Water & Wastewater Treatment Magazine
Issue link: https://fhpublishing.uberflip.com/i/1006919
18 | AUGUST 2018 | WWT | www.wwtonline.co.uk The Works: air quality • FLEET EMISSIONS W ith vehicle emissions being a major contributor to poor air quality, commercial vehicles are increasingly being required to comply with rules introduced at a city level – examples being the London Ultra Low Emissions Zone (set to come into force in April 2019) and a mooted plan to ban diesel and petrol cars from Oxford city centre in 2020. For this reason, and to boost the overall sustainability of their businesses, some water companies are seeking to become early adopters of electric vehicles. United Utilities recently announced an ambitious plan to switch its entire fleet of vehicles from diesel to home- produced energy within the next ten years. The water company is aiming to reduce its annual diesel consumption from 4 million litres to zero. It has already invested in 17 electric vehicles and has nine EV charging points across its sites. UU Chief Operating Officer Steve Fraser said: "Traditional diesel powered vehicles are not great for the environment, so our ambition is to migrate all of our fleet away from traditional fuels over the next 10 years. What's really exciting is our aim to power vehicles with energy we produce ourselves – a truly green solution." As well as being used to power electric vehicles, biogas from wastewater and sludge treatment plants can be converted into CNG to fuel gas-powered vehicles – as demonstrated by the 'bio-bus' created by Wessex Water's GENeco subsidiary. In the long run this may prove to be a more efficient use of biogas than injecting it into the gas grid. to the grid – for example in the capacity market and other forms of DSR – are not. The problem is that the cost of the tech- nology required to clean up the emissions from these generators may be dispropor- tionate to their value. "Our generators will not be able to continue to operate in the Capacity Market from 1st January 2019 onwards, at least not without being compliant with the MCPD," one water company energy manager told WWT. "Essentially this means to continue earning an income from grid services we will need to fit emissions abatement equipment, primarily to prevent NOx, SOx and particulate emissions. Our DSR aggregator has told us that abatement technology is available to retrofit to our exiting diesel generator fleet, but at £40k-£50k per generator I can't see it being worth fitting to generators that are in some cases 40 years old and operating way beyond their expected operational lifespan." What has given the issue added uncertainty is the definition of what constitutes a "balancing service". Many generators are switched on for short periods to avoid using grid electricity during triad periods – times when power from the grid is at its most expensive. Until recently, Environment Agency guidance was that triad avoidance counted as a balancing service, and so unabated diesel generators would be barred from being used in this way. However, in May the EA made a U-turn on this and confirmed that triad avoidance did not count as a balancing service. "Defra and the Environment Agency are right to keep a very close eye on ground-level NOx," Alastair Martin, chief strategy officer at Flexitricity, commented on the policy change. "At the same time, emergency power supplies need to be tested on load, or they won't work. It's best to test them when the electricity they generate is useful, and the triad system is one way of ensuring that." Switching to diesel generation during triad periods can be very financially attractive for water companies, so it is likely that many will impose extra operational controls to ensure they keep within the specified 50 hours. However, some water company sources contacted by WWT believed that the days are numbered for even this kind of activity. "I think we have to recognise that it's not a great idea from an environmental perspective to switch on dirty diesel engines wherever the grid is under stress," said one.