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Biomethane: Renewable Natural Gas
In addition to natural gas, methane can also be produced from renewable biomass as virtually all biomass can be converted to biogas, a mixture consisting primarily of methane and carbon dioxide through a well-established process known as anaerobic digestion. Anaerobic digestion is a naturally occurring process in which consortia of bacteria degrade organic matter in the absence of oxygen. Anaerobic digesters have been employed at waste water treatment plants for decades as means of reducing the volume of organic solids generated in the wastewater treatment process. More recently, digesters have been employed to produce biomethane as a renewable fuel, especially in Europe and Asia.
Estimates of the worldwide energy content of the sustainable, non-food biomass (non-food biomass includes crop residues, forest thinnings, and municipal solid wastes) that is annually available today is almost 100 quadrillion BTUs.[i] Assuming (quite conservatively) that the methane yield from biomass is 25%, over 25 trillion cubic feet of renewable methane could be produced each year, or one-fourth of the annual demand of natural gas.
In the U.S., over 1.3 billion tons of non-food biomass could be practically collected each year. At an average of 10 MMBTU per ton, the available biomass is equivalent in energy content approximately one-third of the U.S. gasoline demand. Though far more dispersed than fossil fuels, the location of the available biomass is generally known, as shown on the accompanying picture.[ii]
Despite many years and millions of dollars of research, a cost-effective means of converting biomass to transportation fuel has proved elusive. Though inedible biomass is comprised primarily of sugars, the sugars are bound in a complex polymer known as lignocellulose; the material that provides both structure and resistance to weather, disease, parasites, etc., to plants. Converting lignocellulosic sugars to liquid fuels (the basis for most biofuel processes) first requires freeing the sugars from the lignocellulosic polymer, a process that remains too costly to make the resulting biofuels cost-effective.
While obtaining sugars from lignocellulosic biomass is quite difficult, naturally occurring anaerobic bacteria are able to convert biomass to biogas, a mixture of biomethane and carbon dioxide, in a well-established process known as anaerobic digestion.
The GRT Technology converts biomethane into renewable liquid hydrocarbons that 1) can be used as a drop in replacement for conventional gasoline without the need for any modifications to either the automotive engine or the fuel distribution system, and 2) are required blending components for aviation fuels. As a result, GRT believes that its technology is uniquely suited towards overcoming the challenges faced in the development of renewable fuels.