Photosynthesis takes carbon dioxide from the atmosphere and stores the carbon in the biomass of plants and trees. This carbon is released when the biomass is converted to energy but the overall cycle of growing biomass through photosynthesis and converting it to useful energy can be considered to produce limited net emissions of greenhouse gases. The processes by which biomass is converted into energy are described, including the thermochemical processes of combustion and gasification of solid biomass, the biochemical processes of anaerobic digestion, and alcoholic fermentation and the extraction of oil from plants. Combustion of biomass to generate electricity is described and the gasification of biomass is discussed. Anaerobic digestion to produce biogas and the alcoholic fermentation of crops to produce biofuel are described. The production of biodiesel by the extraction and purification of vegetable oil from plants is also described. The chapter is supported by 5 examples, 16 questions with answers and full solutions in the accompanying online material. Further reading and online resources are identified.

While coal seems to be out of the picture in the energy transition, there are technologies that make sustainable use of this abundant resource. This chapter covers several technologies, i.e., gasification, magnetohydrodynamics, and coal slurry, which, when combined with carbon capture, can make this a reality.

Bio-based solid fuels are the oldest and most widely exploited energy sources. Bio-based solid fuels have the potential to approach, if not achieve, net-zero-carbon emissions. Biomass is a “net zero” fuel in that the same carbon atoms pulled from the atmosphere as CO2 are sequestered by the biomass as plant tissue and are re-released as CO2 upon burning. This prevents the addition of CO2 into the atmosphere beyond what is present in the natural carbon cycle. Today’s bio-based solid fuels encompass everything from the raw biomass our ancestors relied upon for heat to thermochemically and biochemically processed biomasses for use as solid fuels in a variety of commercial energy generation scenarios. This chapter summarizes solid biofuel sources, processing, and roles in a future net-zero energy system.

Bio-based solid fuels are the oldest and most widely exploited energy sources. Bio-based solid fuels have the potential to approach, if not achieve, net-zero-carbon emissions. Biomass is a “net zero” fuel in that the same carbon atoms pulled from the atmosphere as CO2 are sequestered by the biomass as plant tissue and are re-released as CO2 upon burning. This prevents the addition of CO2 into the atmosphere beyond what is present in the natural carbon cycle. Today’s bio-based solid fuels encompass everything from the raw biomass our ancestors relied upon for heat to thermochemically and biochemically processed biomasses for use as solid fuels in a variety of commercial energy generation scenarios. This chapter summarizes solid biofuel sources, processing, and roles in a future net-zero energy system.

Wood gas. Biogas. Syngas. Landfill Gas. Renewable Natural Gas. Production and use of renewable carbon-based gaseous fuels have a history stretching back centuries and even millennia, providing heat, light and power to support both rural development and urban industrialization. The processes used to generate these gaseous fuels can be separated into two categories: thermochemical and biological, producing syngas and biogas, respectively.  Thermochemical conversion processes produce a synthesis gas, abbreviated as syngas, which is a mixture composed primarily of hydrogen and carbon monoxide, but may also contain carbon dioxide and methane.

Wood gas. Biogas. Syngas. Landfill Gas. Renewable Natural Gas. Production and use of renewable carbon-based gaseous fuels have a history stretching back centuries and even millennia, providing heat, light and power to support both rural development and urban industrialization. The processes used to generate these gaseous fuels can be separated into two categories: thermochemical and biological, producing syngas and biogas, respectively.  Thermochemical conversion processes produce a synthesis gas, abbreviated as syngas, which is a mixture composed primarily of hydrogen and carbon monoxide, but may also contain carbon dioxide and methane.