Special Report

More about the Crave Brothers digester

Crave Manure DigestersOne of the features at Wisconsin Farm Technology Days this year is the anaerobic digester on the Crave Brothers Farm. Clear Horizons of Milwaukee built the digester; they also own and operate it. Karl Crave works for Clear Horizons, he says under the partnership, the farm did not have the capital outlay to build the unit, they have a digester which is being run by people who know how to run it and the farm will eventually own it. Charles Crave says one big advantage to the farm right away was, “About 750 acres less land to spread manure on.” Clear Horizons sells the electricity, some to the farm and some to the grid. They also sell the dry product.

One of the first questions with an operation such as this is whether it is better for the farm to build the digester or to have someone else build it. Karl says that is up each individual farm, every farm has to decide where best to invest their dollars. In the case of Crave Brothers, they found it was better to invest in the cows and the cheese factory and let Clear Horizons do the digester.

The Crave Brothers digester is a basic unit in that it creates methane gas which runs a combustion engine which turns a turbine to generate electricity. “We are running a 633 kilowatt engine that generates enough electricity for about 550 homes.” Some digesters sell the gas instead of running a generator, Crave says the current cost of natural gas and the economies of scale all come into play in making that decision.

What is unique is that the digester tanks are above ground. Some questioned whether those tanks would not freeze up during the cold of winter. The digester has run through two winters with no freeze up.

 AUDIO: Karl Crave talks about the anaerobic digester 4:45

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