119YEARS

of new generation. More than half of

that capacity – 7,902 MW – was fired

by natural gas. What’s more, CCGT

technology accounted for 92 percent

of the gas-fired generation that was

brought online last year.

In 2035, power fueled with natural

gas is expected to surpass coal-

fired power as the dominant source

of power generation in the U.S.,

according to the Energy Information

Administration (EIA), the statistical

arm of the U.S. Department of Energy

(DOE). After 2020, power plants

fueled with natural gas will account

for 70 percent of all new generation

capacity, according to EIA.

By 2040, renewable power capacity

will grow 69 percent, which means

gas-fired plants must be fast and

f lexible to accommodate the growing

amount of intermittent generation.

The transition to CCGT technology

is being driven by low gas prices,

stricter regulation for coal plants, and

the integration of growing amounts

of renewable power. Combined cycle

plants compliment wind and solar

power because they can start and

stop quickly, and thus are capable

of offsetting the f luctuations in

renewable power.

The increasing use of CCGT

technology has led to a sharp

reduction in overall air emissions

from U.S. power plants.  In addition

to rapid-response times, combined

cycle plants emit significantly fewer

emissions of carbon dioxide (CO2),

sulfur dioxides (SO2), nitrogen

oxides (Nox) and other air emissions.

CO2 emissions from power plants

using combined cycle technology are

about 50 percent lower than most

coal-fired plants. Emissions of NOx

and SO2 are 80 to 90 percent lower.

Combined cycle power plants

feature gas and steam turbines. The

gas turbine generates electricity

using natural gas, while the steam

turbine generates electricity using

waste heat from the gas turbine. The

Most new genera-

tion in the U.S. is

being fueled with

natural gas, and

the most domi-

nant technology being used to burn

the fuel is combined cycle.

Combined cycle power plants are

highly efficient, allowing power

producers to wring much more power

from the same amount of natural

gas. The energy conversion rates for

combined cycle gas turbine (CCGT)

plants are high, ranging from 50 to

60 percent.

The number of combined-cycle

projects is expected to increase

3.1 percent a year through 2038,

according to a report from

engineering firm Black & Veatch.

In 2014, the U.S. added 15,450 MW

COMBINED CYCLE: The Preferred OptionBY RUSSELL RAY, CHIEF EDITOR

Panda Sherman. Photo courtesy: Panda Power Funds

Bechtel provided engineering,

procurement and construction

services for the project, which began

commercial production in July 2014.

Construction began in July 2012.

Equipped with advanced emissions

control technology, the Panda

Sherman plant is one of the cleanest

power plants in the U.S., with carbon

monoxide emission less than 10

parts-per-million (ppm) and nitrogen

oxide emission less than 2.0 ppm.

“The plant’s advanced technology

enables the plant to produce higher

power output on higher temperature

days, which is important in this

region,” said Martin Tartibi, senior

vice president at Siemens Energy

Solutions Americas.

The plant can supply enough power

for 758,000 Texas homes.

The Panda Sherman plant uses

“Flex-Plant” technology from

Siemens. It’s the second Flex-Plant

in commercial operation in Texas.

second quarter of 2016. Last year,

the company began commercial

production at the 758-MW Panda

Sherman plant and the 758-MW

Temple plant in Texas.

What follows is a summary of four

modern power projects equipped

with CCGT technology.

PANDA SHERMANBuilt to support Texas’ vast amount

of wind power capacity, the 758-MW

Panda Sherman combined cycle

power plant is one of the fastest

starting power plants of its kind. The

combustion turbines provided by

Siemens Energy can begin producing

power in 10 minutes and can achieve

maximum power production in less

than 60 minutes. The fast ramping

capability allows power producer to

offset the loss of intermittent wind

power when the wind stops blowing.

Siemens provided the plant’s gas

turbines, steam turbine and waste

heat recovery boilers.

process is highly efficient because the

exhaust heat, which would otherwise

be lost in the stack, is re-used in the

steam turbine to generate additional

electricity. The exhaust heat is sent

to a heat recovery steam generator

(HRSG), where the heat is absorbed

by heat exchanger tubes containing

hot water to create steam for the

steam turbine.

One of the biggest developers

of combined cycle power plants

in the U.S. is Dallas-based Panda

Power Funds. The company recently

announced plans to build a third

combined cycle plant in Pennsylvania.

Panda Power Funds has two

Marcellus gas-fueled power plants

currently under construction in

Bradford and Lycoming counties.

The 829-MW Liberty power plant

is expected to begin commercial

operations in early 2016. The

829-MW Patriot power plant is

scheduled to begin operations in the

Riviera Beach. Photo courtesy: Siemens

SGT6-8000H gas turbines to the

Riviera Beach project, each delivering

an electrical generating capacity

of 274-MW. The plant entered

commercial operation on April 1.

