The emergence of new models of energy supply for commercial developments using efficient engine-based technology is gathering pace in Asia, as exemplified by recent on-site power and trigeneration schemes in Singapore and Jakarta.
Gatot Prawiro, GE Energy, Indonesia
Distributed power generation or on-site power generation fits well in Singapore because its energy market has already been liberalized. Several on-site power generation facilities, including a trigeneration and bio-methanization plant, are operating successfully in the liberalized energy markets without any subsidy from the government.
Liberalization has played a positive role in the development of technologies such as combined heat and power (CHP) by allowing non-traditional power generators to own and operate on-site power plants. The successful operation of on-site facilities demonstrates on-site generationà¢€â„¢s feasibility for other industries or firms.
Singapore is home to many high-tech pharmaceutical-manufacturing plants. By running their own power generation facilities, they save on electricity costs and reduce emissions through the very high fuel efficiencies of cogeneration and trigeneration plants. Waste management companies in Singapore are also embracing on-site power, using feedstocks such as wood, food and beverage waste. The output is electricity that is sold back to the grid and as compost for landscaping.
As the Singapore energy markets become more liberalized, some companies have committed to reducing emissions. One such company is the Grand Hyatt Singapore, which with the help of Navigat Energy, GEà¢€â„¢s Jenbacher gas engines distributor, and GEà¢€â„¢s technology, has successfully turned readily available town gas into useful energy at the hotel.
|A fuel-flexible Jenbacher engine installed in Singaporeà¢€â„¢s Grand Hyatt hotel, where it supplies electricity, heating and cooling|
TOWN GAS CCHP AT THE HYATT
In the first trigeneration project of its kind in the world, the Grand Hyatt, Navigat Energy has installed one of GEà¢€â„¢s fuel-flexible Jenbacher gas engines, which uses gas from the townà¢€â„¢s pipeline (locally called à¢€Ëœtown gasà¢€â„¢) to meet the hotelà¢€â„¢s electricity, hot water or steam and dehumidification of fresh air intake needs. The unit has been in operation since August 2010.
Trigeneration refers to the burning of a fuel, in this case town gas, to generate electricity, heating and cooling. A portion of the electricity is generated in-situ, while the exhaust is recovered to produce useful products, namely steam, hot water and dehumidification of the outdoor air for air conditioning purposes.
The trigeneration plant is estimated to reduce carbon dioxide emissions by about 1200 tonnes per year, which is equivalent to removing about 300 cars from the roads. This is achieved when the hot exhaust gas from the gas engine is recovered to generate steam for the hotelà¢€â„¢s laundry plant.
The heat from the engine jacket goes through heat exchangers to preheat the hotelà¢€â„¢s hot water and to operate a thermally driven desiccant dehumidifier, a patent-pending design jointly developed by the National University of Singapore (NUS) and the Grand Hyatt Singapore hotel.
The desiccant dehumidifier provides a lower cooling load, as much of the latent heat is removed from the fresh air intake. This cuts electricity consumption by the centrifugal chillers in the hotel.
Trigeneration systems offer several advantages over conventional refrigeration technology, including:
- trigeneration is operated with heat, using relatively inexpensive à¢€Ëœexcess energyà¢€â„¢;
- produced electricity can be used to cover the hotelà¢€â„¢s electricity requirements;
- lower operating and life-cycle costs;
- greener technology, since water is used as a refrigerant and there is no use of ozone-damaging substances.
Navigat Energy provided a GE Jenbacher JMS320 gas engine for the combined heat, cooling and power (CCHP) plant. The plant initially will be fuelled by the town gas that is used in Singapore, and which is produced by the gasification of naphtha, itself a by-product of petroleum refining. It is not so much considered a waste gas as it is a by-product. The town gas, supplied by City Gas, is easily used when piped into homes and other consumer outlets because it is as simple as igniting a stove.
One challenge overcome was to use it in power generation because it is a low-pressure gas. Another challenge was the integration of all of the components so that they operate in a temperature-cascaded manner for the heat-activated cycle à¢€“ steam generation, hot water and dehumidification. Therefore, the Grand Hyatt Singapore opted for the higher efficiency electricity-driven chillers for cooling.
The system also has been designed to operate on natural gas when it becomes available in the near future. The CCHP plant has replaced the diesel boilers, which had reached their natural lifespan.
The carbon footprint reduction is expected to double when the gas engine is fired by natural gas in the future. As part of the Hyattà¢€â„¢s environmentally conscious corporate objectives, this step would eventually assist the country in reducing its overall carbon footprint and has the support of the National Environment Agency.
