Home-Grown Power Saves Irrigation Fuel

11:55AM Oct 28, 2013
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Anyone who has dealt with an electric utility concerning installing three-phase power from a main line to remote areas like irrigation well sites has suffered sticker shock at typical bids of $50,000 to $100,000 just to get service.

That was the situation Tom and Ellis Moore, Sunray, Texas, faced several years ago as they expanded their 12,000-acre grain and cotton operation in the Northern Texas Panhandle.

In the Moore’s case the estimate was $100,000 for a mile of line, Tom recalls. "That’s when we went looking for alternatives."

Today, on several fields, Moore Farms is generating its own electricity with natural gas-fired engines -- significantly beating the power company’s per-kilowatt rate and realizing significant improvements in overall fuel-use efficiency on the wells and sprinklers powered with the gen sets.

The success they had with generators also led the Moores, two other partners, and manager Richard Hall, Dumas, Tex., to launch Ag H20, a company which provides gen sets and variable frequency drive (VFD) control panels to other irrigators wanting to avoid the high cost of commercial three-phase power.

The reasons to switch are many, not the least of which is overall fuel economy compared with running a natural gas engine on each well.

"In our testing, we had the gas company come out and monitor fuel consumption of two of our wells, each powered with a 350 Chevy V8. Then we had them monitor a similar well powered with a gen set – a 90 horsepower Caterpillar 3304TA driving a 164 KW three-phase generator. The results showed the gen set would use $900 less natural gas per month than the Chevy engines!"

While common wisdom would bet against such efficiency from burning natural gas to turn a generator to make electricity to run a motor to pump water, Moore says much of the savings come from the use of the VFD, which allows softer starts and stops of pump motors, and through computer controls which supply optimum frequency and voltage to meet the well motor’s pumping load.

The Moores were astounded at the gen set’s ability to provide relatively low-cost kilowatts, when compared with the going commercial power rates from their utility. "On $4.50 (per thousand cubic feet) natural gas, we can generate a kilowatt of power for just over 4 cents, compared with nearly 11 cents per kilowatt delivered by the utility. Now, that’s only a fuel cost comparison. It doesn’t include depreciation, parts, oil and maintenance, but fuel costs add up quickly when you consider the upfront cost of three-phase installation."

Also, he notes, "If we get a lighting storm and the power is knocked out, it’s not the farmers who get service restored first by the utility company. If we get a gen set knocked out, we have the flexibility of pulling another one in on a trailer and being up and running again in a few hours."

Moore says other benefits of managing with gen sets include much "cleaner" power and fewer intermittent power losses – so common with public utility power across the country. "When you use three-phase power from the utility company, one or more "legs" of that power are supplying homes and businesses on the grid with 120 and 220 VAC, so you always have some current and voltage imbalance to reduce your motor efficiency. With our gen sets, you have none of that," he explains.

Also, there’s the maintenance angle. One of Ag H20’s gen sets can run multiple (3-5) sprinklers and wells and that’s all on one engine running at about 85% capacity, Moore notes. "We’ve found the best performance for engine life, maintenance costs and overall upfront investment costs is the 85% load rating on our Cat engines. That’s higher than Caterpillar recommends, but they are assuming pumps will be started instantly from a dead stop, which draws tremendous current loads. We, however, can use the VFD to take up to 6 minutes to bring a motor and pump online."

On the three-sprinkler system we visited, the 315 hp. 3406TA engine starts and warms for about six minutes before the VFD panel brings the 100 hp. electric motor on line to start pumping the 400-foot well directly below the gen set to water the circle and produce cooling water for the engine.

Once that’s running, the VFD cues a 75 hp. electric motor and pump to start watering another circle more than a quarter mile away, and subsequently signals an additional 50 hp. submersible pump to start another pivot in yet another adjacent field. The three wells theoretically are pulling 168 kilowatts, and the gen set is rated at 296 KW providing additional capacity for even more demand.

"We’re testing cell phone technology right now so we can control individual gen sets on the farm," Moore explained. "That way, if it rains on one, we can shut it down and save the water while continuing to water the fields that didn’t receive rain."

For more information on AG H20 and the gen set technology, call Richard Hall, manager, at 806-316-8283.