PROJECT DESCRIPTION
BACKGROUND
The technical and economic feasibility, as well as the environmental desirability, of substituting fossil fuels in asphalt mix manufacturing plants needs to be demonstrated. Specifically, the three main processes from which emissions are generated aggregate drying, bitumen heating and electricity generation would be improved by the use of alternative fuels.
OBJECTIVES
The LIFE BATTLE-CO2 project aimed to demonstrate the incorporation of biomass as an alternative fuel in asphalt mix manufacturing. The project planned to develop a new plant configuration, establishing an almost fossil-fuel-free manufacturing process for asphalt mixes, reducing 95% the use of fossil fuels in the asphalt plant. The use of diesel and fuel oil would be avoided in the thermal energy processes in the plant (aggregates and bitumen heating). Biomass incorporation and the reduction of other contaminants associated with the combustion of fossil fuels would significantly reduce greenhouse-gas emissions. The project planned to thus optimise the use of biomass and reduce the carbon footprint of the manufacturing process and the lifecycle of the asphalt mix product.
Tests would be carried out to evaluate the quality of the new products by laying down different asphalt mixes at a construction site for example. The aim was to demonstrate the technical, environmental and economic feasibility of the new manufacturing process. Finally, the project planned to develop a protocol for generating the Product Category Rules (PCRs) for a new Environmental Product Declaration (EPD) for asphalt mixes that will allow other companies to calculate their environmental impacts, easing the deployment of green public procurement in the road construction and maintenance sector.
RESULTS
The LIFE BATTLE-CO2 project demonstrated the feasibility of using alternative and renewable energy sources (solid biomass) in asphalt plants, avoiding the use of fossil fuels in two very energy-demanding points of the process: aggregates (usually heated with fuel oil or natural gas) and bitumen heating (usually carried out with diesel).
Two prototypes for the use of biomass in these processes were installed in the asphalt plant of COLLOSA in Cubillas de Santa Marta, Valladolid: one prototype for the bitumen heating and one for the aggregate heating (rotary drum and burner). The plant became the first asphalt plant that can operate using both fossil fuels and biomass, including a mix of the two depending on the production needs. The mix of the two increases 25% of the production rate of the plant with nearly zero increase in the GHG emissions. This plant is able to manufacture asphalt mixtures using biomass as fuel for aggregates and bitumen heating with a production rate of 35 tonnes of asphalt per hour. Under this set-up, the amount of GHG emissions produced by the plant is reduced by more than 80%, saving nearly 25 kg CO2 per tonne of asphalt mixture manufactured. In the same way, the plant can operate using a mixture of both fuel sources, increasing its production capacity by 20% with no increase in GHG emissions.
The characteristics of the asphalt manufactured under the project were tested at two demonstration sites on two different roads in Spain. Up to 1 000 tonnes of asphalt were laid on the two road sections, confirming that the characteristics and properties of the produced asphalt are equivalent to conventional asphalts.
The project originally intended to demonstrate a third prototype using electricity generated from the thermal waste of the plant via the integration of an Organic Rankine Cycle system. However, the first analyses revealed that although technically feasible, the system was not cost effective, and it was therefore discarded.
The project has developed specific Product Category Rules for the asphalt mixtures following the ENVIRONDEC certification system. In this way, any company in the world has the option of following the protocols and communicate their environmental results in compliance with the standard ISO14025 (environmental label type III). Indeed, during the project COLLOSA obtained the first certification using this standard, becoming the first company with certified Environmental Product Declaration.
From an economic point of view, and based on the assessment developed by the project team, replacing fossil fuels with forest biomass for bitumen heating lead to interesting cost savings , depending on the price of the fuel. This lead to a return of investment of between 3.7 and 5.4 years. Similarly, and always depending on the cost of the fuel, replacing fossil fuels with wood pellets for aggregates heating can lead to return of investment of 2.3 years for wood chips and 9.6 years for wood pellets.
The project represented a change of mindset in the sector of asphalt manufacturing regarding energy supply and use of fossil fuels. The demonstration that the use of a renewable source of energy is a real option opens new opportunities for both the asphalt sector and the producers of biomass, with clear benefits in terms of energy consumption and reduction of GHG emissions, underlining the high demonstration character in a new context, the one within the civil works sector.
Coinciding with the end of the Project, the Ministry of Transportation, Mobility and Urban Agenda has adhered to the National Ecological Public Procurement plan, which specifically includes the Road sector.
Further information on the project can be found in the project's layman report and After-LIFE Communication Plan (see "Read more" section).
