The Environmental Footprint of Infrastructure
University of California, Berkeley
Infrastructure, the backbone of everyday life, has contributed immeasurably to human progress. But as we operate, expand, and maintain infrastructure, we must also recognize its huge environmental “footprint”: greenhouse gas emissions, toxic discharges, water use and pollution, waste generation, human and ecological health impacts, and so on. In the face of climate change and dwindling resources, we must reduce this environmental footprint and maximize the benefits of our infrastructure.
Operating, expanding, and maintaining infrastructure costs a substantial fraction of our gross national product. Although these costs are enormous, we also reap enormous benefits from our infrastructure. In fact, we cannot function without it. Infrastructure is everywhere, but we tend to notice it only when something goes wrong, when a tap goes dry, when a bridge collapses, when phone lines go silent. Few of us stop to marvel at what infrastructure makes possible.
In fact, most people do not have a correct understanding of the concept of infrastructure. To many, the word means only the transportation and utility systems. But infrastructure is much, much more than that. It includes the buildings we occupy, the telecommunications system and the Internet, the energy economy, and the health care system.
Traditionally, society has worried about the technical, economic, safety, and quality performance of infrastructure systems. Lately, we have become interested in its economic costs, societal costs, and environmental costs.
SUSTAINABILITY—A PARADIGM SHIFT1
The U.S. interstate highway system (IHS) launched by the Federal Aid Highway Act in 1956 became the largest infrastructure project the world had ever seen. It was said that IHS would increase the defense readiness of the United States by providing reliable highways for the movement of military personnel and equipment and provide a backbone for interstate commerce. By the time the system was completed some 37 years and more than $400 billion later, it had far exceeded those expectations.
The new highways crisscrossing America from coast to coast and north to south contributed to unprecedented growth in the productivity of U.S. industry (by some accounts, 31 percent in the late 1950s; 25 percent in the 1960s; and 7 percent in the 1980s) (Anonymous, 2008). Interstate highways have made more things possible than anyone predicted. They changed American life forever.
But infrastructure must be periodically reinvented. The flagship investment of the 1990s was the Internet, which has profoundly changed the way we live, work, and play. Like IHS, the Internet has created jobs and eliminated jobs, opened new horizons, spun off new activities, increased productivity, brought many along on virtual road trips, and connected the world in Second Life (http://www.secondlife.com). The Internet became the world’s superhighway much faster than the interstate highways were able to connect the far ends of the United States. And the electronics and telecommunications industries became essential components of all the industries and systems in our infrastructure.
Today, the United States—as well as the rest of the world—needs breakthrough investments in the built environment on the scale and level of relevance of the IHS and the Internet. We need a paradigm shift in our built environment to the paradigm of sustainable development. Using life-cycle assessment (LCA), a systematic methodology that reveals the environmental impacts of every life-cycle stage of every component in the infrastructure, we have learned that buildings, transportation, and water and wastewater systems are responsible for the largest use of energy, water, and raw materials in the world. Physical infrastructure, which was once hailed as a high achievement, now causes people to turn away. Who wants to live near a highway? Or a power plant? Or a water-treatment facility?
Changing the environmental performance of infrastructure will take more knowledge and quicker action. Even as industries try to establish and mitigate their environmental footprint (e.g., industries in the European Union affected by
This section first appeared on the web as http://www.sitra.fi/en/News/articles/Article_2008-0319.htm.
carbon constraints and industries in the United States affected by sulfur dioxide (SO2) regulations), it is high time for infrastructure professionals and industries to get organized and move forward with evidence-based arguments and recommendations for sustainable development.
ENVIRONMENTAL MODELING OF INFRASTRUCTURE
The first things we will need are models of infrastructure. In all models, the real world must be abstracted to make problems understandable, solvable, and manageable. Environmental modeling of infrastructure starts with modeling the complex systems that underlie transportation, energy, water, wastewater, municipal and industrial waste management, telecommunications, and other systems and services. Modeling infrastructure is doubly difficult because most infrastructures are networks of systems with large geographical and temporal dimensions. For example, the electric power system in the United States is more than 100 years old and reaches every corner of this vast country.
Most of these systems, even though they lie within the geographical boundaries of a country, connect with international systems and have supply chains that span the globe. For example, the U.S. civilian air transportation system is closely connected to international civil aviation. Most of the aircraft owned by U.S. airlines were assembled here, but many critical components were produced (or partly produced) in other countries. Mapping these supply chains is often difficult.
Many products and processes, and therefore many economic sectors, are involved in the life cycle (planning and design, construction, operation, maintenance, end of life) of infrastructure systems. Analyzing thousands of products is difficult, but assessing services is even more difficult because descriptions, process models, and data are scarce. In addition, technologies are far from uniform across the United States, let alone internationally, and there are variations in all life-cycle phases. Thus modeling them all is a daunting task. We design, build, and operate infrastructure differently from one state to the next, not to mention from one country to the next, and these differences must be captured in abstracted models.
Once models have been created and tested, they can be translated into basic process-flow diagrams for environmental analyses. A few years ago I attempted to find a comprehensive process-flow diagram for making, delivering, placing, and curing concrete. Although we make and use one billion tons of concrete a year in the United States and 10 billion tons worldwide, I could not find a single model. Mapping the process flow of the Internet and the supply chains that contribute to its (mostly flawless) operation is an even more complex job. Clearly, we have a lot to do in the first step towards environmental analysis.
