On a hot day in NYC, I walked past an idling semi-truck and was blasted with enormous heat rejection from the engine. This got me thinking about a benefit of EVs which has not generally been considered by the government, the media, or environmental groups: waste heat.
New combustion engines (gas and diesel) are about 32-35% efficient. That means that apart from the CO2 they emit, for every 1kWh of movement, 2kWh of heat are dumped directly into the atmosphere. Firstly, this can heat up urban environments, which is a major health concern in tropical regions as the world warms. [One study estimates that electrification can reduce urban temperatures by 0.6C.](https://www.frontiersin.org/articles/10.3389/fenvs.2022.810342/full).
Secondly, direct heat an often overlooked contributor to global warming. Greenhouse gases certainly have an outsized effect, especially over the decades they can stay in the atmosphere, but the effect of direct heat production is larger than it is treated. [This study estimates that over 100 years, direct heat contributes 8% of the total global warming effect of a coal power plant at a similar 30% efficiency](https://www.sciencedirect.com/science/article/pii/S0360544210005694). That’s over 100 years of the greenhouse effect, in the short term the effect of direct heat production is actually greater than the greenhouse effect. Over any timescale, 8% or more of global warming is not something we can overlook.
On the whole, the climate benefits of EVs are only ever treated in terms of CO2 emissions vs. regular ice, but the total contribution of an ICE to global warming is greater than just it’s CO2 emissions.
This argument goes double for residential and commercial heat pumps but that’s another story.
