GHG Emissions Control Options Opportunities for Conservation

SPECIAL REPORT 298: DRIVING AND THE BUILT ENVIRONMENT: THE EFFECTS OF COMPACT DEVELOPMENT ON MOTORIZED TRAVEL, ENERGY USE, AND CO2 EMISSIONS GHG Emissions Control Options Opportunities for Conservation Kara Kockelman Matthew Bomberg Melissa Thompson Charlotte Whitehead The University of Texas at Austin Paper prepared for the Committee on the Relationships Among Development Patterns, Vehicle Miles Traveled, and Energy Consumption Transportation Research Board and the Division on Engineering and Physical Sciences 2009 GHG Emissions Control Options Opportunities for Conservation KARA KOCKELMAN MATTHEW BOMBERG MELISSA THOMPSON CHARLOTTE WHITEHEAD The University of Texas at Austin his paper summarizes the magnitude of greenhouse gas (GHG) emissions reductions one can T expect from a variety of widely discussed (and often debated) policies and design strategies. These include vehicle technologies, transport modes, fuel types, appliances, home and building design, and land use patterns. Through a detailed review of existing literature, the work strives to identify the greatest opportunities for carbon savings, reflecting, to some extent, cost implications and behavioral shifts needed. Greatest near-term gains mostly emerge in relatively conventional vehicle design shifts, dietary changes, and home weathering. In the medium term, significant energy and emissions savings are likely to come from fuel economy regulations approximating those abroad, appliance upgrades, plug-in hybrid purchases, home heating and cooling practices, and power generation processes. In the longer term, building design practices, carbon capture and sequestration, and a shift towards cellulosic and other fuels appear promising. Ultimately, however, to achieve 50- to 80-percent reductions in GHG emissions, relative to current or past levels, major behavioral shifts are probably needed, motivated by significant fuel economy legislation, energy taxes, household-level carbon budgets, and cooperative behavior in the interest of the global community. Additional Details Fuel efficiency standards remain a critical part of the energy and climate change equations. Under current targets, the U.S. will only be at 35 mpg by 2020, though China is already there and Europe is already over 40 mpg. Importantly, fuel efficiency standards are not as draconian as the auto industry has made them out to be: the technology to achieve a 35 mpg fleet average (and higher) is already available, and vehicles achieving this fuel economy will pay for themselves within the vehicle’s lifetime at gas prices as low as $1.50 per gallon. In the absence of agricultural land use changes, biofuels (especially advanced biofuels such as cellulosic ethanol) are a good alternative to gasoline and diesel, achieving significant GHG and petroleum savings. However, biofuels are expected to offer such GHG savings only when produced without converting land to agriculture. Planting on abandoned agricultural land or producing biofuels from non-agricultural sources (biomass waste or algae) can avoid land conversion while providing GHG emissions benefits. GHG savings are expected for mode shifts away from SOV to carpooling and certain transit modes if current occupancy levels are maintained. However, bus occupancies will need to increase in order to achieve such mode-shift benefits. Such occupancy improvements are reasonably likely, if bus supply increases, particularly along lower-occupancy routes and in lower-density neighborhoods, do not match demand increases. While cycling at first appears as a 1 2 GHG Emissions Control Options: Opportunities for Conservation strong contender, increased life expectancies and dietary needs may offset much of the anticipated GHG savings. Mode shifts from truck to train or water obviously can result in substantial sector-level savings, but mode shifts may be undesirable for certain products, and rail is nearing its capacity. An alternative option lies in improving truck fuel economy. However, even a 9% fuel savings results in rather low emissions savings for the U.S., since trucking represents a relatively small portion of total emissions. Red meat production is very energy, and carbon, intensive. Eating less red meat or adopting a vegetarian diet can reduce emissions. However, quantifying this savings is difficult, and studies on life cycle energy required for food production differ. Finally, the fastest way to make buildings more efficient is to find cleaner electricity- generating technologies while insulating attic spaces, particularly in colder climates. In the longer term, reducing space requirements per occupant, promoting shared walls (via multi- occupant buildings), insulated walls (via new construction and