#3. "Methane Digester". Marshall, CA. The single largest source of pollution in the State of California is methane from cows. At Albert Straus’s family dairy a methane digester traps methane before it can enter the atmosphere, breaking it down into solids and liquid fuel that can be used to provide enough electrical power to run the entire dairy operation. Information artwork by Douglas Gayeton. From the Lexicon of Sustainability project.