Natural Gas Power Plants – Including Data from Texas

Natural Gas Power Plants – Including Data from Texas

Natural Gas Combined Cycle (NGCC) power plants have an efficiency of 63%, which is very high. The best, most modern coal-fired power plants have an efficiency of 45%, which is higher than the 33% efficiency of most existing coal-fired power plants in the US.

(Note that NGCC plants have not been operating at their best efficiencies because of the use of renewables. See comments for more information.)

NGCC plants also require a relatively low investment of around $1,000 per KW, and can have a capacity factor of approximately 85%.

Nuclear power plants require an investment of around $6,000 per KW, and have  a capacity factor of over 91%.

Land-based wind turbines require an investment of around $1,500 per KW, but only have capacity factors ranging between 30% and 39% … which is about half that of nuclear, coal, and NGCC power plants.

Capacity factor establishes the amount of electricity actually produced compared with the amount that should be produced using the nameplate rating of the power plant.

In essence, it’s necessary to build wind and solar plants with twice the nameplate rating to get the same output, albeit intermittently, as NGCC, coal and nuclear power plants.

Baseload power, where electricity can be generated 24/7, 365 days a year, consists of nuclear, coal-fired and NGCC power plants. Hydro, when available, can be included as baseload power.

Wind and solar are not baseload power plants.

It’s clear that NGCC power plants have economic advantages over other methods for generating electricity. They are inexpensive, require little space, have high capacity factors, last for forty to sixty years, and provide baseload power.

They do have one shortcoming. They use natural gas directly from the pipeline, as there is no practical way to store natural gas at the NGCC power plant’s location.

New England finds itself without adequate supplies of natural gas because New York State prohibits the construction of NG pipelines that can bring low-cost natural gas from Pennsylvania to the New England states.

When there is cold weather, natural gas is reserved for heating homes which precludes its use for generating electricity. This endangers the reliability of the electric grid in New England.

This brings us back to the recent events in Texas.

EIA Chart : Hourly Generation in Texas, Feb 7 through Feb 17, showing natural gas bearing the brunt of the load.

Natural gas pipelines use compressors to move the natural gas through the pipeline.

These compressors have typically been driven by small, natural gas turbines, such as those built by Solar Turbines. By their nature, pipelines are typically located away from population centers, and the compressor stations are frequently built in isolated areas where electricity is not readily available. The fuel that powers the turbines comes directly from the pipelines which results in a ready supply of fuel to ensure reliability. 

One would think this was an excellent engineering and cost effective solution for driving the compressors.

However, these small gas turbines are being replaced with electric motors in an effort to reduce GHG emissions, which has led to unexpected consequences.

The Texas Tribune reported that Oncor, one of Texas’ transmission and distribution utilities, was required by ERCOT to cut load during the recent weather crisis. Cutting load to less critical users, such as stores and manufacturers, allows demand to be kept in balance with supply. 

In this instance, however, it resulted in cutting electricity to the electric motors driving the NG compressor stations. This, in turn, reduced, or cut off the flow of natural gas through the pipelines.

Deprived of fuel, the natural gas power plants began to fail, exacerbating the problem of insufficient supplies of electricity and the imposition of blackouts.

Apparently, a frenzy of phone calls resulted in turning power back on, almost haphazardly, since no one was certain which circuits supplied electricity to the compressor stations. This was a last ditch effort to keep natural gas flowing to the power plants. 

No one had considered the ramification of replacing small gas turbines with electric motors.

This attempt to cut GHG emissions was a major contributor to the disaster in Texas. 

The effort to prevent the construction of natural gas pipelines, and replace small gas turbines with electric motors at compressor stations, is endangering Americans.

The environmental movement has made it impossible to build coal-fired power plants, campaigned against building new nuclear power plants, and established policies resulting in the elimination of existing nuclear power plants.

Natural gas power plants, and the infrastructure to support them, are essential for keeping the lights on.

. . .

Related Article: Texas and the Looming Energy Crisis

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4 Replies to “Natural Gas Power Plants – Including Data from Texas”

  1. Only the newest, best CCGT power plants achieve 63% efficiency. I doubt there are any in the US.

    The US natural gas fleet efficiency is 37%, overall.

    CCGTs achieve much reduced efficiencies when being ramped up and down. Experiments in Ireland showed that each 2 GWh of wind energy added to the grid reduced CO2 emissions equivalent to cutting back 1 GWh of natural gas electricity energy.

    • You are correct. You’ll notice I said “can” achieve a 63% efficiency. In the US, they have been operating as following load, ramping up and down, because of the renewables that have been given preference. EIA data shows them operating at capacity factors between between 47% and 71% for 2020 indicating they have not been used consistently at their highest efficiencies.
      We have been mismanaging our electric grid and not using our best equipment at optimum efficiencies to placate the left who insist on using renewables and forcing them onto the grid.
      A note has been added to the article to point this out.

        • While that’s true, I think it’s more about how we use the different resources. Is our objective to use the most efficient, least costly and most reliable first, or is it to insert politically correct sources onto the grid.
          As described in The Looming Energy Crisis, auctions are rigged to ensure that wind and solar are chosen ahead of less costly and more reliable baseload power sources.

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