Award-winning CHP System Serves Texas Medical Center
Project proves cost-effectiveness, reliability of large-scale cogeneration
They say everything is bigger in Texas, and that phrase certainly applies to the Texas Medical Center (TMC) in Houston. TMC bills itself as the world’s largest medical complex, and its campus is home to two universities, more than 20 hospitals, three medical schools, and a large number of additional research facilities and institutions. All of the TMC institutions share a critical need for reliable cooling, and many of them are supported by the Thermal Energy Corp. (TECO), a not-for-profit cooperative that serves many of the buildings on the campus.
According to Steve Swinson, president and CEO, TECO, his company serves 17 customers by providing chilled water and steam for 45 buildings on the TMC campus. Today, TECO provides its services through a highly efficient district energy system paired with combined heat and power (CHP) using approximately 30 percent less fuel than grid-supplied electricity and conventional steam production. CHP also helps TECO reduce emissions by an estimated 32,700 tons of carbon dioxide annually, equivalent to removing more than 6,100 vehicles from the road.
The U.S. Environmental Protection Agency (EPA) recently honored TECO as one of three recipients of the 2015 Energy Star CHP Award for its use of this technology. Swinson believes this honor validates the successes his company has achieved through investing in this approach to onsite power generation and heat recovery.
According to Swinson, before investing in CHP, TECO previously operated with electric-driven chilled-water production, gas-driven steam supply, and emergency generators for backup. But, in 2006, the company surveyed its TMC customers about their plans for long-term growth and realized that TECO needed to add capacity to be able to better serve its clients for the next two decades.
“Not only did we need to add capacity to grow, but we needed to make sure we did it in a reliable, cost-effective, efficient manner while being environmentally responsible,” Swinson said.
The resulting master plan to handle future growth included a goal to invest in combined heat and power, which Swinson said has enabled TECO to become much more efficient.
“It’s about 33 percent efficient,” said Swinson, referring to traditional power production. “For every 10 units of fuel that go in, 3.3 units of electricity come out, and the rest of that energy goes up that stack as hot air.”
In contrast, he said, TECO has become a minimum of 68 percent efficient — often nearly 80 percent efficient — by taking a CHP approach.
“With combined heat and power, we produce power on-site,” he said. “The power production process results in reject heat, which we now recover, put in a boiler, and make steam,” he said. “We can generate all of the power we need to run our plant in stand-alone mode and not depend on the electricity grid, which gives us a high degree of reliability. Plus, we’ve dramatically increased our efficiency.”
As planned, TECO has been able to provide all of its own power when the grid is at risk of shutdown and when purchased power costs begin to soar. Swinson also noted the integral role TECO’s district energy system plays in the efficiency achieved by CHP. TECO’s distribution system includes 35 miles of underground piping, which enables it to serve its many customers from its central plant.
“For CHP to work, you’ve got to have something to do with that heat you’re capturing,” Swinson said. “Some of the resulting steam is piped out to customers for their space heating — yes, sometimes we need heat in Houston — and some of the steam is used to run equipment in our plant, so we have a home for all of it.”
SYSTEM STAGES AND SPECS
Swinson noted that, although the master plan was approved in 2007, the CHP project was implemented in stages. The complexity of the $377 million project was heightened by the fact that all of the 24/7 mission-critical facilities served by TECO had to remain operational while the new system was constructed and brought online.
The CHP system, which came online in late 2010, was designed by Burns & McDonnell, a full-service engineering and construction company based in Kansas City, Missouri.
“The project would not have been possible without them,” Swinson said. “They did a design-build performance contract, and they did an excellent job on a very complicated project on a tight site while not interrupting ongoing operations.”
According to Scott Clark, practice leader of Burns & McDonnell’s OnSite Energy & Power division, it was the project of a lifetime due to its scale, complexity, and the critical nature of the facilities being served.
“There’s an electrical system, a power generation system, a chilled water system, and a steam system that all had to remain in operation while construction was going on,” Clark said. “From a construction standpoint, there was literally no laydown area, so everything had to be brought in just in time to be installed. Everything had to be offloaded from the trucks and set in place on the construction site, which required a tremendous amount of planning, phasing, engineering, and construction management to keep all that working in an orderly fashion without dropping service to the medical center.”