Many decision makers are aware of LCAs and their potential to provide infrastructure assessments. In principle, an LCA must quantify all of the resource inputs and environmental outputs of a product, process, or service, not just at the point of manufacture or generation, but through the entire underlying supply chain. Unfortunately, few have used LCA in practice, and it has rarely been applied to real-life situations.
LCA was conceptualized to change practices throughout the entire economy, protect human and ecological health, preserve resources, and support sustainable development. We need to begin using LCA to make infrastructure decisions. Billions of dollars must be invested in infrastructure, but they must be invested to improve environmental quality. Although there is a general consensus among societal stakeholders that this should be done, essential questions remain to be answered by LCA and other kinds of environmentally informed decision making.
Here are some sample questions for which we have no definitive answers:
Is solar-generated electricity more environmentally friendly than wind-generated electricity?
Is traveling by high-speed rail more environmentally efficient than flying or driving?
Should roadways be built to follow natural topographies or should we use cuts, fills, and tunnels wherever needed?
Does centralized wastewater treatment have lower energy requirements than decentralized treatment?
Should we build concrete or steel bridges?
What are the life-cycle environmental emissions of the U.S. telecommunications system?
Should water reservoirs be built on hills or on flat land?
These are just a few of the infrastructure decisions that must be pondered every day, and answering these questions correctly or incorrectly can have profound environmental implications. Yet for many of these types of questions we do not know whether one alternative is more environmentally friendly than another, and we are even farther from being able to supply robust answers based on absolute numbers. Although the temporal and spatial complexities of these kinds of questions are daunting, we must answer them, and do so correctly, lest we continue making decisions without forethought that may result in further environmental damage. Sadly, we are still many years from answers with an acceptable degree of certainty.
AN EXAMPLE: LIFE-CYCLE ASSESSMENT OF PASSENGER TRANSPORTATION MODES
This example illustrates the complexities and challenges of environmental assessment, especially using LCA. In a recent paper (Chester and Horvath, 2009), we explored the total energy, greenhouse gas (GHG), SO2, nitrous oxide (NOx), and carbon dioxide (CO2) burden of several types of passenger transportation: sedan; SUV; pickup truck; city bus; Bay Area Rapid Transit (BART) (considered a subway); commuter rail (Caltrain); and light rail (MUNI). For comparison, we included small, midsize, and large aircraft, and the Boston Green Line light rail (the oldest line of the Boston subway and the most heavily traveled light-rail line in the United States). The results are presented in Figure 1.
Our analysis was based not only on tailpipe emissions, a typical measure of vehicle emissions, but also on the provision of vehicles, the transportation infrastructure, and fuels, in other words, all of the life-cycle phases of vehicles, the physical infrastructure that makes travel possible (e.g., roads, rails, stations,
airports, etc.), and the stages prior to the combustion of fuels or generation of electricity.
Altogether 79 components associated with these transportation modes were analyzed (about 200 different calculations), representing a great variety of technologies, products, processes, and services in the Bay Area, the state of California, and Boston, as well as nationwide and worldwide, wherever the supply chains for these components reach. Thus assessing the environmental performance of these systems was challenging for many reasons, not least because the data were numerous and spanned many decades and were generally difficult to obtain. For example, components of some systems were built decades ago, and some are shared with freight transportation.
Our analysis showed that physical infrastructure and the provision of fuel contributed significantly to environmental effects. For example, they add 63 percent to road, 155 percent to rail, and 31 percent to air transport’s total burden, above and beyond tailpipe GHG emissions, as expressed in passenger kilometers. In addition, usage rates make a big difference in the total environmental burden.
Reducing the environmental footprint of infrastructure presents us with enormous tasks, but also enormous opportunities. Most of the energy we use in constructing, operating, maintaining, retrofitting, and decommissioning infrastructure is based on fossil fuels. We already know that carefully selected, produced, and used biofuels can reduce our fossil-fuel demand. Large-scale efforts, such as the Energy Biosciences Institute at the University of California, Berkeley (http://www.energybiosciencesinstitute.org), could lead to breakthrough technologies for infrastructure.
We must work with the supply chains of infrastructure systems to understand how we can reduce the environmental impacts of raw materials, equipment, products, and services before they are built into infrastructures. We also need to educate current students and the leaders of our society in how to achieve the highest environmental standards in the infrastructure organizations they support, run, finance, or regulate.
Environmental assessment of infrastructure was introduced in the scientific literature decades ago, and LCA studies were introduced about 15 years ago. But we must support current researchers and groom future researchers to improve their understanding of the complex, ever-changing set of systems that comprises our infrastructure. To answer even the most burning infrastructure questions, we will need many more studies that can lead to recommendations that can be readily adopted by practitioners.
A version of this section first appeared on the web as http://www.sitra.fi/en/News/articles/Article_2008-03-19.htm.
Investing in the new paradigm—that the future must be based on principles of sustainability—is the most significant investment we will make in this generation. The question is how far this investment will take us toward reaching our goal.
This material is based on research supported by the UC Berkeley Center for Future Urban Transport (A Volvo Center of Excellence).
Anonymous. 2008. America’s Splurge. The Economist, February 14.
Chester, M.V., and A. Horvath. 2009. Environmental assessment of passenger transportation should include infra-structure and supply chains. Environmental Research Letters 4: 024008 (8pp), doi: 10.1088/1748-9326/4/2/024008. Available online at http://www.iop.org/EJ/abstract/1748-9326/4/2/024008/.