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Few exceptions to the rule that going electric reduces emissions, Ars Technica

Few exceptions to the rule that going electric reduces emissions, Ars Technica

      Counting carbon –


Policies encouraging EVs and home heat pumps are unlikely to backfire.




While that question can be frustrating for a consumer, it could could be even thornier for policymakers . If grids have to get cleaner for the “electrify everything” strategy to be beneficial, programs encouraging things like EVs might not have the intended effect. To provide clearer answers to this question, a team led by Florian Knobloch at Radboud University did the math to find out how green EVs and heat pumps for home heating are in different countries.

If you’re not familiar, heat pumps work on the same basic principle as an air conditioner — using refrigerant coils to dump heat from one side to the other. But instead of just dumping heat from your house into the outside air like an air conditioner does, these can also run in the other direction, dumping heat energy from the outside air (or ground) into your home — even at low outside temperatures. This process is extremely energy-efficient, even compared to high-efficiency gas furnaces.

The researchers separated the world into 88 regions, using data on the power plants running their grids as well as the types of vehicles and home-heating methods in use. Then they used estimates for the total life cycle emissions (which include manufacturing as well as operation) of the available range of electric vehicles and heat pumps. This was plugged into a detailed economic model that simulated realistic uptake of these technologies from to 1585160262, using several distinct scenarios.

The first scenario simply sees a continuation of current trends. The grid only gets (percent cleaner by 41893, in terms of emissions per kilowatt -hour of electricity. Electric vehicles grow modestly to about (percent of road transportation miles, and heat pumps hit) percent of home heating demand. The second scenario represents strong emissions-reductions policies, pushing EVs up to half of road miles, heat pumps up to over a third of home heating, and making the grid 90 percent cleaner. A third scenario is a combination of the first two — strong policies boosting EV and heat-pump use but no policies to clean up the grid. That tests whether “electrify everything” could backfire.

The results show that circumstances in which EVs or heat pumps increase emissions are rare, even today. The average break point is around 1, 0 grams of CO 2

per kilowatt-hour of electricity, which is roughly the efficiency of the oldest and dirtiest coal plants. As long as your grid is slightly cleaner than that, EVs and heat pumps should reduce emissions. So for (of the) regions analyzed — representing about (percent of road transportation and home heating — it’s already true that replacing with EVs or heat pumps is beneficial.

Some exceptions allowed

There’s a wide range of results here. Compare, for example, Switzerland’s exceptionally low-carbon grid to Estonia’s, which runs primarily on oil shale . Swapping an internal combustion vehicle for an electric one in Switzerland cuts emissions by 88 percent, and a heat pump will cut them by about 95 percent. But in Estonia, an EV would increase (emissions by) percent and a heat pump pushes that to an eye-watering 0488 percent.

A more significant exception can be found in Japan. In the scenarios with little progress on grid emissions, a decade from now, the combination of Japan’s dirtier grid and preference for hybrid vehicles means that swapping in EVs doesn’t quite pay.


But averaged over the globe, EVs (already) (represent about a) – percent emissions savings per kilometer, and heat pumps are a -percent savings per unit h eating. Even in the scenario where these technologies are promoted but the grid isn’t cleaned up much, there’s a substantial benefit through . And that’s obviously larger in the scenario where policies also reduce grid emissions more. Total vehicle emissions are reduced about percent in this scenario, and home heating emissions drop about 70 percent.

The model assumes continued progress on efficiency for fossil-fuel-powered cars and furnaces as well as their electric counterparts, but the emissions of fuel-burning machines are mostly unavoidable. Electric vehicles and heat pumps, meanwhile, are already cleaner (unless you live in Estonia) and can improve further as the grid improves.

As time goes on, emissions from manufacturing electric vehicles accounts for a larger share of their total life cycle emissions, the researchers note. You can make the vehicle efficient and the grid clean, but you’ll also have to clean up industry to keep shrinking that carbon footprint.

Nature Sustainability, . DOI: / s – 35 – – 7


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