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Combined Cycle Conversion Brings Shale Revolution to Coal Country

Combined Cycle - Jim Willis reportsJim Willis
Editor & Publisher, Marcellus Drilling News (MDN)


The Marcellus shale revolution taking place in Northeastern Pennsylvania, is now resulting in combined cycle power plant conversions that replace coal with gas in what is still known as the anthracite coal region.

It’s a remarkable development when you think about it.

Coal has been a fixture in the Scranton/Wilkes-Barre area for generations. It is so much a part of the fabric of the community; there is even a National Park smack in the middle of downtown Scranton called the Steamtown National Historic Site. Railroad engines used to run on coal back in the day–so it figures Scranton was a major nexus for trains–the city was really the coal capital of the northeast.

And, now it generates power with natural gas, produced right next door.

Combined Cycle Electricity Generation

So, when natural gas displaced coal at a 50 year-old coal-powered electrical generating plant south of Wilkes-Barre a few years ago, that was interesting and noteworthy. The Hunlock plant was converted to run on natural gas by installing two new turbines. The waste heat from the new turbines now powers the old/original turbine once powered by heat from burning coal. It’s called “combined cycle” electric generation and it’s happening across the United States.

combined cycle - power-plant-scheme

How Combined Cycle Electricity Generation Is Accomplished

Although economics are, obviously, also driving the decision, the Obama EPA has demonized coal to the point that electric generating plants are switching (by necessity) to natural gas in large numbers. Hey, *something* has to create electricity–a very small scintilla of electricity comes from so-called alternative sources like wind and solar.

Fossil fuels will, for generations to come, bear most of the burden when it comes to creating the electricity that powers your smart phone, lights, and your (*cough*) electric car. That’s the stark reality. The following article, from the Scranton Times no less, offers an intriguing look at how utilities convert aging coal-fired electric plants into less-polluting, more efficient natural gas fired plants–in this case plants that run on Marcellus Shale gas from next door…

In 1958, UGI Corp. built a 44-megawatt coal-fired power plant south of Wilkes-Barre, where Hunlock Creek flows into the Susquehanna River.

UGI had morphed five years prior into a public utility licensed to do business in Pennsylvania. Hunlock Power Station was the utility’s first electric plant.

For more than 50 years, Hunlock generated electricity using coal. But in 2010, economic forces and environmental concerns throughout the power industry led to UGI Energy Services’ decision to convert the plant to natural gas.

Combined Cycle - hunlock-creek

Hunlock Creek Power Station

In the old Hunlock, coal consumed in a huge burner created steam, which was then used to spin a turbine. The turbine spun a generator, which converted mechanical energy to electrical energy.

Using this method, about 30 percent of the heat energy created from the burning coal could be converted to electricity…

In Hunlock after 2010, two General Electric LM600 turbines – derived from jet engines used in aircraft – burn natural gas.

The natural gas turbines also generate excess heat, but instead of allowing it to disperse into the atmosphere, UGI captures this heat and uses it to spin the old turbine. This means UGI added two new 40- to 45-megawatt turbines and continued to run its old 40-megawatt turbine off the gas turbines’ waste heat.

Since the change, Hunlock converts 50 percent of its initial heat energy into usable electricity…

The technology is called combined cycle. In the era of cheap natural gas and increased regulatory scrutiny on greenhouse gas emissions, many call it the new paradigm in the electric utility industry…

Per unit of fuel, Hunlock’s new combined cycle operation produces a third of the carbon dioxide emissions as the coal-fired version…Switching to natural gas has also reduced emissions of sulphur and nitrogen oxides by many “orders of magnitude,” he [Mike Mara, UGI’s vice president of operations and engineering] said. And with no more coal, disposal of toxic coal ash is no longer an issue.

Coal-fired plants require endless truck shipments and large sections of the plant devoted to storing coal, he said.

“They were more of a material-handling enterprise than they were a power plant,” he said. “Generating the power was typically the easy part. Now you’ve got a pipe coming in and you’re ready to go.”

Hunlock is one of 34 natural-gas-fired power plants in Pennsylvania, according to the U.S. Energy Information Administration. These range from around 1 or 2 megawatts to more than 1,000 megawatts.

“For the big bulk generation, this seems to be the way things are going,” Mr. Mara said. For Hunlock, “We didn’t do anything cutting edge, we kind of followed the trend of the industry,” he said.

Combined Cylce UGI

…the volume of emissions from power plants has declined over the years. Lower carbon dioxide emissions from natural gas than from coal are driving this reduction.

Coal-fired power plants emit an average of 915 grams of carbon dioxide per kilowatt-hour of power produced, according to findings published Jan. 8 in “Earth’s Future,” a journal of the American Geophysical Union. Combined cycle plants emit 436 grams…

In 2001, coal generated 1.9 billion megawatt-hours, and natural gas generated 639 million megawatt-hours, according to the U.S. Energy Information Administration.

This held steady until 2008, when power from coal started to fall while gas rose significantly. In 2013, coal generated 1.59 billion megawatt-hours, and gas generated 1.11 billion megawatt-hours.

The EPA attributes the switch to a “significant decrease in the price of natural gas compared to the slight increase in the price of coal.”

The drop in the natural gas price occurred after production from tight shale formations, such as the Marcellus, skyrocketed over the past five years. Like many plants, Hunlock benefited from cheap, abundant shale gas in its backyard. Its gas comes from Williams’ Transco line, a branch of which runs through Luzerne County.

Combined Cycle Environmental Benefits

The Hunlock Creek Power Station conversion to a combined cycle operation using natural gas is part of a continuing pattern across Pennsylvania, as the following Energy Information Administration chart (now already couple of years old) demonstrates:


It involves not only conversions, but also new power plants working off of Marcellus Shale. The environmental benefits are huge.  One result of the Hunlock Creek combined cycle conversion, for example, was this; power production went up significantly, while NOx emissions dropped from 495 tons in 2006 to 30.6 tons in 2012. That’s a 464.4 ton or 93.8% reduction.

Sulphur dioxide emissions at the same facility went from 4,405.3 tons in 2006 to 0.9 tons in 2012. That’s a 99.98% reduction.

Particulate matter under 2.5 microns in size (the world’s biggest air pollution issue) was reduced from 211.693 tons in 2006 to 3.5 tons in 2012. That’s a 98.3% reduction.

Carbon monoxide decreased from 42.3 tons in 2012 to 6.6 tons in 2012. That’s a 84.4% reduction. 

Finally, volatile organic compounds (VOCs) went from 5.1 tons in 2006 to 0.1 tons in 2012. That’s a 98.0% reduction.

The picture is a pretty one, isn’t it? And, it’s all happening in what was coal country. Frankly, it doesn’t get any better.

Combined Cycle Hunlock Creel Energy Center Pollution

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