renovations), and solar shielding also are important opportunities. Moreover, neighborhood design impacts should prove helpful, as cities grow and densification facilitates reductions in trip lengths along with mode, vehicle ownership, and vehicle-design shifts, while moderating numerous other problems associated with sprawl. Nevertheless, CO2e savings from switching vehicle designs, fuels, meat consumption, building insulation, and a wide variety of other options are estimated to offer far more significant greenhouse gas and energy reductions than neighborhood design appears to, particularly as American household incomes and preferences for rising home sizes, natural light, on-demand travel and many other comforts of modern life continue to climb. 1. INTRODUCTION Energy and climate change are top planetary issues, and increasingly a part of the U.S.’s political and economic agenda. There is considerable evidence that the earth’s climate is indeed changing as a result of excess greenhouse gases (GHG1) in the atmosphere. Many nations around the world agree that GHG emissions need to be reduced – and sooner is better (Stern 2006). In order to stabilize the concentration of GHGs in the atmosphere, the United Nations Framework Convention on Climate Change (UNFCCC), many European countries, and the state of California (CA) believe that a reduction of 80%2 by 2050 is necessary to prevent the most catastrophic consequences of global warming (Stern 2006, Luers 2007). Major changes in 1 GHGs include carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF6). CO2 makes up the majority of U.S. GHG emissions (84% in 2005, by heat-trapping potential), 80% of which come from fossil fuel combustion (as measured in terms of heat trapping potential). CH4 makes up 7% of all U.S. GHGs, with landfills (1.8% of GHGs), enteric fermentation (1.5%), and natural gas systems (1.5%) serving as the nation’s top three methane contributors. N2O contributes another 7% of all GHGs, with agricultural soil management serving as the top source (5%). HFCs, PFCs, and SF6 account for only 2% of all GHGs, largely due to the changes in regulations concerning other, ozone-depleting consumer substances. Because CO2 makes up such a large portion of all U.S. GHGs, and an even larger portion of household emissions, and because many reports on GHG emissions provide only CO2 numbers, this paper emphasizes CO2 values and reductions, rather than CO2 equivalents (CO2e) (EPA 2008). 2 The 80-percent reduction is relative to 1990 levels (the reference point for the Kyoto Protocol), or 82% versus 2005 levels. U.S. 1990 emissions were 6.310 MMTCE, 2006 emissions were 7.202 MMTCE, and the 80% target emissions are 1.262 MMTCE (EPA 2007c). Kockelman, Bomberg, Thompson, and Whitehead 3 technology, behavior, and laws are needed to bring about such reductions. This report examines the wide spectrum of opportunities for energy and GHG savings, in order to quantify potential impacts and identify those opportunities with greatest promise. It begins with a look at the potential for changes in motorized vehicle technologies and fuels, along with transportation modes and electricity generation. It then moves into building designs, appliances and land use practices, before offering conclusions and recommendations. 2. THE ROLE OF TRANSPORT The transportation sector is responsible for 28% of all man-made U.S. GHG emissions3, which presently tally close to 8 billion tons (over 7,000 million metric tons of carbon-dioxide equivalent [MMTCE]) per year (EPA 2008). Figure 1 provides a breakdown of emissions within the transportation sector. Light-duty vehicles (cars and light trucks) make up 62% of all such emissions (EPA 2006). In addition to representing a large share of total U.S. emissions, transportation sector emissions are growing at a faster rate than overall GHG emissions. For example, total U.S. GHG emissions rose 13% between 1990 and 2003, while those from the transportation sector rose 24% (EPA 2006). Due to stagnant CAFE standards coupled with suburbanization and income trends, energy use from North American transport is expected to increase by 46% between 2003 and 2025 (CCSP 2006), becoming a larger share the total. Any sizable reductions in transportation sector emissions will translate into meaningful overall reductions in U.S. GHG emissions. In general, there are three approaches for reducing transportation emissions: improvements in vehicle technology, a switch to lower-carbon fuels, and travel demand management (EPA 2007). Over the 2007-2050 period, EPA (2007) estimates that the transportation sector’s CO2e emissions will increase by 2 billion metric tons4. Roughly one-half of this growth will come from passenger vehicles, 20 percent

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