Heather L. MacLean

Evaluating automobile fuel/propulsion system technologies

We examine the life cycle implications of a wide range of fuels and propulsion systems that could power cars and light trucks in the US and Canada over the next two to three decades ((1) reformulated gasoline and diesel, (2) compressed natural gas, (3) methanol and ethanol, (4) liquid petroleum gas, (5) liquefied natural gas, (6) Fischer ‐ Tropsch liquids from natural gas, (7) hydrogen, and (8) electricity; (a) spark ignition port injection engines, (b) spark ignition direct injection engines, (c) compression ignition engines, (d) electric motors with battery power, (e) hybrid electric propulsion options, and (f) fuel cells). We review recent studies to evaluate the environmental, performance, and cost characteristics of fuel/propulsion technology combinations that are currently available or will be available in the next few decades. Only options that could power a significant proportion of the personal transportation fleet are investigated. Contradictions among the goals of customers, manufacturers, and society have led society to assert control through extensive regulation of fuel composition, vehicle emissions, and fuel economy. Changes in social goals, fuel-engine-emissions technologies, fuel availability, and customer desires require a rethinking of current regulations as well as the design of vehicles and fuels that will appeal to consumers over the next decades. The almost 250 million light-duty vehicles (LDV; cars and light trucks) in the US and Canada are responsible for about 14% of the economic activity in these countries for the year 2002. These vehicles are among our most important personal assets and liabilities, since they are generally the second most expensive asset we own, costing almost

Forest Bioenergy or Forest Carbon? Assessing Trade-Offs in Greenhouse Gas Mitigation with Wood-Based Fuels

100 000 over the lifetime of a vehicle. While an essential part of our lifestyles and economies, in the US, for example, the light-duty fleet is also responsible for 42 000 highways deaths, and four million injuries each year, consumes almost half of the petroleum used, and causes large amounts of illness and premature death due to the emissions of air pollutants (e.g. nitrogen oxides, carbon monoxide, hydrocarbons and particles). The search for new technologies and fuels has been driven by regulators, not the marketplace. Absent regulation, most consumers would demand larger, more powerful vehicles, ignoring fuel economy and emissions of pollutants and greenhouse gases; the vehicles that get more than 35 mpg make up less than 1% of new car sales. Federal regulators require increased vehicle safety, decreased pollution emissions, and better fuel economy. In addition, California and Canadian regulators are concerned about lowering greenhouse gas emissions. Many people worry about the US dependence on imported petroleum, and people in both countries desire a switch from petroleum to a more sustainable fuel. The fuel-technology combinations and vehicle attributes of concern to drivers and regulators are examined along with our final evaluation of the alternatives compared to a conventional gasoline-fueled spark ignition port injection automobile. When the US Congress passed laws intended to increase safety, decrease emissions, and increase fuel economy, they did not realize that these goals were contradictory. For example, increasing safety requires increasing weight, which lowers fuel economy; decreasing emissions generally decreases engine efficiency. By spending more money or by reducing the performance of the vehicle, most of the attributes can be improved without harming others. For example, spending more money can lighten the vehicle (as with an aluminum frame with greater energy absorbing capacity), improving performance and safety; a smaller engine can increase fuel economy without diminishing safety or increasing pollution emissions, but performance

Life cycle emissions and cost of producing electricity from coal, natural gas, and wood pellets in Ontario, Canada.

The potential of forest-based bioenergy to reduce greenhouse gas (GHG) emissions when displacing fossil-based energy must be balanced with forest carbon implications related to biomass harvest. We integrate life cycle assessment (LCA) and forest carbon analysis to assess total GHG emissions of forest bioenergy over time. Application of the method to case studies of wood pellet and ethanol production from forest biomass reveals a substantial reduction in forest carbon due to bioenergy production. For all cases, harvest-related forest carbon reductions and associated GHG emissions initially exceed avoided fossil fuel-related emissions, temporarily increasing overall emissions. In the long term, electricity generation from pellets reduces overall emissions relative to coal, although forest carbon losses delay net GHG mitigation by 16-38 years, depending on biomass source (harvest residues/standing trees). Ethanol produced from standing trees increases overall emissions throughout 100 years of continuous production: ethanol from residues achieves reductions after a 74 year delay. Forest carbon more significantly affects bioenergy emissions when biomass is sourced from standing trees compared to residues and when less GHG-intensive fuels are displaced. In all cases, forest carbon dynamics are significant. Although study results are not generalizable to all forests, we suggest the integrated LCA/forest carbon approach be undertaken for bioenergy studies.

“Junk food” and “healthy food”: meanings of food in adolescent women's culture

The use of coal is responsible for (1)/(5) of global greenhouse gas (GHG) emissions. Substitution of coal with biomass fuels is one of a limited set of near-term options to significantly reduce these emissions. We investigate, on a life cycle basis, 100% wood pellet firing and cofiring with coal in two coal generating stations (GS) in Ontario, Canada. GHG and criteria air pollutant emissions are compared with current coal and hypothetical natural gas combined cycle (NGCC) facilities. 100% pellet utilization provides the greatest GHG benefit on a kilowatt-hour basis, reducing emissions by 91% and 78% relative to coal and NGCC systems, respectively. Compared to coal, using 100% pellets reduces NO(x) emissions by 40-47% and SO(x) emissions by 76-81%. At

Understanding the Canadian oil sands industry's greenhouse gas emissions

160/metric ton of pellets and

AN ENVIRONMENTAL-ECONOMIC EVALUATION OF HYBRID ELECTRIC VEHICLES: TOYOTA'S PRIUS VS. ITS CONVENTIONAL INTERNAL COMBUSTION ENGINE COROLLA

7/GJ natural gas, either cofiring or NGCC provides the most cost-effective GHG mitigation (

The Four Pillars of Sustainable Urban Transportation

70 and

A rational procedure for estimation of greenhouse-gas emissions from municipal wastewater treatment plants.

47/metric ton of CO2 equivalent, respectively). The differences in coal price, electricity generation cost, and emissions at the two GS are responsible for the different options being preferred. A sensitivity analysis on fuel costs reveals considerable overlap in results for all options. A lower pellet price (

A Life-Cycle Comparison of Alternative Automobile Fuels

100/metric ton) results in a mitigation cost of

Life Cycle Greenhouse Gas Emissions of Current Oil Sands Technologies: Surface Mining and In Situ Applications

34/metric ton of CO2 equivalent for 10% cofiring at one of the GS. The study results suggest that biomass utilization in coal GS should be considered for its potential to cost-effectively mitigate GHGs from coal-based electricity in the near term.