053 BP 1016

BP 10 October 2016

RENEWABLES Operational efficiencies have been identified, and significant energy savings achieved OCTOBER 2016 | BUILDING PRODUCTS 53 about 50,000 tonnes over the next 5 years. It is also helping to provide National Grid with the kind of demand side flexibility it needs in order to integrate more intermittent, renewable energy sources such as wind and solar. Energy supply from renewables is inherently unpredictable; maximising their potential without vastly increasing system costs requires a more responsive demand side, so that variability in supply can be matched by variability in demand. At the start of the project none of Aggregate Industries’ bitumen tanks were individually metered and the company had very little understanding of the efficiency of each tank. This technology has given a complete visibility of how every tank is performing, including second-bysecond metering data and the ability to monitor and control the tanks remotely. This has helped the company to identify operational efficiencies and realise significant energy savings in the region of 350,000kWh per year. Turning off the bitumen tank heaters to respond to short-term fluctuations in supply and demand does not affect the quality of our product at all; bitumen is stored at between 150°C and 180°C and the heaters on modern, wellmaintained and insulated bitumen tanks can be switched off for over an hour with only a 1°C change in temperature. The tanks’ temperature bands act as control parameters; if the temperature is within those bands switching can take place automatically, or if not, nothing happens. The clever part is that the equipment uses frequency signals as a cue, which are instantaneous indicators of the balance between electricity supply and demand. National Grid has to maintain frequency at 50hz to balance supply and demand, so if it falls below 50hz our plant is automatically switched off if conditions are right; if it rises above 50hz, it is switched on. The average duration of a switch is less than 5min.. Essentially the intervention is invisible and has no impact on the company’s operations, yet it is providing a valuable service to National Grid 24 hours a day, 365 days a year. This is the first time bitumen tanks have been used to help National Grid balance UK electricity supply and demand. In the past this balance has mainly been achieved by managing the supply of electricity from power stations. Now, as more of our energy comes from less predictable, renewable sources, National Grid is increasingly looking for ways to manage its electricity demand. It pays companies who provide this service because it is quicker, cheaper and cleaner than relying on power stations. Through this partnership with the Living Grid network, we can create a positive change in the energy system that extends beyond our own organisation. Donna Hunt is Head of Sustainability at Aggregate Industries


BP 10 October 2016
To see the actual publication please follow the link above