Emerging technology for energy production

In close cooperation with Siemens and Aalborg Keystone Boilers the Jotne Group has done a study for Statoil on the Combined Steam Bottoming Cycle technology. The study included structural analyses, 3D models, price estimates, and more. The background for this technology - as well as Waste Heat Recovery Units (WHRUs) - is that only one third of the gas is used in simple-cycle gas turbines. Using traditional WHRUs, the exhaust gas is used for production of process heat by warming water in a heat exchanger.

The more advanced Combined Cycle technology is already used onshore for energy production. Instead of just producing hot water for heating purposes, a combined-cycle unit turns water into steam, which again generates energy via steam turbines.

The environment is the primary beneficiary of the Combined Cycle technology because more energy can be produced per kilogram CO2 emitted than in simple-cycle technology. However, this technology has been used offshore only in a few cases.

"There are several reasons for this," explains Bjørn Johansen of EPM Consultants. "With plenty of free gas available on a platform, there was previously little motivation to invest in new and expensive technology. Also, a Combined Cycle unit is bulky and heavy."

As a result of the international focus on the emission of carbon dioxide and the so-called greenhouse effect, governments are looking for ways to encourage more efficient use of the energy resources.

"With higher taxes, Combined Cycle is regarded as a more cost-effective solution, especially where process heat is not needed on a platform," says Johansen.