Monthly Archives March 2016


DE has been defined by the size of the technology or by specific technologies. It has also been defined on the basis of connection (connected to either the electricity distribution system or, in some cases, the medium-voltage network), dispatch (not centrally dispatched), whether it is located on the customer side of the meter, and noninclusion in system production optimization studies.

However, defining DE by its relationship to the electricity network ensures that DE is a function of the characteristics of that network. For example, a country dominated by very large centralized units, such as France, may define DE as <100 MWe, but another system configuration, such as that in the Netherlands, may define DE as <1 MWe, or two orders of magnitude smaller...

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Table I shows different types of vehicle propulsion systems and the transportation fuels that have been studied for their potential to power the vehicles. Gasoline, CNG, LNG, LPG, methanol, ethanol, and hydrogen can be used in vehicles equipped with conventional spark-ignition (SI) engines. Interest in developing efficient, low-emission, spark-ignition direct-injection (SIDI) engine technologies has heigh­tened in recent years. Although vehicles with SIDI engines can be fueled efficiently with liquid fuels (gasoline, methanol, ethanol, and liquid hydrogen), gaseous fuels do not appear to offer inherent fuel economy benefits when used in these engines...

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The fuel cycle for a given transportation fuel includes the following processes: energy feedstock (or primary



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energy) production; feedstock transportation and storage; fuel production; fuel transportation, storage, and distribution; and vehicle operations that involve fuel combustion or other chemical conversions (Fig. 3). The processes that precede vehicle opera­tions are often referred to as the well-to-pump (WTP) stage, the vehicle operations are referred to as the pump-to-wheels (PTW) stage, and the entire fuel cycle is referred to as the well-to-wheels (WTW) cycle. Various models have been developed that allow researchers to conduct fuel cycle analyses of vehicle/fuel systems...

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1.1 Alternative Transportation Fuels

At present, in the United States and worldwide, motor vehicles are fueled almost exclusively by petroleum – based gasoline and diesel fuels. Since the first oil price shock in 1973, efforts have been made to seek alternative fuels to displace gasoline and diesel fuels and achieve energy and environmental benefits. Some of the alternative fuels that have been researched and used are liquefied petroleum gas (LPG), compressed
natural gas (CNG), liquefied natural gas (LNG), methanol (MeOH), dimethyl ether (DME), Fischer – Tropsch diesel (FTD), hydrogen (H2), ethanol (EtOH), biodiesel, and electricity. Production pro­cesses associated with gasoline, diesel, and each of these alternative fuels differ.

For fuel cycle analyses, gasoline often serves as the base...

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Fuel cycle analysis is requisite when comparing different vehicle technologies powered by different fuels. Figure 1 shows the significantly different greenhouse gas (GHG) emission results obtained by considering only vehicle tailpipe emissions (pump to wheels) versus considering both fuel production (well to pump) and tailpipe emissions (fuel cycle). A number of studies have been conducted to estimate fuel cycle emissions and energy use associated with various transportation fuels and vehicle technologies. The results of those studies were influenced by the assumptions made by individual researchers regard­ing technology development, emission controls, primary fuel sources, fuel production processes, and many other factors...

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Distributed Energy, Overview


Pew Center on Global Climate Change Arlington, Virginia, United States

engineering studies, permitting, interconnection, and setup expenses.

interconnection The link between a distributed energy generator and the load being served by the utility electricity network

lower heating value (LHV) Assumes the heat of vaporiza­tion of water cannot be recovered. For natural gas, LHV efficiency = higher heating value efficiency x 1.1. modularity Increments of new capacity that can be simply and flexibly added or removed to change the unit’s energy output.

operation and maintenance costs (O&M Costs) These are divided into fixed costs and variable costs depending on the relation to hours of operation and capacity factor. photovoltaic (PV) cells Also known as solar cells...

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The preceding arguments attempt to explain the paradoxes surrounding discount rates and the efficiency gap in terms of the workings of what Sutherland terms normal or economically efficient markets. An alternative explanation offered by Stanstad and Howarth focuses on market barriers or market failures that impeded the adoption of cost – effective, energy-efficient technologies. In broad terms, at least two sources of market failure are emphasized in this context: imperfect information and bounded rationality.

Behavioral studies have established that house­holds and businesses are often poorly informed about the technical characteristics of energy-using equip­ment...

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As explained previously, the discount rate reflects the rate at which people are willing to exchange present and future economic benefits. According to standard economic reasoning, discount rates are revealed by people’s observed behavior in markets for savings and investment. A homeowner who takes out a loan at a 4% real (inflation-adjusted) interest rate, for example, reveals a willingness to pay back $3.24 30 years from the present to obtain just $1 dollar today. Similarly, a worker who invests $1 in a mutual fund would expect to receive $10.06 upon retiring three decades in the future given an 8% annual return.

Economists generally agree that market rates of return reveal people’s discount rates...

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