Natural Gas Vehicles Are Easy on Health and Social Costs
If the current renewal rate of the Italian car stock toward methane-fueled cars continues unabated, there will be beneficial consequences for health and the environment. The benefits are significant even when compared with a like-sized expansion of vehicles fueled by Liquefied Petroleum Gas (LPG). These are the main findings of the study conducted by Bocconi CERTET, the University's research center for regional and transport economics on the differential social and environmental impacts of different car fuels.
The research study, part of the netwok on sustainable urban mobility coordinated by CERTET, measures the impact of using natural gas as fuel for auto transport with respect to gasoline, diesel, and LPG. The calculation method used is based on COPERT (COmputer Program to Estimate emissions from Road Transport), ACI data, as well as data coming from car manufacturers.
According to the study, by assuming a 50% yearly growth of methane cars over the 2009-2011 period (extrapolating on latest growth trends) thus reaching the figure of one million methane-powered cars, there would substantial savings on polluting emissions. The alternative hypothesis of LPG-fueled cars only cuts CO2 by 15%. In particular, carbon dioxide (CO2) would be cut by 25% with respect to the emissions produced by the substituted car stock. While for carbon monoxide (CO), nitrogen oxides (NOx) and non-methane hydrocarbons (NMHC) emission cuts would be staggering: -96%-98%.
As far as environmental social benefits are concerned, the research team led by Gabriele Grea has quantified the economic benefits deriving from lesser emissions. The forecasted increase in the number of cars powered by natural gas will generate comparative benefits in terms of nitrogen oxides (NOx), particulate (PM), non-methane hydrocarbons (NMHC) and CO2 equal to €15.2 million. In particular, lower emissions of particulate matter will generate social environmental savings of €7.13 million, while cuts in CO2 released in the atmosphere will generate savings of €4.46 million. Corresponding total figures for the LPG case are €12.9 million, 17% less than the savings in the methane case.
As far as the health impacts of natural gas vehicles are concerned, the study focused on the differentials in particulates produced through combustion. By considering two scenarios over the 2009-2011 period, one where methane autos reach 3.3% of the total car stock (trend scenario) and one where they reach 10% of the market, Bocconi researchers have calculated the potential health impact of methane-fueled cars in metropolitan areas.
In the trend scenario, there is a 1.3% decrease in the number of deaths caused (lung cancer, heart attack, stroke, cardiovascular and respiratory diseases) by a concentration of particulates higher than 20 μg/m3. In the optimistic scenario of 10% penetration, the decrease in the number of annual deaths caused by particulates rises to 4%.
Looking at the diseases caused by high concentrations of particulates in the atmosphere, there would be 2,641 cases less of lower respiratory symptoms among children in Italian metro areas. For adults, major benefits concern asthma (-4,197 cases) and the number of workdays lost (-10,101 days of absence). The corresponding figures for the optimistic scenario with 10% market penetration of methane-fueled in Italian cities are: -8,252 lower respiratory diseases in the children population; -13,115 asthmatics among the adult population; -31,567 health-related absences at work.