According to the United States Energy Information Administration, natural gas already produces less carbon dioxide than coal, oil, diesel fuel, gasoline, and propane. This does not mean, however, that there is no way to reduce the carbon footprint of natural gas for the benefit of our planet and society. With that in mind, many are asking…
Is there a way to make natural gas greener?
Yes! Natural gas can be made greener by:
- Reducing methane leaks in the natural gas supply chain;
- Reducing the carbon footprint in transporting natural gas;
- Increasing power plant efficiency;
- Carbon Capture and Storage (CCS);
- Carbon Capture and Utilization (CCU);
- Capturing biomethane.
Let’s take a closer look at the current state of the natural gas carbon footprint, and see how we are engaging in the six areas mentioned above to make natural gas greener.
How Green Is Natural Gas?
Natural gas is the cleanest of all fossil fuels. The chart below shows the carbon footprint of natural gas compared to other fossil fuels. The chart measures CO2 (carbon dioxide) per BTU (a measurement of heat energy), which is how much carbon is released to produce a given amount of energy. The higher the carbon release, the larger the carbon footprint for that energy source.
As the chart illustrates, natural gas is much cleaner than other fossil fuels, about half the carbon footprint of coal. But can we reduce the carbon footprint of natural gas even further?
The reality is, we can. And as we move further into this century, climate change will impact us to a greater extent. Hence, it will become increasingly more vital that we work to reduce the carbon footprint of natural gas. Let’s dig into some of the ways the natural gas supply chain and its end-use can be cleaned up.
Reducing Methane Leaks in the Natural Gas Supply Chain
Methane leaks and other greenhouse gases are often unintentionally released into the environment before natural gas even has a chance to reach the end-user. These leaks occur in many places, including:
- at the natural gas well;
- at tank farms and storage facilities;
- at gas compressor stations; and
- at NG processing plants.
Methane leaks cause more harm to the environment than the actual use of natural gas for fuel. Thanks to many technological advances, the industry is getting better at identifying and stopping methane leaks.
Using Drones to Spot Natural Gas Leaks
Natural gas companies are increasingly turning to technology to help them detect leaks. Drones can now successfully identify methane gas leaks and help repair crews find the exact source of the leak.
This technology was initially created by NASA but is increasingly being used by natural gas companies. You can read more about how this technology got its start at NASA’s news outlet.
Other Methods for Detecting Methane Leaks
Natural gas companies have other techniques for detecting methane, for example using mobile labs to detect methane in the air. This is unfortunately not very efficient for pipeline protection, but it is a great solution for sites such as natural gas wells.
Another technique being implemented is the utilization of infrared cameras. An infrared camera can detect methane that is invisible to both visible-spectrum cameras and to the human eye.
As research on detecting methane continues, scientists are bound to find even more opportunities to identify and stop leaks. Once the methane leak has been found, pipeline repair crews and well operators can pause operations and seal up any affected areas with relative ease.
Reducing the Carbon Footprint in Transporting Natural Gas
Every step taken to secure, procure, process, store, and distribute fuel consumes energy and has an associated carbon footprint. Transporting and distributing NG is no exception, and represents an opportunity to make it greener.
For example, natural gas can easily be transported through pipelines. This eliminates the need to cool and liquefy the fuel so that it can be transported via tankers and trucks. In addition to not requiring the energy for liquification, the process of moving natural gas via pipeline consumes less energy than if moved via tanker or truck.
Natural gas can also be used locally so that it doesn’t have to be transported as far. The shorter the distance between the source of the natural gas and the end user, the greener the whole process will be.
Increasing Power Plant Efficiency
Power plants are large consumers of natural gas. They use natural gas to create electricity through steam generation units and centralized gas turbines. These processes are more efficient than they have ever been, but they still need improvement.The more efficient a power plant is, the less gas it needs to provide the same amount of electricity. One way to increase efficiency is through the use of combined-cycle natural gas plants. A combined-cycle plant uses a multi-stage process where both natural gas and the resulting exhaust are used to power different turbines.
General Electric breaks down the combined-cycle power plant system into three steps…
Step 1 – Gas Turbines Burn Gas and Drive the Generator
In the first step, the gas turbine compresses air and mixes it with super-heated natural gas. This mixture moves through the gas turbine while it burns, causing the turbine to spin. This process is very similar to a jet engine, but instead of producing forward thrust the energy is focused to rotational energy. This spinning turbine drives a generator that converts the rotational energy into electrical energy.
