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Sugar's energy remedy

Published:Tuesday | May 8, 2012 | 12:00 AM

THE EDITOR, Sir:

I must congratulate the authors of the column 'Achieving globally competitive electricity rates', published Monday, May 7, 2012. However, it must be pointed out that persons, technocrats and all should be careful how they inform the wider public.

Computer heat and power (CHP) systems do pride superior efficiency to conventional power generating schemes, but CHP efficiency is twofold: one efficiency relating to electricity generation, and the other to heat/steam to a process.

The impression given here is that the total electricity produced for CHP schemes is 75-90 per cent, which is not correct. The efficiency, in part, is fuel specific, and as such one has to be clear in stating this also. Apples must be compared with apples.

The efficiency associated with the electricity generating part of CHP is typically 35 per cent, while that for heat recovered is approximately 50 per cent. Many district heating systems are borne from CHP schemes, especially in countries in northern regions. CHP schemes are also widely used in process industries such as breweries, sugar industries, alumina process plants, as well as hospitals.

Combined-cycle power generation, on the other hand, which is associated with generating power using gas turbines, has electrical efficiencies of 45-55 per cent.

Greater thermal energy extraction

In this set-up, electricity is produced in two stages: first, where electricity is generated by a gas turbine, connected to a generator, typically by burning natural gas or gas produced from coal or biomass (gasification). The waste heat from the turbine is utilised by a heat recovery steam generator (HRSG) to raise steam that is expanded through a steam turbine which is connected to a generator which also produces electricity.

Both systems allow for greater thermal energy extraction per unit of fuel, which in turn improve the efficiency. The fact that you can obtain more thermal energy out of the fuel results in more attractive costs $/kWh as well as return on investment (ROI).

The sugar industry in Jamaica would benefit tremendously from such schemes, which would also allow them to extend the sugar production season. This would result in increased revenues and the possibility to supply the grid with excess electricity during the off season.

If my statistics are correct, I believe more than 80,000 hectares of land is owned by the sugar industry, making the potential to plant biomass-based resources that could be burnt along with bagasse from cane production. It must be stated, without prejudice, that the Government is wasting time with respect to the fact that biomass is Jamaica's greatest renewable energy potential.

So much could be achieved if this resource was properly developed and the right systems put in place to benefit the country, as well as reduce fuel imports, whatever the choice of fuel.

While time is running out, the sugar industry ails. Time for action, less talk.

WAYNE GRANT

wrickgrant@gmail.com