Abstract
In almost every country there has been an improvement in the greenhouse gases of new vehicles entering service. In 2004, the author was responsible for advising the Australian government on the 2010 CO2 standards for all light duty vehicles. In that work the lowest attainable CO2 emission at reasonable cost was determined. However no consideration was given to any impact of the non-fuel CO2 contributions to whole of life emissions. The non-fuel related CO2 emissions have grown from 16% in 1980 and now represent about 25% of total CO2 assignable to light duty vehicles and therefore cannot be ignored. The paper reviews the trends in several continents showing that the rate of reduction varies from just over 1% up to 3% per annum but may increase to 7% in the future. A review of the available data on vehicle production (including embedded materials) energy is made and also of typical examples of recycling energy recovery. Next, whole-of-life CO2 emissions are formulated but excluding energy (and CO2) attributed to vehicle maintenance, consumables and infrastructure energy such as road construction and maintenance energy. The numerical formulation is general and thus the optimum life-cycle for given fuel consumption/CO2 emission trends can be identified over a period of several life cycles, chosen here (but not limited to) 40 years. The results show that in an environment where fuel consumption is falling 3.3%/y as it must do in Europe over the next five years the optimum vehicle service life is about 14 years. In Australia where the reduction rate is 2.5%/y the optimum vehicle service life is about 16 years. If the reduction is 1% per annum the optimum service life should be in excess of 25 years. Programs that encourage very early retirement of vehicles from service are shown to be less than optimal even though they are encouraged in some jurisdictions.
KEYWORDS Life cycle analysis, manufacturing energy, cabon-dioxide emissions, service life.