Technologies for the production of renewable natural gas from organic wastes and their opportunities in existing Canadian pipelines

Of all the types of renewable energy, Renewable Natural Gas (RNG) market has been more supported and developed in Canada due to the lower project cost and the existing NG pipeline infrastructure. RNG is defined as a methane-rich gas obtained through combining Anaerobic Digestion (AD) of underutilized renewable sources (organic waste streams) and upgrading technologies. Membrane separation technology is considered one of Canada's most popular upgrading technologies due to the country-old knowledge regarding gas permeation membranes widely used in the NG industry. Membrane systems are used to recover methane from biogas to a level that meets current natural gas pipeline specifications set out by gas utility companies or meets natural gas vehicle fuel standards set out by engine manufacturers. Here we review standards for gas injection into existing Canadian pipelines, commercial biogas upgrading systems in Canada, and Current biogas upgrading to RNG projects in Canada. We focus more on membrane technology and discuss the possible driving force, module, and configuration alternatives. Finally, this review comprehensively examines membrane types and advances in composite type membranes.