
Implementation of heat exchange and storage systems attached to CCGTs is delivering greater demand-response for plant operators, delegates at PowerGen heard. The Italian utility IREN uses heat storage tanks at three gas power plants around Turing – optimizing between the sales of electricity and district heating.
Tapping heat output from three of its gas power plants, the operator uses this to get water close to boiling which is then stored under high-pressure in the tanks. Over 14,000 cbm of heat storage capacity is available, fed by thermoelectric production of its 400-MW Torino Nord CCGT, the Moncalieri 2x400 MW CCGT, the Politecnico HOB plant and the Martinetto heat storage system.
“CCGT operators can only compete in modern electricity markets if they are extremely flexible. Improving ramp-up-time provides some advantage, but we lose the flexibility when we have to respond to heat demand in the winter,” said Enrico Pochettino, head of internationalization and innovation at IREN Group.
“Using heat storage we can regain flexibility.”
Flexibility through storage
The ability to store heat output, and feed it back both to the plans and local district heating – if and when needed; has allowed IREN to respond to daily demand swings more efficiently.
“We can now react more efficiently to day-ahead prices by choosing whether to route output to or from heat storage and maximize the returns, dependent on whether there is more demand for heat or electricity,” Pochettino explained.
“If we were only a power producer we would not be profitable; but thanks to co-generation and the implementation of heat storage we are.”
Waste heat recovery
Heat exchange is not only useful in boosting returns from existing assets. The technology also allows operators of gas-fired cogeneration plans a closer integration with district heating systems – through the capture of flue gases as well as heat pump technology that allows closer integration.
Italian manufacturer XOG employs waste gas power generation technology through its radial outflow turbine system. Reliant on the Organic Rankine Cycle (ORC), the system allows the firm to achieve very high efficiency and capture of flue gases from industrial plants.
Short payback periods
“We installed a waste heat recovery system for a glass producer in Turkey and have seen payback of 3 years or even less. Luca Xodo, head of business development Exergy said, pointing at opportunities for energy-intensive industries.
“In the glass industry for example around 82% [of the heat] is used for the furnace but there is still significant energy available from the flue gas. The average for most glass processing plants around the world is 8 Gigajoules per ton.”