Energy World article: On-site CHP feeds steam to chemical process
The Tata Chemicals Europe CHP plant and also our exciting CCU plans are featured in a two-page article, by Energy Director Peter Houghton, in the March issue of Energy World magazine. It’s a really helpful article that sets out the role that our CHP plant plays in our operations, so we’ve published a version of it here.
It’s almost certain that every home in the UK today has something made using a product manufactured by Tata Chemicals Europe (TCE) in Northwich, Cheshire. Whether it is glass in windows and jars, washing powders and detergents, all produced using TCE’s soda ash, or food products that contain salt or sodium bicarbonate, the chemicals manufactured by TCE are the often unseen raw materials that are used by hundreds of industries to make millions of consumer products. With a long and rich history that began with pioneering the production of soda ash 145 years ago, the chemical plants in Northwich were a founding cornerstone of ICI in the early twentieth century and are now a part of the global Tata Group.
Built on four pillars, TCE today produces soda ash, sodium bicarbonate, pure vacuum dried salt, and energy in the form of steam and electricity. Food, glass, pharmaceutical, detergent and specialist chemical manufacturers all rely on TCE to provide high quality products that are used in the UK and also exported across the globe. Over the past six years, TCE has been transformed by the implementation of a bold new strategy that has changed the fortunes of the business. This transformation included the acquisition of the Winnington combined heat and power (CHP) plant in 2013, resulted in the closure of one soda ash production plant and the creation of the world’s first standalone sodium bicarbonate plant where demand now outstrips supply.
Continuing this evolution, in 2019, TCE announced plans to build the UK’s largest Carbon Capture and Utilisation plant, taking flue gases from the CHP plant and using this gas in the production of sodium bicarbonate.
Combined Heat and Power – an essential pillar in TCE’s Business
With over 380 CHP sites in the UK, in this article we take an in depth look at TCE’s CHP plant. We explore some of the unique features that enable the plant to generate the lowest cost energy for the production of soda ash and sodium bicarbonate that has lowest carbon footprint per ton produced in the world.
145 years ago, Brunner & Mond chose to locate in Northwich, Cheshire, to be near to cotton manufacturing customers in Manchester and the key raw materials required to make soda ash; brine from the vast salt deposits below Cheshire and limestone from the Peak District. Production of synthetic soda ash requires substantial heat in the form of steam. In 2000, Winnington CHP was built to replace two coal fired power stations to generate steam and electricity. At the time, up to 400MW of steam could be generated, however following the closure of the Winnington Soda Ash Works in 2014, the CHP plant was reconfigured to supply up to 200MW steam.
Unlike many industrial CHPs, where heat is a by-product of electricity generation, the chemical production process at TCE is heat intensive, requiring the continuous supply of a large volume of high pressure, high temperature steam to operate. Other than burning coal, there is no other route available to produce the required volume of high temperature steam. The plant can also generate up to 96MW of electricity which is used to power TCE’s production at two sites, to supply other industrial users connected to TCE’s private HV network and sold to energy companies and transmitted on the distribution grid.
Steam Generation Process at Winnington CHP
Winnington CHP is fueled by natural gas transported by pipe from the gas transmission network 12km away. This gas powers one of the two gas turbine trains that operate in a duty/standby configuration. The gas arrives at the site at 70 bar and is reduced to 20 bar. In the gas turbine, it is combusted with compressed air to drive the air compressor, turbine and the electricity generator. The exhaust gases leave the turbine at over 500o C and go from turbine into a heat recovery steam generator that burns additional gas to raise temperature and pressure of steam to 450o C and 70 bar.
The exhaust gases leave the heat recovery steam generator are released into the atmosphere via a 46m tall stack. From 2021 however, 40,000 tonnes per year of carbon dioxide will be captured, purified and liquified from these emissions and used as a raw material in the production of pharmaceutical grade sodium bicarbonate.
Electricity Generation at Winnington CHP
Each gas turbine train generates between 35-42MW/hr of electricity. This variation can be caused by different weather with high pressure, cooler conditions resulting in denser air, meaning that the compressors can drive more air into the turbine, allowing more gas to be combusted and therefore more energy generated – this can be equivalent to £6k per day of variance in electricity sales.
In addition to the generators connected to the gas turbines, the high pressure, high temperature steam goes through a steam turbine before being transferred to the chemical production plants, generating up to a further 16MW of electricity. Electricity demand on TCE’s private network is significant, with the remaining electricity exported to the distribution gird.
When starting up, the plant can go from zero to full power in around 20 minutes using a diesel generator until the compressors are running fast enough to start up the turbine. All electricity produced is at a low carbon footprint, much lower than a typical Combined Cycle Gas Turbine plant.
