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Renewable Natural Gas: the clean fuel
In the last three years, the United States has seen a strong growth in the development of solutions for the production of Renewable Natural Gas (RNG) from landfill and agricultural waste. In particular, policies at both federal level, such as the Renewable Fuels Standard legislation, and local level have promoted the implementation of biogas-to-RNG projects.
The development of RNG projects from landfill and agriculture has accelerated dramatically in the last three years, from 94 to 169 units, a growth of 80%; this growing trend is confirmed in the coming years.
Renewable Natural Gas is a kind of fuel derived from processing raw biogas through multiple treatment and cleaning steps: removing moisture, carbon dioxide and traces of contaminants, reducing the amounts of nitrogen and oxygen. The methane content through these procedures increases from 45/65% to 96/99%.
The derivation of this fuel allows it to be considered zero-emission:
- It prevents the decomposition of organic waste, turning it into biogas
- It captures more greenhouse gases than it emits, thus becoming carbon-negative
Uses and benefits
Currently, Renewable Natural Gas (RNG) is mainly used to produce electricity and fuel for transport, but it also has a lot of potential in thermal and industrial applications.
The benefits of using RNG are multiple:
- Improving quality of life
- Improving local air quality by reducing nitrogen oxide and particulate emissions
- Reduction in greenhouse gas emissions
The energy transition in California
In terms of local US policies to promote and use renewable fuels, the Californian approach has gained support and results through the issuing of legislation:
- For the reduction of methane emissions by 40% by 2030 through the Low Carbon Fuel Standard;
- To regulate the use of renewable energy sources in the transport sector, with specific targets based on the different types of vehicles;
- The California Department of Food and Agriculture has issued the Dairy Digester Research and Development Program, with the main aim of minimising negative environmental impacts through substantial grants for the implementation of agricultural anaerobic digestion projects.
California has the largest dairy industry in the United States, with approximately 1,600 dairies: transforming the agricultural industry into a circular economy has been crucial both economically and for environmental sustainability.
The need to optimise the agricultural system is confirmed by the willingness to fund six pilot projects to demonstrate the generation of RNG from dairy by-product digesters in order to reduce emissions.
SAFE&CEC with Greenlane Biogas and the innovative RNG production system
SAFE&CEC, in cooperation with Greenlane Biogas, has actively contributed to the Californian energy transition. A centralised dairy digestion project was developed, described as a “hub and spoke” model:
- Hub: is a centralised plant where raw biogas from a group of pre-existing dairy farms is collected and treated
- Spoke: a system of low pressure PVC gas collection pipelines to interconnect the participating aggregated farms;
The fuel generated is more than enough to produce and distribute both electricity and RNG.
Greenlane Biogas worked together with SAFE&CEC on this landmark project. It involved covering manure lagoons at the dairies, and then developing a high efficiency process to treat, compress, and upgrade the biogas into RNG and inject the RNG into the natural gas pipeline.
Greenlane’s PSA (Pressure Swing Adsorption) upgrading system was used to remove CO2, N2 and O2 to achieve high gas quality standards. Greenlane’s fully integrated process involved more than 30 pieces of equipment, providing all the gas processing needs of the farms, and injection site. The entire process from the digesters to the injection point included full performance, methane recovery and uptime guarantees.
Greenlane Biogas PSA – Upgrading system
Specifically, SAFE&CEC proposed a solution consisting of an oil-free booster compressor based on the proven IMW CleanCNG2.0 system that injects RNG into the grid. The compressors are structured in modules that can be configured according to requirements, ensuring speed and efficiency in design, transport and installation. The solution is reliable, flexible, equipped with a zero-emission electrical pressure reduction system, designed specifically for RNG applications.
SAFE&CEC CleanCNG 2.0 – RNG Booster Compressor
SAFE&CEC RNG Trailer Fill Post
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