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Study projects emission impacts of inexpensive, efficient EVs: 36% further reduction in LDV GHG by 2050, or 9% economy-wide

7 June 2017

A new study by researchers at the University of Colorado at Boulder projects the emission impacts of the widespread introduction of inexpensive and efficient electric vehicles into the US light duty vehicle (LDV) sector. The work is reported in a paper in the ACS journal Environmental Science & Technology.

Under their optimistic scenario (OPT)—which is based on the assumption that EVs are market-competitive with gasoline vehicles, in particular after 2025—they find 15% and 47% adoption of battery electric vehicles (BEVs) in 2030 and 2050, respectively. Compared to the reference case, in which gasoline vehicles (ICEVs) remain dominant through 2050 (BAU), OPT results in 16% and 36% reductions in LDV greenhouse gas (GHG) emissions for 2030 and 2050, respectively, corresponding to 5% and 9% reductions in economy-wide emissions.

Credit: ACS, Keshavarzmohammadian et al. Click to enlarge.

Total NOx, VOCs, and SO2 emissions are similar in OPT and BAU due to inter-sectoral shifts. They found that moderate, economy-wide GHG fees have little effect on GHG emissions from the LDV sector—but are more effective in the electricity sector.

In the OPT scenario, estimated well-to-wheels GHG emissions from full-size BEVs with 100-mile range are 62 gCO2-e mi–1 in 2050, while those from full-size ICEVs are 121 gCO2-e mi–1.

Compared to prior studies, the model includes a relatively comprehensive suite of available and viable forthcoming technologies, focusing on improved ICEVs and EVs, for meeting demand for energy services in all economic sectors, including the LDV portion of the transportation sector. Rather than pre-specifying mixes of energy sources and shares of technologies in any of the sectors of the economy, we use an optimization model to determine the least costly choices for meeting demand.

—Keshavarzmohammadian et al.

The researchers explored their different scenarios using the ANSWER-MARKAL model with a modified version of the Environmental Protection Agency’s 9-region database (EPA US9R). They adapted cost and performance projections for LDV technologies from the National Research Council (2013) optimistic case.

MARKAL was developed in a cooperative multinational project over a period of almost two decades by the Energy Technology Systems Analysis Programme (ETSAP) of the International Energy Agency. It uses linear programming to estimate energy supply shifts over a multi-decadal timeframe, finding the least-cost means to supply specified demands for energy services subject to user-defined constraints, assuming a fully competitive market. The model computes energy balances at all levels of an energy system from primary sources to energy services, supplies energy services at minimum total system cost, and balances commodities in each time period.

The EPA US9R database specifies technical and cost features of current and future technologies at five-year intervals, with a structure that connects energy carriers (e.g., output of mining or importing technologies) to conversion or process technologies (e.g., power plants and refineries) and in turn to the transportation, residential, industrial, and commercial end-use sectors. The database includes joint Corporate Average Fuel Economy (CAFE) and GHG emission standards for LDVs.

Future LDV transportation demand in the US9R database is specified based on US EIA Annual Energy Outlook (AEO) 2014 projections, allocated to the model’s nine regions and to seven vehicle size classes ranging from mini-compacts to light trucks.

The Boulder team’s BAU reference scenario was unmodified from the 2014 EPA US9R database, including EPA’s efficiency and cost estimates for future gasoline ICEV, HEV, PHEV, BEV, and ethanol vehicles. The OPT scenario substitutes optimistic efficiency and cost improvement for gasoline ICEV, HEV, PHEV, BEV, and ethanol vehicles from the NRC report, and adds and refines upstream emissions and refines cost and performance estimates for other sectors.

The team explored other scenarios including different levels of CO2 and CH4 fees applied to the BAU and OPT scenarios; different levels of LDV demand; and different oil prices.

The researches used the results from MARKAL to estimate well-to-wheel (WTW) emissions rates for GHG, NOx, and SO2 for ICEV and BEV technologies.

Among their findings:

  • Gasoline vehicles dominate in the BAU scenario for the entire time horizon. In the OPT scenario BEVs gain a LDV market share of about 15%—all from 100-mile range EVs (BEV100) by 2030. By 2050, the share climbs to 47% (with 20% share from BEV100 and 27% from BEV200).

  • Total electricity generation is equal in the BAU and OPT scenarios in 2030, but is 4% higher in 2050 in the OPT scenario, mainly due to the increased use of BEVs. Electricity generation from natural gas increases over time in both scenarios, whereas generation from existing coal plants declines. Electricity generation from other technologies including wind and solar are similar between the BAU and OPT scenarios, with these two renewable technologies contributing about 9% of generation in 2050.

  • In the BAU scenario, GHG emissions from the LDV sector decline by 53% from 2010 to 2030 and by an additional 21% from 2030 to 2050, due largely to existing CAFE regulations. Correspondingly, in the BAU scenario the LDV share of total emissions is reduced from 21% in 2010 to 10% in 2030 and 7% in 2050. Direct emissions from the LDV sector contribute 9% and 5% of GHG emissions in the OPT scenario in 2030 and 2050, respectively. The OPT scenario results in GHG emissions from LDVs that are 36% lower than in the BAU scenario in 2050.

