Reductions in carbon intensity, C/E, the carbon emitted per unit of energy generated, reflect the degree to which societies decarbonize their energy sources. The long-term trend has been a shift from coal to oil to natural gas––hydrocarbons with decreasing C/H ratios emitting progressively less CO2 per joule. However, the increasing use of clean low-carbon fuels is not sustainable without somehow disposing of excess carbon because it opposes the trend in the abundance of fossil fuels, with coal resources being the most abundant followed by oil and gas. (more…)

Although the focus of many policy studies of climate change is on establishing the causal links between anthropogenic systems, emissions of greenhouse gases climate change, the line of causation also runs the other way. Short-term fluctuations in climate conditions, particularly in the temperate zones on the planet, affect energy consumption. If the popular expectation that the climate will become warmer becomes a reality, we can expect winters and summers that are warmer than those of the past. (more…)

Climate change caused by the enhanced greenhouse effect is one of the most significant global environmental issues. Increased emissions of GHG to the atmosphere, most notably CO2 , are considered the main cause of global climate change. Increasing energy consumption, a reliance on fossil fuels to meet these needs, and deforestation related to land use change are the main sources of increasing atmospheric CO2. (more…)

Ten industry giants – with business operations spanning the utilities, manufacturing, chemicals and financial-services sector – joined forces with four environmental groups to pressure for setting mandatory limits on CO2 emissions. The group calls for a market based emission trading program. Under a ‘cap and trade’ system, the Government gives or sells permits to business, allowing them certain levels of green house gases emissions. (more…)

Estimation of the future technical potential of biomass as an energy source is dependent on assumptions with respect to land availability and productivity as well as conversion technologies. With the emergence of energy crops as the major source of biomass fuel, land use conflicts, especially in relation to food production, may arise. However, with efficient agricultural practices, plantations and crops could supply a large proportion of energy needs, with residues playing a smaller role without compromising food production or further intensifying agricultural practices. (more…)

The growth in air transportation volume has important global energy sustainable development
associated with the potential for greenhouse gases sources. On local to regional scales, noise, decreased air quality related primarily to ozone production and particulate levels, and other issues, such as roadway congestion related to airport services and local water quality, are all recognized as important impacts. (more…)

It is of interest to examine potential sources of greenhouse gases sources or atmospheric CO2 by analysis of the global distribution of carbon in all its forms. Atmospheric carbon, which can be assumed to be essentially all in the form of CO2 (i.e., 700 Gt carbon equals 2570 Gt of CO2) comprises only about 1.6% of total global carbon, excluding lithospheric carbon. Obvious greenhouse gases sources of direct or indirect additions of CO2 to the atmosphere are therefore fossil fuel deposits, since portions of them are combusted each year as fuels, and terrestrial biomass. (more…)

Fuel efficiency gains due to technological and operational change can mitigate the influence of growth on total emissions. Increased demand has historically outpaced these gains, resulting in an overall increase in emissions over the history of commercial aviation. The figure of merit relative to total energy use and emissions in aviation is the energy intensity (EI).

When discussing energy intensity, the most convenient unit of technology is the system represented by a complete aircraft. In this section, trends in energy use and energy intensity are elaborated. In the following section, the discussion focuses on the relation of energy intensity to the technological and operational characteristics of an aircraft.

Reviews of trends in technology and aircraft operations undertaken by Lee et al. and Babikian et al. indicate that continuation of historical precedents would result in a future decline in energy intensity for the large commercial aircraft fleet of 1.2–2.2%/year when averaged over the next 25 years, and perhaps an increase in energy intensity for regional aircraft, because regional jets use larger engines and replace turbo- props in the regional fleet. When compared with trends in traffic growth, expected improvements in aircraft technologies and operational measures alone are not likely to offset more than one-third of total emissions growth. Therefore, effects on the global atmosphere are expected to increase in the future in the absence of additional measures. Industry and government projections, which are based on more sophisticated technology and operations forecasting, are in general agreement with the historical trend.

Compared with the early 1990s, global aviation fuel consumption and subsequent CO2 emissions level could increase three-to sevenfold by 2050, equivalent to a 1.8–3.2% annual rate of change. In addition to the different demand growth projections entailed in such forecasts, variability in projected emissions also originates from different assumptions about aircraft technology, fleet mix, and operational evolution in air traffic management and scheduling.

We shows historical trends in energy intensity for the U.S. large commercial and regional fleets. Year-to-year variations in energy intensity for each aircraft type, due to different operating conditions, such as load factor, flight speed, altitude, and routing, controlled by different operators, can be 730%, as represented by the vertical extent of the data symbols. For large commercial aircraft, a combination of technological and operational improvements led to a reduction in energy intensity of the entire U.S. fleet of more than 60% between 1971 and 1998, averaging about 3.3%/year. In contrast, total RPK has grown by 330%, or 5.5%/year over the same period.

Long- range aircraft are B5% more fuel efficient than are short-range aircraft because they carry more passengers over a flight spent primarily at the cruise condition. Regional aircraft are 40–60% less fuel efficient than are their larger narrow- and wide-body counterparts, and regional jets are 10–60% less fuel efficient compared to turboprops. Importantly, fuel efficiency differences between large and regional aircraft can be explained mostly by differences in aircraft operations, not technology.

Reductions in energy intensity do not always directly imply lower environmental impact. For example, the prevalence of contrails is enhanced by greater engine efficiency. NOx emissions also become increasingly difficult to limit as engine temperatures and pressures are increased—a common method for improving engine efficiency. These conflicting influences make it difficult to translate the expected changes in overall system performance into air quality impacts. Historical trends suggest that feet-averaged NOx emissions per unit thrust during landing and takeoff (LTO) cycles have seen little improvement, and total NOx emissions have slightly increased. However, HC and CO emissions have been reduced drastically since the 1950s.

Since preindustrial times, ambient concentrations of the greenhouse gases have exhibited substantial increases, inter alia CO2 by 30% to about 360 parts per million (ppm), CH 4 by 145% to more than 1700 parts per billion (ppb), and N20 by 15% to more than 300 ppb. The growth rates in the concentrations of these gases in the early 1990s were lower than predicted; while subsequent data indicate that the growth rates are comparable to those averaged over the 1980s. (more…)

The pressure relief valves protect against the devastating effects of the overpressure. Unfortunately there are so careful with the environment and which are not always made leakproof, and can therefore be emitting harmful gases into the atmosphere continuously. While European directives aimed at reducing emissions of gases causing the greenhouse effect based on a share issue (linked to heavy fines for countries that fail), other solutions much easier go unnoticed. (more…)