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Is Natural Gas Renewable?

Large digesters used to produce RNG

Natural gas is one of the fossil fuels used today on a large scale to produce energy and heat, but what about renewable natural gas?

We all know that the fossil fuels available today on the planet (coal, oil and natural gas) are finite resources, which means that they are not renewable.

In order to be considered renewable, any energy source needs to be an inexhaustible resource of power, such as solar, wind, geothermal, hydro, biomass, tidal, wave, etc.

Is Natural Gas Renewable?

If we keep the current level of natural gas consumption for electricity and heat generation on the planet, we can say that the today’s reserves of natural gas are enough for at least another 250 years.

However, even if these reserves would be enough to power our civilization for a thousand years from now on, they are still limited resources, which means that they are not renewable.

Lately, a new concept called renewable natural gas (or simply RNG) has appeared on the market, and this an energy source that could be considered renewable.

Renewable energy does not refer to clean energy, renewable describes only an energy source that is continuous.

To be considered clean, an energy source needs to produce zero emissions while generating power.

A cleaner energy source refers to a low-carbon energy source such as natural gas.

What is Renewable Natural Gas?

When talking about renewable energy, people think of solar, wind, hydro, geothermal, biomass, etc., but there is also a new form of renewable energy produced from organic waste, wastewater, agricultural waste, plant and food waste and dairy manure, and is called renewable natural gas (RNG).

It is called this way because it contains mostly methane (CH4).

All the organic waste produced during the day is collected into a large “digester” tank where decomposes and creates a mixture of gases (mainly methane) due to the breakdown of the organic materials.

The methane obtained this way is collected, cleaned and conditioned to become renewable natural gas (RNG).

Giving the fact that RNG is obtained from organic waste, we can say this is only another name for filtered and conditioned biogas or biomethane.

This type of gas can be obtained even at home by collecting into a tank (digester) all human and animal waste available and also the daily food waste.

Is RNG Really Clean?

When these organic materials start decomposing, biogas is produced and before being used for cooking, it is filtered using a scrubber (compressed steel wool), which removes the hydrogen sulfate from the composition.

A second filtration is done using water to remove carbon dioxide from the composition and any remains of hydrogen sulfate.

After the filtration process, biogas is much cleaner and contains mostly methane, which means that is can be used for cooking and heating.

A larger facility can produce enough biogas or renewable natural gas to be used for electricity generation, residential heating, cooking and also as transportation fuel.

Pros of Renewable Natural Gas (RNG)

Being a combination of fossil fuels with renewable energy, renewable natural gas has many advantages over fossil fuels and also over other renewables.

1. Is a Renewable Energy Source

Renewable natural gas is another name for biogas or methane obtained from organic waste.

This gas burns with a nice blue flame (slightly different than LPG) because consists mainly of methane (CH4), carbon dioxide (COs), hydrogen (H2) and other gases.

Organic waste materials are produced every day on our planet, which means that as long as we have people, animals and vegetation on the planet, we can have a continuous supply of biogas or renewable natural gas, which can be used for electricity generation, residential heating, cooking and as a cleaner fuel for the transportation sector.

2. Reduces the Level of Air Pollution on the Planet

Using biogas or renewable natural gas in the transportation sector, significantly reduces the level of greenhouse gas emissions produced by vehicles.

In many countries on the planet, buses powered by biogas have managed to significantly reduce the level of air pollution produced by the transportation sector.

Less air pollution produces a cleaner air to breathe, and this means that the people living in those cities will be less affected (less casualties) by the large number of vehicles on the road.

3. Can Be Easily Produced and is Cheaper than Natural Gas

Renewable natural gas or biogas (biomethane) can be easily produced by simply putting all the organic waste produced during the day into a tank called digester.

After waiting one or two days, the decomposition process of the organic waste starts inside the digester, and this is the moment when biogas or renewable natural gas is produced.

The gas can be easily collected, filtered and stored for later use.

Extracting natural gas from the underground reserves is a much more complex process that requires large investments in the extraction process, transportation of the gas and storage facilities.

Renewable natural gas is produced locally, which means that is way more affordable and practical.

