Electric vehicles powered from a clean grid are an essential step toward a zero-emissions future. Yet a focus on driving electric vehicles (EVs) that are lighter, safer, and cleaner can also ensure a better tomorrow for everyone. Large, heavy EV battery packs take up space and increase a vehicle’s overall weight, reducing fuel efficiency. Since about a third of the weight of an EV is its battery pack, the need for better methods of storing electrical energy is intensifying. If overall EV weight was reduced through continued battery innovations, what’s been called “the urgent ticking clock” of clean energy and climate change could be muted.
An October, 2021, article in Nature acknowledges that problems with batteries are already being addressed around the globe, with EV manufacturers focusing primarily on batteries that cost less or have higher energy density. The authors argue that work in battery technology also needs to intensify to reduce pollution from manufacturing and to consume less cobalt and other rare metals and minerals. They say schemes for recycling and reusing battery and other materials need to be put in place before tens of millions of electric vehicles arrive on the world’s roads.
“Make Electric Vehicles Lighter to Maximize Climate and Safety Benefits,” written by a team of academics and civil engineers, welcomes the extensive new and major investments that are taking place around the globe in EVs. With the UK, California, the European Union, and Canada planning to phase out the sale of fossil-fueled vehicles as early as 2030, more and more consumers are mesmerized by the reality of all-electric transportation.
The sector “has come a long way, but many challenges lie ahead,” the authors outline, with EV weight a particular issue.
Replacing Energy-Dense Petroleum with Batteries Has Its Drawbacks
With electrifying vehicles, combustible, energy-dense petroleum is replaced by bulky batteries. The rest of the vehicle must get heavier to provide the necessary structural support. Why does this matter?
- Passenger safety. The likelihood of passengers being killed in a collision with another vehicle increases by 12% for every 500-kg difference between vehicles. The number of casualties in crashes is likely to increase as heavy electric vehicles join lighter existing fleets.
- Heavier vehicles. Because they generate more particulate pollution from tire wear, heavier vehicles require more materials and energy to build and propel them, adding to emissions and energy use.
The Nature authors outline a list of ways they recommend that researchers, policymakers, and manufacturers can address the EV weight issue.
Setting registration charges on the basis of vehicle weight. Paying based on weight can discourage heavy vehicles and encourage light ones. Collecting weight-based charges also addresses another problem for governments — lost revenue from forgone petrol and diesel taxes as more EVs enter the roadways. Varying such charges by weight would maintain revenue while incentivizing people to choose vehicles that are more energy efficient and that impose fewer social costs. It would also reduce other emissions from materials production and manufacturing.
Adding travel distance to the fee. Travel data can be collected by on-board devices. Some insurance companies already offer policies that are based on total mileage and other driving habits. Such an approach would incentivize people to drive less.
Produce lightweight batteries. Various possibilities to produce lightweight batteries include using materials that are more energy-dense and removing heavier components. Solid-state batteries without liquid electrolytes and with the latest anode chemistries are more compact and could offer higher energy densities than is possible for lithium-ion cells. Lithium–silicon batteries can achieve higher energy densities if manufacturers use more silicon in anodes rather than graphite. Improvements can also be digital — wireless battery management systems can shed up to 90% of the web of wires. Using fewer materials helps manufacturers to save money.
Lighten frames. Tesla, Volvo, GM, and other carmakers are exploring how battery packaging can support part of the vehicle’s chassis and even make the vehicle frame itself the medium to store energy. Vehicle structures can become stronger and lighter by using advanced forms of steel, more aluminium and magnesium, and polymers reinforced with carbon fiber. Of course, each material brings its own cost and technical challenges as well as emissions impacts from production and supply chains. Research and development continues with goals to improve conductivity, strength, and how structural batteries handle crashes.
Switch to recycled aluminum. Substituting aluminium for steel reduces vehicle weight and improves energy efficiency. But because aluminium production can have nearly 5 times the embodied carbon emissions of steel, it makes sense to switch to recycled aluminium with a low-carbon grid, which can lower life-cycle emissions to below those of steel.
More road awareness technologies. With heavier vehicles on the road, safety becomes even more important. Cameras, radar, and other sensors help to avoid collisions by monitoring blind spots and driver alertness, keeping vehicles in lanes, adjusting speeds, controlling headlights, and applying the brakes if a crash is imminent. Deploying such technologies across the entire US vehicle fleet could avoid thousands of fatalities, more than one million crashes, and billions of dollars in social costs annually.
Old ideas to improve street safety. Looking to what has worked for road safety should still be encouraged — speed limits, traffic calming road designs, and pedestrian-focused infrastructure. Paris, Brussels, Bilbao, and other cities have limited speeds on most roads to 30 kilometres per hour.
Drive less. Reducing the distance driven can help in meeting climate targets as electric and, eventually, automated vehicles become widely available. Policies should ensure that alternatives such as walking, biking, and public transport are safer, more convenient, accessible, affordable, and reliable.
Government support. Cutting-edge technologies are expensive to incorporate, raising the costs of electric cars. Government support, from the laboratory to the factory to the consumer, is thus essential to spur innovation and development. Weight-based registration charges could supply some of that money. US subsidies for EVs currently increase with the storage capacity of the battery. Basing EV subsidies instead on energy storage per kg (kWh kg−1) would incentivize advances in lighter batteries.
Revisit zoning impacts on driving patterns. Urban designers should consider the impacts of zoning and development on driving patterns to minimize average distances travelled and air-pollution impacts that disproportionately burden vulnerable communities. One legacy of the COVID-19 pandemic is a realization of how much work can be done remotely, with less commuting.
Final Thoughts about EV Weight & Other Issues
Solving these challenges will save lives and protect the climate. As time goes on, cleaner grids will continuously strengthen the climate effects of EVs. Cutting down vehicle weight can similarly help to increase the climate and air quality benefits.
CleanTechnica tracks the latest developments in the sustainable electric vehicle battery area. That includes recent improvements in durability and lifespan as well as efforts to reduce the use of hazardous or toxic materials, refine recycling technology, and focus on supply chains that reduce or eliminate material sourced from conflict zones.
Through 2020, most battery cells and packs used in US plug-in vehicles were produced in the US. Considering that the EV battery industry is dominated by foreign companies — Korea’s LG Energy Solution and Samsung SDI, China’s CATL, and Japan’s Panasonic — this is great news for those who care about the US economy. Yet are there really enough firm commitments for battery minerals to actually match EV sales targets and expected growth a few years from now?
It’s important to note that Tesla is working on its new large-format 4680 battery cells, and it appears they will make their first appearance in the Model Y being produced in Germany. The larger batteries are just part of the story. They are supposed to be mounted in a battery pack that is a structural element of the car rather than simply being raised into position and bolted to the chassis from below.
The concept of the battery as integral to the structural integrity of the vehicle becomes one more innovation that advances the power and place of EVs and works to mitigate the climate crisis.