Heat Transfer International, based in Kentwood, Mich., specializes in production of electric power and steam from biomass including broiler and turkey litter, woody products and municipal solid waste.

The company offers packaged plants incorporating a patented starved air, low temperature gasification system using a ceramic heat exchanger and a hot air turbine module. Ceramic heat exchangers can operate at up to 2,400F, exceeding temperatures in conventional metal units.

The heat generated powers a turbine which can generate between 0.5 and 20 MW. Alternatively, syngas which is produced can be used to generate steam or hot water for industrial or institutional heating.

Litter from 1.1 million turkeys

In 2009, HTI commissioned a plant for Sietsema Farm Feeds near Howard City, Mich. The biomass system uses the litter derived from 1.1 million turkeys raised in the area of operation each year. The installation converts 70,000 pounds of litter to produce 260,000 pounds of steam and 12,000 kWh of power each day. The plant is located in a 15,000 square foot building which allows for further expansion.

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According to HTI President Dave Prouty “this technology has the potential to change the way we do business, since we address the issues of the environment, energy generation and economics.” Estimates of the cost of plants similar to the prototype Sietsema installation range from $3.5 million to $4.5 million but according to Goutam Shahani, HTI vice president, sales and marketing, economies of scale may reduce cost further for a 500 kW installation. During 2010 the U.S. Treasury is offering grants of up to 30% of capital costs for co-generation installations.

Plant provides 75% of power

Initial estimates place power cost at 7 cents to 8 cents per kWh although this value depends on the prevailing revenue from litter as a fertilizer and the cost of alternative fuels such as natural gas. The success of the Sietsema Farms Feeds installation will demonstrate the benefits of the HTI starved air-low temperature gasification technology. A number of feed milling companies are evaluating the system which currently provides for 75% of the power and steam requirements for the Sietsema mill which supplies 1.5 million turkeys and 600,000 hogs each year.

A feature of the HTI system is that it complies with current and anticipated EPA regulations regarding air pollution and control equipment and is scalable in volume.
Subject to satisfactory performance and return on investment, HTI technology may represent a potential to reduce operating costs of feed mills and convert waste products into energy, promoting sustainability and reducing carbon emissions.