John O’Connor outlines the development of Carrington Power Station, the UK's newest gas-fired combined-cycle thermal plant, and its journey from conception through to celebrating its first anniversary as a fully-operational station in September 2017
Civil
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Pic: Greg Harding

Throughout its 90-year history, ESB has always endeavoured to bring light and energy to the people it serves, delivering ambitious projects of large scale to allow individuals and communities to fulfil their potential in every walk of life, delivering a brighter future.

ESB has adapted and changed over the years, from the construction of the Shannon Scheme and the rollout of rural electrification, through to the energy challenges of the 21st century.

Building on 25 years of successful investments in Great Britain, ESB is now celebrating the first year of commercial operation of its newest gas-fired power station at Carrington, near Manchester, which has been delivering efficient, reliable and secure electricity to over one million homes. This project was delivered by a multi-disciplinary team from across ESB with key engineering input from ESB International.

Carrington Power Station sits at the intersection of two important strands of ESB’s group strategy:

  1. We will grow the scale and capabilities of our generation, trading and supply businesses so that they can compete within the GB/Ireland environment, and
  2. We will lead the transition to a low-carbon future in a secure and affordable way.

So, building Carrington completely supports these goals – delivering significant scale to help us compete while lowering the overall carbon intensity of our portfolio.

At 58% efficiency, Carrington is one of the most efficient thermal plants on the UK energy system. It produces enough electricity (around 890 MW) to meet the needs of over one million homes and businesses and, as one the most flexible and efficient plants in the UK, it is helping to ensure both security of supply for customers and the transition to a low-carbon energy future.

Carrington Power Station sits at confluence of the River Mersey and the Manchester Ship Canal, south west of Manchester airport. The development phase started in 2008 and moved into construction following successful project financing in 2012 (discussed in more detail below). It took four years to build and the plant started commercial operation in September 2016. This means it has just celebrated its first anniversary in September.

Putting the team together


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CLICK TO ENLARGE View of the original power plant section of original piles

Carrington is the newest large scale, combined-cycle gas plant to enter the UK market in recent years. The project itself was a key piece of infrastructure on both a local and national level. During the height of construction, the plant employed over 1,000 workers and provided a welcomed boost for the local and wider economy.

Bringing Carrington station to life was more than just a construction project – it featured an entire programme of work streams, including the co-ordination of the energy trading, energy regulation, operation and maintenance, IT and construction work streams. We managed all of these work streams using ESB’s in-house project management process – the Project Delivery Model (PDM).

The project team formed in late 2008, aligned around the key values of listening to others, diversity, respect, critical thinking and acting ethically. The same core team members remained on board pretty much intact to see the project through its construction and commissioning phases. This created excellent continuity, an in-depth understanding of the project and a great sense of ownership within the team.

We also had a number of new engineering graduates working with project team recruited as part of ESB’s prestigious Graduate Development Programme. They partnered with experienced engineers, which allowed the graduates to gain great ‘experience within the experience’.

Back in 2008, this was the first-large scale power project in the UK to be financed in over seven years and represented an investment of around €1 billion.

Given the investment involved, a project like Carrington could not be financed without engineers who had a ‘financial engineering’ approach and skill base. De-risking the project to within the risk appetite of the lenders (and ESB as shareholder), modelling the plant operations (based on economics within a complex energy market) and negotiating extensive financing packages, along with a myriad of construction contracts, were all part of the role of our engineers.

The project received two independent finance awards because of our innovative approach taken with financing in 2012 which included a blend of traditional project financing and export credit financing.

Building the plant


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CLICK TO ENLARGE Left: HDD drill bit. Right: HDD drilling rig (thrust pit)

Given that originally the old Carrington coal-fired power station (240 MW) was located on the footprint of the new power plant, the brownfield conditions required great attention and careful early engineering works. We broke this out into phases.

Before we secured financing in 2012, we launched numerous large-scale projects on site, which helped to prepare for building work on the main plant, as well as minimising risk by commencing activities early. We started:

  • Building the 600mm diameter high-pressure gas pipeline which supplies the plant with fuel;
  • Building the 400kV gas-insulated substation; and
  • The significant ground investigation works (Carrington sits on a brownfield site, which was previously the home of a 240MW coal-fired power station built after World War II).

The high-pressure gas pipeline installation was a significant project in its own right, with a capital cost of approximately £10 million. The pipeline was non-standard and, for a section of over 1km parallel to the Manchester Ship Canal, we installed the pipe using a specialist horizontal directional drill technique.

This involved drilling downwards over 30m into the sandstone layer and reaming the 1km-section of the pipeline route. We then proceeded to weld and pull the 1km-length of pipe into position with force applied by hydraulic jacks. It was a process not without its engineering challenges.

