Heads or Tails ~ stack

Barb at Skittle's Place encourages her readers to write a Heads Or Tails post each Tuesday. This week the theme is "Stack". (don't miss out on all the other HOT posts)

Just up the road a piece at the center point of the Monterey Bay coastline, is a lovely community called “Moss Landing”

Moss Landing is a small fishing village, with a really wonderful artist enclave we locals try to keep a secret. (shhhhhh) They are surrounded by one of our nation’s most fertile agricultural regions frequently referred to as the “salad bowl to the world." People come from all over to go whale watching and shop in amazing antique stores. If you are in the area and have a little extra time…Moss Landing is a fun place to stop between Santa Cruz and Monterey.

What most people think of when they hear Moss Landing, is the electrical generation power plant with its large smoke stacks. When the fog clears you can spot these landmarks throughout the Monterey Bay Area.

When I think of the Moss Landing smoke stakes…I picture flying above them and dropping in a tailspin.

A few years ago I was given flight lessons. Although I LOVE to fly, I just do not have the burning desire to actually be the pilot…but I thought it would be a good idea to learn how to land a plane in case of an emergency. (this is called a “Crash and Burn” course…as in if you do not know how to land the plane…you will crash and burn)

At one point in the training the instructor will cut the engine. Yep. While you are flying along in the air the e-phn instructor will (without warning) cut the engine of the plane you are in. His intent is for the student (without panicking) to restart the engine and resume flying.

For me this happened while flying over the ocean, just above the Moss Landing stacks. As the plane went SILENT and started to lose altitude, I could see the stacks through the windshield. Fear slammed me. In a split second, I went from deeply enjoying the early morning horizon to thinking I was gonna die. While I was able to restart the engine and safely complete that lesson…I was rather angry. I didn’t appreciate the “sink or swim” method of pilot training. I only continued a few more months. While I didn’t earn my license…if something happened to the pilot in a small plane…I am confident I could land us safely.

Whenever I see the Stacks at Moss Landing I remember what they look like from above…as I dropped towards them.

The photos were copied from Wikipedia…cause I left my camera in someone else’s car. The following information ALSO came from Wikipedia…for the benefit of the geeks out there who like this kinda trivia.

The building of the Moss Landing power plant began in 1949 with the first five units. Producing 560MW, these units started commercial generation in 1950. After 45 years of production, the original five units were decommissioned in 1995.

In 1964, the construction of two additional units began (6 and 7), with two new 500-foot stacks. These two units produce 750MW each, with 180-foot tall boilers. They employ a newer technology using supercritical steam at 3600 psi.

The (simplified) generation process for units 6 and 7 is as follows. Natural gas is injected at one end of the boiler to be burned. Primary water is injected at the other end of the boiler to receive the heat produced. The gas simply comes from a natural gas pipeline, and combustion products go up the stack and into the atmosphere.

Water has a much more complicated path. Cooling water is pumped out of the Monterey Bay or the nearby Elkhorn slough. Then it is purified, used to cool down the water coming from the turbines, and discharged into the ocean. That's the cooling water; steam for the turbines is created from the primary water flow, which is pre-heated before entering the boiler. From the boiler, the superheated steam is directed into a first turbine working at high pressure, then into a low pressure turbine. The turbines drive the generators.

To comply with more restrictive pollution regulation, units 6 and 7 were upgraded in 1998 with a selective catalytic reduction unit and digital control systems.

Starting in 2000, the eight 225-foot stacks and 19 fuel oil storage tanks were removed, and two new units were built on the former site. The new units 1 and 2 were brought online in 2002. They are combined cycle units, 50% more efficient than the other units. Because they use two turbines: first, a pair of 170MW gas turbines, then a 190MW steam turbine, for a total of 530MW each.

Combustion products drive the gas turbines directly. First, air is drawn from the air intake to the compressor (driven by the turbine axle), then it is burned with natural gas in the combustion chamber. The hot combustion gasses then go through the actual turbine (driving the axle). From a thermodynamic standpoint, this is the standard Brayton cycle. Because the gas turbine does not transfer energy from the combustion process to the turbine via steam, it avoids the cost, energy loss and environmental impact of the primary water cycle.

At the output of the gas turbines, some of the remaining energy (heat) in the exhaust gas is recovered through a heat exchanger and transferred to water that feeds a steam turbine, similar to units 6 and 7.

On a smaller scale than the supercritical units, units 1 and 2 are also more flexible, with a start-up time of only an hour, against 24 hours for units 6 and 7.

The Moss Landing power plant has a maximum capacity of 2560MW, but the older, less efficient, supercritical units 6 and 7 are only operated during the peak period between June and September.

Some of the power generated from the plant is sent to far-away regions via Path 15, directly connected to the plant, and interconnections like Path 26 and Path 66.

The Moss Landing power plant was built and owned by Pacific Gas & Electric. As part of California's experiment with energy deregulation, PG&E sold it to Duke Energy (DENA) in 1998. In 2006, having invested over half a billion dollars in upgraded capacity, efficiency and emission control, Duke Energy sold the plant to LS Power Equity Partners citing the high cost of natural gas and regulatory uncertainty.

From January through October 2005, the Moss Landing power plant complex released almost 900,000 tons of CO2, 60 tons of NOx and 4 tons of SO2 into the atmosphere, without operating units 6 and 7. These amounts are relatively small, given the amount of power produced, and especially when compared to other coal-burning facilities. Another environmental impact is on the water of the Elkhorn slough and Monterey Bay : under certain conditions, the water is allowed to be released at a temperature 40°F higher than it is taken, thereby perturbing if not killing the surrounding aquatic life. Each day, roughly 1.2 billion gallons of water are cycled through the power plant.