  • Total GHG emissions in the OPT scenario are 5% lower than those in the BAU scenario in 2030 and 9% lower in 2050.

  • BAU LDV NOx emissions decline from about 2 million tonnes in 2010 to 0.4 million tonnes in 2030 and to 0.3 million tonnes in 2050, due to tailpipe emissions limits that have already been promulgated. In the OPT scenario, direct NOx emissions from LDV are about 0.3 million tonnes in 2030 and 0.2 million tonnes in 2050—35% lower than in the BAU scenario. However, total energy system NOx emissions are about the same in 2050 in the OPT and BAU scenarios, because industrial sector emissions are 27% higher in the former.

  • In the BAU scenario, SO2 emissions from electricity generation fall from 5 million tonnes in 2010 to 1.4 million tonnes in 2050, due to existing control requirements and the shift away from coal-fired generation. This reduction is modestly countered in the BAU scenario by an increase in SO2 emissions from the industrial sector. In the OPT scenario, SO2 emissions from the industrial sector in 2050 are 20% higher than in the BAU scenario in 2050, due to increased direct fuel use in place of electricity. This change offsets the reductions from the electric sector that result from less use of coal-fired power generation in the OPT scenario.

Although not directly examined in this study, vehicle cycle emissions are also important in comparing across technologies. ANL (2016) estimated emissions from vehicle manufacturing of about 41 gCO2-eq mi-1 for current midsize ICEV, and about 64 gCO2-eq mi-1 for BEV90 vehicles. In the future, these emissions are expected to decline as electricity sector emissions are reduced and manufacturing processes become more efficient. However, as light duty vehicles generally become more efficient, with lower WTW emissions, the vehicle production cycle will likely comprise an increasing fraction of total life cycle emissions. Thus, in future assessments greater attention needs to be focused on vehicle manufacturing and recycling impacts, as well as on upstream emissions and on the potential for inter-sectoral shifts.

—Keshavarzmohammadian et al.


  • Azadeh Keshavarzmohammadian, Daven K. Henze, and Jana B. Milford (2017) “Emission Impacts of Electric Vehicles in the US Transportation Sector Following Optimistic Cost and Efficiency Projections” Environmental Science & Technology doi: 10.1021/acs.est.6b04801

June 7, 2017 in Electric (Battery), Emissions, Forecasts, Lifecycle analysis | Permalink | Comments (7)


Come on folks, this is a broad scam. There is 10 time as much co2 emissions that are natural compared to human machineries emissions.

LOL, im right as usual. Look at this documentary, only 3% of co2 is due to burning fossil fuel.

What is interesting is how little electrification reduces CO2.
At least they are telling the truth, generating electricity for BEVs generates CO2, and quite a bit if you are making it from coal.
The solution would be to make "smart" charging systems where cars can charge when there is a lot of renewables on the grid. This would require them to be plugged in most of the time (i.e. in places of work, and parked at night), but this should not be impossible. You would not want more than 8Kw charging, and 3Kw would probably do it (if it is plugged in all day).

A 100 mile EV, which might be used 30 miles / day has the advantage that it does not need to be charged every day, so you could skip a day or two while waiting for wind or sun, if you had a smart charger with weather forecasting, and IF you trusted it.

If you're burning natural gas in a CCGT plant, you're well ahead of petroleum.  It's coal that's the problem.

A largely-BEV transportation system will have a great deal of schedulable demand, making it ideal for a high-nuclear scenario.  Using nuclear power for all the base load and much or all of the mid load (substituted by overnight BEV charging load) decarbonizes all of that much more effectively than anything relying on unreliables.

Since NPPs (new and refurbished ones) with safe spent fuel disposal cost 2 to 4 times more then REs such as Hydro-Wind-Solar with adequate energy storage, many countries will soon close their older NPP plants.

Very few new NPPs will be built. China may be a rare exception.

Hydro with large water reservoirs is ideal to produce electricity 'on demand' and supply water for farm irrigation and cities, when required.

British Columbia's new NDP government will block the construction of new Hydro plants and new oil pipelines and still try to convince residents to use BEVs???

Harvey, how is it that no matter how many times something is repeated to you, you never learn?

Since NPPs (new and refurbished ones) with safe spent fuel disposal cost 2 to 4 times more then REs such as Hydro-Wind-Solar with adequate energy storage

This "adequate energy storage" does not exist and cannot be built except in a very few places with favorable geography and climate.  This makes the purported objective unattainable, and the exercise pointless... unless the actual purpose is something else.

many countries will soon close their older NPP plants.

They'll be shut down out of paranoia and lobbying by fossil interests, not economics.  Germany has failed to cut its carbon emissions significantly since its paranoid return to a de-nuclearization program.  It is going to miss its 2020 and 2025 goals by huge margins.

Hydro with large water reservoirs is ideal to produce electricity 'on demand' and supply water for farm irrigation and cities, when required.

Hydropower was just 6.5% of US electric generation in 2016.  Growing that to, say, 50% would require building 6.6 times as much capacity as the US currently has.  This is impossible; neither the rivers nor the water to fill the reservoirs exist.

If you'd talk about powering the world with unicorn farts, at least everyone would know it was a joke.

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