Compost Windrow as Greenhouse Heat Source

• 2009 annual report

Commodities

Practices

• Crop Production: greenhouses
• Soil Management: composting

One problem we all face is volatile and sky-rocketing oil process. We want to research a way to reduce our and other farmers’ dependence on conventional fossil fuels for heating. Unpredictable oil prices make accurate budgeting difficult, and in times of runaway prices, fuel costs can wipe out profits.

On average, The Rhode Island Nurseries uses close to 17,000 gallons of diesel fuel annually to run our tractors and to heat our greenhouses. Of this, nearly half is used for greenhouse heating. We propose to garner heat form large compost windrows to supplement the traditional oil-based heating system in our propagation greenhouses this reducing our oil dependence.

In the future, nursery growers will want to locate close to metropolitan areas to shorten their transportation costs. Since large metropolitan areas are also likely to have a steady need to dispose of yard waste, there will be a ready supply of compostable material. Growers can make good use of compost’s natural heating process to supplement their greenhouse heating, reducing costs, raising profits and reducing global warming impacts.

We wish to capture an otherwise untapped heat source in our on-farm composting operation. We plan to demonstrate that large compost windrows can generate enough heat to supplement or replace traditional carbon-based fuels for propagation greenhouse floor heating.

Greenhouse growers with sufficient compost operations could capture considerable heat for greenhouse or domestic use, increasing nursery profitability and sustainability while reducing nutrient-rich runoff, oil-based carbon dioxide output and global climate change. The finished compost will then be ‘reused’ as growing media.

We will construct a concrete pad 40’ by 20’ as a base for the compost windrow. The pad will be slightly tipped towards the center to retain rather than drain excess precipitation. The pad will contain PEX tubing filled with water and antifreeze fluid. The pad will store a compost windrow on one long side. Compost-heated fluid will circulate in to the adjacent greenhouse. Measurements of daily temperature of air, fluid and compost will be collected along with the number of compost turnings required and actual fossil fuel use.

We plan to share our project results with other nursery operators, farmers, municipal workers and students. IF the project works as projected, we will demonstrate how medium and large compost operations can reduce dependence on fossil fuels by nurseries and compost operations.