Clark noted that Burns & McDonnell was a good partner for TECO because the firm had the right team in place to meet the project’s needs.
“We had all of the elements,” he said. “We have a high-voltage substation group, a group that specializes in chilled water and steam facilities, and a group that specializes in power generation, so it was a good fit for us. We also have our construction division that does the integrated design-build portion of the project.”
Burns & McDonnell have prior experience designing and implementing CHP at other campuses, and Clark said the company is a huge advocate of this technology.
“The great thing about CHP is it’s good for the customer, good for the environment, and it improves reliability,” he said. “The grid, for the most part, is pretty reliable, but, as we’ve seen with Superstorm Sandy and some of the hurricanes and natural disasters that have happened, the ability to island your facility and keep running when the grid is down is a very powerful thing — and worth a lot of money to anybody who’s doing research or health care.”
For the TMC project, Burns & McDonnell designed a CHP system that includes a gas turbine manufactured by GE that generates 48 mW of electricity, and a heat recovery steam generator manufactured by Express Technologies, which captures heat from the turbine’s exhaust.
Referring to the turbine, Swinson noted it’s “literally a jet engine, originally designed to be on the wing of an airplane.”
But, in TECO’s application, he explained: “When that engine spins, there’s a shaft connected to it that spins a generator and makes power. And then, the exhaust that comes out of it is about 900 degrees, so, instead of blowing it into the atmosphere, we collect it and put it in a boiler and make steam.”
The resulting steam is used to serve 19.3 million square feet on the TMC campus. Yet, Swinson also pointed out that simply stating the square footage served can be misleading. Factoring in the rigorous requirements of air changes for medical facilities and the intensely hot and humid climate of Houston, “that might be the equivalent of 70 million or 80 million square feet in a normal office or commercial-type setting,” he said.
Since the CHP system has been in operation for a few years, the results have showcased the extraordinary efficiency of the technology, Swinson said. And, after logging the EPA’s required 5,000 hours of operation, TECO was awarded the 2015 Energy Star CHP Award at an International District Energy Association conference held earlier this summer.
According to the EPA, TECO demonstrates how CHP can partner with district energy systems to help the U.S. reduce carbon dioxide emissions from electricity generation and to better support their host facilities.
In a press release honoring TECO and the other winners, Janet McCabe, EPA assistant administrator, said the 2015 winners “are advancing the president’s commitment to reduce carbon dioxide emissions from the nation’s electric power supply system.”
McCabe also noted, “These winners have found CHP to be a powerful way to save money and better protect our health and climate.”
The project demonstrates how CHP can partner with district energy systems to reduce pollutant emissions from electricity generation, added McCabe.
As a not-for-profit cooperative, TECO has been able to refund an average of $4.345 million per year to its customer base since the CHP system’s efficiency savings began to be realized in 2011.
Swinson is grateful the award validates all of the hard work put in by TECO’s employees as well as its board’s vision for the project.
“Our board members represent the institutions we serve,” he said. “They have a vested interest in TECO’s efficiency and high degree of reliability and understand it’s important to invest in technologies that make that possible.”
And, Swinson added, he’s glad that receiving an EPA Energy Star award is helping to bring more attention to CHP technology.
“Combined heat and power is really a model that we should be using more for energy in our country,” he said.
SIDEBAR: TECO’s TEXAS TAKEOVER
Houston-based Thermal Energy Corp.’s (TECO’s) combined heat and power (CHP) and district energy systems serve some of the world’s most prestigious medical institutions, including:
• Baylor College of Medicine;
• City of Houston;
• Houston Academy of Medicine;
• Houston Community College;
• Memorial Hermann Health System;
• The Institute for Rehabilitation and Research;
• Shriners Hospitals for Children Houston;
• CHI St. Luke’s Health;
• Texas Heart Institute;
• Texas A&M;
• Texas Children’s Hospital;
• Texas Medical Center;
• Texas Woman’s University;
• U.S. Department of Agriculture/Agricultural Research Service;
• The University of Houston;
• The University of Texas Health Science Center at Houston; and
• The University of Texas MD Anderson Cancer Center.
Publication date: 8/24/2015