What about Electric Cars?
Paul Kando
In a global comparison of combustion engine and electric passenger cars, the International Council on Clean Transportation examined the greenhouse gas (GHG) emissions of passenger cars, including SUVs. The report considers present and projected GHG emissions attributable to both vehicles and fuels, from extracting and processing raw materials to eventual recycling or disposal. The study compares the lifetime GHG emissions of today’s cars with cars expected to be registered in 2030. The report considers industrial-scale battery production and regional battery supply chains, including the near-term global warming potential of methane leakage emissions of natural gas-derived hydrogen production. Unlike other GHGs, methane contributes several times more to global warming in the first 20 years after emission than is reflected by its 100-year global warming potential.
photo credit: Topher Belknap
Results show the lifetime emissions of an average medium-size battery electric (BEV) vehicle to be 60%–68% lower than those of an internal combustion engine (ICE) vehicle. And as the electricity mix continues to be decarbonized, the life-cycle emissions gap between the two types will grow substantially.
Electric vehicles are the most important technology in decarbonizing transportation. To keep global warming below 1.5˚C, sales of passenger EVs must represent 35% to 75% of the global car market by 2030, and approach 80% by 2050.
EVs are an increasingly viable choice for an average car buyer. Even a relatively low range (120 miles) BEV will go farther on a charge than 96% of Americans drive on an average day—and testing data suggest that lithium-ion batteries used in new BEVs can power a vehicle for more than a million miles, well beyond a typical vehicle’s lifetime. And when battery capacity degrades to where the warranty kicks in, it still covers about 93% of average daily travel. 87% of US drivers drive less than 100 kilometers (60 miles) a day—i.e., only half the range capacity of an e-Golf, one third of a Leaf, and less than a quarter of a Tesla. Yet, according to a 2019 consumer survey, - more than half - are concerned about the range, charging time and environmental benefits of EVs.
Some drivers, of course, need to travel more on any given day, which leads to questions of charging time, and public charging infrastructure. Charging time is a function of the amount of power being delivered to the EV battery (in kilowatts (kW). The more power, the less time needed to charge. Power, in turn, is a function of voltage (volts, V) and current (amps, A). The higher the voltage and current, the faster the charge.
EV chargers fall into three categories according to charging speed and type of connector used: Level 1 slow charging with alternating current (AC) from the grid delivers a relatively low, up to 2.4 kW direct current (DC) to the battery, but needs only a 120 V 20 A electrical circuit—the same as a hair dryer—and uses an ordinary household plug. Level 2 faster charging delivers 7.2 kW DC but needs a 240 V 30 A split-phase circuit and a special plug like a water heater or a stove. Level 3 rapid charging delivers 50 kW to 100 kW DC —and even up to 350 kW DC to premium BEVs that can accept it.
These charging stations operate like huge smartphone AC/DC adapters that convert AC current from the grid into DC at a voltage appropriate to the BEV’s battery. Level 1 and slower Level 2 chargers can be wired into the electrical service of most residences and businesses. Level 3 rapid chargers and faster Level 2 chargers need dedicated and more expensive electrical circuitry.
BEV battery capacity is measured in kilowatt-hours (kWh) — the amount of energy the battery can deliver or take in at a given power (kW) over a certain time (h). The time it takes to charge a battery from flat to full depends mainly on charging power and battery capacity. To charge a Nissan Leaf, for example, will take 18 hours using a Level 1, 10 hours using a Level 2 and 1 hour using a Level 3 charger.
To drivers, of course, what matters is not kilowatt-hours but the range gained by a given amount of charging time. Typically, cars are mostly parked at home or at work, and 96% of Americans drive less than 124 miles daily. Charging overnight or through a work-day, even with a Level 1 slow charger will provide that much distance. And an hour at a Level 2 public charger will provide well over 60 miles of additional range.
So, is a BEV a smart buy? We will look at costs and climate benefits next week.