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Reduction of Life Cycle Greenhouse Gas Emissions from Roads: The Role of Life Cycle
Assessment and Benchmarking
John Harvey, Ph.D., P.E. Hui Li, Ph.D., P.E.
University of California, Davis
8 July, 2015
The International Scientific Conference “Our Common Future under Climate Change” 7-10 July 2015, Paris, France
Outline
• Road Pavements & Environmental Impacts
• Life Cycle Assessment (LCA) for Pavement
• Standardization and Application of Pavement LCA
• Benchmarking of Pavement LCA
• Gaps of Pavement LCA
• Recommendations
2
Why Care? Pavement Facts (US)
• Scale: 4 million miles public roads, 2.65 million miles paved (asphalt or concrete) roadways
• Mobility & access: three trillion vehicle miles travelled annually
• Value: Roads carry about 67 percent of all freight in the US (tons and $)
• Employment: 300,000 people employed in roads and bridges
• Cost: $182.1 billion spent on highways per year
• Owners: State and local governments, private and institutional owners, federal government
3 Source: FHWA Pavement Sustainability Reference Document Image sources: Pixbay.com and Microsoft Clip Art
Why Care? Pavement Facts (US)
• Energy used each year: vehicles moving on pavement burn 640 billion liters (169 billion gallons) of fuel
• Natural resources used each year (million metric tons): 1,200 crushed stone, 987 sand/gravel, 21 asphalt binder, 72 cement (incl. bridges), all highly recycled
• Emissions from road system: Greenhouse gases (GHGs), air and water pollutants
4 Image sources: Pixbay.com and Microsoft Clip Art Source: FHWA Pavement Sustainability Reference Document
In US, road vehicles
are largest contributor
in Transportation –
With Gasoline and
Diesel accounting for
90% of all emissions
Pavements affect
vehicle fuel use
5
Electricity 31%
Industry 21%
Commercial and
Residential 12%
Agriculture 9%
Transportation 27%
Why Care? Greenhouse Gas Emissions (US)
US Greenhouse Gas (GHG) Inventory 2013, US EPA
Why Care? Material Flows Developed and Developing World
• Developed World
– Natural resource consumption grew with road deployment
– Few new roads being built (now)
– Aging road networks require maintenance, rehabilitation (now)
• Developing world
– Deploying new road networks
From: Sullivan, 2006 6
• CO2-e emissions • India is only beginning road network • Need to work with China and India • In developed world every industrial sector needs
to contribute to reduction
Environmental impact =
Master Equation for Environmental Impacts
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Ehrlich and Holdren (1971) Impact of population growth. e.g. via LCA Science 171, 1211-1217 Slide adapted from R. Rosenbaum, Pavement LCA 2014 keynote address
Population * GDP
Person* Impact
GDP
Increase in wealth and economic activity
Technological efficiency
Life Cycle Assessment (LCA)
• If we are to improve sustainability of pavement must be able to measure impacts
• LCA provides a method for characterizing and quantifying environmental sustainability using a cradle-to-grave perspective, and considering system-wide impacts for a product, policy, or system.
• The purpose of an LCA is typically to compare the performance of alternatives, to anticipate unintended consequences of a decision or technology, or to identify environmental “hot spots” that might be targeted for improvement.
