Biosequestration is the capture and storage of the atmospheric greenhouse gas carbon dioxide by biological processes.This may be by increased photosynthesis (through practices such as reforestation / preventing deforestation and genetic engineering); by enhanced soil carbon trapping in agriculture; or by the use of algal bio sequestration (see algae bioreactor) to absorb the carbon dioxide emissions from coal, petroleum (oil) or natural gas-fired electricity generation.Biosequestration as a natural process has occurred in the past, and was responsible for the formation of the extensive coal and oil deposits which are now being burned.