GEà¢€â„¢s Jenbacher gas engine provides power output of 587 kW with NOx emissions of below 500 mg/Nm3. It was sold to the Tri-Gen Specialist Solution Integrator for the Grand Hyatt Singapore-CNA Group through Navigat Energy, an authorized distributor in Indonesia for GEà¢€â„¢s Jenbacher gas engines.
The town gas used in the project requires careful treatment, and the highest safety standards must be met. To meet these standards, a comprehensive nitrogen flushing system and a comprehensive safety system for the gas valve train had to be installed.
In the last six months of trigeneration operation, the electrical power generated daily is about 8800 kWh and that contributed about 15 per cent of the hotelà¢€â„¢s daily electrical consumption of the hotel. The waste heat captured is also used to produce steam and hot water for the laundry plant, which has reduced its diesel consumption by 40 per cent. Further reduction of diesel will be achieved when natural gas is available in the coming years.
|The Grand Hyatt Singapore has met about 15 per cent of its electricity needs through burning à¢€Ëœtown gasà¢€â„¢ in its CHP installation and also cut its laundry plantà¢€â„¢s diesel consumption by 40 per cent through using cogenerated steam and hot water|
ENGINES FOR DISTRIBUTED POWER
GEà¢€â„¢s Jenbacher technology has led the way for non-traditional power generation companies to employ strategies that contribute to environmental conservation. Jenbacher gas engines have been used at landfill sites, hotels, shopping malls, farms, hospitals and manufacturing sites.
The needs for these different applications vary from heat for hot showers and kitchen use; to enhancing agricultural produce in the greenhouse with carbon dioxide; to turning landfill, agriculture and animal waste problems into power and selling it back to the grid; to steam for manufacturing production lines.
Many of these applications contribute to carbon dioxide reduction and/or environmental production. The Grand Hyatt project is an example of how GEà¢€â„¢s Jenbacher gas engines can function in producing heat and steam to replace diesel boilers. The town gas used in the gas engine is cleaner than the previous diesel fuel.
In the cases of agriculture and animal waste, disposing of large amounts of waste daily can present major problems and comes with a high cost. By using waste to generate power, the waste is turned into energy and compost. Methane, which is released when waste decomposes, is being used to generate power. Methane is 21 times more potent as a greenhouse gas than carbon dioxide.
In landfill sites, gases trapped under piles of solid waste can cause explosions. In landfill applications, the waste is separated into organic and inorganic wastes. Organic wastes are decomposed and methane is released for power generation. Inorganic wastes that can be recycled are sent for recycling. In addition, managers may qualify for carbon credits.
|In adopting on-site power, Singapore Grand Hyatt is following a generation route that has also appealed to firms in Indonesia, which are seeking innovative ways to ensure continuous power supplies|
JAKARTA SHOPPING MALL PROJECT
Much like Singaporean companies, firms in Indonesia are also looking at innovative ways to ensure they have continuous power supplies for their operations.
A good example of this is the Plaza Indonesia, a large shopping mall complex with apartment towers and the five-star Hyatt Hotel in the center of Jakarta. The complex is powered by a 24 MW plant based on nine of GEà¢€â„¢s J620 Jenbacher gas engines, which were supplied and are now operated and maintained by Navigat Energy.
With a strong natural gas supply and a growing demand from the commercial and industrial sectors for more reliable, cost-effective electricity, this type of on-site power project protects the company from Jakartaà¢€â„¢s frequent electricity shortages by generating electricity to support all the complexà¢€â„¢s power requirements.
The Plaza Indonesia Complex is one of Asiaà¢€â„¢s most prestigious developments. With 22 000 m2 in gross area, the project integrates a six-storey retail and cinema complex, a 41-storey office tower and a 48-storey apartment complex adjacent to the existing facilities.
Today, power generation technology is offering companies around the world customized solutions that meet their unique situations and needs. By trusting Navigat Energyà¢€â„¢s power solutions and retaining the help of technology leaders such as GE, these companies can save money, while reducing impact on the environment through cleaner fuels.
On-site power projects also lessen the burden on the local electricity grid, freeing up that energy to meet power needs that are increasing around the world. The Grand Hyatt Singapore and Plaza Indonesia are leaders in providing creative solutions to meet increasing world demand on power.
Gatot Prawiro is the regional executive for GE Energy, Jenbacher Gas Engines, Asia Pacific. The author extends his thanks to Nils Hansen, sales director, PT Navigat Energy, and Ivan Leong, director of engineering, Grand Hyatt Singapore. For additional information, please visit www.ge.com
This article was first published in the Julyà¢€“August 2011 edition of Cogeneration and On-Site Power Production magazine.