Transportation, energy for

It is likely that the reliable crude oil supply will not diminish any time soon. Petroleum-derived fuels will remain the primary source of transportation energy for well into the twenty-first century. Producers and refiners have been, and will be, environmentally responsible. The existing infrastructure of advanced product distribution systems can compete with alternative fuels readily. Future fuels will be competitive, both economically and environmentally. New global market conditions will dictate closure of inefficient facilities and investment in new technology. Larger and more efficient operations will survive and will focus on the niche market. ... 

Chemists and chemical engineers will need to join with experts in other disciplines to invent new ways to generate and transport energy for human use and provide for the needs and aspirations of a growing population in a sustainable manner. New ways will also be needed to minimize the energy used for human activities, including manufacturing. 

Section 8.2 showed the huge sector represented by transport energy. For transport fuel, large scale and large company development is needed to make an impact. This will only happen when the requirements of cost, convenience, and safety have been met. At this point all the other uses of conventional fuels will be opened too. 

When there is no mechanism for ATP synthesis, the energy of electron transport is released as heat. Certain animals that are adapted to cold climates have developed their own uncoupling system, which allows them to use electron transport energy for heat production. These animals have large amounts of a tissue called brown fat, which contains a high concentration of mitochondria. This tissue is brown... 

Reactions represent the dynamic aspect of chemistry, the interconversion of chemical compounds. Chemical reactions produce the compounds that are sold by industry and that play a big role in maintaining the standard of living of our society they transform the food that we take up in our body into energy and into other compounds and they provide the energy for surviving in a hostile environment and the energy for a large part of our transportation systems. 

One-equation models relax the assumption that production and dissipation of turbulence are equal at all points of the flow field. Some effects of the upstream turbulence are incorporated by introducing a transport equation for the turbulence kinetic energy k (20) given by... 

S. C. Davis and P. S. Hu, Transportation Energy Data Book Edition 1 /, ORNL-6649, Oak Ridge National Laboratories for Office of Transportation Technologies, U.S. Dept, of Energy, Washington, D.C., 1991. 

Active Transport. Maintenance of the appropriate concentrations of K" and Na" in the intra- and extracellular fluids involves active transport, ie, a process requiring energy (53). Sodium ion in the extracellular fluid (0.136—0.145 AfNa" ) diffuses passively and continuously into the intracellular fluid (<0.01 M Na" ) and must be removed. This sodium ion is pumped from the intracellular to the extracellular fluid, while K" is pumped from the extracellular (ca 0.004 M K" ) to the intracellular fluid (ca 0.14 M K" ) (53—55). The energy for these processes is provided by hydrolysis of adenosine triphosphate (ATP) and requires the enzyme Na" -K" ATPase, a membrane-bound enzyme which is widely distributed in the body. In some cells, eg, brain and kidney, 60—70 wt % of the ATP is used to maintain the required Na" -K" distribution. 

The term e/(e — 1), which appears in equations 1 and 2, was first developed to account for the sensible heat transferred by the diffusing vapor (1). The quantity S represents the group ratio of total transported energy to convective heat transfer. Thus it may be thought of as the fractional... 

Ascorbic acid is involved in carnitine biosynthesis. Carnitine (y-amino-P-hydroxybutyric acid, trimethylbetaine) (30) is a component of heart muscle, skeletal tissue, Uver and other tissues. It is involved in the transport of fatty acids into mitochondria, where they are oxidized to provide energy for the ceU and animal. It is synthesized in animals from lysine and methionine by two hydroxylases, both containing ferrous iron and L-ascorbic acid. Ascorbic acid donates electrons to the enzymes involved in the metabohsm of L-tyrosine, cholesterol, and histamine (128). 

Using turbulenee models, this new system of equations ean be elosed. The most widely used turbulenee model is the k-e model, whieh is based on an analogy of viseous and Reynolds stresses. Two additional transport equations for the turbulent kinetie energy k and the turbulent energy dissipation e deseribe the influenee of turbulenee... 

Computational fluid dynamics (CFD) is the numerical analysis of systems involving transport processes and solution by computer simulation. An early application of CFD (FLUENT) to predict flow within cooling crystallizers was made by Brown and Boysan (1987). Elementary equations that describe the conservation of mass, momentum and energy for fluid flow or heat transfer are solved for a number of sub regions of the flow field (Versteeg and Malalase-kera, 1995). Various commercial concerns provide ready-to-use CFD codes to perform this task and usually offer a choice of solution methods, model equations (for example turbulence models of turbulent flow) and visualization tools, as reviewed by Zauner (1999) below. 

Consumption in the transportation sector historically has been less than either the industrial sector or the residential and commercial sector, but it is of greater concern because consumption is almost entirely petroleum as opposed to a mix of petroleum, natural gas, and electricity. And because electricity can be generated from a number of different sources, and because there is greater opportunity to substitute one source of energy for another in generating electricity, the price and supply security that exists in other sectors does not apply to the transportation sector. 

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. 

Movement of freight accounts for one-third of all U.S. transportation energy consumption. But if the U.S. share of the export/import cargo shipping market was included, the figure would be even higher. 

Because eveiy means of transportation requires energy for propulsion, how energy is used in transportation is something that is carefully tracked by the Office of Transportation Policy Development within the Department of Transportation (DOT). The transportation sector felt the greatest impact from the oil supply disruptions in the 1970s because it was, and continues to be, the sector most dependent on oil. It is also the sector with the least flexibility to switch fuels, (see also Consumption)... 

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