Binary Cycle

6 Key excerpts on "Binary Cycle"

• 

  eBook - ePub

  Perspectives For Geothermal Energy In Europe

  0

  • Ruggero Bertani(Author)
  • 2017(Publication Date)
  • WSPC (EUROPE)

    (Publisher)

  Chapter 2

  Geothermal Binary Plants for European Development

  Joseph Bonafin

  Turboden, via Cernaia 10 Brescia 25124, Italy [email protected]

  Geothermal projects are like fingerprints; each project is specific in its own way. This implies that some technical and economic prerequisites are required to understand the applicability of a power plant in a specific market.

  Binary technology makes the majority of geothermal sources exploitable, due to low-temperature applicability and flexibility. Organic Rankine Cycle (ORC) is the most widespread cycle for binary technology, with about 2 GW capacity installed and more than 500 projects in 80 countries currently under development. The ORC principle is very simple: it converts the geothermal heat into electricity into a closed process, with no harmful emissions.

  Geothermal power industry requires a multidisciplinary approach; in fact, many teams are involved in each phase of development: from geologist, to drilling experts, to geochemist, to the thermal and mechanical designer, to the financing partner.

  Once the project has reached the feasibility phase and at least one production well proved the resource, the project’s risk decreases and project financing is possible. The operation of a binary geothermal plant is eased by high reliability and low maintenance costs. Although a basic understanding of thermodynamics and heat transfer is required, the reader will be guided with simplified and practical approach to the binary power technology.

  2.1.The Organic Rankine Cycle (ORC) Cycle for Geothermal Applications

  2.1.1.Thermodynamics: Principles

  In binary plants, there is no direct use of geothermal fluid for electric power generation, but a secondary fluid (the binary one) is heated up and vaporized by means of heat exchange with the geothermal fluid, in order to spin a turbine and produce electricity.

  In geothermal power application, the general scheme is as follows (see Figure 2.1

  Sign up to read

  Learn more about book
• 

  eBook - ePub

  Small-Scale Renewable Energy Systems

  Independent Electricity for Community, Business and Home

  • Sven Ruin, Göran Sidén(Authors)
  • 2019(Publication Date)
  • CRC Press

    (Publisher)

  Fig. 2.47 ). It differs from other types of geothermal power plants in that the flow from the source does not contact the turbine directly. The power plants use a secondary liquid with a lower boiling point, such as butane. The liquid evaporates when it is heated by the geothermal flow in a heat exchanger and the steam drives the turbine.

  Figure 2.46 Flash-steam plants are the most common type of geothermal power plant in operation today. Source: DOE/EIA [31]

  Figure 2.47 In a Binary Cycle power plant the heat from the rock is absorbed with a heat exchanger. Source: DOE/EIA [31]

  An advantage of this more complex system is that there are no emissions into the atmosphere, because the geothermal flow is occurring in a closed circuit.

  The disadvantages are that the geothermal stream must be kept under pressure so that it does not evaporate; it requires large flows and about 30% of the resulting electrical energy is consumed in the process.

  Although the achieved efficiency can be low – down to 10% – this type of geothermal power plant has the greatest potential for the future. This is because of the lower demands on temperature and purity of the source than a Binary Cycle plant needs.

  Although it is possible to work with temperatures lower than 100 °C, the efficiency of the electricity output decreases.

  Two types of cycles are used, Organic Rankine Cycle (most common) and Kalina cycle. The Rankine cycle is named after W. J. M. Rankine, a Scottish engineer and physicist. He was an important contributor to the science of thermodynamics. Rankine has developed a complete theory of the steam engine and indeed of all heat engines.

  The Organic Rankine Cycle (ORC) technology is one way to convert heat to electricity. Its main applications are electricity generation from renewable heat sources (geothermal, biomass, solar), but it can also be used for heat recovery from industrial processes. ORC systems can range in size from kilowatts for domestic cogeneration to large geothermal power plants. According to a report in 2017 [32]

  Sign up to read

  Learn more about book
• 

  eBook - PDF

  Net-Zero and Low Carbon Solutions for the Energy Sector

  A Guide to Decarbonization Technologies

  • Amin Mirkouei(Author)
  • 2024(Publication Date)
  • Wiley

    (Publisher)

  Binary ORC systems have several benefits, such as reliability, stability, and sustainability, as well as operating at a wide range of geothermal fluid temperatures that make them suitable for a range of geothermal reservoirs. The systems are also compact and can be built in relatively small sizes. Binary ORCs have some drawbacks, such as geothermal fluid requirements and deployment barriers (e.g., high capital cost), as well as regular maintenance and replacement of equipment that can add to operational costs. 1.4 Geothermal 49 1.4.4 Kalina Cycle (TRL 6) Kalina cycle is another method for power generation from geothermal sources and is based on the principles of thermodynamics and heat transfer. The working fluid is evaporated in a low-pressure turbine, which expands the fluid and drives a gen- erator to produce power. Kalina cycles extract heat from the geothermal fluid in a heat exchanger. The geothermal fluid heats the ammonia–water mixture, which vaporizes and expands through a turbine to generate power. The spent fluid is then condensed, and the process is repeated. Kalina cycle technology is suitable for areas with medium- to high-temperature geothermal resources due to high flexibility with different geothermal fluid tem- peratures and flow rates. The benefits include the ability to: (i) integrate with existing geothermal power plants or as a stand-alone power generation system, (ii) provide a reliable and consistent power supply, (iii) operate continuously with minimal maintenance and downtime, (iii) have high efficiency due to the use of an ammonia–water mixture that has a lower boiling point than other fluids used in traditional binary systems, and (iv) generate power at lower temperatures, which are more common in geothermal resources. Organic Rankine and Kalina cycles are the standard Binary Cycle systems with 10–13% thermal efficiency.