Water Supply
Often industrial CHP plants harness waste heat to distribute hot water in district heating pipework which is then returned to the CHP to be reheated. At Winnington CHP only one third of the water used is returned, the rest is consumed during TCE’s chemical production processes. To support the demand for water in its chemical production processes, TCE has a treatment plant that takes water stored in a local reservoir, that is then filtered, purified and deionized to produce water that is pharmaceutical grade purity with a pH of 7. The treatment plant is one of the largest water treatment plants in Europe to supply a power station.
Operating and Maintaining the CHP
Originally built and owned by Powergen (who became E.ON later on) in 2000, E.ON have operated and maintained the CHP on TCE’s behalf since the plant was acquired back in 2013. The plant requires three operators 24/7/365 who work closely with the chemical production plant managers to supply the required heat and electricity. They also work in tandem with the TCE Energy Team to optimize generation to respond to electricity demand from the grid, able to call on the standby gas turbine train to supply additional electricity during demand peaks.
As renewable generation sources such as wind are dependent on weather, generators such as TCE that can rapidly bring on new sources of electricity generation are becoming increasingly important to the resilience of the national grid. The CHP operates at a constant load, with steam production automatically adjusted using pressure sensors on the steam supply pipeline to indicate changing demand from the chemical production plants. Like all gas turbines, monitoring and maintenance is crucial to the long-term life of the assets. Both gas turbines have significant monitoring instrumentation that helps to predict potential failures and schedule preventative maintenance working with the OEM and specialist turbine management suppliers.
Regulatory, political & economic challenges
TCE are working hard to be at the forefront of industrial innovation, meeting government targets for decarbonisation and increasing exports.
TCE’s energy business is built on one of the UK’s largest and most efficient industrial CHP plants. It is over 80% efficient and indirectly helps to reduce wholesale energy prices for domestic customers. Supporting the regional electricity grid and other local industries via a private high voltage network already, the plant also offers more opportunity to enhance the UK’s security supply at a time when ageing generation infrastructure is being decommissioned. Changes proposed by OFGEM in, for example, its recent Targeted Charging Review published towards the end of 2019 will have a significant financial impact on generators such as TCE. Despite meeting their own energy requirements without the distribution network, industrial generators like TCE (who use their own facilities continuously) will still be charged a fixed fee to use the distribution network for supply purposes.
OFGEM’s proposed changes mean we would also lose another embedded benefit: Balancing Use of System (BSUoS) as part of TCR. That is in addition to vital revenue lost as a result of the TRIAD embedded benefit and also the Levy Exemption Certificates (LECs) changes back in 2013. These benefits were central to companies making the decision to build their own CHP. However, those days are long since gone and that’s largely down to OFGEM actions.
Many manufacturers with industrial CHP generation support clusters of other manufacturing businesses that work as an ecosystem, maintaining local economies, tens of thousands of jobs and millions of pounds of exports. The role of these manufacturers in the wider economy is ignored by OFGEM; located close to raw materials or transport hubs that have grown around them, they help to balance the UK economy away from the South East. Today, the opportunity to innovate and develop industry in the UK is under siege due to OFGEM’s relentless drive for regulatory change which takes no account of industry or the impact on energy intensive manufacturers on UK businesses that rely upon the raw materials produced as inputs to their manufacturing processes.
Serious challenges to the viability of these crucial industrial clusters are being created that risk not only the current businesses, but the opportunities such as those being created by TCE to decarbonise industry and grow exports. Specifically, as a result of changes over the past five years, TCE has lost £7m per annum due to Ofgem reforms, with a potential further £1m per annum loss as a result of the recent TCR review. This lost revenue is deeply damaging to those who operate industrial CHP plants where the cost of operation and maintenance is significant. By eroding the electricity revenue of these plants, the foundation of the manufacturing industries, the clusters and jobs they support is eroded. Ofgem can create a perfect electricity system but destroy our vital manufacturing industries in the process. Manufacturing businesses are centred where there are skills and where raw materials exist…not to take advantage of the electricity system.
To deliver the UK’s exciting vision of industrial development and decarbonisation, opportunities such as TCE’s to create a carbon capture and use plant, increase manufacturing output and export to the rest of the world must succeed, but only will if regulation and policy work in tandem, helping to ensure that efficient industries can remain sustainable.
Carbon capture and use in Cheshire
In 2019, alongside the Minister for Energy and Clean Growth, TCE announced a £16.7m investment to build the UK’s largest carbon capture and utilization plant (CCU). The plant will capture 40,000 tonnes of carbon dioxide from the exhaust gases, equivalent to taking 22,000 vehicles off the road. Once completed, this will be the UK’s largest carbon capture plant, with the next largest at Drax power station capturing only 365 tons per year. In a unique, world first application of CCU technology, the plant will remove around 11% of the carbon dioxide emissions of the Winnington CHP and use this as a raw material for the manufacture of sodium bicarbonate.
Global demand for high grade sodium bicarbonate is increasing and the CCU plant will support TCE’s plans to grow exports of this product that already stand at 66% of production.
First published in the March 2020 issue of Energy World magazine, published by the Energy Institute, energyinst.org