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Mower Fuels: Looking for Alternatives

By Erik Skindrud, regional editor

A city employee fuels up a Kubota riding mower at Rock Hill, S.C.'s refueling station. The city's diesel-fueled vehicles use a mix of soybean oil, used French-fry oil and regular diesel fuel. Gas-powered vehicles get a mix of ethanol and traditional gasoline. Photo: City of Rock Hill, S.C.

The price of gasoline and diesel is prompting a growing number of maintenance departments to explore alternative fuels. Several options promise cost savings--with the added benefit of reduced emissions.

It's the rage in Hollywood--stars like Jack Nicholson, Daryl Hannah and others converting engines to run on ethanol or pure vegetable oil. It sounds like a fashion statement (and it is that too), but Rudolph Diesel in fact designed the engine named for him to run on peanut oil in the 19th century. Henry Ford built the first Model-T to run on ethanol. Only later in the 20th century did petroleum-based fuels become standard.

Today a new segment of the population is turning to the so-called biofuels. They aren't making the switch to be fashionable; they're doing it because it saves money and makes practical sense.

The new pioneers are groundskeeping departments for schools and municipalities in the country's agricultural heartland. Being near crops like corn and soybeans, it turns out, is one key to creating a financial incentive for making a fuel switch.

Propane is a promising technology already used by the U.S. Forest Service and other agencies to achieve very low emissions. Those aren't beer kegs on this mower, they're propane tanks--like the ones you might use with a backyard barbeque. This Ferris riding mower has been specially converted by North Carolina-based ONYX Environmental Solutions. Photo by Erik Skindrud

Rolling in Rock Hill

One such place is Rock Hill, S.C., where the maintenance department operates its own filling station with ethanol and a soybean-oil/diesel-fuel mix.

The city fleet using the fuels includes dump trucks, cars, utility trucks, three John Deere tractors and close to a dozen Kubota ride-on mowers.

Since the fuels are mixtures, and not pure vegetable oil or ethanol, there's no cost associated with mechanics adjusting stock engines, city performance manager Marty Burr said.

"Most people are under the impression that it takes a lot of time and effort to make the conversion, but in fact it takes no time at all," he said.

Many workers were unaware that any change had taken place.

In addition to saving money on fuel, the fuel blends have lower emissions. You wouldn't think that would make a difference in rural South Carolina, but it does. Last year, the EPA gave the region around Rock Hill a "nonattainment" rating for ozone pollution. With emissions restrictions across the country tightening, it may only be a matter of time before all mowers and vehicles in the area are forced to comply with new standards.

The school district in Henderson County, Ky. is on the cutting edge of progressive fuel technology. This is the second fall that local students have ridden to class on busses fuelled with a soy-oil/diesel blend. District mowers and tractors use the same, unless they're gasoline engines. In that case, they use a gas-ethanol mixture.

As in South Carolina, drivers and operators in Kentucky say they can't tell the difference, district maintenance manager Glenn Powell said. Those who pay the bills can, however.

"It was cheaper for us to use a blend than use 100 percent diesel fuel," Powell told the Evansville Courier & Press newspaper. At one point, the soy-diesel mix was 10 cents cheaper per gallon than traditional diesel.

Over the next few years, biodiesel and ethanol blends will become available at many more locations across the country. Whether they will offer big, or more moderate savings over "normal" fuels will depend on world political developments that are hard to predict. It's likely, however, that momentum is moving in the direction of biofuels. Even if the price remains similar, the new fuels offer significant reductions in harmful emissions.

And more restrictive emissions rules look likely, especially for lawn mowers. The numbers vary by maker, but many lawn mowers are relatively "dirty" compared with automobiles and trucks.

Kentucky's Henderson County Schools fuels up all its diesel-powered vehicles at this pump station. Note that busses (rear) and lawn mowers run on the same fuel. Using 20 percent soybean-derived biodiesel results in a savings of about 10 cents a gallon. Photo: Henderson County (Ky.) Schools

Homegrown Oil

The advantage in Kentucky is that the soybean oil going into the busses and lawn mowers grows right down the street, eliminating the need for expensive and waste-emitting transportation.

Henderson County farmer Andy Sprague actually grows part of the oil that goes into the school district's tanks. His curiosity and initiative gave the local fuel project an important push.

Several years ago, Sprague applied for a $200,000 grant from the Kentucky

Consortium for Energy and the Environment. He used the money to build a soy diesel refinery on his farm. The first three months he sold the product he moved 175,000 gallons. The next three he sold 825,000 gallons.

"Once the product started catching on, the product just exploded," he told the Evansville Courier & Press. "We are at full production."

