From an article and video on BizTimes:

Every Monday morning, a crew of workers inside the Milwaukee Brewing Company brews up a special batch of product. Unlike the brewery’s beer, this product is usable right away, and becomes fuel for the brewing process.

For more than one year, the company has been making biodiesel at its brewery at 613 S. 2nd St., in Milwaukee’s Fifth Ward neighborhood. The brewery is owned by Jim McCabe, who also owns the Milwaukee Ale House, which has locations in Milwaukee’s Third Ward and Grafton. The cooking oil from both locations is transformed into burnable biodiesel inside the brewery.

The brewery produces about 110 gallons of biodiesel on most Monday mornings. During warm months, that is enough fuel to power a full day’s brewing each week.

“When we look at our energy bill today compared to one year ago, there’s a big difference,” McCabe said.