Potential to Operate Greenhouses and Aquaculture in Conjunction with Iowa’s Ethanol Plants

With the rapid expansion of Iowa’s biofuels processing industry, the state currently has 29 dry-grind ethanol and 14 biodiesel plants. As the fuel ethanol industry matures, operators of biofuels plants may seek opportunities to sell other co-products. One such opportunity may be in selling waste energy to nearby production facilities for fish, fruits, vegetables, herbs and ornamental plants that could, in turn, be sold locally. This project was designed to answer two questions: 1) is enough waste energy available from an ethanol plant to supply energy to a greenhouse or aquaculture operation? and 2) what crops and/or fish species would carry enough market value to consider producing them in Iowa for Midwest markets?

A discussion group of ISU researchers involved with greenhouse, aquaculture, and biofuels production was assembled to pinpoint the issues that currently face each of these operations. This ad-hoc research team collected market and operational information about greenhouse and aquaculture operations, and estimated waste heat energy available from ethanol plants. Key issues were identified that may lead to success or failure including: selection of high-value crops or fish species, sufficient low-cost energy to overcome the high cost of heat and light during the winter months, and assurance of coordinated management between the ethanol plant and greenhouse/aquaculture facility to avoid costly mistakes. Estimated waste energy from one 50 million-gallon-per-year ethanol plant comes from flue gas at a rate of 6-12 million Btu’s per hour (Btuh) and from cooling water at 3-5 million Btuh. In total, this energy would be enough to heat a 1-5 acre greenhouse on Iowa’s coldest days, or heat as many as 100 30,000-gallon tanks in a reusable aquaculture system assuming an ambient temperature of 65oF. A feasibility study and detailed engineering plans for a specific location would need to be done to better estimate set-up costs, facility design, and product profitability for an operation co-located with a processing plant.

Contacts:
Connie L. Hardy
ISU Extension Value Added Agriculture
1111C NSRIC
Ames, IA 50011
chardy@iastate.edu
515-294-8519

Ray Hansen
ISU Value Added Agriculture Extension
1111C NSRIC
Ames, IA 50011
hansenr@iastate.edu
515 294-0648