Genset Focus

Powering the world’s largest vessel

Floating liquefied natural gas (FLNG) facilities are ground-breaking, helping to unlock large energy reserves from new fields that were previously not economical to reach – but first the facilities themselves need a power supply.

One of the great strengths of turbine-driven power generation is its ability to operate reliably in remote and difficult-to-access locations and also to generate high levels of output for its size and weight.

When it comes to stand-alone power systems, there can be few projects that present more of a challenge than floating offshore projects, and perhaps the best example of these is Prelude – a FLNG facility that is currently the biggest vessel in the world.

The giant hull – which by definition is not a ship as it does not have its own propulsion system, instead needing to be towed by tugs – is 488 metres long and when finished will weigh more than 600,000 tonnes.

It was launched in 2013 and is still being fitted out with the large amount of equipment needed to safely store and process millions of tonnes of LNG each year. When completed, it will be located 120 miles off the northwest coast of Australia.

Running an LNG facility of this size involves countless pumps, valves and control systems, as well as the need to keep thousands of tonnes of liquid gas at temperatures below -162à‚°C and to support a permanent crew of 120 people. This requires a sizeable, constant and reliable source of energy.

This is being delivered by steam turbines, connected to a suite of three 40 MW synchronous generators supplied by Brush, an energy solutions provider for the global power industry. The two-pole DAX units used on the project are similar to those used around the world in public utility, cogeneration and industrial applications, but with additional attention paid to framing and mounting of the generator to account for the pitch and roll motion present onboard a vessel.

Blair Illingworth, chief executive of Brush, says: ‘The power source on an FLNG facility is absolutely critical. The reliability of DAX generators is a big part of why they are popular for powering facilities such as hospitals and large industrial plants. The fact that they have been selected for this project is testament to their reputation for dependable performance in critical applications.

‘As well as reliability, the other major factors on a floating facility are footprint size and weight – every extra kilogramme adds to the overall displacement of the vessel, for which there is a strict limit, and space will always be at a premium. Another strength of the DAX generators is their high level of power output for their relatively compact dimensions.

‘A further key part of the criteria for the generator was minimal requirement for ongoing maintenance,’ Illingworth continues. ‘By following the prescribed operation and maintenance regimes, DAX generators typically have a life expectancy of 25 years or 10,000 starts, so this was obviously also appealing to the project team.

‘When you consider that at the heart of one of our generators is a single-piece steel forging weighing several tonnes and rotating at 3600 rpm, this highlights the criticality of the design and manufacturing processes used by Brush. The generators are a superb example of a large number of highly developed components working together to deliver truly impressive longevity and performance.’

Genset shift to gas predicted

The diesel-fuelled genset market is poised for continued growth in most regions and power classes, a new report from Navigant Research shows. However, diesel is facing increasing competition from natural gas generators in certain markets.

Continued growth in the supply of unconventional gas resources and tightening regulations targeting stationary generator emissions may signal a shift toward cleaner-burning natural gas systems. In the short term, though, countries with strong economic and/or population growth rates coupled with unreliable power grid infrastructure and blackouts will continue to drive diesel genset sales.

Global diesel genset capacity additions are expected to increase from 62.5 GW in 2015 to 103.7 GW in 2024.

Caterpillar gensets to power US gas-fired plant

Caterpillar is to install a 38.8 MW power plant in Owatonna, Minnesota, US.

Powered by four Cat G20CM34 gensets, the new plant replaces one that was damaged by flooding in 2010. Owatonna Energy Station will be built, owned and operated by Southern Minnesota Municipal Power Agency (SMMPA), a collective of 18 municipal utilities, with construction scheduled to begin in 2016.

Each 20-cylinder gas-fired genset will produce up to 10 MW and is equipped with Cat’s electronic control system to ensure precise fuel delivery, the company noted.

‘We are pleased to be working with Caterpillar again on this important resource,’ said Dave Geschwind, SMMPA’s CEO. ‘This project will help the agency further diversify its resource mix with additional natural gas generation, and it will be an important asset in managing future capacity and energy costs.’

‘Considering the new plant’s fast start, high efficiency and low emissions, SMMPA will be able to offer very valuable services to the local system operator,’ said Claudio Martino, regional sales director with Caterpillar. ‘It will provide black start capability, enabling SMMPA and the residents of Owatonna to better manage their power needs.

‘Instead of relying on remote resources, the region can generate power in their own back yard in a reliable and cost-effective manner.’

Flexible low-load gensets are ‘game changers’ says report

Traditional gensets are being modified to run in low-load mode with minimal fuel consumption, but with the ability to respond quickly to output changes from an allied solar photoltaic (PV) array or changes in demand. Such devices are finding increasing application in the mining industry.

A new study, ‘Low-load Gensets for Solar-diesel Hybrid Plants in the Mining Industry’, analyses the technical and strategic fit of low-load gensets for solar-diesel hybrid applications, finding that low-load gensets almost double the solar penetration rate in hybrid systems and are more efficient in these plants.

This solution could considerably lower mines’ operational costs, the report notes, adding that the fast spinning reserve of low-load diesel systems ensures supply in case of variation of demand or of PV production losses, for example from shading.

An attractive target for solar-diesel hybrid plants is the mining industry as power consumption is usually high and mines are typically in remote locations with high costs for diesel and for its transport, the analysis concludes.

‘The demand for raw materials has slowed down and prices have decreased recently. The mining industry is facing substantial challenges. Reducing the costs of operations such as energy expenditures has become an important competitive factor,’ said Dr Thomas Hillig, CEO of consultancy THEnergy and author of the report.

‘One of the game changers could be low-load diesel hybrid power plants giving maximal room to locally produced inexpensive solar and/or wind energy,’ he added. ‘Even at the current low oil prices, optimized hybrid technologies normally beat the current conventional diesel-based electricity prices. The additional investment including the PV system has usually a payback period in the range of four to seven years.

Rolls-Royce gensets to power Bangladesh steel factory

Rolls-Royce is to supply eight gas-fired gensets to power what will be Bangladesh’s largest steel factory.

The factory, located in the port city of Chittagong and owned by industrial conglomerate the Abul Khair group, is undergoing expansion and, once completed, will be Bangladesh’s largest steel milling facility.

The gensets will total 50 MW in capacity and are based on medium-speed 20-cylinder Type B35:40V20AG2 gas engines from Bergen Engines. They are scheduled to be commissioned in 2016.

The power will be used on-site, Rolls-Royce said, while the Abul Khair group plans to use the exhaust gas for steam production in future.