Coal, Gas, Solar

POWER-GEN International Tech Tours

Solar Technology Tour: Walking the Roof of the Orange County Convention Center

Meg Cichon, Associate Editor,

On Monday morning in Orlando, Fla., many people walking in and around the Orange County Convention Center (OCCC) were discussing the abnormally thick fog that had rolled into the area during the previous night. Damp, humid, and cloudy, it didn’t seem like the best climate for a tour around the OCCC’s 1-MW solar rooftop installation at the 2012 Renewable Energy World Conference and Expo, North America, co-located with POWER-GEN International.

“This looks like the thickest fog I’ve seen here in a long time,” said Brian Kennedy, who works at the convention center and was set to lead the tour, “but believe it or not, our solar system is still producing power.”

As the tour start time ticked closer, the fog noticeably cleared by the minute, much to the delight of several tour participants waiting to check out the system. By the time the tour was ready to start, it was a typical sunny Florida day – an ideal day to make solar energy.

The 1-MW array covers an area equivalent to five football fields, and the system is the one of the largest rooftop solar arrays in the Southeast. Johnston Controls developed the system, which features almost 6,000 SolarWorld panels that were installed by Florida-based Solar Source.

Attendees in two separate groups were able to tromp through the electrical workings of the OCCC and check out the array, the four Satcon 250-kW inverters, and the Fat Spaniel monitoring technology. Fat Spaniel was acquired by Power-One in 2010, but the boxes still bear the Fat Spaniel name.

According to Kennedy, the system offsets about 10 percent of the buildings’ electrical use, which he pointed out, doesn’t seem like a lot. However, when you consider that the convention center’s electric bill is $1 million per month, it’s a pretty significant chunk of electricity, he said.  Kennedy mentioned that when they flicked the switch on the system, he checked the monitors and saw that the panels were immediately making about 998 kW at that moment, and mentioned the best months for power generation are April through June.

Since it’s in Florida, Solar Source installed the panels to withstand hurricanes, which wreak havoc on the nation during hurricane season each year. Since Florida has some of the highest wind codes to meet in the entire country, arrays need to withstand wind speeds of up to 150 miles per hour. 

In all, there are five solar PV systems in various locations around the convention center facilities. The small hybrid PV/thermal array offers solar air conditioning through dehumidification, but it’s mostly a demonstration project, as is the small thin-film laminate array, and two other ground-mounted arrays near the parking lot. One of the ground-mounted arrays is bi-facing and uses Enphase micro-inverters, which Kennedy noted were an emerging technology when the system was installed.  The demonstration arrays are used for educational purposes.

Kennedy said the convention center is going to add about 400 kW more to bump up its total installed capacity to near 1.5 MW.

When it was placed in service nearly four years ago, the total project cost was $8.8 million. Today, due to lower modules costs and BOS advances, the price would be less than half of that, said Kennedy.


Technical Tour: Polk Power Station

By Sharryn Dotson, show daily editor

Attendees of POWER-GEN International braved the fog to tour Tampa Electric Co. (TECO)’s 1,026 MW Polk Power Station in Florida. The plant consists of one integrated gasification combined-cycle (IGCC)  unit and two natural gas-fired peaking units. Unit 1, the IGCC unit, began operations in 1996 and uses one 192 MW GE 7FA turbine and one 128 MW GE D11 steam turbine. The peaking units are GE 7FA simple-cycle combustion turbines.

The project was built with $140 million in funding from the U.S. Department of Energy as part of its Clean Coal Technology program. The plant cost a total of $660 million. Bechtel was the engineering, procurement and construction (EPC) contractor for the project.

Polk Power Plant uses coal and petroleum coke blend as fuel, and the plant burns up to 2,200 tons of coal a day, said Lloyd Webb, maintenance manager at Polk. The coal is stored in two silos on site that store five days’ worth of coal, Webb said.

Sam Decubellis, engineering manager at Polk, took a group around the plant to see the gasifier and radiant syngas cooler. The gasifier sits atop the cooler and heats the slurry up to about 2,600 degrees Fahrenheit. The cooler brings it down to about 1,200 degrees Fahrenheit and also circulates the slurry around so the heavy ash falls to the bottom and is removed as slag and water. The tour then went around to the back of the gasification unit to where the two coal silos are situated. From the silos, the tour then went past the coal grinding and brine systems and past the heat recovery steam generator, which uses the steam from the convective syngas cooler and supplies it to the steam turbine.

