The rapid growth of commercial buildings and facilities has significantly increased the demand for electricity, and heating and cooling applications, which account for almost 90 per cent of the energy bill. In energy-intensive industrial sectors, the energy cost accounts for 30-50 per cent of the manufacturing cost. Trigeneration, or combined cooling, heat and power (CCHP), is the simultaneous production of electricity, heat and cooling from a single source. The heat and electricity are produced by a CHP unit, while an absorption chiller is used for producing chilled water from the heat output. The overall efficiency of the trigeneration system can reach up to 85 per cent or even higher depending on system conditions. The trigeneration market has been estimated at about 20,000 MW in India.
Technology basics
An absorption chiller is a refrigerator which uses a heat source to provide the energy needed to drive the cooling process. Absorption chillers do not have moving parts, and there is little or no wear and tear. Further, the technology, and operations and maintenance costs are very low. In addition, the overall life cycle cost is low. This makes them ideal for applications that do not require all the heat from the engine.
Typically, when an absorption chiller is included in the CCHP scheme, the coefficient of performance (CoP) is in the range of 0.6-0.8. If driven by steam, the CoP could increase to 1.2-1.4. The CoP of traditional electric chillers is 4-6. Although the traditional chillers are significantly better in terms of efficiency, they require expensive grid electricity to operate. Absorption chilling is beneficial, however it should only be considered for applications that demand little hot water or steam, but have high and consistent cooling demand.
Trigeneration is mainly used in facilities where there is a continuous or seasonal demand for air conditioning and refrigeration. While CCHPs require additional equipment, they allow users to reduce their cooling load from electric chilling and utilise the energy from the engine, which otherwise may be wasted through dry air coolers. A typical trigeneration system utilises a natural gas engine, which provides several benefits such as high electrical efficiency, high thermal efficiency, low operational costs, reduced electrical consumption from traditional chillers, fast project set up and installation, and flexible power generation.
Government initiatives
Energy Efficiency Services Limited’s (EESL) is offering trigeneration technology to industries and institutions in India through its unique pay-as-you-save business model for an integrated service offering. This includes equipment maintenance, and electricity, heat and power supply. While clients will not bear any upfront costs for technology installation, EESL will recover the capital and operating costs through demonstrated energy savings. EESL developed expertise and a compelling market offering in this technology after acquiring Edina UK Limited for Rs 4.93 billion, a leading supplier, installer and maintenance provider of CHP, gas and diesel power generation solutions in the UK.
For supplying gas, EESL has already signed MoUs with GAIL Gas and Bharat Petroleum to co-create an ecosystem for providing readily available gas, the input fuel for trigeneration, to potential customers. EESL has also signed four MoUs with industries and institutions across Maharashtra. It has signed an MoU with Mahanagar Gas to promote the adoption of trigeneration and CHP technology in the Mumbai area, and another MoU with Maharashtra Natural Gas for the promotion of trigeneration and CHP solutions across the state.
It plans to implement trigeneration technology in hospitals, guest houses, hostels, and offices and other government buildings across Maharashtra. As part of this MoU, EESL is implementing multi-megawatt trigeneration capacity across four government buildings. These are the Medical Education and Drugs Department, the Public Works Department, the General Administration Department (Protocol), and the Tribal Development Department. EESL also signed an agreement with Mahindra & Mahindra to install and service a trigeneration project of 803 kWe capacity at an investment of Rs 250 million. Besides, it has ongoing projects at JJ and BJ Hospitals in Maharashtra. Further, EESL has signed a tripartite MoU with Castrol India, India Gas Solutions and EESL to jointly explore opportunities for natural gas-based trigeneration projects in India.
Also, in November 2019, EESL and Innovative Infocom signed an MoU for the implementation of natural gas engine-based trigeneration solutions at Navi Mumbai, India. For this project, EESL will offer a long-term leasing solution, and make the initial investment. In addition, EESL will operate and maintain the trigeneration plant for an initial period of eight years, which may be extended further. It has been estimated that the potential CO2 reduction from a 2 MW natural gas engine-based power station with a heat recovery system will be around 6.1 million kg annually. Net, net, these initiatives are expected to go a long in way in promoting trigeneration technology, and increasing their acceptability and applicability.