Paul Suff visits Whatley quarry in Somerset to see how Hanson's energy management system works
One business that easily met the original deadline was Hanson UK. The firm complied with ESOS by securing certification to ISO 50001 in September 2015 for its energy management system (EnMS). Senior sustainability manager Martin Crow says Hanson identified more than 12 months ago that 50001, rather than one-off energy audits, was the best option for the aggregates, concrete, asphalt and cement business to comply with ESOS.
‘If we’d taken the ESOS audit route, it would have meant separate reports for all our energy data and audits of every site,’ he says. ‘All this would have been running in parallel with the systems for environment [14001], quality [9001] and health and safety [18001] that we already have in place. It was better for Hanson to see how we could extend 14001 to get 50001 and manage energy through the firm’s integrated management system.’
The international energy management standard includes all the requirements for ESOS and, says Crow, has the added benefit of driving efficiency. ‘ESOS audits will identify areas for improvement but there is no requirement to take action, whereas 50001 requires an organisation to continually improve its energy management.’
Filling in the gaps
The first step towards 50001 was a gap analysis. Although energy had been included in its environmental audits, Hanson was keen to compare its 14001 certified environment management system with the requirements of 50001. ‘We wanted to know where the gaps lay between what we were already doing and what we needed to do,’ explains Crow. ‘A lot of what we had to do for 50001, such as internal audits and monitoring and measuring, was covered by existing procedures.’
The analysis concluded that a procedure for identifying energy improvements and a method for formalising an annual energy management report were required. Crow says: ‘We’d first set corporate energy reduction targets in 2008 and had been active in climate change agreements since 1999, so we were already encouraging businesses to implement improvements. But we needed a stronger system for energy planning and improvement. And energy planning requires an energy review.’
The Hanson EnMS includes an online ‘opportunities improvement database’ to record and manage site objectives and targets (management action plans). This includes ‘energy calculators’ to calculate potential savings from installing more efficient equipment, such as lighting, compressors, fans and motors. There were already 18 health, safety, environment and quality ‘system’ procedures in the integrated management system (IMS) before 50001 and certification has resulted in addition of just one new procedure.
This requires each of the company’s 300-plus manufacturing sites, as well as its Maidenhead head office and IT and shared service centre in Chipping Sodbury, to identify ways to reduce consumption. Only those activities that are exempt from ESOS, such as Mendip Rail, which Hanson operates with Aggregate Industries to move stone to London and the South East, and franchise fleet road haulage are excluded from 50001.
The EnMS process ensures energy management is linked to 14001 and constant improvement as well as to the firm’s overall sustainability targets, says Crow: ‘It seems obvious to link everything together, but historically the links were not clear. We now have a single target tying business and sustainability improvements together.’
Hanson uses kilowatt-hours per tonne (kWh/t) to measure energy use and is aiming to reduce overall consumption by at least 5% against 2010 levels by 2020. In 2015, each site needed to cut energy consumption by 2%. Site targets are reviewed yearly. The firm uses a reporting system, called Entropy, to record and monitor data and information for energy and water use. It feeds into the IMS, recording actions and improvements, and tracking them to ensure they are carried out. The sustainability department has a dedicated IMS audit team and site energy consumption is monitored each month. A non-conformance is raised if a site is more than 5% off where it should be to achieve its energy reduction target. ‘We investigate and, if the variation is not due to a mistake in the data, the manager must develop and implement an action plan to get the site back on course,’ says Crow.
Challenging environment
Achieving the energy reduction targets is a challenge, however, as most of Hanson’s production operations are energy intensive and consumption can fluctuate widely with demand and product mix. Energy consumption per tonne increased in 2014 by 2.9% compared with 2013 and by 6.5% since 2010, according to Hanson’s 2015 sustainability report. It equates to energy consumption of 94.14 kWh/t in 2014 against the overall 2020 target of 83.94.
Nonetheless, Crow believes 50001 will help Hanson make the necessary reductions because the standard has enabled the company to examine energy use across its product range. It highlighted that its three cement plants – Ketton in Rutland, Padeswood in Flintshire, and Ribblesdale in Lancashire – were consuming more than 70% of its energy, with five other operations using a further 10%. ‘14001 did not focus on our big energy users and, until we started working on the energy management standard, we looked at energy across the whole company and set our targets accordingly,’ Crow says. ‘But now we are focusing our efforts on the operations where we can make the most difference. We’re not ignoring the other sites, as there are always opportunities to reduce energy if you look closely enough, but tackling consumption among the biggest consumers should help us reach our targets.’
Energy reduction initiatives at the three cement plants include greater use of alternative fuels. These include profuel – a solid kiln fuel made from paper, plastic and fibrous wastes that are either uneconomic or impossible to recycle – and solid recovered fuel, which is derived from domestic waste and biomass. More than 207,000 tonnes of waste were used to power cement kilns at Hanson’s three sites in 2014, around 61% of their total energy consumption. The Ketton cement works, which consumes 30% of the energy used by Hanson each year, completed the installation of a 12MW solar array in July 2015. It comprises 50,644 solar panels and will save 3,420 tonnes of carbon dioxide emissions a year, provide 13% of the site’s annual electricity consumption and cut its energy bill by around £10m.