LA CARIDADMinera Mexico, a subsidiary of

Grupo Mexico, the country’s largest

mining company and one of the

world’s largest copper producers,

wanted to produce most of its power

in-house. La Caridad I and II, a 500-

MW combined cycle plant in northern

Mexico, is part of the company’s plan

to generate 90 percent of its power

in-house.

The two 1x1 combined cycle units

feature two Siemens SGT6-5000F gas

turbines. The units are rated at 258.1

MW net output and 56.9 percent

efficiency. Siemens also provided the

steam turbines, air-cooled generators,

heat recovery steam generators and

the instrumentation and control

technology. Black & Veatch provided

engineering services for the project.

Unit I was commissioned in

September 2013 and Unit II was

Clean Energy Center in Florida began

commercial operation in April 2014.

The $1.3 billion project uses three

H-class gas turbines from Siemens.

Zachry Engineering was the EPC

contractor on this historic project.

The 1,250-MW combined cycle plant

produces enough power for 250,000

Florida homes.

The combined cycle plant is

expected to save FPL customers

hundreds of millions of dollars

over its 30-year lifetime. The

Riviera Beach facility is 33 percent

more fuel efficient than the plant

it replaced. In addition, CO2

emissions are 50 percent lower and

NOx and SOx emissions are more

than 90 percent lower.

The same turbine used at Riviera

Beach set a world record for combined

cycle efficiency of 60.75 percent

in May 2011 at a power plant in

Bavaria, Germany. Siemens has sold

40 H-Class gas turbines worldwide.

Eleven are in commercial operation

with more than 100,000 equivalent

operating hours.

Siemens  supplied three of its

Flex-Plants offer high efficiency and

operational f lexibility. Innovative

design features enable fast start and

fast ramping up and down across a

large operating window from low

plant turn-down to high plant output Each unit features an SGT6-

5000F gas turbine. In addition to

the gas turbines, Siemens provided

one SST6-5000 steam turbine, two

SGen6-1000A generators, one SGen6-

2000H generator, the SPPA-T3000

instrumentation and control system

as well as two Benson heavy duct-

fired heat recovery steam generators.

The gas turbines, steam turbines

and generators were manufactured

at the Siemens North American

manufacturing hub in Charlotte,

North Carolina.

RIVIERA BEACHIn June 2011, the smokestacks of

the oil-fired Riviera Beach power

plant were demolished. In their

place, Florida Power & Light built

a more efficient plant fueled with

cleaner-burning natural gas.

The Riviera Beach Next Generation

La Caridad. Photo courtesy: Siemens

Eprinted and posted with permission to Siemens Energy from Power EngineeringMarch © 2015 PennWell Corporation

commissioned in April 2014.

Producing its own power with

Siemens’ high-efficiency F-class

technology, the mining company will

be able to reduce its production costs.

The $580 million project allows the

company to cut its electricity costs by

40 percent to 6 cents per kWh. The

project also helps the state of Sonora

and the country by supplying reliable

power to the grid.

What’s more, it will allow the

company to reduce the cost of

producing copper to 89 cents a

pound, down from 93 cents.

The La Caridad I and II power

projects created more than 1,000 jobs

during construction and more than 50

direct jobs for day-to-day operation.

The plant produces about two thirds

of its electricity from the gas turbines.

The rest comes from exhaust heat

which then heats water to create vapor

that powers a second steam turbine.

By capturing the heat, 33 percent

additional electricity is produced.

NINEMILE 6Entergy Louisiana completed

construction of Ninemile 6, a

560-MW combined cycle unit, in

December 2014. Built in Westwego

and serving New Orleans and

southeast Louisiana, it is the

first power plant the utility has

constructed in nearly 30 years.

The need for more generation

equipped with modern technologies

was critical. The retirement of Units 1

and 2, the looming retirement of Unit 3,

and a growing economy created a crucial

need for replacement generation.

“Adding Ninemile 6 to our

portfolio gives us an opportunity to

meet that new need, while satisfying

our customers’ expectations of safe,

reliable and affordable energy,” said

Phillip May, president and chief

executive officer of Entergy Louisiana.

The new unit features dual-fuel

GE 7FA gas turbines, a heat recovery

steam generator from Vogt Power

International, and a steam turbine

from Toshiba. CB&I provided

engineering, procurement and

construction services for the project.

In addition to natural gas,

Ninemile 6 is equipped to burn

fuel oil, an important capability in

the event of a hurricane cutting off

supplies of natural gas. Without a

supply of gas, the plant can continue

producing power with fuel oil from

on-site tanks.

The unit was completed at a cost of

$655 million, well below its original

budget of $721 million.

The project employed 750 people

during construction and created

21 full time jobs for day-to-day

operation.

Ninemile 6. Photo courtesy: Entergy

Eprinted and posted with permission to Siemens Energy from Power EngineeringMarch © 2015 PennWell Corporation