Pradeep Sahukar
Case Western Reserve University - Weatherhead School of Management
Chris Laszlo
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A great public-private partnership that is currently building one of the major railway construction in London, U.K. The two companies have integrated together to reduce carbon footprint through innovations. One such innovation is the creation of low weight aggregate from the tunnel clay. They are also sharing their lessons learned and possible innovations that could be incorporated in the design phase of new constructions.
Bechtel is a pioneer in the program & project management space. They utilize their Six-Sigma methodologies to identify potential process efficiency opportunities. Together with Crossrail and other some small & medium enterprises, Bechtel has been able to create a comprehensive sustainability program by way of innovations that address the question of environmental impact. Some of these innovations will become a benchmark for large-scale projects through the country and across the world.
One of the major causes of CO2 emissions in the construction industry is during the production of cement. During the process of converting calcium carbonate to calcium oxide CO2 is emitted, as well as when the hydrocarbon derived fuel is used in the kiln that calcize the clay, CO2 is emitted. Together with a small group (3 members), Bechtel has come up with an innovative idea of converting the tunnel clay into low weight aggregates. The clay excavated from the tunnels is used and pellets are formed and put through the kiln to produce aggregates that can be used to manufacture concrete. This is used as a substitute for limestone or granite aggregate. Bechtel's trials used 50% substitution with the consequent benefits of reducing the mass of the concrete (this can release significant value in terms of property development, allowing a developer to build higher with no increase in foundations). It also saves on the damage done to the environment by quarrying operations - impacts on inter alia ecology & water resources.
Use of these process efficient techniques, Bechtel & Crossrail have been successful in reducing the carbon footprint by 10 percent within the overall construction lifecycle. Key partnerships have enabled the Crossrail project to reduce energy use, such as the use of hybrid excavators that consume 25 percent less fuel and produce 30 percent less carbon emissions than conventional excavators. They also substituted nonpetroleum biodiesel fuel in generators used to operate cranes, selected LED site lighting that consumes 47 percent less energy, and relied on zero emission hydrogen fuel cells as portable power sources. By monitoring digital dimming, movement detection, and photocell light equipment, the team was able to provide a continuous real-time picture of consumption that helped to promote operational efficiencies.
With more than 250 machines spread across nearly 40 construction sites, Bechtel and Crossrail achieved an 85 percent reduction in particulate emissions on Europe’s largest construction project. Through a combination of new engine performance standards, retrofitting of particulate controls, hybrid technologies, and training, the project has significantly reduced particulate emissions.
Bechtel as a construction company is playing a major role in building better infrastructure. Crossrail’s comprehensive carbon management plan is aggressive. After estimating that 15 percent of the project’s lifecycle carbon emissions would be attributable to construction, Bechtel set out to reduce the carbon footprint by 5 percent — all without increasing costs. This led Bechtel to work with many partners to find alternatives to reduce the carbon footprint. As a result, Bechtel and their partners were able to find innovative ideas/solutions that addressed the traditional carbon emission footprints by means of heavy construction. Since most of the excavation led to lot of clay being taken out, they worked with a local partner to see if they can use this clay to make low weight pebbles and use them in the construction. To date, they have exceeded these goals — cutting emissions by nearly 10 percent.
Their way of doing meaningful business is to engage and collaborate with small & medium enterprises such as the David Ball Group & the Newstone and help them grow. Bechtel sees itself being a part of the growth journey of these small & medium enterprises. “Some of these small enterprises don’t have the pressure from the shareholders, so they invest time & effort in building or innovating products that will enable them to grow. That coupled with demands from the stakeholders is creating a ripple effect requiring innovation at all levels, be it at the client level or down the supply chain and so it is important that companies like Bechtel & other large corporations work with these small enterprises and help them by providing key subject matter expertise,” says Mike De Silva. He also said that the sweet spot is to find an innovation that reduces cost as well as provides a performance benefit. Bechtel as an organization has seized this opportunity of partnership and have created a “Future Fund”. Its objective is to identify the innovative and technological opportunities that could help the company work more safely, increase productivity, and reduce costs. In his paper titled “Sustainability and the Property Lifecycle”, Mike said that when presented with a wide range of options, "the choices we make should be deliberate and seek to balance economic, environmental and social costs and benefits at a local and global level." And through the conversation it was clear that Bechtel as a company embodies this to generate sustainable value for their clients.
The low weight aggregate used from the tunnel clay is used as a substitute for limestone or granite aggregate. Trials used 50% substitution with the consequent benefits of reducing the mass of the concrete (this can release significant value in terms of property development, allowing a developer to build higher with no increase in foundations). It also saves on the damage done to the environment by quarrying operations - impacts on inter alia ecology & water resources.
Carbon calculations based on importing granite from Scotland to SE England versus locally converting the clay to aggregate showed a 50% reduction. It is important to note that (normal) aggregates are purchased by the tonne but are used in concrete mixes by the cubic meter. This is because concrete is sold by the cubic meter. When comparing the price of different aggregates, it is necessary to take account of their density. Thus, one tonne of LWA replaces 4.3 tonne of normal aggregates. When this was considered the cost of the clay based aggregate was £20/tonne and "normal" aggregate £25/tonne (June 2013 prices).
Reduction in the use of tradition lime stone aggregates reduces the carbon footprint. This method saves the damage done to the environment by quarrying operations - reducing the impact on inter alia ecology and water resources. Using these innovative ideas, Bechtel has helped Crossrail reduce the carbon footprint by nearly 10 percent, without adding costs to the project.
This new infrastructure addresses the UN SDG Goal #9, and specifically the goal of developing quality, reliable, sustainable, and resilient infrastructure, including regional and trans-border infrastructure, to support economic development and human well-being. Reduction in carbon footprint through out the construction process allows the infrastructure to remain sustainable. It also addresses the UN SDG Goal #17 through a successful multi-stakeholder partnerships. This innovation was done in partnership with Crossrail and a small group in the U.K., by way of sharing knowledge, expertise, technology, and financial resources, to support the objective of total carbon footprint in the project.
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Michael De Silva, Sustainability Manager - Crossrail Project
