Cogeneration is clean and cost effective. It promotes energy sustainability by making efficient use of fuel or heat that would otherwise be wasted. Cogeneration can notably reduce carbon emissions and energy costs. While simple cycle applications can have 40-50% efficiency, combined heat and power systems can yield up to 90% efficiency, helping to decarbonize the electric power grid, district heating systems, factories, etc.
Cogeneration power plants run with the flexibility and reliability of aeroderivatives, generating specific outputs of electricity and heat exactly when needed. The low power derating at high ambient temperatures secures power and heat supply across the operation range better than heavy duty gas turbines. Using inlet conditioning, it can be guaranteed over the entire ambient temperature range as well as the life of the gas turbine. This means the system can adapt to intermittent renewables or emergency power production.
GE Gas Power’s aeroderivative gas turbines operate in hundreds of cogeneration plants globally, offering the advantages of both heavy duty gas turbines and gas engines. GE Gas Power serves moderate size applications with high power density solutions. Hospitals, universities, airports, and industries enjoy the benefits of cogeneration: performance, operational flexibility, cost effectiveness, and more.
A cogeneration plant operating on a heavy duty gas turbine can produce +40MW of electric power; but its high heat-to-power ratio is undesirable in small to medium applications. In addition, high exhaust temperature and flow rate – even in partload operation – make it difficult for operators to control variations in heat demand. The simple cycle electric efficiency of GE aeroderivative gas turbines can reach 43% at baseload (more efficient at partload than the same size heavy duty gas turbine at baseload).
Aeroderivatives: better efficiency
GE aeroderivative gas turbines have a lower exhaust temperature and a much lower heat-to-power ratio than heavy duty industrial turbines. This preferred solution supplies high quality steam to smaller industrial cogeneration applications.
Heavy duty gas turbines require routine on-site maintenance stops, causing a plant stop for several weeks. In contrast, gas generator replacement of aeroderivative gas turbines for major maintenance work requires a plant stand-still of <3 days, guaranteeing a CHP plant availability of +98.7%.*
Benefits of a CHP system are easy to quantify. A plant with three aeroderivative units can offer 95% cumulative availability in a continuous operating application. A plant with 10 large reciprocating engines (single availability of 93%) can yield availability of <50%. To match the aero gas turbines, two more reciprocating units would be needed: 20% excess in plant size and CAPEX.
Aeroderivatives: more reliable and efficient
GE aeroderivative turbines offer 99.9% operational reliability and +99% start reliability technology, per SPS ORAP data, another of many cogeneration plant benefits. This performance is the highest of any thermal power system. Aero gas turbines reliably go from cold start to maximum power delivered to the grid in as quickly as five minutes.
Medium speed diesel engines can be configured to run on ethane, butane, and propane, but the result is often a performance drop and output derating. GE aero gas turbines can operate at top performance in CHP systems on gas and liquid fuels without significant power and cogeneration derating.
Fuel flexibility and aeroderivatives
The wide spectrum combustion system of aero gas turbines supports global decarbonization by operating on natural gas, LPG, hydrogen, diesel, biofuels, ethanol, and other fuels. Cogeneration plants can benefit by switching between fuels for efficiency as costs change, generating reliable power from varied sources.
Aeroderivative combustion systems achieve NOx, CO and UHC emissions standards without exhaust gas treatments, to help meet current environmental standards. They also help to benefit cogeneration applications in residential areas where noise is a concern, with acoustic enclosures for outdoor installations configured down to 80 dBA.
Cogeneration helps to meet and exceed standards
Combustion in reciprocating engines can produce up to 10X more harmful emissions than aero turbines in the same conditions. Even with remediation, it can take several minutes to reach emission compliance. Further, low frequency mechanical ‘knocking’ from reciprocating pistons will require sound proofing at significant cost. A benefit of CHP systems with aero-derived turbines: none of these issues are present.
Aeroderivative gas turbines can be restarted immediately after a shut-down. Compared with heavy duty type gas turbines, daily starts do not impact maintenance costs or shorten the turbine’s life: there’s no downtime auxiliary load consumption, minimum operating run time or stop time. Rapid response time means aeroderivative turbines can help meet the fluctuating heat requirements of a cogen plant.
Aero gas turbines: fast response time
Aero gas turbines benefit cogeneration facilities with a less than one minute response time from partload to full load. They were derived from aircraft engines for fast, multiple load changes without impact on maintenance costs or the lifetime of the gas turbine.
Reciprocating engines, which require pre-warming, lube oil, and cooling conditions to start, have a slower response time and maintain a substantial parasitic load to warm the engine for start readiness.
Aeroderivative gas turbines in CHP plants yield cost savings over reciprocating engines, which can decrease the cost of electricity. Savings on lube oil alone can be more than $1M USD per year. Plant operating hours are actual on-time hours, meaning fewer maintenance and operational expenses.
Savings by Design
Aeroderivative generator sets have the highest power density, which reduces plant cost for land, maintenance area and storage facility.
The LMXPress package reduces foundation work and, with 95% pre-assembled in the factory, can be installed much faster than any reciprocating engine or heavy duty gas turbine.
Savings at every level
Aero gas turbines yield about 22X more power output per unit than reciprocating engines; savings are also significant in shorter outages, a fraction of the man-hours, and rapid installation.
The operational flexibility of GE’s aeroderivative gas turbines provides the high reliability and availability needed in a wide range of CHP applications. GE aeroderivatives are a proven solution to operate in small to mid-size industrial settings or noise-sensitive areas next to hospitals, universities, or urban areas.
