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Combustion engines produce a lot of waste heat. Switching to electric vehicles would eventually eliminate this UHI contribution.



It is well known that combustion engines such as those used in most cars and trucks, produce a lot of waste heat; up to 65% of heat energy produced by the engine is wasted and released into the urban environment. This waste heat can be a significant contributor to the UHI effect. Switching to electric vehicles would eliminate this heat source, as electric motors are far more efficient and do not produce large amounts of waste heat. Obviously we would need to simultaneously switch the electricity supply from fossil fuels to renewable energy sources to avoid increasing the UHI effect from urban power plants. That transition is already under way in Massachusetts, and in Cambridge, however (RPS, RGGI, GWSA, etc.). We can therefore assume that the electric supply will continue to become less fossil fuel intensive over time, and that electric vehicles will become a net gain in UHI reduction.

Category of the action


Who will take these actions?

The city of Cambridge can lead the way by committing to an all electric vehicle fleet as soon as possible. Starting with passenger vehicles such as the two Chevy Volts currently in use by the Mayor and Commissioner of DPW, the city can switch these and other such vehicles to all electric vehicles in the future (the Chevy Volt still has an onboard combustion engine to charge the batteries when they get low). Other vehicles to target include the Traffic and Parking vehicles for example, which already include a Prius Hybrid, which is more efficient, but still produces waste heat.

The city can replace light duty vehicles in use by DPW with all electric alternatives in the future as those become available. Heavier duty trucks will take longer as electric drive trains are not yet commonly available. Even so, the city can stay on top of that technology as it develops.

To facilitate this transition the city could commit to leasing instead of buying future vehicles in order to take advantage of the rapidly advancing technology. In doing so the city also increases the supply of used electric and hybrid electric vehicles which can replace conventional vehicles for people who cannot afford to purchase such vehicles at the retail price for new vehicles. 

The city could also promote community adoption of electric vehicles by installing more charging stations, requiring charging stations in future parking garages constructed by private developers when possible, and allowing residents to request charging stations at on-street parking spots, which could then be converted to EV residential parking only. The charging stations generate revenue and therefore the cost of a charging station can be earned back by the city or by private companies operating the station such as e.g. ChargePoint.

What are other key benefits?

In addition to immediately reducing the UHI effect, a switch to electric vehicles powered by renewable energy will reduce future climate change and therefore reduce the future severity of the UHI effect.A more immediate and tangible benefit is reduced pollution from combustion engine exhaust, including nitrogen byproducts, ozone and particulates.

What are the proposal’s costs?

Electric vehicles are still somewhat more expensive than conventional vehicles to own and operate, but not compared to hybrids. A Nissan Leaf can be leased new for around $300/month, which is comparable to a Toyota Prius (also around $300/month). Furthermore, because it is cheaper per mile to drive an electric vehicle than a gas vehicle because electric vehicles have lower maintenance costs, overall the government would save money on an electric fleet vs. a gasoline powered hybrid fleet.

The primary concern with electric vehicles is the potential need to replace the battery, but on a standard 3 year lease that is not a concern. As the technology continues to improve, the range will also increase; Tesla has already announced the Model 3 for 2017, with a price comparable to a Nissan Leaf but with twice the range:

Time line

The city would announce immediately a commitment to switch all vehicles to full electrics as soon as possible, whenever economically and technologically feasible.

Over the next 3 years as vehicles in the municipal fleet come up to their end of life or end of lease, the city would evaluate replacing each vehicle with an all electric. If the city decides against an all electric vehicle, it would publicize the decision and criteria, to help the public understand why that particular vehicle cannot yet be an all electric. In particular the Mayor's and DPW Commissioner's vehicles should be evaluated for Tesla Model 3 replacements as the price point is predicted to be equivalent, and a 200 mile range should make that a perfectly useable car for those purposes.

The city would publish a graph showing the percentage of its fleet that is electric, including hybrid electric and plug-in hybrid technologies, so that the public can track the progress.

As the technology continues to improve, the fleet would increasingly become all electric in the subsequent 10 to 15 years. Eventually heavy duty trucks, including garbage pick-up trucks would be replaced with all electric or alternative energy drive trains that reduce waste heat and fossil fuel consumption.

In the long term, say by 2050, all vehicles owned and operated by the city should be electric or low/no combustion vehicles.

A switch from leasing back to owning could become feasible as the technology stabilizes and maintenance costs are significantly reduced or can be amortized more easily across an all electric fleet.

As electric vehicles become more common, the number of charging stations permitted by the city would naturally increase and gasoline filling stations would start to naturally decrease as demand is reduced.

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