We tackled the site-enabling works to help minimise the ground risk for the project. As mentioned above, Carrington sits on a brownfield site of an old coal station, so we had to break out the previous plant foundations, which were over 4m deep. In the end, it took some of the largest concrete-breaking equipment in the UK to expose the original piling.

As that happened, we realised that the drawings of the original piling were limited and inaccurate – there were clearly far more than the original estimate of 4,000 piles. The original piles were never intended to be reused, given the uncertainty regarding their long-term integrity, nor could they be removed.

So, we set about creating an accurate digital map of all the old piles. This then allowed us to ‘thread’ 3,073 new piles through the maze of original piles to support the new plant’s foundations given the ground conditions.

The construction of the main power plant kicked-off in earnest after September 2012, with a final commissioning phase for the last nine months of the build, culminating with plant take-over in September 2016. At its peak, there were over 1,000 workers located on site and the project clocked up over 5 million worked hours.

A new approach to safety

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CLICK TO ENLARGE Steam turbine rotor (Pic: Greg Harding)

Our approach to health and safety at Carrington was, and still is, based on continual improvement and learning from the past. It is a proactive, rather than reactive, approach. We progressed a ‘zero harm’ philosophy for the project right from the initial concept phase. Good planning was critical and, from a very early stage, the project team focused on building safety into the design and overall approach.

Carrington’s safety strategy was built on four core ESB safety pillars of: Leadership, Competency, Compliance and Engagement. Overall, our focus was primarily on behavioural safety and engaging people around doing the right thing. We engaged psychologists to help us with this specific approach.

A partnership approach with our contractors and a joint safety vision that each individual worker physical signed were all part of creating the safety culture on-site.

To help create a safe, healthy and supportive working environment, we specified and provided excellent facilities for the site workers: from canteen facilities, individual lockers and drying facilities with clean and optimum site conditions. We also invested in a free, on-site, fully-equipped medical centre staffed with nurses and paramedics all with the purpose of proactively influencing safety.

We are very proud that three people with serious non-work related health emergencies were managed by our medical staff. Over the course of the project, we received several awards in recognition of an exceptional and innovative approach to safety:

  • British Safety Council Certificate – 5 Star Occupational Health and Safety;
  • British Safety Council – Sword of Honour;
  • National UK Joint Council Award for Safety in Engineering Construction;
  • Alstom Gas Projects EHS Award 2015;
  • EPIC 2016 Best Practice Award – Engineering Construction Industry Association.

The plant has a nominal output of c.884.6MW with an efficiency of over 58%, utilising General Electric (formerly Alstom Power) combined cycle gas turbine technology. The two gas turbines are GT26 designs, which is a proven and reliable technology. Gas turbines are in single-shaft arrangements, allowing the plant great flexibility to meet the market requirements. Each single-shaft power train has its own heat recovery steam generator and steam turbine.

To reduce land transportation and local disruptions, all key pieces of equipment were delivered using a specialist barge along the Manchester Ship Canal (MSC) and received at a jetty created at the boundary of the site. Electrical energy from the plant is connected to the UK National Grid via a purpose built 400kV sub-station. Cooling for the plant is provided by a bank of hybrid cooling towers with make-up water provided from the MSC.

Conclusion


Carrington Power Station has been a landmark project for the ESB Group. In fact, it is one of the largest projects that company has ever undertaken. On a personal level, it has been a very challenging but rewarding journey over the last number of years, as the saying goes, it really took a village to raise a child.

The key driving force behind this project was the dedicated engineers and project team members who were so committed and focused. I’d like to take this opportunity again to thank them all for bringing this project to life.

Ultimately, through engineering skills and ingenuity that are deeply rooted in ESB’s DNA, Carrington is providing a secure supply of energy to support economic growth and the everyday societal needs. At the official opening in March, UK Minister for Energy Jesse Norman MP warmly commended ESB for delivery of a project that provides a flexible complement to renewable energy on the UK system. This is an engineering project that will positively touch the lives of millions of people and will make a tangible difference over the next 30 years.

Watch this video about the launch of Carrington Power Station:

Author:
John O’Connor, chartered engineer – project director of Carrington Power Station

http://www.engineersjournal.ie/wp-content/uploads/2017/11/Carrington-Power-Station-1024x576.jpghttp://www.engineersjournal.ie/wp-content/uploads/2017/11/Carrington-Power-Station-300x300.jpgMary Anne CarriganCivilelectricity,ESB,gas
Throughout its 90-year history, ESB has always endeavoured to bring light and energy to the people it serves, delivering ambitious projects of large scale to allow individuals and communities to fulfil their potential in every walk of life, delivering a brighter future. ESB has adapted and changed over the years,...