Natural gas is coal’s main competitor in the electricity generation industry.
Over the past decade, natural gas has been quickly replacing coal, and many industry experts believe that it will eventually replace coal entirely.
While coal use has been diminishing, generating electricity with natural gas has been growing. In 2009, natural gas generated
22.1% of U.S. electricity. By 2018, natural gas had grown to be generating 35.1% of U.S. electricity.
Natural gas use in electricity generation is on the rise, while coal use is steadily declining. There are many reasons for this, and this article will examine them.
Natural Gas vs. Coal Electric Generation
Natural gas and coal are vastly different materials. How they are mined, transported, and used in the generation of electricity is considerably different. In this article we’ll address:
- How coal power plants work.
- How natural gas power plants work.
- How each material is transported to its respective power plant.
- The efficiency of coal and natural gas.
- The cost of natural gas compared to coal.
How Do Coal Power Plants Work?
A coal-fired power plant starts by pulverizing coal to burn it in a furnace. The burning coal heats water in a boiler, which becomes steam. The
steam is highly pressurized. It’s then released over a turbine.
When the steam is applied to the turbine, it spins an electromagnet housed inside copper coils in a generator. This final step produces the flow of electrons, which we all know as electricity.
Afterward, the steam must be cooled before it comes out of the turbines. This is commonly done through water that’s sent through a condenser. The water cools and condenses the steam so that it can be sent safely out of the turbine.
How Do Natural Gas Power Plants Work?
There are two types of natural gas power plants used to generate electricity. The first type is called a simple cycle power plant, and the second is called a combined cycle power plant. Here’s how each works to generate electricity.
The Simple Cycle Power Plant
In a simple cycle power plant, natural gas is sent to a furnace where it heats the air. The hot air is then used to turn a turbine which then turns an electromagnetic generator.
The electromagnetic generator then produces a flow of electrons that can be used to power our electric grid. Water did not have to be used to create steam to turn the turbine.
The Combined Cycle Power Plant
Combined cycle power plants are more complex than simple cycle power plants, but much more efficient. This type of power plant combines the technology used in a coal power plant with simple cycle power plant technology.
These power plants begin the process of generating electricity by burning natural gas to heat air. The heated air will turn the turbine, which spins the generator. Upon completion of this process, exhaust heat is then used to boil water into steam.
This steam is pressurized and sent into a turbine that turns a second generator. The process ends when the steam is sent through a condenser and converted back into water for recycling. You get electricity from two different generators without using any additional natural gas.
How Does Coal Reach the Power Plant?
Transporting coal to a power plant can be an inefficient process. Trains, trucks, and large ships are commonly used modes of coal transportation. This requires even more energy and increases the chances of losing or destroying the coal. For example, a coal-filled ship could sink, and all the coal could be lost.
Consequently, some coal power plants are built close to the mining operation itself. In cases such as this, coal can be transported on conveyors and large trams, as it doesn’t have to travel long distances.
In some countries, coal can be crushed and mixed with water to create a pipeline-compatible slurry. However, this transportation method is not used in the United States.
How Does Natural Gas Reach the Power Plant?
Natural gas is transported to power plants through the use of pipelines. These pipelines can run hundreds of miles and transport a tremendous amount of gas in a relatively short time.
A multitude of federal and state agencies oversee the pipelines, helping to keep them as safe and efficient as possible.
Natural gas movement through pipelines can be tracked every step of the way. Drones and other monitoring devices can notify inspectors as soon as, or even before, problems arise. As a result, less natural gas is lost during transport when compared to coal.
Coal vs. Natural Gas Efficiency
According to the Tennessee Valley Authority, a combined cycle power plant can convert up to 50% more natural gas energy into electricity. Coal-fired power plants, however, are only steam-powered plants and therefore cannot take advantage of this benefit.
Moreover, transporting coal itself is more expensive than transporting gas. Coal transport is, effectively, so expensive that the EIA has said coal transport can be more expensive than coal mining. Because it’s so expensive to transport coal, it also loses efficiency in this area.
Natural Gas vs. Coal Cost
The New Hampshire Department of Environmental Services conducted an interesting study on the total cost of using different fuels to generate electricity. They examined the capital costs and indirect social costs of generating a kilowatt-hour of electricity from both coal and propane.
The capital costs examined were the cost of the fuel and the operating and maintenance costs of using the fuel. The indirect social costs examined were health and environmental costs.
The analysis showed that coal costs 10.29 cents per kilowatt-hour, while gas costs only 8.09 cents per kilowatt-hour. The 20% lower cost of natural gas came in the form of lower operating and maintenance costs, and lower health and environmental costs.
Natural Gas vs. Coal Emissions
Coal typically produces more carbon dioxide than natural gas. Coal also emits other harmful substances not always discussed. Coal emissions, according to the EIA, may consist of:
- Sulfur dioxide
- Nitrogen oxides
- Carbon dioxide
- Mercury and other heavy metals
- Fly ash and bottom ash
Sulfur dioxide can cause acid rain, while nitrogen oxide may cause smog. Furthermore, particulates can lead to lung disease. These three substances can cause respiratory diseases in both humans and animals. Mercury and other heavy metals can cause developmental damage. Even captured fly and bottom ash can end up leaching into local water supplies.
Natural Gas Emissions
Natural gas primarily releases carbon dioxide and methane into the atmosphere.
Carbon dioxide emissions produced from natural gas is only half that of coal. Also, new technologies enable natural gas companies to recover and reuse carbon dioxide normally released into the atmosphere during natural gas mining.
Methane leaks are also easier to detect, and pipeline companies can quickly stop them before becoming an issue. Since methane is burned and used as energy, keeping it from leaking is in every company’s best interest.
Summarizing the Advantages of Natural Gas Over Coal
- Less expensive
- More efficient
- Less damaging to the environment
- Easier to transport
- Less harmful to human and animal health
Natural gas burns more efficiently and costs less to mine and transport. It is better for human health and the environment. Even the social cost (the indirect damage to the environment and human health) is significantly lower when producing electricity with natural gas than it is with coal. Generating electricity using natural gas is superior to coal. And, one day, natural gas will completely replace coal worldwide.
Milestone companies is proud to be leading the charge in constructing oil and natural gas pipelines across the United States and Canada. We are proud to be eco-friendly, constructing pipelines and related infrastructure with the environment in mind. Find out how oil and natural gas pipeline construction can be eco-friendly, while also being cost-effective.