Renewable Natural Gas (RNG) is derived from anaerobic decomposition of a wide variety of organic materials, including dairy and agricultural waste and wastewater and landfill constituents. Within the natural gas industry, the term “biogas” refers to gas produced directly from digesters or landfills; it is often burned on- or off-site in generators for conversion to electricity or simply flared. 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.
Natural gas companies may be motivated to bring RNG into the pipeline for several reasons: 1) They wish to fulfill their Renewable Portfolio Standard using this “green” product, 2) Their customers request green products, 3) Specific industries within their system want to use green products and green gas, and/or, 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”.
RNG has served the vehicle market in Europe for many years, particularly in Sweden. By the year 2005, Sweden had already surpassed a goal of 45% replacement of natural gas for transport, and near-term goals focus on an even higher percentage of replacement. Eventually, Sweden would like to be energy independent, with 100% of gas fuels derived from RNG or other renewable sources. Swedes enjoy a fuel product which is tax-exempt and filling stations are required to provide a biofuel as an alternative to fossil-fuel based petrol. Local regulations also provide incentives; free parking exists for individuals who own NGVs. The number of NGV models available for consumers is increasing, as is the number of cars which use natural gas/biomethane rather than petrol/diesel. It is hopeful that this country will follow Sweden’s lead in promoting RNG for vehicle use, starting with fleet vehicle applications.
Environmental investigations, particularly of former manufactured gas plant (MGP) sites, have increasingly employed the use of environmental forensic techniques to identify the types of wastes present and the source of the wastes. Environmental forensic methodologies have been especially effective in discerning MGP-derived coal-based wastes, primarily containing polynuclear aromatic (PAH) compounds, from other waste mixtures. Former MGP coal tars and dense non-aqueous phase liquids (DNAPLs) possess distinct “chemical fingerprints”, based upon the gas production process used and other factors. Analysis of specific fingerprints may elucidate the source of the contamination and consequently identify parties potentially involved with site cleanup efforts. Determining the sources of contamination in and around former MGP sites can be critically important to the design of remediation systems, to the structuring of insurance recovery cases and to allocating responsibility among multiple parties. As such, environmental forensic methods have been increasing applied to routine site investigation efforts and has even been advanced into investigations of indoor air quality.
The use of chemical fingerprinting has been highly successful in discerning wastes from wholly different sources or even between MGP-type wastes from different plant operations. REEthink has provided fingerprinting techniques services and technical support for identification of organic and inorganic wastes at particular sites. We have been successful in supporting customers in discerning true responsibility of waste ownership and for allocation of cleanup resources. Analytical methods employed have been traditional GC/MS investigations, but GC/IRMS techniques have been used to discern extremely low level waste concentrations. REEthink and, in particular, Dr. Saber have led effort 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.