In front of the silos, the workers have started construction on what will be part of Tampa Electric’s carbon capture testing, which will remove 300,000 tons per year of carbon dioxide from an 18 percent side stream, or about a 20 MW side stream. The project is planned to run from 2014 to 2015 once it receives funding from the DOE. However, the planned project is only for carbon capture and not sequestration.

POWER-GEN International delegates head to the swamp

By Dr. Heather Johnstone, Chief Editor, Power Engineering International

Close to 80 POWER-GEN International delegates got the opportunity on Monday to visit the Cane Island Power Park, which is home to one of the most efficient generating units in Florida.

Cane Island Power Park comprises four units with a combined capacity of 735 MW and is fuelled by natural gas although in an emergency fuel oil can also be burned. It is located near Intercession City in northwest Osceola County. Although Cane Island is little bit of a misnomer, it is an island of sorts because it is surrounded by swamps as opposed to water. It is jointly owned by the Kissimmee Utility Authority (KUA) and the Florida Municipal Power Agency, with the former operating the plant.

On the day we visited, Unit 4 was the only one operating so this provided the delegates with unprecedented access to the generating equipment of the other units much to their delight.

Unit 1 is the smallest with a generating capacity of 40 MW and features a LM6000 two-shaft aeroderivative engine from GE. It entered commercial operation in 1995 and is used for peaking and reserve load because of its quick start capabilities – the unit can be up and running within an impressive nine minutes.

Although Unit 2 began operating in the same year it has two significant differences. It is decidedly larger – its generating capacity is 120 MW – and it operates in combined-cycle. Its combustion turbine is an 83 MW GE MS7001EA, the heat recovery steam generator (HRSG) is a Nooter/Eriksen triple-pressure design, rated at 956 oF, 887 PSIG and a combined steam flow of 300,000 pounds per hour. Unit 2’s steam turbine is a GE Fitchburg model rates at 43 MW. It is normally cycled for intermediate load. And although its start-up is not as quick as Unit 1, it can still be up and running within a respectable 19 minutes.

There was then a gap of around seven years before Cane Island’s third unit came on-stream in 2002.

Unit 3 is also a combined-cycle generating unit, comprising a159 MW MS7241FA+e gas turbine, a HRSG with a triple-pressure, reheat design from Aalborg, rated at 1050 oF, 1950 PSIG and a combined steam flow of 550,000 pounds per hour. The steam turbine is GE A10 model, rated at 93 MW.

When we visited, the steam turbine of Unit 3 was undergoing its first major maintenance outage, which was being conducted by GE. All the component parts of the steam turbine had been recently returned to site and were laid out in the steam turbine hall like a giant puzzle. What was particularly interesting was we got an opportunity to watch how the maintenance engineers fitted the different parts of the steam turbine back into the housing. Cane Island expects Unit 3 be back online in January/February of next year.

Because Unit 4 was operating during the visit it was not possible to get too close it to. The 300 MW combined-cycle unit was commissioned in 2011 and entered commercial operation in June of this year.

With it being such as new generating unit it is not surprising to hear that it is recognized as one of the most efficient power plants in Florida. Its gas turbine is a Frame 7FA from GE. It was built by Texas’ Zachry Construction Corp. and cost a cool $475 million, which is more than the cost of Units 1 to 3 combined.

One interesting aspect of Unit 4 is that its HRSG features eight duct or supplementary burners, which provides between 20-30 MW of extra power. Unit 3 also feature duct burners, but produces only 5 MW of extra power.

We were able to see Unit 4’s duct burners in action via a small window in the HRSG. To say it was hot looking in would be an understatement – the burner temperature would be somewhere in the region of 1200 degrees F.

Despite the visit involving a lot of walking from unit-to-unit the feedback from the delegates was extremely positive and everyone appreciated the openness of the engineers from KUA. And unlike the odd alligator, which occasionally wanders onto the site, they made us feel very welcome.