Under the pilot plan, announced this week, Sunset Scavenger will place biodegradable bags and what are tastefully called dog-waste carts in a popular San Francisco dog park. The dog poo will then be put into a methane digester, where bacteria will eat away at it for two weeks before it turns into methane gas. The gas can then be used to power appliances such as cookers and heaters that currently run on natural gas. It can also be used to generate electricity.