Potential for energy savings in old and new auto engines

Reitz, John R.

doi:10.1063/1.35461

Cited by 1 publication

(2 citation statements)

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“…Losses due to the use of accessories and automatic transmissions may nearly halve the total. Thus, effective efficiency is no more than 10-12%, and can be as low as 7-8% (Reitz, 1985).…”

Section: -20 Kj/mmentioning

confidence: 99%

“…As with buildings, major improvements in automotive efficiency require no technical breakthroughs and can come from a combination of gradual adjustments and Widespread applications of existing techniques (Reitz, 1985). To begin with, cars have been unnecessarily powerful: unless driving requires unusually rapid acceleration, travel on uncommonly steep roads or heavy towing, there is no reason to have any standard passenger cars rated over 35 kW.…”

Section: -20 Kj/mmentioning

confidence: 99%

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Global Warming and Future Fossil Fuel Consumption

Smil¹

1989

Energy Studies Review

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(National Research Council, 1982 andClark, 1982; US Environmental Protection Agency, 1983Smil, 1985; US Department of Energy, 1985; Bolin et ai, 1986; Trabalka and Reichle, 1986;Abrahamson, 1989;Schneider, 1989). TItis paper begins with a brief summary of these surveys and then focuses on the overall likelihood that a dramatic reduction in the emissions of greenhouse gases can be achieved by way of reductions in fossil fuel consumption. We shall see that there is great potential for the latter, but that there are also severe limits on the scope for achieving this potential. Facts and ConjecturesWe know with sufficient confidence that tropospheric concentrations of CO, have risen from their pre-industrial lcvel (determined from air bubbles trapped in polar ice) of about 280 parts Fig. 1). But we are much less clear about the make-up of anthropogenic emissions responSible for these increases. The rates of current Co, generation from burning of fossil fuels can be calculated fairly accurately.' Annual releases during the late 1980s were nearly 20 billion tonnes (t), while releases due to natural gas flaring, cement production and combustion of wastes totalled less than 2 billion t/yr. But there is considerable uncertainty about the net annual CO, emissions from tropical deforestation and conversion of forests, grasslands and wetlands to fields. Recent estimates put these emissions at anywhere from 2 billion to 9 billion tof CO 2 (Smil, 1985; Trabalka and Reichle, 1986). Such a large range in estimates is attributable to the large variability of carbon content in plants and our poor knowledge of actual conversion rates. ' The best available historic data (summarized 96 in Clark, 1982) translate into roughly 700 billion tonnes of cumulative emissions from fossil fuels in the period 1850-1990, while Co, releases from ecosystem changes caused by pioneer agriculture and deforestation total close to 600 billion t for the same period. Although these two cumulative totals are surprisingly similar, combustion of fossil fuels is now undoubtedly by far the more important source of anthropogenic CO,. But atmospheric concentrations of other greenhouse gases have also been increasing rapidly: methane concentration roughly doubled during the industrial era and levels of the principal chlorofluorocarbons have nearly doubled since their first measurement in 1977. The atmospheric concentration of these gases is only a small fraction of the C02 level, but since they are stronger absorbers of longwave radiation they are responsible for roughly one-half (US Environmental Protection Agency, 1989) of the overall absorption of outgoing longwave terrestrial radiation.' Still, combustion of fossil fuels remains the single largest source of anthropogenic 1/ Release of CO2 during fuel combustion is a matter of complete oxidation of carbon. Coal has higher CO2 emissions per unit of liberated energy than oils and natural gases, whose hydrogen contributes to energy release when its oxidation yields water. I have been using the followin...

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“…Losses due to the use of accessories and automatic transmissions may nearly halve the total. Thus, effective efficiency is no more than 10-12%, and can be as low as 7-8% (Reitz, 1985).…”

Section: -20 Kj/mmentioning

confidence: 99%

Section: -20 Kj/mmentioning

confidence: 99%