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FW: Gas or Electric



This information from a colleague who has done quite a bit of engine
emissions work.

-----Original Message-----
From: Haines, Howard [mailto:hhaines@state.mt.us]
Sent: Wednesday, January 09, 2002 4:28 PM
To: 'Estes, Laura'; Tomas Vinson (E-mail)
Subject: RE: Gas or Electric


Dear Laura and Tomas,

I am not on the P2Tech, but you can post it there. This reads like someone
should have shown up at one of my workshops with the Health and Air Quality
Impacts of Bio-based Fuels and Lubes in Small Engines slide show. These were
given in Montana, Minnesota (2), Michigan (7), New York, Washington D. C.,
and are now being done in parts of Canada.

As of January 2002, the newer lawnmowers would be the most efficient
mechanical units in terms of energy, CO2 emissions, and reduced pollution
for areas that do not have air quality problems.  

Newer lawnmowers are almost all 4-stroke engines (see the EPA report at
OTAQ), and some have electronic fuel injection-quite a bit cleaner than
older 2-strokes, and more energy efficient (less CO2 emissions).  For data,
look at a number of reports by CARB and Southwest Research Institute.

In most of the data I have seen, the reasoning behind electric lawn mowers
(and vehicles) is to move the pollution out of an air shed that has poor air
(exceeding regulated pollutant levels), and away from people, to an air shed
where the electricity is produced.  The idea is to reduce pollution at the
site of use so that other pollution sources (like industries that have fewer
energy options) can operate in the same air shed.  In most cases when you
think about it, electric mowers don't make much sense except for the utility
companies.  True, a coal-steam plant in Montana may be 33 to 35 percent
efficient, but it looses (rule of thumb) about ten percent to move it down
to California.  With that size of operation, the typical battery and
recharge losses (30 to 45 percent) would cut the efficiency or increases the
emissions even more.  From an energy or emissions standpoint, an electric
lawn mower is like cutting butter with a chainsaw.  

Gas turbines for electric production are not all that efficient compared to
the large thermal plants, but they are cheap.  As for emissions, just look
out the back of any turbojet airplane and see the difference.

Fuel cells where the heat can be used can get up to 85 percent efficiency,
but they are just now starting to come down in price. If you don't think a
fuel cell-powered mower is possible, then I won't worry you with the one I
saw at a unit of the Department of Defense in Utah.  They also have a fuel
cell-powered utility vehicle (bigger than a golf cart, smaller than an auto)
that has an overall efficiency of somewhere in the mid-40s.  There are plans
for a fuel cell-powered snowmobile as well, but that is still on paper for
the time being.  

For a specific comparison of fuel economy, CO, HC, and PM emissions between
2- and 4- stroke small engines, see the fourth, sixth, and seventh slides
(titled Emissions of 2-stroke vs 2-stroke Engines) in the Health and Air
Quality Impacts of Bio-based Fuels and Lubes in Small Engines slide show (at
http://www.deq.state.mt.us/CleanSnowmobile/montana/hpp.pdf ).  In the fourth
slide, a comparison of CO and HC is done for two 2-stroke snowmobile engines
circa 1995 and 1998, a 1998 personal water craft engine, a 4-stroke engine
is a utility-type engine (a bit bigger, but not unlike a lawn mower), and an
advanced 4-stroke engine (with emission controls similar to an automotive
engine).  The sixth slide down compares fuel consumption, and the seventh
illustrates particulate matter emissions.  The data were all developed at
Southwest Research Institute, some of which was paid for by this Department.

Information on cleaning up these small engines also on the web site
(www.deq.state.mt.us\cleansnowmobile or www.cleansnowmobilefacts.org .  Just
by using an ethanol blend fuel and low emissions lube oil in a two-stroke
engine, we measured reductions of CO by 9 to 38 percent, HC reductions of 16
to 27 percent, and particulate matter reductions of 25 to 70 percent.  NOx
was not affected, and NOx emissions from 2-stroke engines are low-so low
that they produce ammonia.  A number of colleges have also been looking into
cleaning up and quieting down 2-stroke engines as illustrated in the results
from the SAE Clean Snowmobile Challenge (also on the web site).  Catalytic
converts are available and used (in Europe, Asia, and some places here) for
engines as small as chain saws.  It would not be a problem to put one on a
lawn mower.  

I suspect many on the P2Tech list will not have to worry about snowmobile
emissions, but the same principles apply to jet skis, personal watercraft,
small marine engines, and ATVs.  This site represents over $1 million in
research done in or for the greater Yellowstone (as in National Park)
region.

Back to the first topic of keeping the area around buildings trimmed in a
acceptable (pollution-prevention) method.

I would suggest a more efficient way to keep the grass short-use a drought
resistant grass variety (like buffalo grass) and/or your neighbors' horses
(or sheep) to periodically mow it.  I also limit watering.  If I don't
water, I don't have to mow here in Montana. I keep it dry enough to where
dandelions don't grow, but it stays green to keep the dust down. I know that
some places in this country it rains (Seattle, WA, Beaumont TX, New Jersey,
New York, Michigan), so other methods might be needed.  Like possibly not
growing any grass at all: put in a vegetable garden with mulch, or do
something a bit more natural. 

This was less than 15 minutes of thought/typing, and I apologize if it was
boring.  Just know that someone has been working on the problem of 2-stroke
engine emissions because once you are out the U. S., almost all the vehicles
use either diesel or 2-stroke engines.

Howard Haines
Bioenergy Engineering Specialist
Montana Department of Environmental Quality
Hhaines@state.mt.us