When the price of natural gas soared in 2005, greenhouse owner Phil Glasbergen knew it was time for a change. “We had locked into a lower price in our natural gas contract at the time, but the rising price and uncertainty about where the gas market was going was a big concern. So as part of an upgrade to our facility we added a 100 HP boiler capable of burning wood pellets and other alternative fuels,” he says.

Glasbergen owns and operates Glasbergen Greenhouses with his father John and brother Peter. The three-acre facility in Fenwick, Ont. specializes in potted plants. “We operate from February through November,” he explains. “Through the winter months we maintain a minimum temperature to keep the water pipes from freezing. The new boiler does this job nicely at this time of the year. The only time we run the gas boilers in winter is to melt the snow load on the greenhouse during a snowstorm. During these times we like to keep the greenhouse at 60 degrees F.”

Glasbergen says the pellet-burning boiler provides 60 per cent of his heating needs. It also saves money. “With natural gas alone, we were spending about $260,000 a year for heating. With wood pellets plus gas as backup, in the last year our heating costs came to about $200,000.”

Heating is a major input cost for greenhouse businesses. In Ontario it represents 25 to 40 per cent of the total cost of production, according to a 2003 report (updated in 2007) on the Ontario Greenhouse Floriculture Industry from the province’s Ministry of Agriculture, Food and Rural Affairs (OMAFRA). “Long term natural gas contracts have cushioned some of the cost increase but for most [greenhouse businesses], fuel costs have increased by 30 per cent while wholesale prices have increased by less than three per cent,” the report states.

Although the price of natural gas dropped significantly this winter, “how long it’s going to stay low is anyone’s guess,” says technical consultant Jack Smit of Westbrook Greenhouse Systems, Grimsby, Ont. The company supplies equipment to greenhouses across North America. “Most greenhouse people who are looking to alternative fuels either believe that gas will go up and it’s just a matter of time before it settles in at a higher value. Or they don’t have natural gas available in their area. Some of them are burning Number 6 bunker oil at very high prices — plus dealing with the pollution factor. They’re saying, well, we’re going to switch over to one of these alternative fuels to try and lessen our headaches and reduce some of the cost.”

Search for new options
In the race to reduce heating costs, a lot of experimentation has been going on. Much of this has revolved around biomass, which describes materials that are organic and can be used as fuel. Biomass can come in bulk form, such as wood chips. Or it can be pelletized from wood or other materials. According to Smit, “People have been burning corn, soybeans, oat hulls. An awful lot of it is wood chips or wood pellets — even pelletized cardboard and food scraps. I guess the most bizarre one that I heard of was a company out of Michigan. They were going to get scraps from the diaper companies and pelletize that stuff to be burned as fuel.”

Pros and Cons
Although biomass fuels are widely used in Europe, they are relatively new to North America. On the plus side, biomass is renewable, it does not depend on fossil fuels and it can be produced locally at minimum cost. This benefits the end user and also contributes to keeping employment local.

In terms of environmental impact, biomass fuels do not contribute to the risk of global climate change. Burning these fuels is “carbon-neutral,” meaning the amount of carbon released during combustion is equal to the amount absorbed by the plant while it was growing. Ontario Power Generation (OPG) has been testing biomass as part of its Greenhouse Gas Management Plan. According to OPG literature, “The expected environmental benefits include the reduction of net carbon dioxide (CO2) emissions and reductions in other air emissions.” However, biomass fuels are not necessarily pollution-free. While oat hulls burn relatively clean, there is an odour, which some have compared to burnt popcorn. In recalling an experiment burning soybeans, Phil Glasbergen says it created a haze around the neighbourhood. “We only burned one load. And we went around to our neighbours asking them to please bear with us for a week until we get rid of this stuff. It did burn very well, but with that haze, we quit with it pretty quick!”

Biomass fuels also require more labour and management. Unlike natural gas — which is piped in and flows with a flick of a switch — biomass is a solid fuel that must be delivered, stored and fed into the boiler, often via augers. The resulting ash is augered out (usually automatically) and must be disposed of. Equipment must be maintained and there are mechanical parts subject to breakdown.
Although Glasbergen has experienced few problems burning wood pellets, he says, “If money was no object, and we had the heavy equipment to move stuff around, I’d move the ash to a pit and just clean it out myself instead of having a company pick it up and haul it away.”

Burning bulk fuel can be more challenging, according to the greenhouse operators interviewed. These businesses chose bulk fuel because their heating demands require a lower-priced fuel source and bulk materials are usually cheaper than pellets. Vanderveen’s Greenhouses is a five-acre facility that specializes in the production of potted and bedding plants. It is located in Carman, Man., about 60 km south of Winnipeg, an area with cold winters. Vanderveen’s is one of the first installations in Canada to successfully burn bulk crop residue for a large commercial heating application. Its fuel source is flax shives, a by product of flax straw processed for the pulp and paper industry. Says Gordon Vanderveen, “I know a lot of greenhouses in Ontario burn wood chips and I guess there’s a lot more available there. Here it’s tough to get huge amounts of wood chips and the mill that processes the shives is only three miles away.” But getting the system to run smoothly took considerable babysitting, he adds. “We replaced a lot. We had problems with everything from augers jamming to sensors not working. Our engineer worked with the company who sold us the boiler. Basically, the boiler was designed to burn coal. That’s why there was a lot of tweaking — to suit burning of the flax.”

For Colonial Florists, a seven-acre facility in St. Catharines, Ont., fuel quality was a key issue. Colonial burns three-inch or smaller wood chips, derived from construction waste. As a propagator of vegetative annuals, it must heat at high temperatures, and wood chips are the lowest-priced alternative fuel available. But it’s gone through several suppliers to find the right price/quality fit. “With some wood chips there were too many impurities, whether it was dirt or residual metal, that would jam up our augers,” says co-owner Ron Vanderzalm. “In some cases there was too much moisture so we weren’t getting the proper BTU value from the wood.” According to industry sources serving southwestern Ontario, the moisture content of post-industrial derived wood chips should be less than 30 per cent and have a calorific (energy) value of 7,000 BTU.

Even when greenhouses find the right alternative fuel supply, there is no guarantee it will be available over the long term. Bevo Farms, a large supplier of propagated plants, successfully burned cedar shavings for eight years at its 34-acre facility in Langley, B.C. But when mill production slowed down and the shavings were getting harder to come by, Bevo was forced to find another fuel, according to president and general manager Leo Benne. Bevo is testing sawdust briquettes (called pucks because they are molded to about the size and shape of hockey pucks). “The density of the pucks is higher than the cedar shavings, so there’s a little less volume of material going through the facility,” explains Benne. “But is it easier or more difficult to work with? No. It has very little impact on our operational costs. And it’s costing us quite a bit more than cedar shavings. I worked it out by gigajoule. For the cedar shavings it was $3 to $3.50 per gigajoule. For the pucks it’s $5.50.”

Benne admits the pucks cost less than natural gas, but right now he’s eyeing ground-up pine wood. “Those trees are just standing there. They’re dead, so people are going in and grinding them up. Really, we’re looking for the cheapest fuel to get our hands on.”