The Experts below are selected from a list of 11967 Experts worldwide ranked by ideXlab platform

Jan Hensen - One of the best experts on this subject based on the ideXlab platform.

  • application of large underground seasonal Thermal energy storage in district heating system a model based energy performance assessment of a pilot system in chifeng china
    Applied Thermal Engineering, 2018
    Co-Authors: Luyi Xu, Ignacio J Torrens, Xudong Yang, Jan Hensen
    Abstract:

    Abstract Seasonal Thermal energy storage (STES) technology is a proven solution to resolve the seasonal discrepancy between heating energy generation from renewables and building heating demands. This research focuses on the performance assessment of district heating (DH) systems powered by low-grade energy sources with large-scale, high temperature underground STES technology. A pilot DH system, located in Chifeng, China that integrates a 0.5 million m3 borehole Thermal energy storage system, an on-site Solar Thermal Plant and excess heat from a copper Plant is presented. The research in this paper adopts a model-based approach using Modelica to analyze the energy performance of the STES for two district heating system configurations. Several performance indicators such as the extraction heat, the injection heat and the storage coefficient are selected to assess the STES system performance. Results show that a lower STES discharge temperature leads to a better energy performance. A sensitivity analysis of the site properties illustrates that the Thermal conductivity of soil is the most influential parameter on the STES system performance. The long-term performance of the STES is also discussed and a shorter stabilization time between one and two years could be achieved by discharging the STES at a lower temperature.

Luyi Xu - One of the best experts on this subject based on the ideXlab platform.

  • application of large underground seasonal Thermal energy storage in district heating system a model based energy performance assessment of a pilot system in chifeng china
    Applied Thermal Engineering, 2018
    Co-Authors: Luyi Xu, Ignacio J Torrens, Xudong Yang, Jan Hensen
    Abstract:

    Abstract Seasonal Thermal energy storage (STES) technology is a proven solution to resolve the seasonal discrepancy between heating energy generation from renewables and building heating demands. This research focuses on the performance assessment of district heating (DH) systems powered by low-grade energy sources with large-scale, high temperature underground STES technology. A pilot DH system, located in Chifeng, China that integrates a 0.5 million m3 borehole Thermal energy storage system, an on-site Solar Thermal Plant and excess heat from a copper Plant is presented. The research in this paper adopts a model-based approach using Modelica to analyze the energy performance of the STES for two district heating system configurations. Several performance indicators such as the extraction heat, the injection heat and the storage coefficient are selected to assess the STES system performance. Results show that a lower STES discharge temperature leads to a better energy performance. A sensitivity analysis of the site properties illustrates that the Thermal conductivity of soil is the most influential parameter on the STES system performance. The long-term performance of the STES is also discussed and a shorter stabilization time between one and two years could be achieved by discharging the STES at a lower temperature.

David R Mills - One of the best experts on this subject based on the ideXlab platform.

  • advances in Solar Thermal electricity technology
    Solar Energy, 2004
    Co-Authors: David R Mills
    Abstract:

    Abstract Various advanced Solar Thermal electricity technologies are reviewed with an emphasis on new technology and new market approaches. In single-axis tracking technology, the conventional parabolic trough collector is the mainstream established technology and is under continued development but is soon to face competition from two linear Fresnel reflector (LFR) technologies, the CLFR and Solarmundo. A Solarmundo prototype has been built in Belgium, and a CLFR prototype is awaiting presale of electricity as a commercial Plant before it can be constructed in Queensland. In two-axis tracking technologies, dish/Stirling technologies are faced with high Stirling engine costs and emphasism may shift to Solarised gas micro-turbines, which are adapted from the small stationary gas turbine market and will be available shortly at a price in the US$1 ppW range. ANU dish technology, in which steam is collected across the field and run through large steam turbines, has not been commercialised. Emphasis in Solar Thermal electricity applications in two-axis tracking systems seems to be shifting to tower technology. Two central receiver towers are planned for Spain, and one for Israel. Our own multi-tower Solar array (MTSA) technology has gained Australian Research Council funding for an initial single tower prototype in Australia of approximately 150 kW(e) and will use combined microturbine and PV receivers. Non-tracking systems are described of two diverse types, Chimney and evacuated tubes. Solar chimney technology is being proposed for Australia based upon German technology. Air is heated underneath a large glass structure of about 5 km in diameter, and passes up a large chimney through a wind turbine near the base as it rises. A company Enviromission Ltd. has been listed in Australia to commercialise the concept. Evacuated tubes are growing rapidly for domestic hot water heating in Europe and organic rankine cycle engines such as the Freepower 6 kW are being considered for operation with Thermal energy developed by evacuated tube and trough systems. These may replace some PV in medium sized applications as they offer potential for inexpensive pressurised water storage for 24 h operation, and backup by fuels instead of generators. In the medium term there is a clear trend to creation of smaller sized systems which can operate on a retail electricity cost offset basis near urban and industrial installations. In the longer term large low cost Plants will be necessary for large scale electricity and fuels production. Retrofit central generation Solar Plants offer a cost effective transition market which allows increased production rates and gradual cost reduction for large Solar Thermal Plant. In the paper the author describes current funding systems in Europe, Australia, and the USA, and makes suggestions for more effective programmes of support.

