EVs: A Climate Solution?

Electric vehicles are viewed as a major climate solution, and rightly so, considering the amount of emissions that are offset when internal combustion engines are replaced by batteries. However, EVs will not be the climate solution that they are promised to be if EV batteries are charged overnight. At night, renewable energy sources are far less productive, or even completely non-productive in the case of solar panels. Instead, the energy used to charge EVs at night is primarily produced by burning fossil fuels.

Though the EV itself is not emitting greenhouse gases, the energy production required to recharge the battery is. This is a major issue that must be addressed.

By 2035 in California, it is reasonable to predict that there will be almost 5 million privately-owned EV cars on the road, plus an additional 1.5 million commercially-owned electric light and medium duty trucks, 30,000 electric buses, and 90,000 heavy duty trucks. This number of EVs will require more than 200,000 MWH of energy every day.

With this many EVs on the road, there must be a substantial increase in renewable energy production facilities, as well as commercially accessible daytime fast chargers. This will mean a significant increase to infrastructure in terms of energy production, transmission and distribution, and commercial EV charging stations.

Let’s take a closer look at energy production, current summer load, and predicted EV expansion in California. Energy production data can be found on the California Independent System Operator (Cal ISO) website.

California’s Energy Supply and Demand Today

Figure 1 displays energy demand and production during a typical weekday in California in July 2024. Production is illustrated by sources: renewables, natural gas, imports, and batteries. Production from all sources equals demand.

Table 1 displays energy demand and energy production at 11 AM and 7 PM. Large hydro and nuclear are included for completeness. During peak load periods, from 6 PM to 7 PM, almost 50% of the electric energy consumed was produced by natural gas fired production facilities. At 11 AM, when solar panels and wind turbines should be highly productive, almost 30% of the electric energy consumed was produced by natural gas fired production facilities.

This means that in July of 2024, when renewable energy sources have access to abundant sunny daylight hours and windy days, natural gas is still providing a significant amount of energy throughout the day and in the evening during peak load periods. This significantly reduces EVs’ efficacy as a climate solution.   

2035 Energy Demand with Overnight EV Charging

Figure 2 displays anticipated energy demand and production during a typical weekday in California in July 2035 with 5 million EVs plugged into residential chargers every evening. Figure 2 was developed assuming renewable energy production capacity and battery storage capacity have been increased.

Table 2 displays energy demand and energy production at 11 AM and 10 PM. Increased renewable energy production and battery storage capacity will be offset by EV charging. This means that the amount of energy that is produced by natural gas fired production facilities remains at 50% during peak load periods. To implement this alternative, electric utilities will need to build additional energy storage facilities and renewable energy producers will need to build additional production facilities.

2035 Energy Demand with Overnight and Daytime EV Charging

Figure 3 displays anticipated energy demand and production during a typical weekday in California in July 2035 when 2 million EVs are plugged into residential chargers every evening and 3 million EVs are charged during daylight hours. Figure 3 was developed assuming renewable energy production capacity has been increased even more than in Figure 2, but energy storage capacity was not increased.

Table 3 displays energy demand and energy production at 11 AM and 10 PM. Increased renewable energy production and battery storage capacity will be aided by daytime EV charging. This will reduce the amount of energy produced by natural gas fired production facilities to zero during daylight hours, and to 35% of production during peak load periods. To implement this alternative, electric utilities will need to build more energy storage and distribution facilities, and renewable energy producers will need to build additional production facilities.

Daytime EV Charging: A Key Climate Solution

To reduce the amount of infrastructure build-out that will be needed and use renewable energy when it is available, EVs should be charged during the day. Ideally, EV owners will charge their EVs whenever they are home during daylight hours, such as on the weekends or when working from home. Low-cost solar panels will create an incentive for daytime charging.

It’s important to recognize that daytime charging stations, when powered by renewable energy sources, can supply energy to EVs with no greenhouse gas emissions. Nighttime residential charging stations can supply energy to EVs with 0.2 pounds of CO₂ emissions per mile driven. The average internal combustion engine powered passenger car emits 0.77 pounds of CO₂ per mile driven. So, while nighttime charging reduces CO₂ emissions by 75%, daytime charging reduces CO₂ emissions by 100%.

EVs that are used to commute can also be charged during the day. Level 2, 8-hour chargers can be installed at commuter parking lots, including transit centers, office and industrial buildings, and schools. This would allow commuters to leave their cars connected to a charger throughout the workday. Alternatively, Level 3, 30-minute chargers with valet parking could be installed in commuter parking lots; in this case, valet drivers would move EVs every 30 minutes to maximize EV charging during the day.

Note: Fleet EVs used to deliver materials, transport people, etc. on a continuing basis will need to be charged when the EV is parked for the night unless EV manufacturers develop EV s with replaceable batteries. This may be the preferred alternative for buses and heavy-duty trucks.

Costs of Increased EV Charging

Many electric utility professionals will be quick to point out that the solutions outlined above will require expensive investments to build infrastructure, including renewable energy production facilities, energy storage facilities, and distribution facilities. It’s important to note that this will be true regardless of whether daytime EV charging is incentivized. In fact, not incentivizing daytime charging and continuing down the path of rapid EV expansion with traditional overnight charging will lead to a greater need for new infrastructure, at an even greater cost to electric utilities.

If today’s practice of charging EVs overnight is maintained into 2035, electric utilities in California will need to increase their transmission and distribution systems to accommodate a 60% increase in peak load. This is likely to increase the cost of electric rates by up to 250%. If 75% of EVs are charged at night, electric utilities can anticipate a 40% increase in peak load. This will also require a large infrastructure build-out, increasing electric rates by about 150%. If 50% of EVs are charged at night, only a 25% increase in peak load should be anticipated. This will require the least amount of investment in new infrastructure, though consumers could still anticipate a 100% rate increase.

Of course, electric utilities will need to recover the cost of building, maintaining, and operating new facilities. By planning for and incentivizing daytime EV charging starting now, electric utilities can both reduce infrastructure costs and improve EVs’ effectiveness as a climate solution. Now is the time for electric utilities to work with energy producers and the automotive industry to develop a plan for a high quality, cost-effective, zero-emission transportation system.