Chains energy

Energy is a key issue and is closely associated with the environment. Global environmental issues must be addressed, where the energy chain from resources to end users is of vital importance. 

Figure 217. Trend shift of energy chain between energy supply and demand sides...

Fig. 5.2 The main crop-to-energy chains. BtL Biomass-to-Liquid, GtL Gas-to-Liquid, ETBE Ethyl tert-butyl ether, MTBE Methyl tert-butyl ether, MeOH Methanol, DME Dimethyl ether. Pyrolysis oil, HTU-Diesel (Hydro Thermal Upgrading), ethanol and hydrogen from ligno-cellulosic species are not considered here because of their minor practical relevance in the near future...

Whenever a monomer unit is added to the growing chain, the p-electrons come down to s-level and this process is accompanied by a release of about 20 K cal of energy. Chain propagation can be brought about without the help of any external energy. 

Energy-chain analysis of hydrogen and its competing alternative fuels for transport... 

Although in principle stationary and transport-specific energy chains can be analysed, here the assessment of the latter is explained in more detail, and is then referred to as well-to-wheel (WTW) analysis. The primary focus of WTW analysis in Europe is on global environmental impact, i.e., greenhouse-gas emissions expressed as C02-equivalents. Other issues of interest are (a) primary energy demand (which equals resource utilisation), (b) local pollutant emissions and (c) full energy or fuel supply costs. Well-to-wheel analysis covers the entire fuel supply chain from feedstock extraction, feedstock transportation, fuel manufacturing and fuel distribution to fuel use in a vehicle. 

In Section 7.3, process-specific technical information on alternative fuels, which is needed for the WTW analysis is presented, and in Section 7.4 drive-system-specific data are provided, which are then merged in a WTW analysis of complete energy chains in comparison in Section 7.5. In reality, the potential number of realistic alternative fuel chains and drive system combinations is much larger. Owing to limited space, a set of most relevant processes is presented. A separate section (7.6) discusses the resource utilisation of the energy chains presented in Section 7.5. Section 7.7 finally combines specific GHG emissions for relevant alternative fuel supply chains with specific costs in a portfolio analysis. 

In energy chains related to the provision of CMG, several GHG-emission relevant credits need to be taken into account. Biogas from municipal organic waste is credited for its fertilising effect, accounting for savings of 0.54 g of synthetic nitrogen... 

In this energy chain, coal is gasified to generate synthesis gas. The H2 CO ratio required for an optimum efficiency is adjusted via the CO shift reaction of a part of the carbon monoxide (CO) contained in the synthesis gas. The remaining synthesis gas is converted to liquid hydrocarbons via Fischer-Tropsch synthesis or via methanol synthesis with a downstream MtSynfuels (trademark by Lurgi) process (see beginning of Section 7.3.4). The liquid hydrocarbon yield amounts to about 0.40 MJ per MJ of hard coal, which is of the same order of magnitude as in the case of BTL ( 0.40 MJ/MJ) to calculate the thermal process efficiency, the electricity export must also be taken into account (see Table 7.12). 

Figure 7.5. Overall well-to-wheel (WTW) primary energy requirement for different energy chains (hybrid ICE and FC vehicles, electric vehicle (EV)).

Among liquid fuels (XTL), only biomass-derived hydrocarbons (BTL) are a relevant option from the perspective of lowering GHG emissions not so other fossil-based liquids (CTL, GTL). Even if CTL fuel supply paths were upgraded by carbon capture and storage, the resulting specific CCF-equivalent emissions would only be reduced to the level of conventional gasoline or diesel energy chains. 

Figure 9.30 Flow diagram of the energy chain from food to essential processes in human life. The ATP utilised by the NayK ATPase maintains the ion distribution in nerves that is essential for electrical activity and, in addition, maintains neurotransmitter synthesis, both of which provide communication in the brain and hence consciousness, learning and behaviour (Chapter 14). ATP utilisation by myosin ATPase is essential for movement and physical activity. ATP utilisation by the flagellum of sperm is essential for reproduction and ATP utilisation for synthesis of macromolecules is essential for growth.

Table 2 Description of the Geometrical and Energetical Features of the Significant Low-Energy Chain-Pairings...

Diazomethane. Although CH2N2 photolysis has been widely used as a methylene source, the reaction of CH2 with CH2N2 has received little attention. The quantum yield in the photochemical decomposition of CH2N2 is about four at both 4360 A. and 3650 A.96 The mechanism is believed to involve a short energy chain, in addition to the simple process... 

At the present time there is no experimental or theoretical evidence which would support a photon chain mechanism. However, if reaction (30) does occur, the spectral and photochemical evidence is that the next reaction should be the transfer to 3nu or some other repulsive state, as discussed in Part II. Two O(3P) atoms would then be formed by predissociation. The reaction (28) would then decompose two additional ozone molecules. A quantum yield of four could then be achieved without invoking either a photon or energy chain. In view of the uncertainty of the quantum yields greater than two and the maximum reported yield of six, this mechanism is perhaps the simplest necessary to explain the reasonably acceptable experimental evidence. 

Energy Chain. Schumacher (71) has presented a detailed mechanism based on an energy chain to explain quantum yield of greater than two. This chain assumes that reactions using vibrationally excited oxygen molecules are involved. McGrath and Norrish (54) have recently shown that vibrationally excited Cb S,-) is formed in the flash photol-... 

The chemical industry is experiencing important changes, the driving force for which is not only the need to improve competitiveness and consolidate market positions while complying with regulations and rules for the protection of human health and of the environment, but also the increased awareness that in the near future all the raw materials and energy chain supply will have to be reconsidered. 

Since hydrogen, like electricity, is secondary energy, the energy chain s front end converters (the power plants, the reformers, the electrolysers, the liquefiers and others) have to be taken into the safety considerations, too ... 

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