Cogeneration: A Successful Response to the Energy Crisis?

This article examines the concept of cogeneration, a term for the simultaneous production of both electricity and other useful energy in a single facility by a cascading use of heat energy. It analyzes the rise of cogeneration through the lens of the Public Utility Regulatory Policies Act of 1978 ( PURPA ), enacted by Congress to improve the distribution of electric energy and encourage the conservation of resources, as well as the efforts of the Federal Energy Regulatory Commission ( FERC ) to encourage cogeneration. This article discusses a number of the issues raised and left unresolved by this federal policy of encouraging the development of cogeneration energy sources. It describes the attraction of cogeneration in an era of rising energy costs, and then goes on to discuss the legislative and administrative responses to the prospect of expanded cogeneration. Finally, it explores the impact of cogeneration on utilities, as well as the efects of the policy on regulatory control of utilities

Cogeneration: A Successful Response to the Energy Crisis?

This article examines the concept of cogeneration, a term for the simultaneous production of both electricity and other useful energy in a single facility by a cascading use of heat energy. It analyzes the rise of cogeneration through the lens of the Public Utility Regulatory Policies Act of 1978 ( PURPA ), enacted by Congress to improve the distribution of electric energy and encourage the conservation of resources, as well as the efforts of the Federal Energy Regulatory Commission ( FERC ) to encourage cogeneration. This article discusses a number of the issues raised and left unresolved by this federal policy of encouraging the development of cogeneration energy sources. It describes the attraction of cogeneration in an era of rising energy costs, and then goes on to discuss the legislative and administrative responses to the prospect of expanded cogeneration. Finally, it explores the impact of cogeneration on utilities, as well as the efects of the policy on regulatory control of utilities

Advanced Cogeneration Technology Economic Optimization Study (ACTEOS)

The advanced cogeneration technology economic optimization study (ACTEOS) was undertaken to extend the results of the cogeneration technology alternatives study (CTAS). Cost comparisons were made between designs involving advanced cogeneration technologies and designs involving either conventional cogeneration technologies or not involving cogeneration. For the specific equipment cost and fuel price assumptions made, it was found that: (1) coal based cogeneration systems offered appreciable cost savings over the no cogeneration case, while systems using coal derived liquids offered no costs savings; and (2) the advanced cogeneration systems provided somewhat larger cost savings than the conventional systems. Among the issues considered in the study included: (1) temporal variations in steam and electric demands; (2) requirements for reliability/standby capacity; (3) availability of discrete equipment sizes; (4) regional variations in fuel and electricity prices; (5) off design system performance; and (6) separate demand and energy charges for purchased electricity

Advanced cogeneration research study: Executive summary

This study provides a broad based overview of selected areas relevant to the development of a comprehensive Southern California Edison (SCE) advanced cogeneration project. The areas studied are: (1) Cogeneration potential in the SCE service territory; (2) Advanced cogeneration technologies; and (3) Existing cogeneration computer models. An estimated 3700 MW sub E could potentially be generated from existing industries in the Southern California Edison service territory using cogeneration technology. Of this total, current technology could provide 2600 MW sub E and advanced technology could provide 1100 MW sub E. The manufacturing sector (SIC Codes 20-39) was found to have the highest average potential for current cogeneration technology. The mining sector (SIC Codes 10-14) was found to have the highest potential for advanced technology

Performance and operational economics estimates for a coal gasification combined-cycle cogeneration powerplant

A performance and operational economics analysis is presented for an integrated-gasifier, combined-cycle (IGCC) system to meet the steam and baseload electrical requirements. The effect of time variations in steam and electrial requirements is included. The amount and timing of electricity purchases from sales to the electric utility are determined. The resulting expenses for purchased electricity and revenues from electricity sales are estimated by using an assumed utility rate structure model. Cogeneration results for a range of potential IGCC cogeneration system sizes are compared with the fuel consumption and costs of natural gas and electricity to meet requirements without cogeneration. The results indicate that an IGCC cogeneration system could save about 10 percent of the total fuel energy presently required to supply steam and electrical requirements without cogeneration. Also for the assumed future fuel and electricity prices, an annual operating cost savings of 21 percent to 26 percent could be achieved with such a cogeneration system. An analysis of the effects of electricity price, fuel price, and system availability indicates that the IGCC cogeneration system has a good potential for economical operation over a wide range in these assumptions

Calibration and validation of a combustion-cogeneration

This paper describes the calibration and validation of a combustion cogeneration model for whole-building simulation. As part of IEA Annex 42, we proposed a combustion cogeneration model for studying residentialscale cogeneration systems based on both Stirling and internal combustion engines. We implemented this model independently in the EnergyPlus, ESP-r and TRNSYS building simulation programs, and undertook a comprehensive effort to validate the model's predictions. Using established comparative testing and empirical validation principles, we vetted the model's theoretical basis and its software implementations. The results demonstrate acceptable-to-excellent agreement, and suggest the calibrated model can be used with confidence

The development of a generic systems-level model for combustion-based domestic cogeneration

