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Mankind's prosperity has been dependent on availability of affordable energy in the recent centuries. Today, the need of sustainability requires precise energy efficiency evaluation. Unfortunately, the traditional metrics like energy return on investment (EROI) suffer from the system boundaries and from the inability to describe labor and physical capital in terms of energy. Therefore, they tend to omit up to 50% of input energy consumption. The price of energy model (PERM) and cost of energy model (CERM), derived via matrix description of production process, show that the ratio of the average energy input cost to the average useable energy output cost describes energy efficiency completely. The same holds for the ratio of energy prices, if shares of aggregate rents, taxes and subsidies in the input and output prices are similar. The above price (cost) ratio can serve as an EROI check and eliminate the need for a lengthy process analysis. The results enable the extension of energy efficiency metrics by social and environmental effects, measurable mostly in monetary terms. [ABSTRACT FROM AUTHOR]

To consider the environmental impacts of energy resource exploitation and better estimate the energy return of investment (EROI), this paper establishes a new emergy-based method (EmEROI) that can capture the essence of energy resource exploitation. The EmEROI method treats environmental impacts and labor as particular forms of energy, and all forms of energy can be quantified by solar transformity, which is expressed in emjoules as a common unit. The Daqing oilfield is used as an example, and the corresponding EmEROI value is calculated via the proposed method. The results are then compared with standard EROI estimates. Our EmEROI result is much lower than the standard EROI result and presents a more pronounced declining trend. Our results also indicated that the EmEROI estimates conform well to actual conditions and are not as affected by industrial energy intensity levels as the standard EROI. Thus, EmEROI has the potential for use as an integral aspect of energy resource exploitation project evaluations. [ABSTRACT FROM AUTHOR]

A recent upsurge of investment in photovoltaic (PV) industry in China has made outstanding contributions to the adjustment of energy structure. In order to further promote the investment and construction of PV projects, the state has published many fiscal subsidy policies. In addition to unified national subsidy standard, local standards have been developed according to local fiscal revenue. They either have greatly improved return on investment (ROI) or have no significant effect as a result of too many impact factors. This paper utilizes multi dimensional big dates of distributed PV projects to obtain the weight of factors influencing the ROI from the calculation equation of ROI, which is fitted with innovative big data mining method of LSSVM-PSO. Results show that construction cost, sunshine duration, retail electricity tariff and subsidy have the greatest impacts. This study provides decision makers with quantitative basis for more comprehensive understanding on economic aspect of the distributed PV projects. [ABSTRACT FROM AUTHOR]

In this study, a new thermochemical route to produce lignocellulosic ethanol based on DME (dimethyl ether) hydrocarbonylation is proposed and economically assessed. The process is designed and evaluated using current kinetic laboratory data for hydrocarbonylation reactions. Only available technologies or those expected to be available in the short term are considered for the process design, which involves biomass pretreatment and gasification (indirect circulating fluidized bed), gas clean-up and conditioning, methanol synthesis, DME production by methanol dehydration and DME hydrocarbonylation. The process is designed to be both energy self-sufficient and electrical energy neutral. For a plant size of 2140 dry tonnes/day of wood chip (500 MWHHV) the minimum selling price of ethanol (for a 10% rate of return and a biomass price of 66 $/dry tonne) ranges from 0.555 to 0.592 USD2010/L of automotive grade ethanol with fixed capital costs between 333 and 352 M USD2010. Energy efficiency of biomass to ethanol ranges from 44.35 to 45.53% (high heating value basis). These results compare favorably with the “state of the art” production of ethanol via biochemical pathway from lignocellulosic biomass, revealing that the DME hydrocarbonylation route is a promising one that could be cost-competitive in the near future. [ABSTRACT FROM AUTHOR]