Answer to Question 1
Steam, thermal oil, and gasification are three methods used in CHP.
Answer to Question 2
The algae photobioreactor (PBR) uses a closed system consisting of transparent tubes or an aquarium-like structure through which the wet algae is moved. The PBR system allows high sunlight penetration. The enclosure protects against intrusion of unwanted contaminants, organisms, and bugs. Also, the temperature and other parameters can be better controlled in the closed PBR system.