Hanson has established a group of significant energy using facilities (SEUFs). It consists of the eight largest energy users in each business division or those that consume more than 2% of Hanson’s total energy. Each of the 32 sites will undergo a full energy survey at least every six years, with six audits completed annually. Several sites, including Whatley quarry in Somerset, were audited in advance of 50001 certification.
Over time
Another challenge to driving down consumption is that, over time, energy demand can rise as a site, particularly a quarry, matures. ‘Generally, the reserve [rock] is close to the plant when a quarry begins production,’ says Crow. ‘But as time goes on, the rock is further and further away from plant so trucks travel a greater distance. And, the deeper the quarry gets, the more water comes, which means more pumping.’
Whatley illustrates how difficult it can be to cut energy consumption in such an environment. The quarry, Hanson’s largest, producing around 4 million tonnes of aggregate a year, is in a belt of steeply dipping carboniferous limestone in the Mendips. Since the present plant opened in 1987, the quarry has expanded and now covers 120 hectares. It is more than 100 m deep, and the furthest point is around 1.6 km from the plant. As it has deepened, its base has sunk below the natural water table and up to 25 million litres a day in the winter and 15 million litres a day in the summer have to be pumped out. The water is pumped into the plant to clean the aggregate before being recycled and discharged into the Whatley Brook or pumped into the Mells River to help maintain its flow.
The team at Whatley has done much to reduce energy consumption. Simple measures include: stopping the crusher conveyor belts when they are empty and when operators take a break; replacing conventional office lighting with LED bulbs; turning lights off when production buildings have no one inside; and embedding awareness among staff by promoting energy reduction and through a ‘switch it off’ campaign.
Pat Orman, maintenance manager at Whatley, says the audit of the site before 50001, which was conducted by energy services business Ameresco, identified several areas where savings could be made. One focused on making more efficient use of pumping equipment. ‘There are three large pumps at the bottom of the quarry running 24 hours a day, 365 days a year,’ Orman says. ‘We also have a plant supply pump that feeds water around the quarry for dust suppression. We have stopped using the supply pump and have installed pipework to feed off the larger pumps. The annual saving is £27,000.’
Whatley also hosts an asphalt plant, which produces around 350,000 tonnes a year, and further investment is planned to improve it, says Hadley Alexander, asphalt operations manager. ‘The forms required by the energy management system have been completed and improvements identified. These include replacing the old Marini plant with a modern and more energy efficient one. Measures already taken include a new covered aggregate storage area to reduce energy use for drying material.’
The opportunities and improvements database allows sites to share ideas on saving energy. ‘If we see something we think can work here, we’ll investigate,’ confirms Martin Symons, production manager at Whatley. He says Hanson now bases its investment decisions on the lifecycle of equipment rather than the initial cost.
More than carbon
The 50001-certified EnMS and the introduction of ESOS have shown how energy reduction has been accorded a higher priority at Hanson. ‘Before ESOS the main focus was on driving down carbon emissions,’ says Crow. ‘We’ve still got a challenging 2020 carbon target [to reduce emissions by 10% against 2010 levels], but improving our energy efficiency is also a key objective.’
On the achievement of 50001 certification, head of sustainability Paul Lacey says: ‘This forms an important part of our drive to embed energy improvements across the business and demonstrates our commitment to reducing energy use, maximising carbon efficiencies, delivering products and services with lower embodied carbon and supporting national and European energy and carbon reduction targets. Having an energy management system that meets the standard also represents a significant step towards achieving our own challenging 2020 sustainability goals.’
Case study: VSD project at Bulls Lodge
In 2014 an audit of the Bulls Lodge sand and gravel quarry near Chelmsford, Essex, revealed several opportunities to better control the site’s water process pumps by installing variable speed drives (VSDs). ‘A trial indicated that the site could achieve potential annual savings of more than £45,000 for an initial outlay of around £65,000. That’s a potential 15 months’ payback,’ says Mat Newton, Hanson’s energy manager.
Sand and gravel quarries are pumped to allow them to be worked dry or operated as lakes with extraction below water level. Normally, a conveyor draws raw material into the processing plant, where unwanted clay and silt are removed and the sand separated, dewatered and stockpiled. Gravel then passes over a series of screens that sift it into different sizes.
Washing involves a significant amount of water. Bulls Lodge also has asphalt and concrete plants, both of which have a number of water pumps.
VSDs convert the incoming electrical supply of fixed frequency and voltage into a variable frequency and variable voltage that is output to the motor with a corresponding change in the motor speed and torque. Speed can be varied from zero rpm to typically 100–120% of its full rated speed in either direction. Using VSD to control the flow rate from a pump can result in large power savings given that a small reduction in speed to more accurately match demand can significantly reduce power consumption and enhance the operational life of some equipment.
Newton says VSDs offer several benefits, some of which are relatively easy to quantify, and others that are less tangible. Energy savings on rotodynamic pump installations are typically between 30% and 50%, for example, while motors running at lower speeds are quieter and there is less wear, particularly in bearings and seals. And, by matching pump output flow or pressure directly to the process requirements, small variations can be quickly corrected by a VSD than by other forms of control, which improves process performance.
Learning points
- Do a gap analysis, comparing current management systems and the requirements of ISO 50001
- Identify the largest energy consumers
- Set energy targets
- Establish a system to drive continual improvement
- Facilitate the sharing of energy-saving ideas
