Cement is one of the most used materials and also one of the industries with the heaviest carbon footprints globally. For Rick Bohan, Senior Vice President of Sustainability for Portland Cement Association (PCA), it's also part of the solution towards carbon neutrality. Concrete can make buildings more energy efficient, roads more fuel efficient, and it can be repurposed, recycled and reused over time, he says.
With a holistic approach to the construction supply chain, PCA drew a plan that foresees actions that include new technologies, the use of additives in cement and concrete, reducing the use of fossil fuels in construction and rationalizing the use of resources across the entire value chain, in addition to regulatory changes and increasing support from the government. No material will get us to carbon neutrality alone, but with a joint effort it is possible to reach carbon neutrality.
What is the US cement industry's strategy towards decarbonization?
We're looking at a full value chain approach that uses all sorts of technologies through the cement production process and optimizes the use of cement. Our approach to carbon neutrality includes carbon capture as well as the production of low carbon cements. We know right now that our clinker levels in cement are higher than in Europe, but if you look at the clinker amount in concrete, it is roughly the same. It’s interesting because here in the US, the ready-mix concrete industry tends to use fly ash and slag at the concrete producer level, whereas in Europe they put it in during the cement production. In any event, we're looking at lower clinker levels in cement and lower amounts of cement in concrete. To lower clinker levels, we are replacing clinker with decarbonated raw materials, such as slag and limestone.
We are seeing a great number of companies announcing the shift towards portland limestone cement over the past few months…
In the US, we're seeing a rapid shift towards portland limestone cement (PLC), and there are a couple of reasons for that. One reason is that users and the government have realized that this is a really easy win for them - PLC can reduce the carbon footprint of cement by 10 percent right off the bat, so we're seeing a lot of demand for the product. Likewise, on the supply side, every plant can produce PLC, and almost on a weekly basis, we're seeing more and more plants and companies moving to PLC. In addition to PLC, which reduces the clinker in cement, our roadmap also includes reducing the amount of cement in concrete, which can be replaced with other materials such as fly ash and slag. Fly ash is a byproduct of burning coal, and here in the US we're shutting down a lot of coal-fired power plants. Incorporating fly ash into concrete allows the material in fly ash storage facilities to be purposefully reused.
Are there standardization challenges in this shift, for example, in concrete formulations?
It’s a question of optimization. When you build with concrete, you can optimize material use by assessing the best approach or formulation needed for a particular application. For example, a designer can use a more traditional approach – for cement, this is known as ASTMC 150 – or they may use a blended cement - what's called a C595 - or maybe they want to use a performance-based specification for cement - an 1157 product. It’s also possible that they’d look at the project and rather than using two types of aggregate in the cement blend, decide they are going to use three or four. Back in the day, it was unusual to see people using any material beyond fly ash in concrete. Nowadays there are designers taking advantage of this whole menu of opportunities, and they are incorporating everything that's available. By also focusing on using aggregates that are locally available, they’re helping reduce the carbon footprint even further. This is really what our roadmap is all about, taking a holistic approach and being intentional about how we use cement and concrete, where and when we use it, and the professionals involved. This helps reduce the carbon footprint as we go from clinker to cement to concrete, and then, in the construction phase. And we want people to realize that concrete is not a problem, concrete is the solution. On one hand people say, ‘cement and concrete have a CO2 footprint’, and that’s correct, but we’ve also got a roadmap to carbon neutrality. Not only can we get to carbon neutrality, we can do so by addressing the great challenges we are facing as a society – things like infrastructure that can withstand the realities of climate change. This is a great opportunity for collaboration as it’s critical to get support from both the policy side and the public to realize and enact these changes.
Is there an approach to the rest of the cement value chain?
Even though we don't control the downstream portion of our value chain, we're taking the lead by showing people different opportunities they have. Take construction for example. The construction sector has recognized the need to optimize how they build and make it more efficient. In addition to looking at the construction schedule, companies are considering other construction-related activities with heavy emissions. For example, there is a lot of carbon that goes into things like earthwork. So, shifting from earthwork equipment that uses diesel to natural gas power or to electric vehicles is an opportunity to reduce emissions. Another example is preparing buildings for occupancy. Many people don't realize that when a building is built, before the tenants move in, there is a lot of testing on the heating, mechanicals, the pumps for fire protection, and other systems. This is referred to as flush and fill; we're filling things up and flushing them out to make sure everything works. There’s a lot of energy that goes into that process, and we’re starting to realize how wasteful it is and finding a better way to do it. These are a couple examples of how the construction section is focusing more and more on optimization. That's a key part of our roadmap, the whole concept of optimizing. We can control optimizing the production of cement and concrete, and we want to encourage and inspire those that use this material to optimize as well. The final link in our value chain is carbonation. You might be surprised to learn that 10 percent of CO2 emitted during the manufacturing and transportation of both cement and concrete is going to be absorbed back into the concrete over its lifetime. It doesn't happen overnight, but as long as you have an exposed concrete surface, that CO2 is going to be absorbed and permanently sequestered. And then, at some point in time, that concrete building will be demolished and hopefully recycled. When you demolish a concrete building you are increasing the surface area of the concrete, meaning it can absorb more CO2. Then you can take that concrete, crush it in smaller parts and use it either as aggregates in fresh concrete, or potentially you can use it as a raw feed in the cement kiln.