8 ISO = International Organization for Standardization
W, P W, P W, P
Generic Life Cycle Assessment
Raw Material
Acquisition
Material Processing
Manufacturing or
construction Use
End-of-Life
Recycle
Remanufacture
Reuse
M,E
W, P W, P
M,E M,E M,E M,E
M = Materials E = Energy W = Waste P = Pollution = Transport
Recycle
Kendall, A., Keoleian, G. A., 2009 9
- Pavement performance - Rolling resistance - Albedo - Leachate - Lighting
Pavement Life Cycle
Materials Acquisition and
Production
Construction / Maintenance & Rehabilitation
Use End-of-life
- Material extraction and production
Transp
ort
- Equipment Use - Transport - Traffic delay
R R
- Recycle - Landfill
From: Kendall et al., 2010
R : Recycle
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Transp
ort
Where can we improve technological efficiency
- Materials and Pavement design
Development of Consensus on Practice of Pavement LCA
Next:
• Workshops in Aug 2015 – China
– South Africa
• 4th Symposium in 2016 in Chicago
Standardization and Implementation of Pavement LCA
• Europe – European Standard published in 2012 (EN 15804) – Development of national tools: Dubocalc (NL), Ecorce and
Seve (FR)
• US – Federal Highways Administration pavement LCA guidelines
in 2015 – Illinois Tollway moving towards use in contractor selection – Increasing development of Product Category Rules and
Environmental Product Declarations
• Rest of the world? Beginning to learn • Overall trend: consider Cost + LCA in pavement type
selection and contractor selection 12
Pavement Materials PCRs
13
• Specific to a material
• Typically cradle-to-gate (i.e., excludes use and/or end-of-life)
• PCRs (and EPDs) are available for many basic materials
• Becoming more prevalent
• Credits for EPDs in LEED v4
• Pavement PCRs – Cement, concrete, lime
aggregate in place
– Asphalt, asphalt mixes under development
Environmental Facts Functional unit: 1 metric ton of asphalt concrete
Primary Energy Demand [MJ] 4.0x103
Non-renewable [MJ] 3.9x103
Renewable [MJ] 3.5x102
Global Warming Potential [kg CO2-eq] 79
Acidification Potential [kg SO2-eq] 0.23
Eutrophication Potential [kg N-eq] 0.012
Ozone Depletion Potential [kg CFC-11-eq] 7.3x10-9
Smog Potential [kg O3-eq] 4.4
Boundaries: Cradle-to-Gate Company: XYZ Asphalt RAP: 10%
Adapted from N. Santero
Example LCA results
Environmental Product Declaration (EPD): Concise, quantitative information Increasingly important in pavement product competition
Example Pavement Scenarios That Can Be Analyzed with LCA
• Network level:
– Timing of maintenance and rehabilitation treatments, funding levels, policies for network application
• Project level:
– Selection and design of pavement structures, recycling strategies, pavement and rehabilitation design lives, materials sourcing and transport alternatives
• Evaluation of new materials, new structures, and new construction approaches
• Pavement heat island effects, water cycle effects, effects on lighting energy, effect on vehicle energy use, etc.
Takeaways
• Environmental considerations measured by LCA will increase as market drivers, considering all life cycle phases.
• New materials and structures are beginning to be benchmarked on their environmental impact with LCA.
16
World-wide Benchmarking
• Benchmarking of LCA should lead to better understanding of practice and results
– assumptions, life cycle inventory (LCI) process models, differences in inventory results for individual materials
• Benchmarking should also help increase the transparency of LCA
– to understand someone else’s data and assumptions and compare it to your own helps reduce the tendency to treat LCI results from any source as “golden black boxes”
– This is important because information in many inventories has been used extensively and is widely accepted, but has not been subjected to recent critical review
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Benchmarking of LCA: GWP with French and Californian Inventory and Assumptions
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Harvey J., A. Saboori, M.Dauvergne, W.Steyn, A.Jullien, and H. Li, and T. Wang. Comparison of New Pavement Construction GHG and Energy Impacts in Different Regions. The 2nd International Symposium on Pavement Life Cycle Assessment. Davis, California, USA. October 14-16, 2014.
Benchmarking of Pavement Design
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Spider diagram of all indicators (ECORCE) with French energy and HMA plant fuel.
Gaps – Technical and Implementation Issues
• Life Cycle Inventory data for much of world is sparse:
• Use phase modeling gaps
• End of Life approach
• Project delivery environment may affect LCA implementation – Europe: Design-Build or Design-Build-Maintain
– US: Design-Bid-Build (low-bid)
• Decisions regarding what LCA should be used for – Policy development
– Guidance for design and project management
– Design selection like Life Cycle Cost Analysis (LCCA)
– Part of contractor selection (like Netherlands, France)
Photo: D. Jones
Recommendations • Use LCA to evaluate benefits and unintended consequences of
pavement policy decisions before implementation • Integrate LCA principles and calculations into pavement design,
procurement policies and pavement management systems (PMS) • Encourage and facilitate an active and comprehensive market for
LCA data – PCRs and widespread creation of EPDs – Support and incentivize use and improvement of public LCI databases – Need for an authority and guidelines to resolve conflicts in PCRs
between industries
• Current gaps should be addressed to make pavement LCA more useful to decision-makers – Improved models for pavement-vehicle interaction – Additional tools and data (EPDs, and development of other data)
• Develop an approach for incorporating pavement LCA with LCCA into the design-bid-build project delivery process
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