British broadcasting giant turns to biomass
The British-based broadcasting giant, BSkyB Ltd., has installed a combined-heat-and-power system at the company’s Heathrow, London studio complex that broadcasts Sky Sports, the program responsible for broadcasting most of the Premier League’s European futbol matches. The sustainable studio, as the company calls it, will use a Pratt & Whitney Power Systems/Turboden supplied Organic Rankine Cycle turbine to create 1MW annually with the help of a biomass boiler supplied from VAS that will produce power and hot water for the studio.
Stephane Senechal, sales area manager of the biomass department at Turboden, said the plan is to reduce the buildings carbon footprint by 20 percent, and the ORC technology will help to do that. “The system vaporizes a high-molecular mass organic fluid instead of vapor in a close cycle,” according to Senechal, “resulting in excellent electric performance and several key advantages,” advantages that Senechal said include high cycle efficiency, 90 percent turbine efficiency and no erosion of the blades all while providing simple start-stop procedures without an operator needed.
According to Turboden, the Rankine cycle used in the turbine at the Sky studio is based on a turbogenerator that works as a normal steam turbine to transform thermal energy into mechanical energy and then finally, into electrical energy. Instead of using steam, the ORC system vaporizes an organic fluid, typically oil or water mixture, which according to Turboden, leads to a slower rotation of the turbine and lower pressure and erosion of the metallic parts and blades. The ORC system set up in the biomass CHP plant first heats thermal oil to a temperature of roughly 300 degrees Celsius in a closed loop system. The hot oil is then drawn into the ORC system before evaporation, and the resulting vapors then expand in the turbine, resulting in mechanical energy that is converted to electrical energy. The vapors are cooled and condensed to a temperature of roughly 80-90 degrees Celsius and reused for different heating applications, and the condensed organic fluid is also pumped back into a regenerator in the closed loop system, allowing the cycle to restart.
The Sky CHP system will use woody biomass sourced from a 25 mile radius, and at full capacity, the system will require 32 tons of woody biomass delivery per day. The Heathrow facility also employs wind energy to provide some electricity, but the wind energy at the facility is not enough to make a significant impact on the Studio’s goals of reducing the carbon impact of the facility, according to Sky officials.
Feedstock supply agreements are already in place with several supply companies, according to Senechal, and the Sky biomass project is one that can be duplicated. The project is a good stage for similar projects because it demonstrates some key factors such as environmental protection, the good return of the investment due to the high availability of the power produced from the plant and the low operating requirements created by implementing the Turboden system. The PM Group provided design and management services for the CCHP plant, also assisting Sky with environmental permitting applications and operating consents.
The system will begin operations in early 2012