4. Generating Renewable Natural Gas Produces Additional Byproducts like Fertilizers

Any digester tank (big or small) will produce RNG or biomethane, but also other useful products for the garden.

The organic water produced by decomposing organic materials inside the digester, can be collected and used in the garden because is a water full of nutrients and very beneficial for plants.

5. Reduces the Use of Firewood

In many poor countries where wood is mainly used for cooking and heating, building a digester to convert the organic waste produced daily (human and animal waste) into useful renewable natural gas or biomethane is a great idea.

The biogas produced is free and burns cleaner than wood, reduces the use of firewood, which saves the forest and keeps the air cleaner in the community.

6. Renewable Natural Gas Helps in Waste Disposal

A large digester tank used to decompose organic materials for renewable natural gas production at a large scale, will consume daily all the organic waste (human, animal, agricultural, wastewater and food waste) available in the area, and will help the local community to properly dispose its waste.

Instead of being dumped in the landfill, the organic waste produced by the community will be used to produce cleaner energy and fertilizers for the garden in a much more efficient way.

7. RNG Can be Stored to Produce Energy On Demand

Even if we talk about a renewable energy source, renewable natural gas or biogas is not an intermittent source of power like the other renewables such as solar and wind power.

Solar power is produced only during the day when the Sun is up, while wind power can be produced all day long, but only if the wind blows with enough speed to generate a significant amount of power.

However, renewable natural gas is produced 24/7 if we keep feeding the digester tank with organic waste.

We only need to feed the digester with the organic waste produced daily, and this is enough to ensure a continuous production of renewable natural gas (biogas).

8. RNG Can Use the Existing Natural Gas Infrastructure

Many utility companies in the U.S. have understand that RNG can be easily and cheaply produced, so they have built large digesters fed with the organic waste produced by the local community.

After the filtration process, the biogas produced by the digesters has been turned into renewable natural gas, and because the gas uses the existing natural gas infrastructure, it is used by all type of customers.

Being produced at a large scale by a utility company, RNG is used by homeowners, businesses, factories, to produce electricity and even as fuel for the transportation sector.

9. RNG is Considered Carbon-Negative

When organic waste decomposes in nature, methane (which is a very potent greenhouse gas), carbon dioxide and other gases escape into the atmosphere producing air pollution.

By removing the organic waste from nature to feed the digester tank, and capturing methane and the other gases released during the decomposition process to produce a renewable fuel, a good amount of greenhouse gases are removed from the atmosphere, which makes the air cleaner and fights against climate change.

Cons of Renewable Natural Gas (RNG)

Being a fossil fuel that can be produced all the time, it has only two disadvantages mainly produced by the emissions released when burning the gas.

1. RNG is Not 100% Clean

Despite the fact that RNG or biogas can be produced continuously (is a renewable energy source), RNG is still a fossil fuel that releases greenhouse gas emissions when burning.

Being a low-carbon energy source, RNG releases the smallest amount of emissions among all fossil fuels, but it can’t be considered clean because we have some emissions involved here, and these emissions still affect the environment even in a small way.

It can be considered useful only in communities where a large amount of organic waste is produced, and the RNG produced replaces an energy source that is way more harmful for the environment.

2. RNG is Interchangeable with Traditional Natural Gas

When RNG or biogas is produced at home, it is very useful because we are turning the organic waste produced in the household into cleaner energy and we are also getting organic products for the garden.

However, when produced by a utility company at large scale, RNG uses the same infrastructure like traditional natural gas, so the customer will never now what fuel uses for cooking and heating its house, it is natural gas? it is RNG at the price of natural gas? or it is a mix of both fuels, which means that is not that clean, and way more expensive than it should be.

Final conclusion

RNG can be produced at home for free (why would I pay for it), which is a big advantage for the owner because it helps him to turn the smelly organic waste produced daily (mostly food waste and animal waste) into a cleaner and free fuel and also useful products for the garden (organic water and natural fertilizers).

Article written by:

I am a writer and reporter for the clean energy sector, I cover climate change issues, new clean technologies, sustainability and green cars. Danny Ovy

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