Guardian Energy Guardian Energy, ethanol, renewable fuels, Little Falls, Benson, Claremont, and Winthrop, Minnesota as well as Mason City, Iowa and Minden, Nebraska, ethanol plant, joint venture, energy, guardian, locally owned, Lima, Ohio, Guardian Lima, LLC OH Guardian Energy is one of the largest Ethanol Producers in the US. We purchase local corn to use in our processing facilities, where we produce ethanol, animal feed (DDGS), and …