Britain’s biggest electricity distributor, UK Power Networks, is exploring new ways to tackle the net zero carbon challenge as part of its £600 million annual investment to upgrade power supplies and provide new network connections.
Compared to ordinary concrete, ground granulated blast-furnace slag (GGBS), a by-product of steel production, uses a fifth of the energy to manufacture and produces less than a fifteenth of the CO2 emissions.
A new electricity substation in west London used 1,139m3 of concrete, incorporating 50% GGBS cement replacement, saving 133 tonnes of CO2 emissions. A second substation in north-west London used 563m3 of concrete, incorporating up to 50% GGBS cement replacement, saving 50 tonnes of CO2 emissions. A third project, on electricity pylon foundations in east London, used 120m3 of GGBS (70% of the mix), which saved a total of 44 tonnes of CO2 emissions.
Jonathon Peirce, who leads UK Power Networks’ sustainability in construction forum, said: “Our working practices are moving with the times and we are looking to design lower-carbon concrete into more new substation designs and refurbishments.
“Climate change is a huge challenge, but there are improvements we can make and it is down to all of us to take responsibility for it. The time for change is now and the quicker the better.”
Concrete is the most frequently used construction material in the world and Ordinary Portland Cement (OPC) production accounts for 4-5% of worldwide CO2 emissions, during manufacturing and curing, whereas GGBS produces less CO2, when it is fired and cured. GGBS is combined with OPC in variable proportions, from 20 to 80% of the total mix.
Allan Ponsonby, head of engineering design at UK Power Networks said: “As a respected corporate citizen UK Power Networks challenges the way in which we deliver our infrastructure upgrades, to be as efficient and sustainable as possible. The substitution of Portland Cement with GGBS is one technique we shall continue to utilise as part of our strategy for a greener and more sustainable future.”
Chris Leese, director of MPA UK Concrete, commented: “It’s extremely positive to see UK Power Networks specifying a GGBS concrete mix for these essential projects, which can significantly reduce the overall greenhouse gas emissions associated with the production of concrete. The increasingly widespread use of these mixes is just one of the ways that the concrete and cement industry is helping to support the circular economy and the transition to a net zero economy. It has been working towards a clear strategy to reduce its environmental impact for over a decade, with innovation having already helped to deliver a 53% reduction in absolute carbon emissions since 1990.”
Last year UK Power Networks, which delivers electricity to more than eight million homes and businesses across London, the South East and East of England, became the first electricity distribution network operator in the UK to achieve the Carbon Trust Standard for Carbon, recognising organisations that achieve year-on-year reductions in greenhouse gas emissions.
UK Power Networks has reduced its CO2 emissions by 15,887 tonnes, a 20.5% reduction from 2014/15 baseline. The company also has a Green Action Plan, which focuses on reducing carbon emissions from the company’s fleets and generators, reducing waste, water usage, air and noise pollution, while increasing the biodiversity at many of its sites.