Carbon dioxide (CO2) may be one of the chief contributors to a changing climate, but for plants, it’s one of the chief nutrients. That simple fact is creating opportunities for B.C. farms to reduce greenhouse gas emissions as part of their regular operations, using some home-grown know-how.
“[Carbon dioxide] is the most natural fertilizer there is,” says Victor Krahn of SunSelect Produce Inc., established 25 years ago in Abbotsford. The Krahn family operates 70 acres of greenhouses in Aldergrove and Delta producing bell peppers, tomatoes and cucumbers.
But boosting carbon dioxide levels in the average greenhouse to optimize production is expensive.
A shipment of liquefied CO2 costs 14 cents a kilogram. Capturing CO2 emitted by the natural gas boilers used to keep greenhouse temperatures steady cuts costs to about seven cents a kilogram, but the cost of gas and the relatively low CO2 it yields is a drawback.
The most appealing fuel, and richer source of carbon, is biomass – typically, waste from pulp mills. When burned, emissions are approximately eight per cent carbon dioxide – but a lethal blend of carbon monoxide, methane and other components means it can’t be piped directly into the greenhouse.
But through ProSelect, a joint venture with the Dutch company Procede BV, SunSelect was able to develop a system that allows greenhouse growers to make the most of a cheap and abundant fuel source while reducing its carbon emissions.
Known as GC6, the system was developed at a cost of $5 million with financial assistance from B.C.’s Innovative Clean Energy Fund and the federal monies from Sustainable Technology Development Canada. It employs a proprietary organic solvent to capture and remove CO2 from boiler emissions.
The first working system debuted at SunSelect’s Delta location last year, alongside two Vyncke wood-burning boilers from Belgium. It has cut CO2 costs at the greenhouse to less than five cents a kilogram. “It cuts our CO2 costs in half, basically,” Krahn says.
While natural gas has traditionally been the fuel of choice in summer, when heating needs are less but carbon demands are high, biomass now stands to fulfil a greater share of its heating fuel needs year-round.
GC6 has also boosted SunSelect’s credentials as a carbon-neutral vegetable producer. By substituting biomass for non-renewable natural gas, and then capturing carbon emissions from its boilers to nourish its crops, SunSelect is deemed to absorb more carbon than it emits by the Vancouver-based group Offsetters Carbon Neutral Society. Offsetters audits the operation to determine the volume of carbon being absorb, then equates the absorption level to so-called carbon credits.
The units are then offered to businesses such as floatplane operator Harbour Air and Tinhorn Creek Vineyards near Oliver, B.C. Sales of the credits yield revenue for green businesses such as SunSelect.
“That revenue stream tied directly to our final decision to implement the whole solution of CO2,” Krahn says. “That’s a direct revenue stream we wouldn’t have otherwise.”
Now in its second year of operation, SunSelect’s carbon-capture system is attracting interest from growers elsewhere in B.C., as well as Ontario and around the continent. While the technology was designed solely for biomass boilers, Krahn says Procede engineers are looking at adaptations that would allow the system to capture carbon from the emissions of coal and other fuels.
Greenhouse growers aren’t the only ones tackling carbon emissions.
Ottawa granted $1.3 million from its Agricultural Greenhouse Gases Program in April 2012 to researchers at UBC Okanagan that will help fruit growers improve crops management to both reduce greenhouse gas emissions and enhance the volume of carbon plants sequester.
The three-year project will work with an apple grower, a vineyard and a raspberry grower in the Fraser Valley to study the best possible balance between fertilizer and water. The theory behind the research is that a well-fed plant will absorb more CO2 during photosynthesis. Some of the carbon absorbed by the plant would be retained in the root system, removing it from the atmosphere.
While tools exist to help growers determine when to irrigate, and for how long, correlations between irrigation practices and carbon sequestration hasn’t received much attention.
CO2 isn’t the only greenhouse gas targeted by the research. The effects of irrigation on nitrous oxide (N2O), a greenhouse gas 300 times more potent than carbon dioxide, are also being investigated.
Vehicle emissions are a relatively minor source of N2O, 70 per cent of which is the result of farming activities. Applying too much fertilizer – either manures or commercial preparations – is a major source of nitrates that contribute to the release of nitrous oxides.
When nitrates accumulate in the soil, they become a food source for bacteria that convert it under anaerobic conditions to oxygen and N2O. The bacteria thrive in wet soils, which also contribute to the anaerobic conditions that lead to N2O emissions.
“If you’re using irrigation methods that wet the soil too much, to saturation, then you’re creating anaerobic conditions in the soil and the [bacteria] will be active and may be producing nitrous oxide,” says Louise Nelson, associate dean, research, at the Irving K. Barber School of Arts and Sciences at UBC Okanagan and one of the researchers involved in the project.
“We’re hoping at the end of all this we should be able to say to the farmer, ‘OK, if you want to be environmentally conscious and reduce the possibility of greenhouse gas emissions, we would recommend that you use this type of irrigation and this type of nitrogen fertilizer in this amount.’”
B.C. aquaculture operations are also taking steps to address carbon emissions.
Tidal power is a key energy source for farms, delivering oxygen to sites and clearing away waste, but electricity is still required for many aspects of the farms’ operations.
The hatcheries where farmed salmon spend their first eight months require steady power to keep water moving through the tanks, and staff residences at farms along the coast demand power, too.
But it’s here that advances in generator technology make better use of energy.
Diesel generators run the feeding systems at each farm for about four hours a day, explains Ian Roberts, a 20-year veteran of the industry who now serves as communications manager for Marine Harvest Canada. The excess power from the 60-watt generators charges batteries that provide power to farm residents for the rest of the day.
“It used to be unaffordable,” Roberts recalls. “[Good systems] weren’t really available ... at a reasonable cost when I started. ... We were running generators 24 hours a day.”
Power Serve Energy Ltd. in Campbell River now supplies inverters that capture the energy and store it more efficiently and at a fraction of the cost as two decades ago.
Shellfish growers require even less power, and Roberta Stevenson of the B.C. Shellfish Growers Association says many of the association’s members live off the grid, within a couple of nautical miles of their farms. This means lower fuel requirements and, in turn, lower emissions.
“A lot of our farms use no machinery whatsoever, we use human power – say for clam digging or oyster picking,” she says. “They’re pretty low impact.”
