Electric vehicles are largely seen as an environmental good and a tool for slowing climate change. But are electric vehicles (EVs) really as green as we think?

All-electric vehicles and hybrids produce low or no exhaust emissions. That means virtually zero greenhouse gas emissions produced by the vehicles themselves—definitely a good thing for the environment. But other factors come into play when determining how much pollution your electric vehicle generates. These include where your local power grid gets its electricity, what time of day you charge, the climate where you live, the battery manufacturing process, and your driving patterns.

The above five factors all affect an EV’s performance—and how much, if any, of a negative environmental impact it has. Let's look at each in turn. 

1. Sources of Electricity

Electric cars generate energy via electrochemical reactions in their lithium-ion batteries, which doesn’t require burning fuel the way a gas-powered car does. Battery vehicles run solely on electrical energy. Hybrids reduce emissions by using a battery in low-demand settings like city driving while engaging the gas engine the rest of the time. Most hybrids and EVs also have some kind of regenerative braking, which uses kinetic energy to charge the vehicle’s battery and further increases its efficiency.