Regarding regulations, what are the main constraints that the US cement industry faces to advance in, for example, carbon capture technologies?
Carbon capture in particular is going be a very expensive venture. By expensive, not just financially, but also in terms of energy. What you're really doing is building a plant within a plant, and the amount of energy that it's going to require is significant. The capital expense and the operating expenses that go with carbon capture is not something the industry can absorb overnight. The industry has identified 10 key policy priorities, one of which is the need for support from the government in the form of tax incentives, grants and subsidies, as well as updating regulation. This would apply to carbon capture as well as a number of other solutions we’ve identified. We need to know from the government how new technologies are going to be permitted and how we demonstrate compliance. For carbon capture, we also need to think about what happens to the carbon after it’s captured. For example, in some regions of the country, there are facilities where we can ship CO2 and it can be used for things like oil recovery or turned into some kind of product, but that’s not yet available widely.
So infrastructure will be critical for this technology to advance?
Infrastructure is a big piece of the puzzle for the United States to consider and not just for carbon capture. In addition to needing a pipeline to help move captured carbon, we’ll also need pipelines when we move away from traditional fuels and increase uptake of transitional and transformative fuels like natural gas and ultimately, hydrogen. These processes also use a lot of energy, and that means we need a much more reliable and robust electric grid. So, not only are we talking about pipelines, we're also talking about power lines. The public has to be aware that industries like cement manufacturing can get to carbon neutrality, but to do that, there has to be supporting infrastructure built out. It’s also important that this infrastructure is built efficiently and in an environmentally sound manner. You can see this goes beyond just one plant - this isn’t an issue solely for the industry to address but rather society more broadly – we need support from academics on the research side, government on the policy side, and the public on acceptance.
Are there financial incentives in the US that support the implementation of new technologies such as carbon capture or the development of clinker-free cements?
We have talked very extensively with the federal government, in particular the Department of Energy, about programs to incentivize innovation. Currently, a program called "45Q", a government tax credit to incentivize carbon sequestration technology, is being tailored to increase effectiveness. Right now, we like the idea that the program exists, but it's just not enough, and we’re supportive of trying to expand it. Regarding lower carbon cement and concrete, we’re working with various government agencies to increase adoption. However, we don't want to sacrifice the strength, durability, resilience and sustainability of the concrete that everybody has come to expect. The answer isn’t recommending using less cement, clinker or concrete – making that the only solution will impact the strength, durability and quality of our infrastructure. The government recognizes that, and we're working to educate political leadership as part of this process.
What would be required on a national and state level to accelerate the adoption of these technologies (e.g. carbon capture and clinker-free cement)?
There are a number of major policy levers that need to be implemented by national and state governments in order to move forward with our goal to carbon neutrality. A few that we’re advocating for in the near-term include carbon capture, streamlined regulation and permitting, acceptance of alternative fuels and acceptance of lower carbon cement blends. For carbon capture, we need accelerated research, funding and investment in manufacturing, material innovation and carbon capture, utilization, and storage (CCUS) technologies and associated infrastructure. We also need more streamlined regulation and permitting practices for facility and infrastructure modernizations. We need acceptance of coal combustion residuals (CCRs), alternative fuels, CCUS, and other technologies. We need market acceptance of new, lower carbon cements. PLC, for example, is available now and many plants are producing this cement mix which has a carbon footprint 10 percent lower than traditional portland cement. What we need is for those that are tasked with specifying materials for private and public projects to ask for PLC. Finally, adoption of performance-based standards when specifying building materials is key in the near term.
The bipartisan infrastructure bill and public works have started to require the use of materials with a lower carbon footprint. How is the cement industry in the US coping with these new requirements and how will it affect the cement industry?
The cement industry is already working to produce lower carbon options, including many plants transitioning over to producing PLC, which reduces carbon emissions up to 10 percent. We want to ensure that these new requirements are considering the bigger picture, and what it really means to “go green”. Because concrete is a carbon sink, it could already be considered a low-carbon material. Over the course of its lifecycle, a building could reabsorb and permanently sequester about 10 percent of the CO2 emitted during its production. Concrete also makes buildings more energy efficient, roads more fuel efficient and requires less maintenance over time in comparison to other materials. It can also be repurposed, recycled and reused, saving infrastructure resources and minimizing time, energy and money spent on new construction. In addition to this, our roadmap to carbon neutral also charts out actions that will help further reduce the carbon footprint of cement and takes into account the entire value chain.
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