Define microbial fuel cells and give two uses.
a) They are devices that convert chemical energy into electrical energy using microorganisms. Uses: wastewater treatment, renewable energy production
b) They are devices that convert solar energy into electrical energy using microorganisms. Uses: medical diagnostics, food preservation
c) They are devices that convert mechanical energy into electrical energy using microorganisms. Uses: transportation, communication
d) They are devices that convert heat energy into electrical energy using microorganisms. Uses: cooking, heating