There is no question about it. We are living in exciting times. Just this past year, 90 cities, ten counties and two states, have set targets for 100 renewable energy in the U.S. alone. Oil giants like Exxon Mobil and Shell are lobbying to advance the case for a carbon tax, solar is now cost competitive with fossil fuel powered electricity, and the Green New Deal is fundamentally changing the public’s rhetoric and confidence in climate solutions. Each day a fully decarbonized economy is looking more likely. However, the path to decarbonization is not linear.
For instance, while we are winning battles with low hanging fruit such as replacing gasoline powered light-duty vehicles electric vehicles, we lack the technology needed to decarbonize aviation. The crux of this problem is due to the prevailing heuristic—electrify everything and decarbonize that electricity. While this is a great solution, projecting our global carbon emissions by 2050 today entails that we must assess what sectors can and can’t be electrified with current technology, and what must be done if a sector falls into the latter column.
Our transportation and building sectors show a ton of promise. While some heavy-duty transport will face challenges, EVs are projected to make up 65 percent of new sales by 2050 and the replacement of fuel oil and natural gas by heat pumps for space and water heating in buildings is promising. Industry, however, does not show the same promise quite yet.
Industry is responsible for 28 percent of global greenhouse gas emissions. To make matters worse, due to rapid urbanization and material demand, while carbon emissions from the building and transport sector have grown by 23 percent since 1990, emissions from the industrial sector has grown 69 percent.
So, industry is an issue. It is a growing share of global emissions and it is a naturally hard sector to abate. This begs the question, why is decarbonization so hard? Why can’t everything be electrified? Looking at the four largest emitting materials in the industrial sector, the answer comes down to three technical reasons.
First, 45 percent of CO2 emissions can’t be abated by a change in fuels, only by changes to processes. What this means is that in the production process, CO2 emissions are inherent to certain products. For example, in cement production, limestone must be heated to make cement. Beyond the fuel used for heating, carbon naturally stored in limestone is released from the rock, and is responsible for 60 percent of carbon emissions, a process known as calcination. That means if cement production were completely electrified and powered by renewables, over half of the current emissions associated with production would remain.
Second, 35 percent of CO2 emissions come from fossil fuels that generate high-temperature heat. High heat as in over 3000 oF high. Similar to the issues around decarbonizing aviation, it is extremely hard to supply energy to equipment that needs this level of power without relying on the dense hydrocarbons found in fossil fuel.
Third, industrial plants have long lifetimes, which exceed half a century. Retrofitting old plants is met with a high level of aversion, and the economics of upgrading equipment in a retrofit case is much less favorable than choosing efficient equipment during new plant construction.
Industry does have plenty to improve on even with these roadblocks, and while more challenges exist in this sector, it should not discourage us from trying to decarbonize the sector. The following avenues exist. We should electrify where possible, use sustainably sourced biofuel and hydrogen fuel for technologies that can’t be electrified, offset emissions with carbon capture and storage, and restructure material use to curb demand-side pressure.
Many technologies can be electrified. The technologies that can’t be electrified don’t have to be powered by fossil fuel. With coal being the leading fuel used in industrial processes such as steel production, technology exists that can change these manufacturing methods to rely on sustainably sourced biomass, either in the form of wood pellets or liquid biofuel. In other circumstances, hydrogen fuel through renewably powered electrolysis will replace coal usage. For the 45 percent of emissions that aren’t related to direct fuel use, carbon capture storage, which traps CO2 from manufacturing-related emissions and sequesters it, will be deployed at an increasing scale.
These technologies are all feasible, but cost and growth of industry remain an issue. As these technologies scale up, we must compensate for the fact that we will be producing between 2 to 4 times the amount of materials in 2050 compared to current levels. The last and cheapest option is to not focus on production side measures, but instead rework our demand and build a more circular economy. Doing such is where the building sector comes in.
