Paving the Way to Sustainability: Cutting Carbon in Asphalt Production

Asphalt and bitumen plants, known for high energy consumption and emissions, face a dual challenge and opportunity on their path to sustainability. This article outlines some practical and innovative strategies that asphalt plant managers can employ to significantly reduce their carbon footprint, focusing on areas directly within their control.

Measuring to Manage: The First Step to Carbon Reduction

The journey to lowering carbon emissions begins with effective measurement. Understanding exactly what your plant is doing allows you to see the tangible results of any changes made. It’s crucial to measure and collect detailed energy data from all sources – be it electricity, gas, diesel, or steam. This data should be captured at granular intervals, ideally every 1-5 minutes, to enable accurate and meaningful process improvements.

Unified Energy Data

To make this data actionable, it needs to be converted into a common unit, such as kJs or CO2, using emission factors. This standardisation provides a unified view of energy consumption, essential for accurate analysis and decision-making.

Incorporating External Factors

 When evaluating energy usage, it’s beneficial to consider the impact of external environmental conditions, like weather. These factors can significantly affect energy usage, and understanding their influence can lead to more informed, effective decisions, for example, an often-overlooked aspect of asphalt production is the moisture content in the aggregate. 

It’s essential to understand that the drying process can significantly impact fuel consumption. In the production cycle, the first third is dedicated to combustion, the next to drying and heating the stone, and the final stage to mixing in the bitumen. However, if your aggregate is wet, the bitumen won’t adhere properly, necessitating an additional drying process.

The cost implications here are considerable. For instance, with an aggregate moisture content of 6%, it takes 4 litres of fuel to dry one tonne of aggregate. And that’s before an additional 3 litres of fuel are needed to heat the aggregate to 150°C. Clearly, the drier your aggregate, the less fuel required, translating to significant cost savings.

So, how can you minimise moisture content in your aggregate? Here are some practical tips:

Protective Measures: Cover your fine aggregate, particularly in winter, to shield it from rain. Fine aggregates, composed of dust and sand, are prone to retaining moisture.

Strategic Stocking: Always use stock from the top of the aggregate pile, where it’s likely to be drier.

Optimised Storage: Store your aggregate on a slope to facilitate water drainage.

By implementing these simple yet effective strategies, you can significantly reduce fuel consumption in the drying process, enhancing both the efficiency and sustainability of your asphalt production.

Automating Data Collection

Ideally you should be automating the data collection from various meters. An automated systems can feed into dashboards or reports, saving time and providing real-time insights for better decision-making. 

Automating data collection from fuel consumption meters, temperature sensors, and production output meters not only saves time but also ensures consistent and accurate data for analysis. 

Automated control systems  such as N2P’s TC404 enable quick adjustments to operational parameters in response to real-time data, allowing for immediate energy savings and process improvements.

Process Experimentation and Optimisation:

  • Experiment with a change in process such as adjusting baghouse temperatures or bitumen tank heating practices, and observing their impact on energy use. 
  • We have written a handy guide on Efficiency optimisation for asphalt plants which contains some useful suggestions to try.
  • Even short-term process changes, if data collection is accurate, can provide valuable insights.
  • Try using environmentally friendlier fuels (e.g., diesel from recycled tyres) or increasing the use of Recycled Asphalt Pavement (RAP) in mixes.

By managing and analysing energy data, embracing automation, and being open to process innovations, asphalt plants can significantly reduce their environmental impact.

 For those seeking to navigate these changes with expertise, N2P Control Systems offers solutions tailored to make your journey towards sustainability both achievable and profitable. 

Get in touch to explore how our technology and expertise can assist you in this vital transformation.