Page 53 - Energize July 2021

TECHNICAL

From waste to wealth: RNG is a win-win

Information from Cummins

The phrase, “renewable natural gas” (RNG) puts a positive face on the recovery and reuse of methane
gas that leaches out of landfills, one which is entirely justified, as RNG is every bit as green from a financial
aspect as it is from an environmental one.

his is particularly important today, as the United States has Landfill emissions are estimated to account for 16% of global n
rejoined the Paris Accord with a renewed commitment to methane emissions. The good news is that proven technology
Treducing greenhouse gases and is looking seriously at options already exists to capture this gas and convert it into a powerful
including carbon credits and carbon taxes to drive down the use of source of natural energy which can be used to displace a
fossil fuels and preserve a cleaner world for future generations. corresponding amount of fossil fuels. Plus, when RNG is refined
In this article, we will discuss how the reclamation of methane to 96 to 98% purity, it can be used as a vehicle fuel in natural
gas is transforming what used to be an environmental liability into gas engines that are simpler in design (no diesel particulate filter
an economic opportunity – not just for refuse collectors and landfill or diesel exhaust fluid needed) and meet or exceed ultra-low
companies, but for municipalities and the transportation sector as emissions standards.
well. That is why RNG usage has recently surpassed compressed Today, 53% of all the natural gas being used to fuel vehicles,
natural gas (CNG) and liquified natural gas (LNG) combined – and is produce electricity and heat homes is RNG, with LNG and CNG
expanding exponentially with a 267% increase from 2016 to 2020, accounting for the remaining 47%. This has been aided by an
according to the Coalition for Renewable Natural Gas. exponential growth in the number of RNG methane reclamation
facilities, with almost as many under construction or in development
A rising trend as are currently in operation.
Clean-burning natural gas is a widely accepted, proven fuel source The increased use of RNG over the past five-year period has
which has significant benefits in terms of environmental impact. prevented the equivalent of 3,5-million t of CO 2 being released into
That’s why it is a primary source of energy for residential homes, the atmosphere. The California Air Resource Board (CARB) has
buildings and more. The natural gas in most pipelines is derived confirmed which of the energy-weighted Carbon Index value of RNG
primarily from wellheads tapping into petrochemical reservoirs deep in its Low Carbon Fuel Standard Programme is carbon negative and
within the earth. below zero at -17.95 gCO 2e/MJ.
The RNG movement has been embraced by virtually all major
Renewable natural gas is different players in both the energy development sector, the retail sector,
It is a purified form of methane (CH 4) captured in landfills, where refuse/recycling firms, as well as many states and municipalities.
organic matter (cardboard, plants, etc.) aided by bacteria, While the number of RNG sites has doubled in recent years, there
decomposes and produces a gas which has tremendous potential still exists a tremendous opportunity to expand further, as only
– both for good or bad. Left alone, an uncapped landfill releases 15% of all US landfills (300 out of 2000 potential sites) are currently
methane into the atmosphere, where it negatively affects the ozone tapping into this natural energy resource.
layer and impacts global climate change for over a century.
Studies have shown that, “over a 20-year period a kilogram
of methane warms the planet as much as 80 times more than
a kilogram of carbon dioxide (CO 2).” It is also a contributor to
the thermal expansion of oceans (and glacial melting) which
“continues for centuries even after the gas has dissipated from
the atmosphere.”
1
Common sources of methane
• Wetlands
• Mud volcanoes
• Rice fields
• Termites
• Cows
• Manure
• Oil and gas production
• Coal mining
• Landfill Figure 1: Advanced treatment of LFG for use as a vehicle fuel 2

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