Electric Motors: Moving Us Into the Future
Electric motors are way more powerful than combustion engines, with a power to weight ratio over 30 times better.
There’s a good reason massive machines like locomotives and mining equipment use electric motors instead of combustion engines: burning gas or diesel just doesn’t provide as much power with as much precision. A diesel locomotive train burns diesel to generate electricity, then uses its electric motors to provide the muscle to move.
Electric motors pack a punch at the other end of the size spectrum, too. You won’t find any combustion engines in household appliances. It’s all about electric motion.
Not only do electric motors move objects we can see, but they also move the invisible: sound and energy. Did you know that speakers have tiny electric motors that turn pulses of electricity into sound? Or that heat pumps use electric motors to compress refrigerant and force it to flow?
Aside from energy flowing through the chips in LED lights and computers, most of the energy your home will use over the next three decades will power electric motors. On the “electrify everything” trail, we can take many practical steps to start using electric motors instead of combustion engines:
Replace fuel-burning lawn mowers, leaf blowers, chain saws, and other yard equipment with plug-in or battery-powered electric equipment.
Replace fuel-burning water heaters with electric heat pump water heaters.
Replace fuel-burning furnaces and boilers with electric heat pumps.
Replace fuel-burning vehicles with battery electric vehicles.
Weekly Poll: Have You Electrified Everything?
Help! Should I buy a plug-in (corded) lawn mower or a battery-powered lawn mower?
All things considered, it’s more sustainable (and affordable) to buy plug-in corded yard equipment because batteries are not that great (yet). But just ask my son Ian how much more convenient it is to go cordless: he’ll happily mow the yard with a battery mower, but absolutely refuses to get out the extension cord to use our plug-in mower.
Batteries in new equipment are much better than batteries you might find in used equipment. Older batteries contain toxic metals like lead, cadmium, or cobalt. New equipment uses lithium iron phosphate (LFP) batteries, which don’t contain any of those toxic metals. Since LFP batteries are across-the-board better than older batteries (last longer, weigh less, and recharge faster), it makes sense to get old batteries out of circulation. I recommend against buying a used battery-powered lawn mower with any other type of battery besides LFP.
But honestly, LFP batteries are still not that great. For one thing, they are still more expensive than lead acid batteries. For another, they still don’t store very much energy compared to gasoline or propane. And finally, batteries wear out much faster than electric motors. You can expect an LFP battery to provide about 4,000 charge-recharge cycles before its performance seriously degrades, whereas an electric motor should be reliable for tens or hundreds of thousands of use cycles.
Future batteries should be able to provide tens of thousands of charge-recharge cycles at which point it will make little sense to buy corded equipment. Today, assuming your yard is small enough and you can manage an extension cord better than my son, the sustainability nod today still goes to a lawn mower without a battery. Unless the power grid goes down, with a plug-in mower you’ll never have to worry about running out of power in the middle of the job and you’ll never have to worry about disposing of a dead battery.
Help! I don’t understand how a heat pump hot water heater can use so much less energy than a gas water heater.
The theme of “electrifying everything” is to replace wasteful equipment, like water heaters than burn natural gas, with efficient equipment. The reason that heat pump hot water heaters are so much more efficient than fuel-burning or older electric water heaters, is that heat pumps don’t produce heat. They turn an electric motor to run a compressor that pressurizes and forces refrigerant to flow from hot to cold. The refrigerant doesn’t create heat; it simply absorbs and releases heat.
Think about what a tank of hot water is doing most of the time. It’s losing heat to the air around it. A heat pump water heater simply collects this heat and puts it back in the tank. A gas water heater has no way to collect heat from the surrounding air; so it just keeps burning more gas to keep putting more heat in the tank. And in fact, when the gas water heater fires up, it sucks out all the warm air around the tank in order to keep its flame burning.
Help! Should I buy an electric vehicle now or wait until the technology improves?
If you’ve ever driven an electric car, you know that electric motors are already much better than combustion engines. Electric vehicles are just more fun to drive—you get great acceleration and precise control of the motor at all speeds. Electric motor technology will continue to improve, but since it’s already ahead of fuel-burning engines there’s no need to wait to buy an electric vehicle on account of any future improvements in electric motor performance.
Electric vehicles still have a long way to go in terms of affordability and practicality, though. Batteries are the bottleneck. In next week’s post I’ll explore the steps we can take for sustainability when choosing batteries. But knowing that motors are already good enough, and it’s just batteries that are the problem, we can make smarter decisions when shopping for a new vehicle.
Any vehicle that contains a fuel-burning engine requires fuel to operate, which includes all types of hybrid cars. In general, a life cycle analysis of all types of fuels shows that they are less sustainable than electricity for producing movement. The main advantage to electricity is that it can be generated anywhere on Earth from sunlight. With a battery-based vehicle, we can simply park it next to a solar module and recharge it using solar energy that will never run out. When the battery wears out, we can recycle the materials in it to make new batteries. It’s not possible to do that with fuel.
If you can afford an electric vehicle, and the driving range of the vehicle meets your needs, from a sustainability perspective it is a good idea to go electric now. However, we can expect that batteries will become much better in the next few years. This is likely to reduce the cost of electric vehicles and increase their range.
Given all this, three sustainability guidelines for vehicle shopping:
Avoid buying a new vehicle with a fuel-burning engine. This includes hybrid vehicles.
Buy or lease an electric vehicle that meets your budget and your driving needs.
If you are unable to find an electric vehicle that you can afford, consider buying a used vehicle with a fuel-burning engine. As prices come down, your next new vehicle can be electric.