I should preface this by stating that I drive an EV and heat my house with a ground-source heat pump. So I’m hardly against substituting electricity for direct combustion of fossil fuels.
But the data are what they are.
Best guess is that all types of lawn-care type activities, both residential and commercial, including mowing, leaf blowing, and so on, together account for as much as 2% of U.S. gasoline consumption. Residential (non-commercial) yard care of all sorts accounts for maybe 0.6% of U.S. gasoline consumption.
Since C02 production is directly proportional to gasoline use, that means residential lawn mowing is rounding error in terms of global warming impact.
For the average American, using an electric lawn mower in no material way offsets the global warming impact of driving an SUV, truck, or car. Choice of car is more than 100 times as important as your choice of lawn mower.
I hope nobody is surprised by that, despite the ludicrous estimates of the environmental impact of lawn mowing that can be found on the internet.
Source: Saint Philip Neri and the chicken, 16th century, as quoted by Pope Francis.
Study: On Twitter, false news travels faster than true stories
Massachusetts Institute of Technology, 2018
“A lie can travel half way around the world while the truth is putting on its shoes.”
Often attributed to Mark Twain, circa 1900.
Falsehood flies, and the Truth comes limping after it.
Lawn mowers, yet again.
The point of this post is to estimate what fraction of U.S. gasoline use is attributable to lawn mowers.
Each gallon of gas burned creates roughly the same 20 pounds or so of C02. Therefore (ignoring NOx, nitrogen oxides), the fraction of gasoline consumption attributable to lawn-mowing will tell me the contribution that gasoline-based lawn mowing makes to global warming, relative to gasoline-driven passenger vehicles, in the U.S.
In other words, residential lawn mowing’s share of gasoline burned is lawn mower’s share of C02 released. And that shows how U.S. gas lawn mowers (in aggregate) compare to our passenger vehicles (in aggregate), in contributing the world’s warming.
In previous posts, I showed how a modern (overhead-valve) lawn mower engine stacks up against a typical car, in terms of pollution per hour (Post #1775 and related posts). (Pollution being defined in various traditional ways (e.g, particulates, nitrogen oxides.) In round numbers, an hour of mowing produces roughly the same pollution as an hour of driving a typical car.
While “pollution” as used above includes particulates and smog-forming emissions, it doesn’t include C02 at all. Yet, while most smog-forming emissions are relatively short-lived, the increase in atmospheric C02 from fossil-fuel combustion is a nearly-permanent addition to atmospheric greenhouse gasses, in the context of a human lifespan. (As in, like, forever — here’s a little something published in Nature Climate Change to brighten your day REFERENCE). Most of it will still be affecting climate 300 years from now. A good chunk of it — say a quarter — will still be warming the climate millenia from now.
(Separately, the big shocker to me was finding out that gas in gas cans is major source of pollution. Per my actual test, old plastic gas cans (“Blitz cans”) are ridiculously permeable to gasoline, and gas stored in old plastic cans is a large source of smog-forming gasoline vapor. This, apparently, is why the California Air Resources Board (CARB) has such stringent standards for gas cans. And why, until recently, “CARB-compliant gas can” was synonymous with “awkward to use”.)
Post #1773: Gas vs. electric mowing, part 3: Why do all gas cans suck?
For the estimate above, I did my own number-crunching, with clear documentation as to sources of data and details of calculation, because estimates on the internet are all over the map. The plausible estimates were mostly published by state governments. The ludicrous ones appear to come from fanatical but innumerate environmentalists.
And, of course, it’s the ludicrous ones that get recirculated the most. You might think that’s something unique to the internet, but per the quotes above, the internet merely speeds up and amps up long-noticed aspect of human nature. Lies are juicer than the truth, and propagate accordingly, seemingly regardless of the medium of propagation.
In any case, to validate my prior estimate (an hour of mowing is like an hour of driving), I decided to look at estimates of the fraction of U.S. gasoline consumption that goes to lawn care.
And — no big surprise — those estimates seem to have the somewhat the same bullshit nonsense level as the estimates of the pollution generated by an hour of mowing. So I thought I’d take an hour this morning and try to separate fact from fiction, on this question.
Some calculations, and some citations, regarding the fraction of U.S. gasoline use attributable to lawn mowing.
Crude per-household use calculation, lawn mowers: 0.6%.
