Emission carbon dioxide

Fuel switch. The choice of fuel used in furnaces and steam boilers has a major effect on the gaseous utility waste from products of combustion. For example, a switch from coal to natural gas in a steam boiler can lead to a reduction in carbon dioxide emissions of typically 40 percent for the same heat released. This results from the lower carbon content of natural gas. In addition, it is likely that a switch from coal to natural gas also will lead to a considerable reduction in both SO, and NO, emissions, as we shall discuss later. 

The control of carbon dioxide emission from burning fossil fuels in power plants or other industries has been suggested as being possible with different methods, of which sequestration (i.e., collecting CO2 and injecting it to the depth of the seas) has been much talked about recently. Besides of the obvious cost and technical difficulties, this would only store, not dispose of, CO2 (although natural processes in the seas eventually can form carbonates, albeit only over very long periods of time). 

For my part, although I may be somewhat of a visionary, I see a solution to the problem by chemical recycling of excess carbon dioxide emissions into methyl alcohol and derived hydrocarbon products. 

In 1990, a test using scrap tires (2x2 in. I DE) to generate steam for electricity was conducted at the Elexsys plant. The I DE replaced 20% of the plant s coal. Results showed that IDE is an environmentally sound fuel. Particulate emissions were reduced by the lower ash content of IDE, volatile organic compounds (VOC) were reduced because of more efficient burning of I DE compared to coal, and carbon dioxide emissions were reduced because I DE contains half the fixed carbon found in coal. Nitrogen oxide, chlorine emissions, and metals were also reduced, and ferrous metals and dioxins were nondetectable (7). 

Vinyl compares favorably to other packaging materials. In 1992, a lifecycle assessment comparison of specific packages made from glass, paperboard, paper, and selected plastics concluded that vinyl was the material that has the lowest production energy and carbon dioxide emissions, as well as the lowest fossil fuel and raw material requirements of the plastics studied (169). Vinyl saves more than 34 million Btu per 1000 pounds manufactured compared to the highest energy-consuming plastic (170). 

Fig. B.4. Carbon dioxide emissions for various power plants as a function of overall efticiency (after Davidson...

To comply with carbon reduction goals, some countries impose taxes on carbon dioxide emissions. Since biofuels have lower full-cycle carbon dioxide emissions than fossil fuels, biofuels are more cost-competitive with fossil fuels in regions where these taxes are imposed. 

Transportation is also the emissions leader. About 75 percent of carbon dioxide emissions and 45 percent of nitrogen oxide emissions come from the transportation sector. If rising levels of CO, are found to be responsible for global warming, and measures are put in place to severely curtail CO, emissions, the measures will have the greatest impact on the transportation sector. 

Concerns about global climate change have led to extensive research and high-level international debates about the need for targets and timetables to reduce carbon dioxide emissions. Some policymakers believe that current uncertainties in how to approach the issue do notjustify an all-out effort to reduce carbon dioxide emission, while others feel that this is a crisis needing immediate attention. 

Transportation accounts for about one-fourth of the primary energy consumption in the United States. And unlike other sectors of the economy that can easily switch to cleaner natural gas or electricity, automobiles, trucks, nonroad vehicles, and buses are powered by internal-combustion engines burning petroleum products that produce carbon dioxide, carbon monoxide, nitrogen oxides, and hydrocarbons. Efforts are under way to accelerate the introduction of electric, fuel-cell, and hybrid (electric and fuel) vehicles to replace sonic of these vehicles in both the retail marketplace and in commercial, government, public transit, and private fleets. These vehicles dramatically reduce harmful pollutants and reduce carbon dioxide emissions by as much as 50 percent or more compared to gasoline-powered vehicles. 

Marland, G. and Rotty, R. M. (1984). Carbon dioxide emissions from fossil fuels A procedure for estimation and results for 1950-1982. Tellus 36B, 232-261. 

The model has been fed with data obtained by analytical measurements of the Isocyanate decrease, water concentration, carbon dioxide emission, etc. 

The carbon dioxide emission has been quantified using the apparatus shown in Figure 1. Under controlled conditions of temperature and relative humidity the emitted carbon dioxide was continuously trapped in a solution of ethanolamine in dimethylformamide (11) and titrated continuously to a preset potential with tetrabutylammonlum hydroxyde in isopropanol. 

The influence of the relative humidity on the carbon dioxide emission from a DABCO-catalyzed paint film is illustrated in Figure 3. 

The effect of the type of catalyst is illustrated in Figure 4. The carbon dioxide emission curves using DABCO as a catalyst show an "autocatalytlc" effect. So far this phenomenon has remained unexplained it may be due to physical (diffusion hindrance) or chemical effects. 

The type of catalyst has a significant influence on the carbon dioxide emission. The measurements confirm the information from the literature that DABCO preferentially catalyzes reaction 2. 

Figure 1. Apparatus for the continuous determination of the carbon dioxide emission from a paint layer during curing.

Figure 3. Carbon dioxide emission from a paint film with DABCO as a catalyst, at different relative humidities (23°C)...

Figure 4. Carbon dioxide emissions from paint films prepared with different catalysts, at 85Z R.H.

The carbon dioxide emission at OZ R.H. after exposure of the paint film in a lOOZ gaseous carbon dioxide atmosphere (carbon dioxide-saturated paint film) has been determined after various curing times (Figure 7). 

The use of the lignin fraction is much more cumbersome currently the best-known chemical of a real commercial importance is vanillin, which is obtained by oxidation of the black liquor. Another example is a product called spray-dried lignosulfonate (as sodium salt) obtained from the older, acidic sulfite pulping process. It is sold as a commercial product primarily as a concrete additive for enhanced strength. Since the cement industry is one of the big contributors of carbon dioxide emissions (due to the production of calcium oxide from calcium carbonate), the use of this renewable, wood-derived product not only is fossil-carbon neutral in itself but also reduces carbon dioxide emission due to the diminished need for cement in large infrastructures made of concrete. 

One of the most straightforward methods to reduce carbon dioxide emissions is to enhance the fuel efficiency of engines. The three-way catalyst, although very successful at cleaning up automotive exhaust, dictates that engines operate at air-to-fuel ratios of around 14.7 1. Unfortunately, this is not the optimum ratio with respect to fuel efficiency, which is substantially higher under lean-burn conditions at A/F ratios of about 20 1, where the exhaust becomes rich in oxygen and NOx reduction is extremely difficult (Fig. 10.1). 

Because of its strong acid character sulphuric acid can decompose alkaline carbonates, violently forming a huge amount of carbon dioxide. Emissions are possible if the mixture is made without using any protection. The container can detonate if closed. 

Brantley, S.L. and Koepenich, K.W. (1995) Measured carbon dioxide emissions from Oldoinyo Lengai and the skewed distribution of passive volcanic fluxes. Geology, 23, 933-936. 

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