General Electric has devised a way to generate energy from a unique kind of waste: the excess heat from its own gas turbines. An innovative system based on a process understood for decades but previously too expensive to implement can capture waste heat from any industrial gas turbine and return it to the energy cycle without any additional emissions or water consumption.
The Department of Energy recently granted GE and Idaho National Laboratory $2 million to further develop the technology, which could potentially increase the efficiency of industrial engines—which often run at only 35% efficiency—by 20% to 40%. Further, GE claims a gas turbine operating more than 8,500 hours per year will consume almost 3 million fewer gallons of water annually employing this technology.
The technology is based on a process known as the Organic Rankine Cycle that converts low temperature heat into useful work that can be used to generate electricity. The process usually requires expensive organic working fluids, and thus has been less than cost-effective for companies to adopt. GE has eliminated the need for fluids, using an evaporator to efficiently transfer the heat, significantly lowering the capital cost of the system.
INL will conduct technical analyses and help guide design as GE researchers improve efficiency in the prototype at research centers in New York and Germany. Suffice it to say that in times of spiking energy costs and increased pressure to reduce emissions, an affordable system that reduces waste and saves water while increasing efficiency should receive a warm reception.