Kevin likes to be outdoors fishing and camping. He also enjoys playing video games and completing puzzles. Because he loves building things and making paper airplanes, Kevin would like to pursue a career in building airplanes. Kevin's science heroes include his father, an environmental engineer, and his uncle, a chemical engineer.
Kevin toured his local wastewater treatment plant and discovered they were harvesting biogas from organic sludge. He had read that cow flatulence contains methane, and he began devising a scheme to harvest biogas from cow manure.
Kevin collected cow excrement and separated it into 1,000-gram batches. He placed each batch and 250 ml of distilled water in metal tubes or "digesters," and vacuum-pumped each digester to remove all air. He incubated the digesters at 100° Celsius and then collected and measured the amount of gas generated by each digester. Kevin found that weekly depressurization of the digesters produced the most methane.