The provision of heat and power to dwellings from micro-cogeneration systems is gaining credence around the developed world as a possible means to reduce the significant carbon emissions associated with the domestic sector. However, achieving the optimum performance for these systems requires that building design practitioners are equipped with robust, integrated models, which will provide a realistic picture of the cogeneration performance in-situ. A long established and appropriate means to evaluate the energy performance of buildings and their energy systems is through the use of dynamic building simulation tools. However, until now, only a very limited number of micro-cogeneration device models have been available to the modelling community and generally these have not been appropriate for use within building simulation codes. This paper describes work undertaken within the International Energy Agency's Energy Conservation in Building and Community Systems Annex 42 to address this problem through the development of a generic, combustion based cogeneration device model that is suitable for integration within building simulation tools and can be used to simulate the variety of Internal Combustion Engine (ICE) and Stirling Engine (SE) cogeneration devices that are and will be available for integration into dwellings. The model is described in detail along with details of how it has been integrated into the ESP-r, Energy Plus and TRNSYS simulation platforms

Cogeneration computer model assessment: Advanced cogeneration research study

Cogeneration computer simulation models to recommend the most desirable models or their components for use by the Southern California Edison Company (SCE) in evaluating potential cogeneration projects was assessed. Existing cogeneration modeling capabilities are described, preferred models are identified, and an approach to the development of a code which will best satisfy SCE requirements is recommended. Five models (CELCAP, COGEN 2, CPA, DEUS, and OASIS) are recommended for further consideration

The application of cogeneration systems to the cooling of food and buildings in East Timor : a thesis presented in partial fulfilment of the requirements for the degree of Master of Technology at Massey University

Cogeneration is generation of both heat and power simultaneously using a single primary energy input. Cogeneration recovers "waste heat "from a conventional power generation plant to produce useful energy, leading to the increased overall efficiency of fuel input. This also achieves cost savings, and reduces greenhouse gas emissions where fossil fuels are used. The objectives of this study are to assess the technical and economic viability of a cogeneration system for the cooling of food and buildings in East Timor. The findings of this research provide a basis for recommending action and further research to East Timor's decision-makers on energy issues. Technical assessments in this study focus on cooling, electricity demand, and fuel supply as the basis for choosing the type and size of a cogeneration system. The financial viability of the cogeneration system is assessed using net present value (NPV) and sensitivity analysis. The NPV of the cogeneration system is compared with the NPV of conventional energy supply for cooling and electricity. There is low demand for cooling for comfort and food preservation in East Timor, due to low levels of industrial and commercial investment, and the vast majority of people still living in poverty. Although cooling demand is low overall, numerous government and commercial buildings have installed cooling systems. In this study, six buildings (2 office buildings, a bank, a hotel, a university and a mini-market) were selected based on their relatively high cooling demand and their geographic proximity to one another. The cooling demand of these six buildings was modeled based on a room-by- room approach. The results showed that their overall hourly cooling demand averages 600 kilowatt-cooling, while peak load was 707 kilowatt-cooling. This cooling demand was primarily driven by ambient temperature, number of people present and lighting load. Power demand in East Timor is low. The total operable power supply capacity for the entire country is 22 megawatts, of which more than half is located in Dili. Electricity demand is predominantly driven by residential consumption, rather than commercial and industrial consumption. Although there is low electricity demand, East Timor faces an immediate electricity deficit of 24 megawatts, which is higher than the existing operable capacity. In the six selected buildings, the overall peak and average electricity loads were 489 kW and 422 kW respectively. This load was mainly driven by air conditioning, computers, and lighting applications during working hours. Electricity generation relies on diesel, which is imported from Indonesia. Diesel will remain the main source to generate electricity due to a lack of feasible alternatives. East Timor is rich in natural gas both offshore and onshore. However, until now there has been no plan to provide natural gas distribution pipelines to East Timor. Based on the cooling and electricity demand and fuel availability, diesel was chosen to drive the cogeneration systems. The size of the cogeneration system was selected so as to fulfill both the electricity demand in the six selected buildings and be able to export surplus to the local grid. There are two reasons for employing a larger engine capacity. Firstly, a small engine will not be able to generate sufficient heat to drive an absorption cooling system with a capacity of 600 kilowatt. Secondly, export electricity will increase revenues generated from the cogeneration plant. Financially, the net present value (NPV) of both the cogeneration system and the conventional energy supply system were lower than zero, which means that neither system can be viable financially. The cogeneration system's NPV was lower than that for the conventional energy supply system, due to its higher capital and operating costs. High operating costs were due to fuel costs, with low revenues being due to heavy subsidies on electricity. If fuel and electricity subsidies were removed, a cogeneration system could become a more attractive option compared to a conventional system. However, removing the electricity subsidy would result in the large majority of people being unable to afford electricity

Comparison of Integrated Gasifier-Combined Cycle and AFB-steam turbine systems for industrial cogeneration

In the cogeneration technology alternatives study (CTAS) a number of advanced coal fired systems were examined and systems using a integrated coal gasifier IGCC or a fluid bed combustor AFB were found to yield attractive cogeneration results in industrial cogeneration applications. A range of site requirements and cogeneration sizing strategies using ground rules based on CTAS were used in comparing an IGCC and an AFB. The effect of time variations in site requirements and the sensitivity to fuel and electricity price assumptions are examined. The economic alternatives of industrial or utility ownership are also considered. The results indicate that the IGCC system has potentially higher fuel and emission savings and could be an attractive option for utility ownership. The AFB steam turbine system has a potentially higher return on investment and could be attractive assuming industrial ownership