Aggregate Industries knows a lot about building roads so it’s appropriate we’re blazing a trail when it comes to making the most of DSR opportunities. We’re well known in the industry for being pioneers in the use of new technology and we’re always looking for ways to reduce our energy consumption and costs, and at the same time reduce our emissions. When we found out that DSR can help us do all these things – and generate revenue – we became very interested.We teamed up with energy specialists Open Energi to identify those activities of ours that fit the dynamic frequency response management profile. In other words, activities where we can safely automate the switching on or off of power – without affecting quality – in order to help balance the grid.
The first plant we included in the scheme was our bitumen tanks which heat bitumen for the making of asphalt for road surfaces. We found that turning off our bitumen tank heaters to respond to short-term fluctuations in supply and demand doesn’t affect the quality of our product at all; bitumen is stored at between 150-180 degrees centigrade and the heaters on modern, well-maintained and insulated bitumen tanks can be switched off for over an hour with only a one-degree 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 five minutes. Essentially the intervention is invisible and has no impact on our operations, yet we are providing a valuable service to National Grid 24 hours a day, 365 days a year. We are paid for being available, regardless of how often we are required to respond.We’re well known in the industry for being pioneers in the use of new technology and we’re always looking for ways to reduce our energy consumption and costs, and at the same time reduce our emissions. When we found out that DSR can help us do all these things – and generate revenue – we became very interested. Equipment was initially fitted to 244 of our bitumen tanks at 40 asphalt plants around the country. So successful has it proved that we’ve extended it to 11 quarry pumps at two quarries, and we are also reviewing all our sites, operations and equipment to identify further activities to bring into the scheme.
Embracing this innovative technology has helped us achieve 3.6MW per year of flexible demand for the grid. In terms of emissions that is almost 50,000 tonnes of CO2 avoided over five years – equivalent to saving 390,000 flights between Paris and London!
And thanks to Open Energi’s metering and monitoring equipment, we have new data which can help us identify where the bitumen tanks may be inefficient or not running correctly, which in turn we can use to make adjustments to achieve even more energy savings.
Through our partnership with the Living Grid network, we’re happy to share our experience of this emerging technology and encourage others to take up the opportunity too. Together we can create a positive change in the energy system that extends beyond our own organisation.