A Greenhouse Gone Greener

By Anna Simet | March 14, 2014

Although my mother did not pass her green thumb onto me, as most women do, I have a deep admiration of flowers.

I love looking at them, but know very little about growing them.

Well, until this week. Now I know slightly more.

 For an article I’m writing for the May issue of Biomass Magazine, I learned quite a bit about the challenges greenhouse owners face when it comes to keeping their flowers and plants in the right growing conditions.

The Metrolina Greenhouse in Huntersville, N.C., is the largest single-story greenhouse in the country, at 162 acres. To put that into perspective, that’s about the size of 123 football fields.

They’ve been heating with biomass (wood waste chips) for over three years. Chatting with Jeff Woolsey, the boiler and systems engineer at Metrolina, he explained to me that plants in different stages of growth require different growing conditions. That means not only do they have to worry about keeping the massive greenhouse heated, but have to make sure each section is at the correct temperature.

To achieve this, Metrolina uses computers that draw on data from weather stations—wind, light, temperature, etc.—and determine the work that the boilers need to do.

I’m not explaining this as eloquently as Jeff did, but you get the idea.

Metrolina also has a massive hot water storage system that Jeff explained is much like a battery. During warm, bright weather, heat is stored for later use. Although four 8 MW boilers are in place, he said if they did not have the heat storage that they do, they’d need four more boilers of the same size.

Jeff said that since they’ve been using biomass, Metrolina has been paying about half the cost of what they were paying for natural gas.

Before I have to give you a spoiler alert, I’ll stop there. It really was an interesting conversation, and I’m excited to share with you what I have learned.

The Metrolina bit is a portion of an article that will detail a few unconventional biomass thermal end users. In it, you’ll also find details about Honeywell’s Hopewell, Va., massive caprolactam (primary feedstock in nylon polymer) plant, which draws a portion of its power from landfill gas that arrives via a 23-mile pipeline.

In production now, you’ll find this and many more waste-based energy stories in the May issue of Biomass Magazine.