David, this is a good article and I'm happy to hear of this company's progress toward commercialization. Sure, true carbon accounting can be arcane, but that's not a reason to just throw around "net zero" even if brevity caused ideas to collide in this bit:
"High efficiency natural gas boilers produce nearly net zero carbon dioxide; the plants absorb the gas during photosynthesis." Uh...No. Definitely not.
Look at the sentence: natural gas boilers produce carbon dioxide, period. They cannot produce "nearly net zero carbon dioxide". We're off track here, so let's get back:
"High efficiency natural gas boilers use minimal fuel and produce minimal carbon dioxide while the greenhouse's added insulation value to the building below and the avoided trucking of produce are likely to create "net zero" or even net negative carbon operations".
Why be sticky? Because ideas direct action and opinion and they matter. Your construction almost suggests the boiler exhaust is piped into the plants and the carbon absorbed by the plants is sequestered forever - the first would likely be a building code violation, but the absorption of CO2 by the plants guarantees nothing regarding the disposition of the now-plant entrained carbon. Let's say disease wipes out the crop and it is required to go to landfill: now enough of the carbon is converted to methane at 21 times the global warming potential and enough of that methane is released to wildly blow the net zero idea. When the company uses its dead plants in a compost pile to heat water piped through the soil beds (as done by Douglas Durst's organic farm over 20 years ago), they can tell us that story, but leave the plants out of it because even if they're buried and turned to oil, the carbon can be re-released and likely will. You (and they) do not know, which suggests skipping the point is best until it is known.
A further point is that the construction of the building & creation of its materials has also incurred a large carbon debt, which is why my version says "net zero" operations - all buildings incur large carbon debt and this greenhouse is relatively efficient compared with conventional greenhouses. Their carbon story is likely better than the one you told, and, I'm guessing, the one they told you. Meanwhile, I'm only writing this out because those of us who interpret science and environmental topics to the public all want to be accurate and can help each other do so, don't you agree? Once we give people excess credit for slap dash ideas or statements, understanding of science and better ideas are both devalued - in this case heating w/solar thermal and compost (the biomass boiler idea is only marginally better than the NG boilers BTW).
Keep up the good work, and, again, this comment is directed toward the firm's PR people more than you.
Tom Kacandes, tom@solaradvantagesolutions.com
Lufa Farms has broken even on its operations in chilly Montreal, over 50 degrees of latitude north of the Equator.
The next time you’re in Montreal or New York, the lettuce in your Caesar salad might come from the building across the way. Demand for locally grown produce is rising in urban areas, and at least some commercial farming will happen on rooftops.
There was a time when New Jersey fed the Big Apple; produce was consumed locally before advances in refrigeration and transportation transformed agriculture into a global business. Your supermarket’s produce might have been shipped from half a world away.
Rising energy costs and concerns about food security have led some Canadian entrepreneurs to reconsider and reimagine local farms. Farmland has long since been paved over, but there’s plenty of space for rooftop greenhouses.
Lufa Farms is on the verge of an urban greenhouse-building spree. It proved its concept in Montreal, breaking even on operations earlier this year, and is negotiating Series A financing to build at least four more multi-crop facilities in Canada and the U.S.
Being successful in cold Montreal, the “most hostile” environment for a greenhouse, proves that the model will be sustainable closer to the equator, said co-founder Kurt Lynn. The tricky part is turning a profit by scaling a “farm” to the right size and carefully managing energy efficiency.
In an interview today, Lynn described how Lufa Farms devised a system of insulted “curtains” to shield sensitive crops from direct sunlight and keep the harvest safe during Canada’s frigid winter nights. Select supplemental lighting also helps control energy costs.
High efficiency natural gas boilers produce nearly net zero carbon dioxide; the plants absorb the gas during photosynthesis. Biomass will be utilized in the future, Lynn noted.
The underlying building receives the added benefit of a 20 percent energy cost reduction, Lynn said. “We provide a huge insulator to the building below.” Greenhouses also take advantage of heat escaping through the rooftop.
Additional greenhouses will soon be under construction in Montreal with a potential site having been chosen in New York City. The Bronx and Brooklyn are the most favorable boroughs, Lynn noted. Boston is also under consideration.
Lufa farms competitor Brooklyn Grange has already constructed the largest rooftop farm in the United States on an old Navy warehouse in Brooklyn. BrightFarms is planning another that would yield one million pounds of hydroponically-grown produce annually, including herbs, lettuces, and tomatoes.
“We look at food creation in the same way as you look at making subway stops,” said Lynn. “We’re considering high density residencies such as senior’s home; there’s going to be a boom in the future, and [farming] is good occupational therapy.
(Image credits: Lufa Farms)
Tomato plants grow over 20' high within the greenhouse(s). "It's like a jungle in there," Lynn said.
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