Not far away, Kentucky's own Commonwealth Agri Energy is refining ethanol from corn.

This diesel-powered Kubota tractor is a Rock Hill, S.C. workhorse. Here it's hooked up to a PTO-drive Bush Hog mower attachment. No engine conversion is required to use the biodiesel fuel mix, city performance manager Marty Burr said. Photo: City of Rock Hill, S.C.

The Ethanol Option

Not everyone has biodiesel available in the neighborhood, although that may change soon. More commonly available is ethanol, or ethyl alcohol. In Brazil, many car engines have been modified to run on almost pure ethanol. Racing fans have long been familiar with alcohol as a fuel, used with dramatic results in funny car drag racing.

Next year, Indy cars will start running on pure ethanol--Indy Racing League events are using a mixture of methanol and ethanol this year.

Unlike racing, most ethanol burned on American highways is in the form of E10, a blend of 90 percent gasoline and 10 percent ethanol. The product is commonly available in the center of the country, less so on the coasts. Over the past two years, it's found enthusiastic converts in the lawn maintenance field.

Ethanol blends have the advantage of burning cleaner than pure gasoline, reducing emissions.

"It's better if you can reduce the carbon monoxide you're breathing in when you're mowing your lawn," Sam Spoffoth of the Central Ohio Fuels Coalition told the Columbus Dispatch newspaper.

According to Jeff Devine, E10 mixtures are ideal for small engines like lawn mowers. In fact, engine manufacturer Briggs & Stratton recommends that small engines don't exceed the 90-10 percent ratio.

If ethanol content is too high, engines can burn hot and actually melt plastic components in the fuel system.

Devine, who runs Como Mower Service in Columbus, Ohio, offered LSMP readers some advice about using E10.

"The 90-10 mixture is a little harder on a two-cycle engine like a leaf blower," he said. "Ethanol is a solvent and it can actually cause an engine's cylinder walls to break down more rapidly. Two-cycle engines and older engines should stick to a high-octane fuel.

"If you're going to use E10, one of the things you may want to do is to add heavier-duty fuel lines. Ethanol can deteriorate a fuel line--in a bad case, the line can turn to the consistency of chewing gum."

Since ethanol is hotter and more volatile, it burns more rapidly. The difference with 90-10 mixture is slight, but ethanol blends get slightly poorer fuel mileage.

In most cases, the lower cost of ethanol blends will offset their slightly lower mileage.

Finally, small engines should not be stored for long periods with ethanol blends. Doing so can attract water and cause corrosion.

Athletic field superintendent Kent Hauser (left) rides the John Deere while Jon Douglas rides the orange mower at right. Both use diesel-powered engines fuelled with 20-percent soybean-derived biodiesel. Photo: Henderson County (Ky.) Schools

Small Engine Fuel Guidelines


The following information is reproduced from engine manufacturer Briggs & Stratton's web site. It's important to stick with approved fuel types to ensure the health and longevity of your equipment.

Recommended Fuels

Use clean, fresh, regular unleaded gasoline for Briggs & Stratton spark ignition internal combustion engines.

Fresh fuel prevents gum from forming in the fuel system or on essential carburetor parts. Purchase fuel in quantity that can be used within 30 days to assure freshness and volatility tailored to the season.

Unleaded fuel is required in the USA. Engines fitted with exhaust catalytic converter require unleaded gasoline. Leaded gasoline will foul or damage the exhaust catalyst and will void warranty on engine emission control defects.

The use of unleaded gasoline results in fewer combustion deposits and longer valve life.

Clean fuel, free of dirt and water, is required for optimal engine operation. Inspect portable storage containers to make sure gasoline is free of dirt, grass debris, rust particles, and water.

Fuel Blends and Additives

B&S allows the use of oxygenate blended gasoline where the oxygenate content is up to 10% ethanol (gasohol) or up to 15% MTBE (Methyl tertiary butyl ether) by volume. However, ethanol blended gasoline can attract moisture which leads to separation and formation of acids during storage. Acidic gasoline can damage the fuel system of an engine while in storage. B&S strongly recommends removing ethanol-blended fuels from engine during storage.

Use of gasoline containing higher than the EPA approved limits, or volume percentage of ethanol more than 10%, or MTBE more than 15%, may cause engine damage and will void engine warranty.

In some areas, state or local laws require that the service pump be marked indicating the use of alcohols or ethers. However, there are areas in which the pumps are unmarked. If you are not sure whether there is alcohol or ethers in the gasoline you buy, check with the service station operator.

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June 27, 2019, 1:57 am PDT

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