Step on the gas

Step on the gas!

The global energy sector is in the midst of a tectonic shift. Coal, which accounts for a third of the world’s energy supply is losing favour to natural gas, which is emerging as the preferred fuel for energy generation on account of being more environment-friendly. This shift is changing power systems across the globe. We bring you an example from Assam, India.

Text: Payal Bhattar Photo: Wärtsilä

Gas is touted to overtake coal as the second leading source of global energy consumption by 2035, behind oil. Numbers validate this prediction. In 2017, gas consumption witnessed the strongest growth of 3.7% (year-on-year) in over a decade and more than double the average growth rate seen in the last five years. According to the 2018 Global Gas Report by Snam (Societal Nazionale Metanodotti), International Gas Union and The Boston Consulting Group, ‘Gas consumption is widely projected to grow in the long run under virtually all major scenarios. The majority of forecasters expect gas to grow from the current 22% to over 24% of the global energy mix by 2035.

As countries and utilities gear up for the transition to natural gas, for environmental and financial reasons, technologies and power systems are evolving too. Generation plants are becoming more flexible and smarter and conventional technologies like the gas turbines are being replaced by gas engines, which offer higher efficiency, reliability and better ramp-up time. India is a case in point.

 

In Focus: Gas engines

“Gas engine gensets provide an effective grid balancing mechanism within the grid system by having a flexible generation alternative with fast ramp-up and ramp-down technology, which can generate electricity as per the actual demand pattern throughout the day,” says Anurag Arora, Sr. Business Development Manager, Wärtsilä India.

“These gensets with improved efficiency, result in saving fuel cost and helping optimise the overall cost of electricity produced with increased availability and reliability of power supply during the variations experienced in the supply and demand pattern,” he adds.

According to experts, the overall efficiency of gas engines, including waste heat, can be as a high as 80% compared to just 50-55% from condensing power plants in the most modern gas-steam cycle units. These engines are also better suited for distributed generation and help provide more autonomy and security at a localised level.

The Lakwa Replacement Power Plant (LRRP) in Assam is an ideal example. Launched in 2016, by Assam Power Generation Corporation Limited (APGCL), this 70 MW power plant in India was inaugurated in May 2018. APGCL had invited tenders for the project and it awarded the EPC contract to a consortium of Wärtsilä India Pvt. Ltd and Europe-based Wärtsilä Finland Oy. 

The LRPP project involved a phase-wise replacement of old, four open-cycle gas turbines of 15 MW each with 7 environment-friendly interconnected gas engines generating sets (GEGs) of 10 MW each (Wärtsilä 20V34SG, capacity). The new GEGs would help APGCL cope with round-the-clock energy generation, produce energy as and when needed and offer grid-support functions in case of sudden power losses.

“With the installation of our new plant at APGCL, Lakwa, the utility company would be able to generate 40% more power in the same location with a projected generation cost saving of about 15%. This also increases the self-dependency of APGCL to manage and control its power supply situation,” says Arora.

Apart from lower operating expenses, the GEGs also offered higher flexibility compared with the gas turbines that were to be replaced. Wärtsilä had all of 24 months from commissioning to supply and install the new engines.

 

Delivering against all odds

As work on the project progressed, the challenges associated with it grew. Lakwa is remotely located, has a high-water table clubbed with loose soil and low bearing strength of soil. The company had to carry out huge piling works (479 piles, 600 mm in diameter) for the foundation of the equipment. Also, it was tough to dispose the excavated soil due to poor road conditions and slushy surroundings.

“We had about 1225 hours of incessant rains during the construction phase. Heavy rains during the morning hours resulted in non-availability of manpower for entire days. Slippery ground, water logging due to a high-water table and flooding of areas in the vicinity of site compounded the challenges for transportation of equipment to site, civil construction, and erection of the equipment,” says Haresh Thakur, Associate Vice President, Project Management, Wärtsilä India as he recounts the enormity of the tasks.

Flooding of areas meant a limited dry spell for inland transportation of equipment (including GEG sets each weighing 137 tonnes), which had to be transported by road from Haldia port over 1500 kilometres involving weak bridges. The company had to incur additional costs for construction of temporary roads to reduce the transportation time and prevent idling of man and machinery. Sometimes, even the temporary roads constructed would sink on account of heavy rainfall, which would further add to the challenges. Also, timely delivery of equipment and materials from the suppliers spread across various states in India posed logistical challenges of varying magnitudes. 

On site, the challenges were of a different scale. “Accommodating a new power plant within the existing plant area imposed major space constraint in terms of access to working areas and movement of cranes etc. At times, we had to rearrange and re-sequence the activities involving installation of major equipment and associated piping and cabling works” says Thakur.

The other big concern was security. The project faced several threats from local organisations and social outfits. This added to the pressures related to hiring local contractors and manpower who possessed limited experience in terms of erection of plant and machinery of this magnitude given the stringent timelines. To compound the matter, several of Wärtsilä’s regular contractors expressed their unwillingness to take up project work at this site.

Therefore, the company had to adopt a combination of regular contractors and local contractors’ approach. Also, the company had to additionally train the local contractors and manpower to meet the quality standards whilst adapting Wärtsilä's Health & Safety standards (HSE) norms. Despite these hardships, the project was completed in record time and inaugurated well within the original schedule – a major achievement that has been appreciated by both APGCL and ADB, the sponsors for this project.

  

A bright future

The Lakwa Power Plant Replacement is one of the sub-projects financed by Assam Power Sector Investment Program (Joint initiative of ADB & the Government of India), which is a USD 300 million multi-tranche financing facility to upgrade and expand power systems in Assam.

According to the project’s co-financer ADB, during 2011-12, peak electricity demand of Assam was 1,250 MW compared to the available capacity of 960 MW. For the deficit 290 MW (23.2%), the state purchased as much as 200 MW from open market through bilateral trades from power traders and Indian Energy Exchange at higher costs. ADB estimates that at the current generation capacity, Assam would still have a deficit of about 516 MW by FY 2019. The Lakwa Power Plant will help change this scenario.

“The economic benefits will accrue primarily as a consequence of reduced fuel burn from the replacement of generators. The investment will increase availability of power generation in Assam by 190 GWh per year. Energy efficiency improvement will reduce carbon emissions by 42,000 metric tons per year,” explains Kenichi Yokoyama, Country Director, India Resident Mission, ADB & Aziz Yusupov, Energy Specialist, South Asia Regional Department, ADB.

There is no doubt then, that Wärtsilä’s new environment-friendly gas engines will play a bigger role in reshaping the energy future of not just Assam, but several other such energy deficit economies around the world. The LRPP is a testimony of the shape of things to come in future.

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