Source: OFF-HIGHWAY AND PUBLIC-USE GASOLINE CONSUMPTION ESTIMATION MODELS USED IN THE FEDERAL HIGHWAY ADMINISTRATION Final Report for the 2014 Model Revisions and Recalibrations,Publication Number – FHWA-PL-17-012 June 2015
The U.S. consumes about 136 billion gallons of gasoline per year, of which 91% is for light cars and trucks (Cite: US Energy Information Agency).
The U.S. has about 130M households (Cite: U.S. Census Bureau, via Federal Reserve Bank of St. Louis).
Ergo, by the magic of long division, average annual U.S. gasoline consumption works out to be a nice round (136B/130M =~) 1000 gallons per household.
(Separately, this squares with survey-based estimates showing about 650 gallons of gasoline consumed annually per licensed U.S. driver (CITE), and, based on harder statistics, about 230M licensed drivers (CITE). (That is, 650 x 230M drivers /130M households =~ 1150 gallons of gas per year, per household).
I use about 2 gallons of gas per year, mowing my large suburban lawn, using a mower with a modern overhead-valve Honda engine. I’m guessing that’s an upper bound for per-household use, as my yard is larger than average.
This suggests that gasoline use, attributable to household lawn mowing, accounts for somewhere around (2/1000 =~) 0.2% of total U.S. gasoline use.
But, per the EPA graphic above, households only account for about a third of all gasoline use, for all types of lawn care (e.g., mowing, leaf blowing, snow blowing, and so on). So total U.S. gasoline consumption for lawn care, of all types, by all sources, would therefore be about 0.6% of all U.S. gasoline consumption.
EPA, 2015: 2.7B gallons for all lawn care activities, residential and commercial, about 2% of total U.S. gasoline consumption.
Separately, the same EPA source (for the graphic, above, Table 42) directly estimates 0.9B gallons of gas used for residential lawn care activities annually, and a further 1.8B used for all types of commercial lawn care, for a total of about 2.7B gallons of gasoline use for all types of lawn-care type activities. This would therefore amount to (2.7B for lawn care/137B total =~) 2% of total U.S. gasoline consumption.
U.S. Department of Energy (2011): Mowers alone, residential and commercial, 1%.
” Mowers consume 1.2 billion gallons of gasoline annually, about 1% of U.S. motor gasoline consumption.”
Source: Clean Cities Guide to Alternative Fuel Commercial Lawn
Equipment, U.S. DOE, 2011.
Conclusion
Source: RC groups.com
I’d say that’s more than enough research to get a usable answer.
Almost all gasoline in the U.S. is used for private on-road light vehicles (cars, trucks, SUVs). Per the EPA cite above, 91% of it.
From the perspective of global warming, that’s the problem.
The amount of gas used by household lawn mowing is regrettable, but it’s rounding error in the big picture.
Buying an electric lawn mower in no way expiates the sin of driving a gas-guzzling car. Or, really, any car, for that matter.
Keep your eye on the ball. Despite what you may read on the internet.
Addendum: Lawn services that do residences are classified as what, exactly?
I never did find a direct answer to this via the U.S. EPA. By looking at the earliest versions of their work, I infer that the original split between residential and commercial yard work is by ownership of the equipment. Initially, it was referred to as “privately owned” versus commercial equipment.
The upshot is that if a commercial service cuts somebody’s yard, the EPA likely counts that as commercial use. So to get apples to apples, I likely need to move some part of the EPA’s commercial use back to the residential sector. That is, if I really intend to assess the impact of mowing one’s yard / having one’s yard mown, relative to the impact of cars.
This will increase my initially-cited estimate of 0.6% of using gasoline being used for mowing. But, by how much?
Best I can tell, something like three-quarters to four-fifths of Americans mow their own lawn. (You know what I mean: Of those who have a lawn … e.g., CITE). But that really ought be to weighted by lawn area, as it’s almost certainly true that the larger the private lawn, the more likely it is to be cut by a professional. I did not find that information anywhere, so …
If I stick with the lower cited number and pretend that only three-quarters of residential lawn mowing is done by individuals (that is, using privately-owned mowing equipment), because three-quarters of people with lawns mow their own, I need to adjust the initial 0.6% upward to 0.8%. (The EPA residential sector estimate omits about a quarter of U.S. residential lawn mowing, because a quarter of private lawns are commercially mown.)
The conclusion is unchanged. In the U.S., gasoline used in lawn care is trivial compared to the gasoline used by passenger vehicles.
