What is Renewable Natural Gas and How Does it Help the Environment?

This renewable, carbon-negative fuel is the fastest way to net-zero emissions

Introduction: What is Renewable Natural Gas?

Renewable natural gas is a type of biogas that can be used as a substitute for traditional natural gas. It’s renewable because it’s produced through the anaerobic digestion of organic waste materials, such as food scraps, agricultural and food processing waste, manure and even sewage. Unlike traditional natural gas, it is not a fossil fuel.
The anaerobic digestion process uses special microbes to break down organic matter in an environment without oxygen. This produces methane, the primary component of natural gas.
RNG can be used as an alternative to traditional natural gas as a fuel for heating, cooking or even generating electricity. It can also be used as a fuel for vehicles that have been designed to run on natural gas. One of its main advantages is that it is a renewable and sustainable energy source, as it is produced from organic waste materials that would otherwise decompose and release methane into the atmosphere (a potent greenhouse gas). Because making and using RNG reduces these greenhouse gas emissions, it is a valuable tool in fighting climate change.

How does RNG production help the environment and benefit us globally?

RNG is made from organic wastes that would otherwise emit methane when decomposing in landfills or other oxygen-free environments. Methane is a potent greenhouse gas that is highly effective at trapping heat in the atmosphere (more so than carbon dioxide in the short-term). When wastes are instead anaerobically digested in closed digestion tanks, the methane can be captured and prevented from being released to the atmosphere.
The methane produced in the anaerobic digestion process is captured and used as fuel. This renewable methane then replaces some of the fossil methane that would otherwise be needed for energy. Substituting RNG for fossil methane reduces reliance on these non-renewable resources.

Why is RNG considered carbon-neutral or even carbon-negative?

While RNG does emit carbon dioxide when combusted, the CO2 is a far less potent greenhouse gas than the methane that would have emitted from the landfilled organic waste, reducing overall emissions.

In addition, the carbon dioxide produced when biomethane is burned comes from plant matter that already fixed this carbon from atmospheric CO2. In other words, the formerly living material from which biomethane is made took carbon dioxide from the air while growing. Therefore, the combustion of biomethane does not increase the amount of CO2 present in the atmosphere but it makes it circulate in short carbon cycles. Thus, anytime biomethane replaces fossil fuel, CO2 emissions are prevented.
Even with ongoing electrification efforts in residential and commercial sectors, fuels are required for high-heat industrial processes, as well as for power grid reliability, for the foreseeable future. As such, carbon-negative fuels are necessary to reach net zero emissions.

How does the Anaerobic Digestion process take place to produce Renewable Natural Gas?

The process of breaking down organic matter to produce methane is known as anaerobic digestion. This process occurs in the absence of oxygen and involves the action of microorganisms that break down organic matter to release methane as a byproduct. Here is a 6-step process to describe how anaerobic digestion takes place:

1. Collection of organic waste materials
   Organic materials include food waste from households, restaurants and food processing plants, agricultural plant waste and manure, and sewage biosolids are collected and transported to a central processing facility.
2. Pre-treatment
   The collected waste materials are then pre-treated before they can be processed, and this may involve grinding or shredding these materials to increase their surface area, as well as adding to or decreasing water content, to make them more readily digestible by microorganisms.
3. Anaerobic Digestion
   The pre-treated organic waste materials are then placed in a sealed vessel or tank known as a ‘digester.’ The digester is designed to exclude oxygen and maintain the optimal conditions for anaerobic digestion, including temperate, pH, and nutrient levels.
4. Methane Production
   As the microorganisms break down organic matter, they produce biogas, a mix of methane, carbon dioxide, water vapor and other gasses. The biogas is collected and purified through a series of steps to remove the elements that aren’t needed.
5. Upgrading
   The purified biogas is then upgraded to renewable natural gas (RNG) by separating out the carbon dioxide. RNG must be nearly pure methane to meet the specifications for use as a fuel. The RNG can now be put into a natural gas pipeline system and be distributed to business and residences to and used to fuel furnaces, cooktops, or water heaters. It can also be used to generate electricity or as a transportation fuel in vehicles designed to run on natural gas.

The Benefits of Renewable Natural Gas (RNG)

There are a few advantages of renewable natural gas that should be considered when thinking about eradication of pollution from the environment. RNG:
● Is renewable and sustainable
● Reduces greenhouse gas emissions
● Substitutes for traditional fossil natural gas
● Reduces demand for fossil fuels

RNG is produced from organic waste materials that would otherwise decompose and release methane into the atmosphere, so it is a sustainable energy source. By capturing methane through the anaerobic digestion process, RNG helps reduce greenhouse gas emissions and combats climate change. It can be used as a fuel for heating, cooking, generating electricity and as a transportation fuel in vehicles designed to run on natural gas. Processing organic waste materials also helps reduce odors and water pollution. As a substitute for fossil fuels, it reduces our reliance on non-renewable resources and focuses on a transition towards a more sustainable friendly energy system.

Are there any disadvantages of RNG production?

Like any energy source, RNG has some potential disadvantages as well:
● Requires infrastructure and processing facilities
● Is currently less available and more expensive than fossil gas

RNG production requires the development of infrastructure and processing facilities, such as anaerobic digestion plants and gas upgrading equipment. These facilities require investment to build and operate. Without state policies that offer sufficient incentives, RNG will be more expensive to use than traditional fossil natural gas.

The Bottom Line

Any type of organic material can be used to make RNG. The production of RNG has environmental benefits, as it reduces the amount of organic waste that ends up in landfills and captures the methane produced from it. It helps reduce greenhouse gas emissions and mitigates their negative impact on the environment, playing a significant role in the transition to a more sustainable planet.