Renewable Natural Gas (RNG) is a refined product from raw biogas, which is produced from the anaerobic decomposition of a wide variety of organic materials, including live animal manure, agricultural waste, industrial-grade food waste, “green-bin” wastes, wastewater treatment materials, landfill constituents and others. Depending upon the source, raw biogas may also contain inorganic compounds which become entrained in the gas. Biogas is not clean enough to be considered for inclusion in the natural gas pipeline grid. Cleaned biogas or biomethane, more commonly referred to today as RNG, is the target product for inclusion in the natural gas pipeline grid or for vehicle fuel applications.
In order to allow RNG to the natural gas pipeline grid, it must be cleaned sufficiently to pipeline quality standards. This means that the RNG must comply with analytical standards which make it “highly similar” to natural gas. The customer and the pipeline should not notice a substantial difference between natural gas and RNG. Safety of the RNG is also very important; it cannot contain compounds which are of concern to human health and the environment.
Natural gas companies may be motivated to bring RNG into the pipeline for several reasons: 1) They wish to fulfill their Renewable Portfolio Standard or company commitments using this “green” product, 2) Their customers request green products, 3) Specific industries within their system want to use green products and green gas, 4) Specific markets, such as the compressed natural gas (CNG)/vehicle fuel market in their territory or state is increasing and RNG provides an additional “green bonus”, and/or 5) It makes good business sense.
Environmental investigations have increasingly employed the use of environmental forensic chemistry techniques to identify the types of wastes present and the source of the wastes. Environmental forensic methodologies have been developed for contamination in air, water and soil. Wastes have distinctive “chemical fingerprints”, based on source, type of production and length of time in the environment. Analysis of chemical fingerprints may elucidate much information specific to the source, and analytical profiles can be amassed in databases, useful for future applications.
Forensic chemistry techniques can also be applied to other platforms, such as natural gas, biogas profiling and trace constituent identification. Analytical profiling techniques can determine the source of problems within a pipeline and can indicate the likelihood of compounds in a variety of source materials. Microbiology can also be applied, as bacteria thrive under specific conditions for growth and produce specific products from degradation of organics and inorganics. As with hazardous waste profiling, “following the chemistry” can lead to the answers specific to problematic compounds in natural gas and biogas/RNG.
Forensic chemistry, across platforms, has been a powerful tool for risk assessment, source identification and fate and transport of compounds which impact “environments”. REEthink and, in particular, Dr. Saber have led industry-wide research in the development of these useful forensic techniques, and have authored numerous groundbreaking papers which resulted in advanced databases for forensic chemistry examination. Originating in hazardous waste site investigations, the analytical techniques are now applied to analyses of biogas and RNG.