Step 2: Heat Recovery Steam Generator
Simply stated, the Heat Recovery Steam Generator (HRSG) uses exhaust heat to generate steam. Normally, the exhaust heat is simply vented to the atmosphere, wasting a significant amount of heat energy. The HRSG recovers this heat and transfers it to water, creating steam. This steam is then delivered to the steam turbine.
Step 3: Steam Turbines Drive the Generator
The third step is what you typically see in simple-cycle electric power plants. The high-pressure steam turns the steam turbine, adding more rotational energy to the generator shaft, which creates even more electricity.
According to eniday.com, most energy generators today use simple-cycle plants. If they were to switch over to combined-cycle plants, they could increase their efficiency by up to 30%.
Carbon Capture and Storage (CCS)
Carbon capture and storage, or CCS, is a technique that is used to capture carbon dioxide before it vents to the atmosphere. This CO2 is then permanently stored underground.
Carbon capture has historically been used to remove the CO2 from raw natural gas at the NG collection site. This conventional process uses high pressures to separate the carbon dioxide from the natural gas. These systems take a lot of energy to run, and hence, are not as green as they could be.
To make this process more efficient, researchers at Rice University have found a lower-energy way to capture the carbon dioxide found within natural gas. They do this by using medium pressures to bond the CO2 to inexpensive polymers. When the pressure is reduced, the carbon dioxide separates from the polymers. The separated CO2 can then be safely sequestered and sent back underground for storage. The medium-pressure process can capture 4 times more carbon dioxide than high-pressure methods, making the fuel both purer and greener.
Carbon that is sequestered underground can stay in storage for hundreds of years or can be brought back up after researchers have found ways to put it to good use.
Carbon Capture and Utilization (CCU)Carbon that is captured doesn’t always have to be stored. Instead of being stored, the carbon could be used to make fuel of its own.
The most profitable uses for captured carbon at this point is for Enhanced Oil Recovery (EOR). This involves pushing CO2 into oil wells. This process pressurizes the wells and allows the extraction of more oil than would typically be possible.
The University of Toronto is researching ways to use stored carbon to create feedstock and other useful chemicals. Doing so would generate an additional revenue stream and would reduce the cost of mining natural gas.
There many other opportunities for CCU, such as for concrete curing and algae cultivation. Technology continues to advance in the area of carbon capture and utilization. Many of the promising uses for captured carbon will become more economically viable as these technologies continue to advance.
Capturing Biomethane (RNG)
Biomethane, or renewable natural gas, is created from sources that would otherwise be considered hazardous to the environment. Sources of biomethane include:
- organic waste piles,
- food waste.
Left alone, these sources decompose and naturally create methane gas. This methane is released directly into the atmosphere and is a significant contributor to global warming. According to Princeton University, methane contributes thirty times more to global warming than does carbon dioxide.
Biomethane naturally occurs all over the world in landfills, farms, ponds, and even people’s backyards. Gas companies can use this renewable natural as a direct replacement for natural gas extracted from NG wells. Not only is biomethane a renewable fuel source, capturing it is considered carbon-neutral and has a net-positive effect on global warming.
As an example, a plant is currently being created in California which will convert 700 tons per day of food waste and 300 tons per day of biosolids into RNG. Every year, the reduction of CO2 emissions due to this process will be equivalent to taking 47,500 cars off the road.
As unreal as it sounds, this source of renewable natural gas may be even greener than renewables like solar and wind. This is because solar panels, wind turbines, and batteries do not need to be manufactured to take advantage of the energy we already generate with biomethane.
Milestone’s Roll in Making Natural Gas Greener
Milestone is proud to play a part in making natural gas greener. Not only do we construct and maintain natural gas pipelines, but we also construct efficient processing plants and natural gas infrastructure. These efficient facilities release less methane and use less fuel to deliver pure, clean natural gas to power plants and end users. We also partner with science and technology companies to employ the most up-to-date advances on our worksites.
With each passing year, we find better and more efficient ways to reduce the carbon footprint of natural gas. New technologies and advanced research are helping companies procure, store, and use natural gas in safer and more efficient ways than ever before.