Combined heat and power systems

About 10 percent of the district energy systems are part of combined heat and power systems where both electric energy and useful thermal energy are produced. The electric generation capacity of these systems totals about 3,500 MW, about 0.5 percent of... 

This fuel cell has shown promise for combined heat and power systems (CHP systems). In such systems, the waste heat is used to heat buildings or to do work. Efficiency in a CHP plant can reach 80%. These plants could replace heating plants and power sources in colleges and universities, hotels, and apartment buildings. 

T)man (2005) reported on a case study of a CHP (combined heat and power) system installed at a dairy facility in Ireland. The CHP system generates electricity and uses the generated heat to provide steam. The overall efficiency of the process is 58%. Reported energy savings were 1.7M euros/year with reduction of 27,920 tons of CO2. 

A plant is proposing to install a combined heat and power system to supply electrical power and process steam. Power is currently taken from a utility company and steam is generated using on-site boilers. 

The development of district heating systems is linked with the development of other systems such as combined heat and power systems, which generate waste heat, together with power. These increase the fuel use efficiency [35]. Also heat pumps should be introduced in residential heating systems [18]. In some countries like Norway, district heating system s GHG emissions have been compared with those of individual heating systems and it has been found that the first have lower C02 emissions. 

A major cost in the operation of a dryer is in heating the air or gas. Frequently, the hot gases are produced by combustion of a fuel gas or atomised liquid, and considerable economy may be effected by using a combined heat and power system in which the hot gases are first passed through a turbine connected to an electrical generator. 

A 250 kilowatt atmospheric system is planned for a Toronto, Ontario, Canada site. The system will be operated by Ontario Power Technologies (formerly Ontario Hydro). The unit will supply 145 kilowatts of heat to the site heating system. Electric efficiency is expected to be about 47% (LHV). Operation of the combined heat and power system is expected in late 2001. 

Barclay F J, 2002, Fundamental thermodynamics of fuel cell, engine, and combined heat and power system efficiencies. Proceedings of the Institution of Mechanical Engineers, Part A, Journal of Power and Energy, 216, 407-417. 

The PEM fuel cell is the leading alternative for building-integrated applications, where multi-functionality would allow current natural gas burners to be replaced by combined heat-and-power systems, possibly with the additional option of supplying hydrogen to a one-vehicle filling station. One may think that if the automobile industry is successful in developing a viable... 

This workshop was held to discuss problems and opportunities in the development and application of biomass fuelled combined heat and power systems (CHP), and to make recommendations for research, demonstration and implementation of CHP systems. Although the development of cohesive and coordinated policies relating to CHP was recognized as being important, the discussion focused on technical issues and recommendations. 

AppHcation of combined heat and power systems (CHP) Condensate systems integration Boiler personnel training Technology transfer... 

The crucial need to avoid contact with any heating medium with a temperature exceeding 463 K should have led them to veto a steam supply which could do just that, even if only briefly during the operating cycle. There seems, therefore, to have been a serious mis-match between the intentions of the chemists which required saturated steam, and those of the service engineers whose combined heat and power system required the generation of highly superheated steam. 

Microgeneration technologies include small wind turbines, solar photovoltaic (PV) systems, small-scale hydro and micro CHP (combined heat and power) systems,... 

Technical Perspectives on 1-10 kW Residential Combined Heat and Power Systems Operated on Natural Gas... 

Novel highly efficient conversion technologies for mobility (electromobility) and combined heat and power systems (CHP) with independence on fossil fuels, in particular crude oU, are of utmost interest to face the energy challenges of the future [1, 2]. Fuel cell technology, based on... 

Schmid et al. [16] compared steam reforming and autothermal reforming of methane. They assumed that the anode off-gas was burnt in an external burner. The heat was utilised for heating purposes of a combined heat and power system. The analysis revealed much lower practical efficiency for autothermal reforming compared with steam reforming at 73% hydrogen utilisation in the fuel cell anode, as shown in Figure 5.44. 

One is the DACHS combined heat and power system developed by the German company SenerTec. The device has an electrical power output of 5.5 kWei, a thermal power output of 12.5 kWth, a high electrical efficiency of 25%, while the thermal efficiency is about 65%. The overall efficiency is therefore high at 90%. It has a size of 1.06-m length, 0.72-m width and 1-m height, a weight of 5 20 kg and noise emissions of less than 56 dB. Possible fuels are natural gas, liquefied petroleum gas, bio-diesel and diesel. 

The unit was then improved for onboard methanol processing dedicated for the automotive drive train [573] but also for residential combined heat and power systems [575]. The catalyst bed was uniform and filled with a combined precious metal/base metal multi-component catalyst. The reaction produced 2.4 mol hydrogen per mole methanol [573], which corresponds to a S/C ratio of about 0.4 and an O/C ratio of about 0.6 in the feed. These conditions resulted in 58 vol.% dry hydrogen content of the reformate. The maximum temperature in the fixed bed was reduced to 400 °C... 

The Japanese combined heat and power systems are usually smaller. As one prominent example, from numerous systems under development in the Japanese and Asian markets. Figure 9.30 shows the combined heat and power system working with a natural gas fuel processor and a PEM fuel cell, which was developed by Ballard for Tokyo gas [606]. The system achieved an efficiency of 38% at an electrical power output of 800 Wei. 

Figure 9.30 Combined heat and power system developed by Ballard for Tokyo gas [606],...

PEM fuel cells are in development to be ultimately deployed in the real world. The real world can vary considerably, from indoor use in buildings or warehouses to outdoor use under arctic conditions. Load variations can vary from continuous idle with occasional periods at maximum power for backup power systems, to highly dynamic operation in transport applications or working at continuous power for Combined Heat and Power systems. The level of control over all relevant parameters can be limited in a fuel cell system, and malfunctioning of control hardware can lead to conditions that fall outside the intended operating window. When compared to testing an MEA in a fuel cell laboratory in test hardware that excludes all influences but those deliberately applied by the operator, a large number of imperfections can be listed ... 

Hawkes AD, Aguiar P, Croxford B, Leach MA, Adjiman CS, Brandon NP (2007) Solid oxide fuel cell micro combined heat and power system operating strategy Options for provision of residential space and water heating. J Power Sources 164 260-271... 

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