A few days ago I was asked by a client in Australia 'How do you propose we broadly consider reduced CO2 emissions from using EV buses instead of diesel vehicles in our business case?'
It was a good question, and one that forced us to think about what benefits we should be calculating, as well as full lifecycle emissions and impacts.
We concluded, in collaboration with the client, that it is based on a range of factors, and differs location to location and country to country.
A simple answer...
On the surface it is a relatively straight forward question to answer - Electric Vehicles, when running only on electricity, have zero tailpipe emissions.
However this of course over simplifies things and does not consider electricity production, battery development, transport, and other location and environmental factors.
A slightly more complex answer...
Electric vehicles can result in a reduction of 50-80 percent, and potentially as high as 90%, in carbon emissions, depending on circumstances, and how electricity is generated and the types of vehicles being used. However, it can also be less - a lot less.
If we look at research online, especially research undertaken by Volkswagen in the UK and by MIT, we see that:
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Electric cars have a 50% - to 80% reduced carbon footprint
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In terms of emissions: on average petrol based cars emit over 350 grams of CO2, per mile, compared with 260 grams for a plug-in hybrid, and 200grams for a full batter-electric vehicle
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For buses, benefits can be even higher - a trial in Otago showed a saving of 2,511kg of CO2 Emissions which was a 90% reduction in emissions compared to a regular diesel buses
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A US study by the Union of Concerned Scientists showed battery electric busses are better for the climate, everywhere in the United States - however the range they were better was between 1.4 and 7.7 depending on region.
The above tells us that there are benefits, however, that the benefits differ location to location.
What could we considered when calculating benefits of EVs locally for a Business Case?
While from a policy perspective the idea of a zero emission vehicle is very attractive, consideration of life cycle emissions is essential.
You simply can't monitor only while the vehicle is in use. Stages of manufacturing and maintenance, electricity production and and battery development, all require consideration.
We see two solutions to answer the question:
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Apply a range: If budget and timeframes are tight - consider a range (possibly 40% to 70% reduction in C02 emission) and apply this with sensitivity testing in the business case. It won't be perfect, but it will consider the majority of scenarios.
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Consider specific criteria: If you have time and budget, and need more specific outputs, the best outcome is to consider specific criteria that relate to your location, environment, energy grid, and the specific EVs you are bringing. Key criteria that could be considered are below.
Key Considerations for criteria (subjective of course!)
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Manufacturing of the vehicle and transport to your location
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Development of batteries and their usable life (noting that apart from a few countries electricity is majority non-renewable energy so this is part of the life cycle)
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Electricity generation locally - eg percent renewable
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Distance travelled per annum on the network - especially on a bus network (eg headways total KMs, as the more distance travelled the greater the benefits)
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Percent of fleet going to be EV - if the whole fleet being EV is not a possibility, or if there will be staging
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Ridership levels
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Staging of the network
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Environmental, weather and topography considerations that impact EVs operating capability.
Note: One of the key factors is what percent of the fleet will be EV - for information a study in the US showed that across the board 79% battery electric buses and 21% Diesel hybrid buses lead to the most optimal cost and benefits (considering environmental constraints).
By considering these, you will be well placed to undertake a more accurate C02 reduction assessment.
Summary
While evidence shows C02 reduction benefits from an EV bus fleet, there are multiple factors that impact what the actual reduction will be.
Given the above, either a general range can be applied, or if you require accurate information, individual criteria can be answered and then a result formulated.
Keen to get others thoughts on how this is considered and applied in other parts of the world:)
Transit Trends · Andrew Collings, KA Advisory. Read and comment on the original on LinkedIn.
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