available today to decarbonize the largest emitting sector, so let’s get to work.

The objective of the Riding on Electrons project was to analyze the economic feasibility of Battery Electric Bus (BEB) deployment for the Port Authority of Allegheny County (PAAC) and ancillary benefits of electrification in the city of Pittsburgh. Our analysis used a discounted cash flow model from National Renewable Energy Laboratory (NREL) to compare the cost savings attributed to electrifying a portion of PAAC’s fleet. We chose to explore what would happen if the Port Authority committed to twenty-five percent (25%) of its new bus purchases being electric, or about 15 buses per year. 

We considered the purchase price, as well as operating costs incurred over the lifetime of the bus. These included costs of maintenance, fuel, and charging infrastructure. BEBs purchase prices are significantly higher than diesel buses – up front, a diesel bus costs about $512,208, while a BEB costs $887,308.  This cost barrier is, at least on its face, an issue consistently raised by local governments. However, the savings in fuel costs and maintenance over the life of the bus more than offset the higher initial price. 

Maintenance: While many parts (such as suspension components, tires, etc.) are common to both diesel and BEBs and wear similarly, diesel buses go through 2 to 3 engines and transmissions during scheduled overhauls over the lifetime of the chassis. The average cost for maintenance on a diesel bus works out to $0.88/mile ($28,876/year). BEBs should not require battery replacement during their 12-year lifespan, and many manufacturers warranty their batteries for 12 years. These batteries should have >80% capacity remaining at the end of the transit application and could then be sold for stationary storage projects (for electrical utilities) or recycled as raw material for new batteries. This residual value was not included in our study but will only make BEBs more attractive compared to their diesel counterparts.. Based on preliminary field tests of BEBs, maintenance costs are estimated at $0.30/mile ($9,844/year).

Fuel:  We assumed a $3.29/gallon price for diesel fuel (obviously prior to the conflict in Ukraine) and a $0.10/kWh electricity price. This yields an energy cost of $0.18/mile for the BEB versus $0.74/mile for diesel bus. Assuming each bus is driven 32,814 miles per year, this means the energy cost will be $24,366 for the diesel bus and $5,955.74 for the BEB. 

Consequently, that annual order of fifteen BEBs represents savings of more than $4 million for the PAAC over the lifetime of the buess – and the savings begin to accumulate at year three! 

Our analysis shows that PAAC is in a unique position to be a leader in the transition to a sustainable energy future while reaping financial benefits at the same time. If the pilot of 15 buses is successful, we recommend replacing buses and non-revenue PAAC fleet vehicles as they are retired with 100% EVs by 2025. 

This will achieve a completely electrified fleet by 2037 without changing the current vehicle replacement schedules. 

The BEB technology is here, the need is here, and the time is now.

Cumulative Discounted Net Cash Flow Savings of BEB

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