HEI is a nonprofit corporation chartered in 1980 as an independent research organization to provide high-quality, impartial, and relevant science on the health effects of air pollution. Typically, HEI receives half of its core funds from the US Environmental Protection Agency (EPA) and half from the worldwide motor vehicle industry.

Vehicle fuels and technologies have made great strides over the past three decades but progress has often been accompanied by new, unintended emissions and potential health consequences that need to be addressed as well. HEI’s Board of Directors appointed SCET to advise on what technologies and fuels are coming forward, how fast they are expected to arrive, and any potential emissions or other unintended health consequences.

SCET—co-chaired by Tina Vujovich (formerly of Cummins Engine, Inc.) and Alan Lloyd (President of the International Council on Clean Transportation and former Secretary of the California EPA)—includes leading national and international experts from government, industry, academia, and the non-profit sector.

The new SCET report reviews a range of new technologies and fuels, from improved internal combustion engines, to hybrid and other electric drive technologies, to existing and new bio- and other types of fuels. The purpose of the report, the authors say, is to elucidate, as well as possible, how each technology may affect emissions, environmental quality, GHG emissions, and, in turn, what effect it may have on health in a qualitative fashion.

It is very likely that our near-term future will be a multifuel future. Rather than relying as extensively on oil as the source of energy to power vehicles—most of it imported to the United States and Europe from other countries—we will use increasing amounts of ethanol and other potentially renewable fuels as well as electricity. Developing fuels that are truly carbon-neutral is not yet within reach, but progress is being made. On the technology front, there is much continued interest in further reducing traditional emissions as well as reducing GHG emissions, improving fuel efficiency, thereby helping reduce the carbon footprint from the transportation sector.

Also, as we begin to reduce dependence on oil as the chief energy source, the century-old domination of the conventional internal combustion engine is also expected to change substantially. Although the internal combustion engine will endure through the next 10 to 15 years, it will be supplemented, and in some cases superseded, by the electric powertrain.

—“The Future of Vehicle Fuels and Technologies”

Among the findings of the report are:

• New gasoline direct injection (GDI) technology offers improvements in fuel economy. The major concern related to the use of GDI is higher emissions of PM, both mass and UFP emissions, although these emissions are likely less than those from lean-burn engines. These emissions have not been well characterized and their potential health effects are not well understood. There are also some indications of regulatory actions in California to reduce the mass and the number of PM from these engines under its LEV III standards, and actions in Europe that could affect the emissions of UFPs.

• SCR systems are being introduced to control the emissions of NO_x from diesel engines. The introduction of urea as the reducing agent gives rise to concerns regarding the formation of nitrogen-containing compounds, including nitro-PAHs, in emissions and possibly other toxic compounds. Thus, even though the combination of DPF and SCR will substantially reduce criteria pollutants and unregulated pollutants, conclusions regarding the overall risk from air toxics are difficult to draw at this point because such exhaust has not been characterized in detail. The Committee noted that the second phase of the HEI ACES study will characterize exhaust from heavy-duty engines equipped with DPF and de-NO_x exhaust aftertreatment systems (model year 2010).

• Hybrid, all-electric drive, and fuel cell technologies are likely to see substantial market penetration by the end of this decade. SCET identified three areas for potential attention: potential increased in-vehicle exposure to low-level electro-magnetic fields (EMF); potential increased exposure in the battery lifecycle—from extraction to production to use/accidents to disposal—to lithium, other metals, and battery chemical solutions; and displaced emissions of conventional pollutants at electric power plants which, if not controlled, could increase population exposure.

• Emissions from the use of fuels containing more than 10% ethanol—including the impact of blending, driving cycles, exact engine and emissions-control technology—are not well understood. However, it is expected that the use of ethanol will lead to increased emissions of acetaldehyde and ethanol itself, and to reduced emissions of hydrocarbons, CO and benzene. More research is needed on the emissions and operability effects of ethanol blends in onroad and nonroad applications. The outlook for other alcohols and oxygenates is less certain at this point.

• Although information on emissions from the use of fatty acid esters (biodiesel) in diesel is limited, there is concern that the use of biodiesel will possibly lead to increase in emissions of NO_x and aldehydes while reducing emissions of hydrocarbons, CO, and PM. More research is needed on the impact of biodiesel on the emissions and operability of engines equipped with new technologies.

• There is increased development and use of a number of fuels from unconventional sources such as tar sands, oil shale, and coal. Fuels from such sources may have different fuel formulations and emissions characteristics; they also pose a number of broader environmental questions.

• Phaseout of lead is one of the most notable developments of the last quarter of the twentieth century; it is expected that lead will be eliminated from the gasoline used in all countries in the near term. However, the use of metal additives as octane boosters or for other purposes continues to be an area that deserves scrutiny. Although fuel suppliers in the United States do not appear to be inclined toward metal additives, metallic fuel additives are being used in Europe and their use is being considered in some developing countries. Use of manganese in gasoline and diesel is also continuing in some developing countries. The use of metallic fuel additives is of concern because of the emissions—and possible health effects—of metallic nanoparticles; such emissions may also adversely affect aftertreatment systems.

HEI will re-convene SCET in about 18 months to update its assessments and its advice to HEI about the status of the various fuels and technologies and emerging issues and concerns.

In response to these comprehensive findings, the HEI Research Committee has issued an Action Plan for investigations underway or soon to begin. These include:

• HEI is undertaking a review of the literature on UFP. The review will encompass information on the contribution of mobile sources to atmospheric UFPs, health effects of UFPs and the potential for environmental exposure leading to potential health effects in humans. HEI is forming a panel to review the literature in these areas, including HEI’s own contributions. The Panel’s report is expected to be completed by early 2012.

  The Research Committee will also consider whether it should develop and implement short term (e.g. 1- and 3-month) animal exposure studies for GDI engine exposures.

• As SCET notes, the introduction of urea to control NOx emissions is a major new direction in emissions control and, given the possibility of formation of nitro-organic compounds, deserves close scrutiny. Plans for HEI’s ongoing Advanced Collaborative Emissions Study (ACES) had anticipated and included this topic. Specifically, Phase 2 of ACES will perform detailed characterization of emissions from several 2010 engines, outfitted with particulate control and SCR or possibly other de-NO_x devices, employing several engine operating cycles. These studies are scheduled to start during mid-2011, and their results will be available during 2012.

• The Committee will convene an intensive workshop where data from all relevant groups active in biofuels emissions testing and characterization will be presented and assessed. The information presented will be the basis for the Committee’s plan of future actions.

• HEI will review data on changes in composition of fuels and emissions as they become available to evaluate whether they need further study.

• HEI’s scientists will also conduct searches and initial reviews of the science literature on: EMF emissions and potential effects and the toxicity of lithium and other battery components.

• The National Particle Component Toxicity Initiative (NPACT), HEI’s effort to understand the effects of power plant, traffic, and other emissions, will be completed this year, offering answers on the potential effects of displaced emissions.

Resources

• Communication 16. The Future of Vehicle Fuels and Technologies: Anticipating Health Benefits and Challenges

• Action Plan In Response To Communication 16: The Future of Vehicle Fuels and Technologies: Anticipating Health Benefits and Challenges