Top Hat Mushrooms has been cultivating shiitake mushrooms from their facility in Scio, Oregon, since 1991. Growing mushrooms on a commercial scale requires a steady temperature, humidity level and flow of fresh air circulating in the facility, so energy is a big part of the company’s operating costs.
Robin Gillette, CEO of the family-owned business, continually thinks about ways to save energy and minimize expenses. Energy Trust of Oregon has helped him invest in energy efficiency with support from cash incentives.
Most recently, Top Hat installed a new heat recovery system that utilizes warm air generated by their production process. The project resulted in 967,000 kilowatt-hours of annual estimated energy savings. In addition to lower energy costs, Top Hat got an upfront boost from Energy Trust cash incentives of $92,000.
“We are 100% fans of Energy Trust,” said Gillette. “We have worked on many projects with them, and those improvements allowed us to gain a competitive edge in terms of price, quality and food safety.”
Expanding efficiency
Top Hat is now the largest producer of organic shiitake mushrooms in the United States. After expanding the business and landing a contract to supply shiitakes to many Costco stores, Top Hat needed to scale up its operations. Gillette worked with Energy Trust to confirm his ideas for a new energy-efficient heat recovery system that would support the added production.
At the Scio facility, Top Hat prepares five-pound bundles of mushroom-starter substrate then stores them in three climate-controlled rooms until they are ready to fruit. The process requires warm, humid air, and produces carbon dioxide and heat as a natural byproduct of aerobic metabolism. The air handling system needs to continuously supply outside air to maintain acceptable air quality and 70-degrees in each room.
Having been an electrical contractor before starting the mushroom business, Gillette thinks like an engineer. He leveraged the idea of capturing the heat produced by the growing process to warm the incoming fresh air, rather than just releasing the warm process air directly outside. Top Hat had installed a small version of this system in another area of the facility, and Gillette thought they could scale it up for their expansion.
Gillette worked with Best Heating and Cooling, an Energy Trust trade ally contractor, to assess his ideas, refine the system design and recommend equipment. to calculate proposed system comparisons, review the project and confirm the equipment choices. Energy Trust also added value by calculating estimated energy savings and ROI along with a cash incentive estimate.
Best sourced the two 25-ton heat pump units and added heat exchangers configured to use the warm stream of exhaust air to heat up the incoming fresh air, improving equipment efficiency. The heat pumps can also work to cool air when outdoor temperatures exceed 70 degrees. With two units, Top Hat has built in some insurance to keep the system running if one of the units goes offline, ensuring reliability for customers.
“We need to be able to supply orders reliably, every week without a hiccup,” said Gillette. “Our business model is to be more efficient by minimizing our expenses and ongoing energy costs—it’s the responsible thing to do. This new heat recovery system helps us do all that.”
Here’s how Justin Hovland responded (I have edited copy in story to reflect what I got from this): Early in the project we did some scoping calculations to compare the proposed system with a passive heat pipe, leading Top Hat to rule the heat pipe option out. Then we were basically giving the chosen system our stamp of approval, but we didn’t do the sizing or selection. However, the energy savings calcs were an added value to Top Hat in addition to determining the incentive levels.