  • advances in Solar Thermal electricity technology
    Solar Energy, 2004
    Co-Authors: David R Mills
    Abstract:

    Abstract Various advanced Solar Thermal electricity technologies are reviewed with an emphasis on new technology and new market approaches. In single-axis tracking technology, the conventional parabolic trough collector is the mainstream established technology and is under continued development but is soon to face competition from two linear Fresnel reflector (LFR) technologies, the CLFR and Solarmundo. A Solarmundo prototype has been built in Belgium, and a CLFR prototype is awaiting presale of electricity as a commercial Plant before it can be constructed in Queensland. In two-axis tracking technologies, dish/Stirling technologies are faced with high Stirling engine costs and emphasism may shift to Solarised gas micro-turbines, which are adapted from the small stationary gas turbine market and will be available shortly at a price in the US$1 ppW range. ANU dish technology, in which steam is collected across the field and run through large steam turbines, has not been commercialised. Emphasis in Solar Thermal electricity applications in two-axis tracking systems seems to be shifting to tower technology. Two central receiver towers are planned for Spain, and one for Israel. Our own multi-tower Solar array (MTSA) technology has gained Australian Research Council funding for an initial single tower prototype in Australia of approximately 150 kW(e) and will use combined microturbine and PV receivers. Non-tracking systems are described of two diverse types, Chimney and evacuated tubes. Solar chimney technology is being proposed for Australia based upon German technology. Air is heated underneath a large glass structure of about 5 km in diameter, and passes up a large chimney through a wind turbine near the base as it rises. A company Enviromission Ltd. has been listed in Australia to commercialise the concept. Evacuated tubes are growing rapidly for domestic hot water heating in Europe and organic rankine cycle engines such as the Freepower 6 kW are being considered for operation with Thermal energy developed by evacuated tube and trough systems. These may replace some PV in medium sized applications as they offer potential for inexpensive pressurised water storage for 24 h operation, and backup by fuels instead of generators. In the medium term there is a clear trend to creation of smaller sized systems which can operate on a retail electricity cost offset basis near urban and industrial installations. In the longer term large low cost Plants will be necessary for large scale electricity and fuels production. Retrofit central generation Solar Plants offer a cost effective transition market which allows increased production rates and gradual cost reduction for large Solar Thermal Plant. In the paper the author describes current funding systems in Europe, Australia, and the USA, and makes suggestions for more effective programmes of support.

Robert A. Taylor - One of the best experts on this subject based on the ideXlab platform.

  • evaluating the benefits of using short term direct normal irradiance forecasts to operate a concentrated Solar Thermal Plant
    Solar Energy, 2016
    Co-Authors: Edward W Law, Merlinde Kay, Robert A. Taylor
    Abstract:

    Abstract Past studies about using direct normal irradiance (DNI) forecasts to operate a concentrated Solar Thermal (CST) Plant have not considered intra-day forecasts. This is a critical research gap because short-term forecasts are recommended for managing variable output from renewable energy generators, including CST Plants. This study evaluates the benefits of using 1-h forecasts to decide updated bids for a CST Plant after making initial bids from 48-h forecasts. The benefits are represented by the financial value calculated from revenue and reserve generation (RG) payments, and the reliability calculated from the equivalent forced outage rate (EFOR). Simulating a CST Plant operating in the Australian National Electricity Market for one year showed that using 1-h forecasts increases financial value by $1.04–1.13 million and reduces EFOR by 20–21% points for a 50 Megawatt (MW) CST Plant with 7.5 h of storage, and increases financial value by $0.7–$0.9 million and reduces EFOR by 20–23% points for a 50 MW CST Plant without storage. Reduced RG costs contributed towards 76–98% of the financial value increase for both CST Plants. A CST Plant without storage that uses 1-h forecasts achieves an EFOR of 10–11%, whereas a CST Plant with storage that does not use 1-h forecasts achieves an EFOR of 21–22%, so using 1-h forecasts may improve reliability more than adding storage to a CST Plant without storage. Using 1-h forecasts does not achieve the same total net value as a perfect 48-h forecast, but it achieves close to maximum value per unit electricity generated. Overall, CST Plants should use short-term forecasts if permitted under local electricity market regulations because they can achieve higher financial value and reliability. Future studies should use short-term forecasts when allowed by the local electricity market to more accurately demonstrate the value of CST Plants.