  Sign up to read

  Learn more about book
• 

  eBook - PDF

  Energy Conversion Engineering

  Towards Low CO2 Power and Fuels

  • Ahmed F. Ghoniem(Author)
  • 2021(Publication Date)
  • Cambridge University Press

    (Publisher)

  Some pack- ages allow the user to add data and functionality to extend the capability. 6.13 Summary Converting low- and intermediate-temperature heat sources, such as geothermal, solar, and nuclear energy sources, to work is efficiently done using a two-phase power cycle. In the absolute majority of applications, the working fluid is water/steam. With even lower- temperature sources, such as waste heat (from industrial plants) and low-quality geo- thermal sources (to be discussed in detail in Chapter 9), it is possible to use an organic fluid (with lower critical pressure) instead of water as a working fluid. Rankine cycles are closed cycles in which the working fluid is externally heated and cooled in a cyclical fashion, and a pump (instead of a compressor) is used to raise the pressure of the liquid (instead of a gas) following condensation, which contributes to improving the cycle efficiency even with relatively lower maximum temperature (compared to the case of gas turbine cycles). Because the working fluid is isolated, it is possible to use lower- quality fuels (such as coal of different grades [see Chapter 12] or biomass [see Chapter 14]) as the heat source. On the other hand, maintaining the efficiency requires lowering the lower (condenser) pressure by using low-temperature coolant, as well as raising the maximum pressure of the cycle. Similar to Brayton cycles, reheat and regener- ation (internal transfer of heat between the expansion side and the liquid heating side) are used to further improve the efficiency. 6.13 Summary 361 Cycles whose maximum pressure is higher than the critical pressure of the working fluid are called supercritical cycles, and gain efficiency improvements by reducing the temperature difference between the heat source and the working fluid (and the corresponding irreversi- bility).

  Sign up to read

  Learn more about book
• 

  eBook - PDF

  Renewable Energy Technologies

  • Jean-Claude Sabonnadière(Author)
  • 2010(Publication Date)
  • Wiley-ISTE

    (Publisher)

  Performance tests carried out at the end of this period showed that the net electric power obtained, 1.7 MW, corresponded well to the 2.0 MW of the scheduled power, keeping in mind the correction to make for a shortfall of 3ºC in the temperature of the heat source (121ºC instead of 124ºC). This success, allowed the designer of the process (Exergy Inc.), the owner of the power plant (Orkuveita Husavikur) and two engineering firms involved (Power Engineers Inc., Exorka) to fuel the debate over the comparison of the energy output of the Kalina cycle and the organic fluid Rankine cycle. However, this was marred by corrosion problems affecting the turbine. The turbine, originally an axial flux KKK, was replaced by a GE radial flux turbine, apparently satisfactory. Deep aquifers Widely distributed in the continental platforms and generally well recognized by petroleum operators, deep aquifers can constitute geothermal sources for producing electricity from the moment that the parameters of temperature, porosity and permeability allow the production, at the surface, of a fluid with sufficient output 310 Renewable Energy Technologies and enthalpy. Temperatures above 90ºC and outputs of some tens of l/s are the parameters desired for Binary Cycle production. If, for the moment, projects are still in the technical-economic demonstration stage, still there are a few countries of the European Union, notably Germany, that include incentives for developing such projects in their energy policy. Historically, it is in Australia that the first small geothermal installations were placed over aquifers to supply isolated farms with electricity. Thus, at Mulka (south Australia), a 1,300 meter well drilled in the Great Artesian Basin in 1904 was reconditioned in 1985 and equipped with an organic fluid Binary Cycle device. An artesian output of 10 l/s of water at 86ºC allows producing 10 to 15 kW.

  Sign up to read

  Learn more about book
• 

  No longer available |Learn more

  Thermodynamics and Heat Power

  • Irving Granet, Maurice Bluestein(Authors)
  • 2014(Publication Date)
  • CRC Press

    (Publisher)

  The ball is called SOCCKET and utilizes a pendulum-type mechanism inside the ball to provide energy to charge LED lights or batteries. 8.11 Review The stated purpose of this chapter is the study of the conversion of energy from one form to a more useful form. We started our study with a review of the Carnot cycle and then went on to the prototype Rankine, reheat, and regenerative steam cycles. These are “ideal” 417 Vapor Power Cycles cycles in the sense that we ignored irreversible effects such as friction, pressure drops, heat losses, turbulence, and so on. Having studied these cycles, we then turned our attention to the equipment that is used for their practical realization. Many other fluids and cycles using them have been proposed and constructed in addi-tion to those cycles that use either water or gas as their working fluid. Binary fluid cycles using mercury or ammonia and water are examples of such alternates. The direct conversion of the energy of a source to electrical energy without the use of a circulating fluid or moving parts has come under intensive development in recent years. In this chapter, we looked briefly at the thermoelectric converter, fuel cell, thermionic con-verter, MHD generation, solar energy, wind, and nuclear power. Most of these sources are not suitable at present for the large-scale generation of power. However, they are a welcome supplement to our energy supplies and, with further development, will become increasingly economically useful. Cogeneration has recently become a feasible method of energy utilization. By the simple expediency of using the low-temperature energy for process or heating requirements, it is pos-sible to combine electrical energy generation with heat requirements to obtain greater energy utilization than when each requirement is performed separately. While cogeneration does not introduce any new concepts, the savings in energy can be considerable.

  Sign up to read

  Learn more about book