Sundance Forest Industries' new SunPlus reman plant believes they have solved the problem of poor indoor air quality - and its potential impact on employees - with an unusual decision to convert in-plant forklifts to natural gas. Ian Tarves, SunPlus specialty products manager, says three recently acquired Cat lift trucks were converted to natural gas on purchase, and the result has been much cleaner air when the machines are handling lumber inside the plant. "We intended that our building would be totally enclosed and heated, so we needed something to move our lumber inside our plant that wouldn't produce fumes. What we found looking at the various options is that natural gas caused the least amount of problems with our employees."

Tarves says emissions during jobs like container loading are even more of a concern. "When you load a container, you are working in a very close, confined space. You don't need noxious fumes. When you run propane, gas or diesel in there, by the end of a shift odds are the operator has a splitting headache - or worse. I've had carbon monoxide poisoning from loading containers before," Tarves says. "I know it's not a whole lot of fun."

Power loss, productivity and efficient refuelling were considered in making the decision, he says. Power loss, compared with other fuels, is minimal, while productivity hasn't suffered as the machines can complete a 10.5-hour shift before refuelling.

Fuel tanks were mounted so as not to obscure visibility: a larger tapered tank in the front and a smaller tapered tank at the rear.

Compared to gasoline on a BTU-basis, natural gas is a considerably cheaper way to go. In a one-to-one BTU equivalency test, gasoline at 50 cents a litre compares to natural gas at 25.9 cents per litre. That is a 50 per-cent saving.

Tarves says a natural gas-powered forklift is nearly as powerful as a gasoline-powered unit. "I have driven forklifts with natural gas, gasoline, propane and diesel engines. There is a slight difference (with natural gas) but not enough to amount to anything in the way of reduced performance."

SunPlus already had run a natural gas line into the site. A skid-mounted refuelling station consists of four vehicle refuelling appliances (VRAs) manifolded together. A VRA is essentially a small vehicle refuelling compressor. The VRAs are hooked into 23 storage tanks. This gives SunPlus the capability of using gas supplier Northwestern Utilities "quick fill" system; it takes operators only two to three minutes to fill a 35-litre tank. The lift truck operators do not require certification to operate the natural gas refuelling station. Northwestern Utilities also says that natural gas is much safer than propane. For example, propane will liquify at temperatures below -40ĄC and lose compression, while it takes -160ĄC at slightly less than 3,000 psi for natural gas to liquify. Pressure in the forklift natural gas tanks is about 2,800 psi, so cold-weather starting is not a problem.

The utility says operators initially worry about the amount of pressure in the tanks, since it is almost 10 times more than the pressure of propane tanks. But natural gas tanks, fittings and tubing are rated at three to four times higher than the 2,800 psi in the tanks.

Once fuel within the tanks diminishes to 200 psi, the operator hears an alarm telling him that fuel is running low. At that pressure, he still has enough fuel to drive to the refuelling station. Otherwise, should he run out of fuel, he can switch temporarily to gasoline.

Sundance Forest Industries controller Mike Dion says the natural gas forklift conversions and fuelling station should pay for itself within three to five years. Given its successful experiment with forklifts, Sundance plans to convert a few yard machines (lift trucks) to natural gas as well. However, they can expect a 10 to 15 per-cent drop in horsepower with these conversions, as the diesel engines that power the machines are not designed to burn natural gas.