“We’ve always been at the forefront of sustainability, so it made sense to upgrade our traditional power to highly-efficient microturbines to lower energy consumption,” said John Traynor, director of engineering, Ritz-Carlton San Francisco.
At the core of the CCHP system, four Capstone C60 Microturbines generate electricity and heat to provide base-load power and air conditioning that support much of the hotel’s 440,000-square-foot grounds. Using natural gas, the CCHP system provides the 336-room hotel with 240kW of electricity and 120 refrigeration tons (RT) of cooling year-round at 80 percent efficiency, which is near maximum overall efficiency for this type of system.
For Ritz-Carlton, guest comfort is paramount, which makes the quiet, low-vibration microturbines an ideal power source for the hotel’s relaxing ambiance.
According to Traynor, purchasing the CCHP system resulted from an ongoing plan to lower the hotel’s energy consumption and reduce energy expenses.
“The hotel’s parent organization strongly wanted to deploy the highly efficient CCHP system to offset energy loads,” Traynor said. “Our philosophy is to reduce our carbon footprint and minimize our impact on our community and the environment. We’re always looking to advance our sustainability profile and Capstone microturbines align with our corporate vision for environmental stewardship.”
With a 1MW peak electricity demand and significant chilling requirements that approach 300 RTs, Ritz-Carlton San Francisco needed a cleaner, more efficient power system to align with its industry-leading corporate standards for conservation. The hotel’s original inefficient 300 RT electric chiller ran 24/7 year-round, even though the hotel’s chilling needs often were well below the chiller’s capacity.
The newer microturbine-based CCHP configuration meets 70 percent of the hotel’s cooling demand and is designed to satisfy base-load chiller demand for the whole year. This allows the facility to shut off the inefficient 300 RT chiller for eight months each year.
“The big payback is the tremendous amount of heat that comes from the four microturbines,” Traynor said. “Heat recovery is key to reducing a hotel’s energy consumption and costs.”
Exhaust heat from the four microturbines is captured by a Carrier Corporation 120 RT double-effect absorption chiller, which can be manually configured to operate as either a chiller or heater. When in cooling mode, the chiller recycles the microturbines’ exhaust heat to achieve a COP of approximately 1.3.
Since the rooftop CCHP system was commissioned in 2005, the hotel has reduced its energy consumption 20 percent and saved an estimated US$120,000 each year in energy costs. With financial support from California’s Self Generation Incentive Program and the U.S. Department of Energy, the hotel’s return on investment took less than four years. According to the Pacific Region CHP Application Center, the Capstone microturbine system at Ritz-Carlton San Francisco saves enough electricity annually to power 200 average American homes.
With such tremendous energy savings, greenhouse gas emission reduction is inevitable. The clean-and-green Capstone system emits 40 percent less CO2 a year than conventional systems – a benefit equal to planting 150 acres of pine and fir forest. In fact, the CCHP system reduces 800 tons of CO2 each year when compared with traditional onsite energy systems. Additionally, with NOx emissions less than nine parts per million at 15 percent exhaust oxygen, the Capstone system emits 90 percent less NOx a year than conventional systems, which is equivalent to removing 250 cars from the road.
And the CCHP system at the hotel requires nominal maintenance compared to its traditional system.
“The microturbines run all the time with minimal maintenance,” Traynor said. “The past six years have been a good performance indicator.”