Over the decade that Consumer Reports has been testing electric mowers, performance has improved dramatically. That's a big win for consumers, and this year is no different.

From the Ego LM2101 push mower, $500, to the Cub Cadet RZT S Zero ZTR, $4,000, electric models occupy top slots in nearly every category in Consumer Reports' lawn mower tests.

Powered by lithium-ion batteries, electric mowers start effortlessly, run quietly, and eliminate the need for messy engine maintenance. And while they might appeal to anyone with a lawn, the biggest winner could be the environment.

Emissions
“Electric mowers are vastly preferable to gas models because they generate no tailpipe emissions,” says Simon Mui, a lithium-ion battery expert at the Natural Resources Defense Council. Compared with gas engines, which emit carbon monoxide and unburned hydrocarbons, he says, "Electrics offer a lot of public-health benefits.”

Power Source
Of course, where your power comes from will have an impact on just how clean your electric mower is. The electricity you use to charge your battery is likely coming from a nonrenewable source: Nationally, only about 13 percent of electricity is produced from renewable sources, meaning the rest comes largely from fossil fuels.

The EPA's Power Profiler can give you a breakdown of where your electricity comes from to help you assess your mower's environmental footprint.

Landfill
There are other environmental considerations with battery-powered mowers. It’s not cost-effective to strip batteries for parts, so when they die they’re typically frozen, crushed, and tossed in landfills. The liquids in lithium-ion batteries don’t pose big hazards, Mui says, but they do contribute to landfill waste.

Limitations
Although today's lithium-ion batteries last much longer than they did even just a few years ago, the technology hasn’t reached the point where pros can rely on them. And that's an issue, according to Dave Mullen, vice president of product marketing for Cub Cadet, which makes gas and electric mowers. A homeowner might use her mower for 30 minutes or less per week, but Mullen says commercial landscapers are using equipment eight to 10 hours per day, sometimes six days a week. The point being, refilling mowers with gas is more practical than continually recharging batteries.

Cost
Top-scoring electric riding mowers, including the Ryobi R48110 rear-engine rider, $2,500, and the Cub Cadet RZT S Zero ZTR, $4,000, are significantly more expensive than similar-performing gasoline models, although there’s a good chance you’ll recoup the higher upfront cost.

It's also worth pointing out that a brand-new gas mower has a much more efficient engine than a similar model from five years ago. So even if you're not able or inclined to give up gas entirely, mulching clippings and cutting less frequently is a great place to start becoming greener. Your lawn will thank you.