When we discuss the restructuring of our building sector, we focus on operational energy. We prioritize building efficiency, complete electrification, and onsite renewable generation. This makes perfect sense. Operational energy used in buildings consumes 40 percent of global energy, and when looking at the total footprint of a building, operations account for 80-90 percent of that footprint. However, exclusively focusing on building operations will make full decarbonization across sectors harder.
First, while the majority of a building’s footprint is from operational not embodied energy, the share of these two categories is evening out. In high-performance buildings, which are becoming increasingly prevalent with stricter building codes, electrification, and decarbonization, embodied energy is estimated to account for 50 percent of a building’s footprint.
Second, construction is the intersection between the building and industrial sector. Currently, the production of four materials are responsible for two-thirds of global industrial CO2 emissions. These materials are steel, plastics, aluminum, and cement. Think about the sheer quantity of materials needed to construct a single building. Compare the number of plastic bags, t-shirts or water bottles it would take to equal the material demand of construction. The result: construction is one of the largest use segments of global material consumption. One-third of steel, one-fifth of plastics, one-quarter of aluminum, and two-thirds of cement is consumed by the construction industry each year. It seems that if we need to decarbonize these hard to abate sectors, why shouldn’t we restructure the way the construction industry consumes material?
The good news is that solutions exist, and the better news is that to use less material does not demand that we all live in tiny houses. The sustainability consulting firm Material Economics outlines the steps needed to cut industrial emissions through buildings. By recirculating materials through better recycling efforts, focusing on more deliberate waste reduction, reusing building components, increasing material efficiency, and prolonging the lifetime of buildings we can transform the material demand needed, leading to cost-effective decarbonization of the industrial sector.
Recycling rates for construction and demolition waste are abysmal. Currently, only five percent of end-of-life steel from buildings is reused. Recycling demands fewer raw material inputs and therefore has a lower carbon footprint. Recycled material, such as aluminum is over ten times less carbon intensive than primary material, and the footprint of recyclable material is only expected to decrease between now and 2050. By designing for disassembly, increasing access to facilities, and incentivizing proper disposal through policy, we can increase recycling rates significantly.
Wasteful construction practices that exist are largely due to bad habits rather than necessity. Squaring our shoulders and getting on top of this problem can be instrumental in the effort to decarbonize industry. Waste rates during construction are between ten and twenty percent. That means for every five to ten houses built, an entire house worth of new materials is added to the waste stream. Increasing communication, planning, building material resources, and material return policies can reduce waste rates to under five percent.
The reuse of building components is a simple yet effective way to cut much of a building’s end-use demand entirely. Currently, 48 percent of wood in the construction and demolition waste stream can be salvaged but is still hauled to the dump. New construction can continue to upcycle materials that are currently sent to the landfill by employing networks that allow for easier access to salvaged materials and ending the practice of rapid demolition that results in material degradation.
Increased material efficiency refers to strategies that reduce new materials needed without impeding function. This has been seen in bottling companies redesigning plastic water bottles to cut down on material use. Overspecification in structural building codes leads to the use of 20-30 percent more cement than what is needed. Furthermore, advanced materials such as high-strength steel can cut material use by 30 percent. These avenues can open by disseminating structural information through building information modeling software and increasing the availability of specialized materials.
The simplest method is to lengthen the lifetime of our buildings. The average lifetime for buildings is 50 years. By designing with durability in mind, we can prolong the life of our buildings. Building lifetime can be extended further by ensuring buildings are adaptable. Over time, buildings change in function and architectural aesthetics shift. Designing buildings with increased modularity to allow for easier maintenance, renovations, and additions for either functionality or aesthetics will incentivize remodels over demolition for new construction.
Allowing the array of demand-side solutions to work in combination can yield immediate results in a sector that desperately needs solutions for emission abatement. Broadening the scope of green building to include responsible material use can play an instrumental role in exemplifying how other sectors can transition from a linear to a circular economy. If we focus on the demand side solutions proposed by Material Economics, we can reduce global industrial emissions by 56 percent. Using these strategies in conjunction with production side solutions such as electrification and carbon capture storage, we can transform industry from being a hard to abate sector to a carbon neutral sector in much less time and with much less money.
