Regulatory mechanism for biomass renewable energy in Brazil,a case study of the Brazilian Babassu oil extraction industry

Brazil has launched the PROINFA program, a regulatory mechanism to incentivize renewable electricity generation. In the light of this new framework, the best economical option for cogeneration was analyzed using one of the biomass resources available in Brazil-Babassu. Thus not only the possible power production but also the potential of such a regulatory tool to enhance the electricity production based on this biomass source, was analyzed. The power production was based on a steam power cycle cogeneration technology within the Babassu palm oil extraction industry in Brazil (Orbignya ssp. (Palmae)). Was used as base for this study: the energetic matrix for the oil extraction plants (for the two main profiles: oil extraction and refining only, and greater vertical integration with the production of other associated products obtained from the Babassu palm oil), utilization of an extraction–condensation turbine, and steam production operating at three levels of temperature and pressure (2.06 MPa/350 °C, 4.56 MPa/420 °C and 6.2 MPa/450 °C). To analyze the economic performance, the framework drawn up by the PROINFA was taken. From the analysis, the best economical/technical option for the design of the cogeneration system was found to be in industrial units with extraction and treatment of crude Babassu oil—steam generation at 4.56 MPa and 420 °C and, for units with a more vertically integrated production scheme—steam generated at 6.2 MPa and 450 °C. As a result, it became clear that the given framework may help the development of new renewable energy sources, but it does not give the necessary threshold to start new projects, neither does it incentive the maximization of the power production for this specific biomass resource.     

Performance of an innovative 120 kWe natural gas cogeneration system

The paper deals with an innovative (120 kWe, 195 kWt) natural gas (NG) combined heat and power (CHP) system, at present under development, which has been set up at the FIAT Centre of Research (CRF), Turin, Italy. The main characteristics of the CHP system are: the use of an automotive derived internal combustion engine, a high part load electrical efficiency due to a variable speed operation strategy and an advanced exhaust gas after-treatment to meet the most stringent pollutant emission regulations.     

Some problems with the development of combined generation of electricity and heat in Russia

The current state of cogeneration in Russia is analyzed. It is characterized by a sharp decrease in industrial heat consumption and a reduction in the demand for electricity. As a result many cogeneration plants presently operate under off-design conditions, which change their economic indexes to the worse. The ways of introducing small-scale cogeneration installations are considered, which show promise under the existing conditions of limited investments. The problems that accompany the introduction of modern highly efficient large-capacity power units at cogeneration plants are analyzed.     

Risk hedging against the fuel price fluctuation in energy service business

Energy service business, or energy service company (ESCO), is expanding among industrial users as a means of energy saving. The ESCO business normally tends to become a long-term operation. During the operation, fluctuations of fuel and electricity costs significantly impact on the stability of the profit from ESCO business. Therefore, it is essential to reduce the risk of fuel and electricity cost fluctuations. Generally, a transaction called “financial derivative” is used as a measure of hedging against the fuel price fluctuation. In the case of ESCO business, it is necessary to manage the risk of both electricity and fuel price fluctuations because the variation in electricity price strongly affects the profit from ESCO as that in fuel price does.     

热经济学中计价方法的探讨

Yong经济学是以Yong为核算对象的成本核算方法，以最小产品成本为目标函数，结合一定的Yong经济学评价指标，对能量系统进行分析、评价，得到改进的途径。文章基于Yong成本方程，对Yong费用方程进行了讨论，明确了过程Yong损的计价方法，提出了有效的Yong经济学系数。用能级概念可以更为全面的描述能流的品质，能级匹配是减小系统Yong损失的有效途径。文章将能级的概念引入热经济学计价体系，提出了基于能级分析的计价策略和评价指标。以联产模型为实例，进行了讨论。     

Waste energy recovery: An excellent investment opportunity

As energy costs increase, harnessing of waste energy in an efficient manner is becoming increasingly more important. This paper presents a new perspective on the use of Rankine cycles as applied to thermal energy from industrial waste heat and renewable sources. It shows that Rankine cycles can efficiently and in a cost-effective manner convert waste energy to power, heat pumping and cogeneration. Economics of waste energy recovery are discussed and examples of several applications are cited. It points out that life cycle cost of equipment is a more rational purchasing criteria than the first cost. Conclusions and recommendations are given for a more rapid commercialization on these new energy conserving systems.     

Maximum useful energy-rate analysis of an endoreversible Joule–Brayton cogeneration cycle

Endoreversible Joule–Brayton cogeneration cycle has been optimized based on a new criterion, total useful energy-rate (including power output and useful heat output), and the efficiency at maximum total useful energy rate has also been determined. The effects of various cycle parameters on the maximum dimensionless total useful-energy rate and the efficiency at maximum total useful-energy rate have been assessed. Variations of dimensionless total useful-energy rate with respect to efficiency have also been analyzed. The reversible Joule–Brayton power cycle is a special case of the analyzed cycle.     

Thermodynamical,economical and environmental evaluation of high efficiency gas turbine cogeneration systems

The paper evaluates the thermodynamical, economical and environmental characteristics of a cogeneration system composed of a gas turbine and a waste heat boiler (system A). Two other systems for increasing power generating efficiency are also evaluated, namely systems B and C, which are constructed by incorporating a regenerative cycle and a dual fluid cycle, respectively, into system A. It has been estimated that system C satisfies an environmental constraint that the nitrogen oxide density exhausted should be less than 100 parts in 10⁶, and that systems A and B also satisfy this constraint if a small amount of steam is injected into the combustor. The power generating efficiencies of systems A and B, in this case, and that of system C have been estimated to be 33.5%, 38.5% and 41.2%, respectively; i.e. the efficiencies of systems B and C can be improved noticeably compared with that of system A. The economics of these systems have also been evaluated based on the value of a profit index, and the systems are all estimated to be economically viable under the conditions assumed. As a result, it has been shown that it is possible to construct cogeneration systems with satisfactory characteristics of both environmental protection and profitability if system A is used in districts where the heat demand is large, system C in districts where the heat demand is small, and system B in districts with intermediate heat demand.     

Structure optimization of energy supply systems in tertiary sector buildings

Trigeneration systems, also known as Combined Heat, Cooling and Power (CHCP) systems, are interesting alternatives to supply different energy services in urban districts and in large buildings, particularly in warm areas such as Mediterranean countries. These systems can provide substantial benefits from economic, energetic, and environmental viewpoints, since the cogenerated heat can be used for heating in winter as well as cooling in summer with an absorption refrigerator. This paper develops an optimization model using Mixed Integer Linear Programming (MILP) to determine the type, number and capacity of equipment in CHCP systems installed in the tertiary sector as well as to establish the optimal operation mode for the different plant components on an hour-by-hour basis throughout the year. The objective function to be minimized is the annual total cost. The optimization model considers the legal constraints imposed to feed the surplus autogenerated electricity into the grid at a regulated feed-in tariff. The optimization model is applied to design a system providing energy services for a hospital located in the city of Zaragoza (Spain). The effects of the financial market conditions and energy prices in the optimal structure of the system are analyzed.     

新型分散式发电装置--微型燃气轮机

微型燃气轮机体积小、重量轻、适用燃料范围广、发电效率高,可靠近用户安装,并可同时提供热力和空调通风服务,是一种新型的分散式发电装置,具有广阔的应用前景.文章介绍了美国Capstone公司生产的一种微型燃气轮机的内部结构及其工作原理,指出了微型燃气轮机与传统的小型内燃发电机相比具有显著优点,还讨论了微型燃气轮机可能的应用领域和范围.