Current Status of Biological Biogas Upgrading Technologies

Abstract

To limit global warming, ratio of renewable sources in the energy mix has to be considerably raised in the following years. While application of e.g. wind and solar power usually generates fluctuations in the electric grid, biogas produced in anaerobic processes is an easy-to-store renewable energy source. Raw biogas contains generally ~55–70% methane and ~30–45% carbon-dioxide. Although raw biogas can be utilized directly for combustion or combined heat and power generation (CHP), its methane content can be raised to >95% by upgrading technologies, thus it can be valorized. By upgrading and cleaning, the quality of the upgraded biogas may reach the quality of the natural gas and it may be injected to the gas grid or used as fuel for devices optimized for natural gas. Several physico-chemical upgrading methods are available on the market (e.g. high pressure water scrubbing, pressure swing adsorption, membrane technology, etc.) to remove the carbon-dioxide content of the biogas. Opposite to the physico-chemical methods, where basically the CO2 removal is the main goal, in biological biogas upgrading technologies microorganisms are applied to convert the carbon-dioxide content of the biogas to methane (chemoautotrophic upgrading), or algal biomass (photoautotrophic upgrading). The expectations are high towards biological biogas upgrading technologies in the field of energy storage linked with carbon-dioxide capture. In this paper, latest research results concerning biological biogas upgrading are summarized, viability and competitiveness of this technology is discussed together with the most important future development directions.

Efficiency Increase of Biological Methanation based Power-to-Methane Technology Using Waste Heat Recovery with Organic Rankine Cycle

“…Industrial-scale P2M technology can be divided into biological and catalytic methanations [21,22]. While catalytic processes mainly use nickel and ruthenium-based catalysts [15] and take place at high temperatures, above 250 °C, biological methanation uses methanogenic microorganisms as biocatalysts [14] and takes place at much lower temperatures, usually below 70 °C, due to the thermophilic bacterial strains.…”

Spiral-Pipe Gas Anaerobic Digester

“…Compared with other sources of renewable energy, such as solar and wind energy, biogas can be stored more efficiently with minimal energy loss. Therefore, the production and use of biogas hold substantial promise for further development, with diverse applications . Raw biogas can be used directly, such as in combustion or fusion processes.…”

“…Raw biogas can be used directly, such as in combustion or fusion processes. However, CO 2 , the primary impurity in biogas, severely reduces its practical value . Hence, in most cases, biogas must be upgraded to improve its quality.…”

Investigation of Carbon Footprints of Three Desalination Technologies: Reverse Osmosis (RO), Multi-Stage Flash Distillation (MSF) and Multi-Effect Distillation (MED)

“…Among the causes of global disasters, climate change is the leading cause of natural disasters, extreme weather, food shortages, and ecosystem collapse [1][2][3]. A significant cause of climate change is an increase in the surface temperature of the earth (global warming), which is caused by an increase in greenhouse gas (GHG) concentrations.…”