Since the start of the industrial revolution, humans have released hundreds of billions of tons of greenhouse gases into our atmosphere, acidifying oceans, increasing the frequency of extreme weather events, and raising sea levels with the worst effects yet to come. The general consensus from the Paris Climate Summit in 2015 is that in order to halt the relentless march of climate change and its forecasted catastrophic consequences, one step we need to take is to transform our fossil fuel based economy to one powered by zero-emission renewable energy.

The good news is that investments in solar and wind generation have become competitive and in many cases cheaper and more profitable than similar investments in fossil fuels. The graphs show how new investments in solar and wind installations in the US have outpaced  fossil fuel installations for the past 3 years.



The Need for Energy Storage

Globally, the conversation has shifted from “can renewables compete with fossil fuels?” to “how much intermittent renewable energy can our power grid handle?” Currently, power grids rely on a steady and predictable stream of power generation. They can handle only so much of the fluctuation that comes from solar, which surges during the day, and wind, which surges when it’s windy.

The investment required in energy storage facilities to fulfill the needs of a 100% renewable energy grid is believed to be very high. Millions of large industrial-scale batteries or other energy storage solutions or large scale utility demand response programs are needed to smooth out those surges. But what is often forgotten is that a creative solution is currently being built at an accelerating rate in the form of vehicle batteries. Electric vehicles herald in a new age of clean air on busy city streets, but they can also serve a secondary, and very beneficial role, of solving the energy storage issue of renewables.


Electric Vehicle Sales Are Growing

Mass adoption of electric vehicles is swiftly approaching. Many of the drawbacks of electric vehicles are being addressed including inexpensive vehicles with 200-335 miles of range to the rapid expansion of ultra-fast charging stations that can bring batteries to 80% in 15 minutes or less. Several countries in Europe now see zero-emission vehicles as the logical solution to addressing air pollution and are looking to implement bans on new fossil-fuel powered vehicles as early as 2025. Some major cities are even going a step further and will be banning all diesel-powered vehicles from their cities. It seems the age of the fossil fuel powered vehicle is coming to an end.


EVs and the Grid

How big of an impact can an electrified transportation sector have in creating a green energy grid? Let’s look at the numbers. On average, vehicles in America are driven 30 miles a day. An average vehicle requires about 10 kWh of energy to cover this distance. The battery pack in a current generation mass-market Chevy Bolt holds 60 kWh. If we leave a 50% margin over normal daily usage, 75% (or 45 kWh) of battery capacity remains unused on an average day. If this available capacity were used to store cheap energy like solar during the day and sold back to the grid at night or during peak use, many problems in a 100% renewable energy grid would be solved. This concept is known as Vehicle to Grid (V2G) and is already being tested in many cities. If the 251 million cars and trucks on the road today all had batteries similar to that in the Chevy Bolt, 11,295 GWh of available unused storage capacity would be available to fill in gaps of intermittent renewable power. But will this be enough to achieve a zero carbon energy grid?


Currently, the United States consumes 3.4 million GWh/year or 389 GWh/hour of electricity from fossil fuels and nuclear. If we were to replace these with renewables, a 100% electric fleet with an average battery size found in the Chevy Bolt would have more than enough stored energy – 27.8 hours worth to be specific – to keep the country powered until the sun rises again in the morning and this isn’t touching the 15 kWh in each vehicle battery that is set aside for the average daily driving requirements.

An intensive, peer reviewed study evaluated billions of 100% renewable energy grid scenarios using 4 years of real weather and grid load data. They concluded that with 15kWh set aside from each electric car for grid energy storage, a 100% renewable energy grid could power 90%-99.9% of hours entirely on renewable electricity at costs comparable to today’s prices. Something to note is that the study was done in 2013 before the second generation of electric vehicles like the Chevy Bolt, Tesla 3, and other large battery, mass market vehicles were introduced to the public. Using 45 kWh for battery storage from a Chevy Bolt instead of 15kWh that was used in the study would increase total storage capacity by 300% making it much easier, and cheaper, to run America’s grid on renewables.


EV battery degradation in a V2G environment

A widespread belief is that recruiting EV batteries into a V2G environment would overwork the batteries with the added V2G cycles and would prematurely reduce their working capacity. This concern was tested in a study published in 2015. The authors of the paper built a plug-in vehicle that was interconnected to a power regulation market in the US. The vehicle was capable of back feeding to the power grid, by integrating bi-directional, on-board AC/DC and DC/AC converters and a digital communication device into the vehicle.

The study concluded, among others things,  that “[the] degradation of the propulsion battery caused by the additional power transfer is proven to be very small, and thus not a major issue because the charge/discharge power level is much lower than the maximum power of the battery system required for vehicle acceleration.”


EV charging away from home

Another widespread belief is that in a V2G scenario, electric vehicles would often need to be charged at a person’s work during the day when solar is plentiful and that this would present logistical problems for tracking energy consumption away from home. “Smart chargers” will easily be able to address this issue by determining which account is consuming the power (the EV owner) and who the power company needs to compensate for the electricity being consumed (business owner). Aside from adding charging infrastructure at businesses, which is already starting to happen, tracking consumption will be a no-brainer.

V2G integration into our zero carbon energy grid makes sense because it reduces the need for investing in expensive energy storage since the vehicles we will be driving could already provide that service. It also allows a vehicle owner that participates in V2G services to generate revenue from their vehicle while they sleep.

The graph compares estimates of the installed capacity of photovoltaic power cells made in 2000, 2002, 2005 and 2007 by the International Energy Agency with the actual data. Propelled by plunging costs and government policy, the actual growth far exceeded  the forecasts.


As the same factors hold true for electric vehicles, don’t be surprised when you see a substantial reduction in total US greenhouse gas emissions from a zero carbon energy and transportation sector occurring sooner than you think. You can help accelerate this transition by making a pledge that your next vehicle will be electric and by adding solar collectors to your home.

Ryan Logtenberg is president at 2 Degrees Institute. This post originally appeared on Skeptical Science.