  • calculating the financial value of a concentrated Solar Thermal Plant operated using direct normal irradiance forecasts
    Solar Energy, 2016
    Co-Authors: Edward W Law, Merlinde Kay, Robert A. Taylor
    Abstract:

    Abstract This study examines the effect of direct normal irradiance (DNI) forecast accuracy on the financial value of a concentrated Solar Thermal (CST) Plant. Other factors such as electricity market regulations, Plant site local climate, and operating strategy are not considered. A CST model varied over 11 combinations of Solar field sizes and storage sizes is used to simulate Plant operation for three forecast methods and a perfect forecast. The financial value is calculated using revenue and reserve generation payments resultant from Plant operation. Results show when the root mean square error (RMSE) of a 48-h DNI forecast is between 325 and 400 W/m 2 , a 1 W/m 2 improvement increases the financial value by $400–1300 per 6 months operation for a CST Plant with Solar multiple between 1.25 and 2, and storage size between 0 and 20 h. Similarly, when the mean absolute error (MAE) is between 250 and 300 W/m 2 , a 1 W/m 2 improvement shows an increase of $1000–3600 per 6 months operation. If two forecast methods have similar MAE or RMSE, then the method that tends to over-predict DNI achieves higher value. For all forecast methods, increasing Solar multiple or storage size increases financial value. Financial value expressed using only revenue is overstated by 14–64% compared to using both revenue and reserve generation payments, depending on the CST Plant configuration and the forecast method. CST Plants with small Solar fields or small storage sizes gain proportionally more from investing to obtain better DNI forecasts because more accurate forecasts help these CST Plants generate more electricity from the limited Solar field Thermal output, and use more of the limited stored Thermal energy to increase revenue instead of reduce reserve generation payments caused by forecast errors.

  • calculating the financial value of a concentrated Solar Thermal Plant operated using direct normal irradiance forecasts
    Solar Energy, 2016
    Co-Authors: Robert A. Taylor
    Abstract:

    Abstract This study examines the effect of direct normal irradiance (DNI) forecast accuracy on the financial value of a concentrated Solar Thermal (CST) Plant. Other factors such as electricity market regulations, Plant site local climate, and operating strategy are not considered. A CST model varied over 11 combinations of Solar field sizes and storage sizes is used to simulate Plant operation for three forecast methods and a perfect forecast. The financial value is calculated using revenue and reserve generation payments resultant from Plant operation. Results show when the root mean square error (RMSE) of a 48-h DNI forecast is between 325 and 400 W/m2, a 1 W/m2 improvement increases the financial value by $400–1300 per 6 months operation for a CST Plant with Solar multiple between 1.25 and 2, and storage size between 0 and 20 h. Similarly, when the mean absolute error (MAE) is between 250 and 300 W/m2, a 1 W/m2 improvement shows an increase of $1000–3600 per 6 months operation. If two forecast methods have similar MAE or RMSE, then the method that tends to over-predict DNI achieves higher value. For all forecast methods, increasing Solar multiple or storage size increases financial value. Financial value expressed using only revenue is overstated by 14–64% compared to using both revenue and reserve generation payments, depending on the CST Plant configuration and the forecast method. CST Plants with small Solar fields or small storage sizes gain proportionally more from investing to obtain better DNI forecasts because more accurate forecasts help these CST Plants generate more electricity from the limited Solar field Thermal output, and use more of the limited stored Thermal energy to increase revenue instead of reduce reserve generation payments caused by forecast errors.

Xudong Yang - One of the best experts on this subject based on the ideXlab platform.

  • application of large underground seasonal Thermal energy storage in district heating system a model based energy performance assessment of a pilot system in chifeng china
    Applied Thermal Engineering, 2018
    Co-Authors: Luyi Xu, Ignacio J Torrens, Xudong Yang, Jan Hensen
    Abstract:

    Abstract Seasonal Thermal energy storage (STES) technology is a proven solution to resolve the seasonal discrepancy between heating energy generation from renewables and building heating demands. This research focuses on the performance assessment of district heating (DH) systems powered by low-grade energy sources with large-scale, high temperature underground STES technology. A pilot DH system, located in Chifeng, China that integrates a 0.5 million m3 borehole Thermal energy storage system, an on-site Solar Thermal Plant and excess heat from a copper Plant is presented. The research in this paper adopts a model-based approach using Modelica to analyze the energy performance of the STES for two district heating system configurations. Several performance indicators such as the extraction heat, the injection heat and the storage coefficient are selected to assess the STES system performance. Results show that a lower STES discharge temperature leads to a better energy performance. A sensitivity analysis of the site properties illustrates that the Thermal conductivity of soil is the most influential parameter on the STES system performance. The long-term performance of the STES is also discussed and a shorter stabilization time between one and two years could be achieved by discharging the STES at a lower temperature.

  • model based energy performance assessment of the world largest underground seasonal Thermal energy storage in a pilot district heating system in chifeng city
    4th Sustainable Thermal Energy Management International Conference (SusTEM 2017) june 28 2017 Alkmaar The Netherlands, 2017
    Co-Authors: J Torrens I Galdiz, Xudong Yang, F Guo, Ja Hense
    Abstract:

    District heating systems play an important role in supporting energy transition by using and storing energy delivered by renewable and other low-grade energy sources such as industrial waste heat. However, this low-grade heat is not always able to satisfy the heating demand, including space heating and domestic hot water (DHW). This mismatch is even more evident when looking at it seasonally. A proven solution to resolve this discrepancy is to implement seasonal Thermal energy storage (STES) technology. This research focuses on the performance assessment of district heating (DH) systems powered by low-grade energy sources with large-scale, STES technology. A pilot DH system, located in Chifeng, China that integrates a 0.5 million m3 borehole Thermal energy storage system, an on-site Solar Thermal Plant and excess heat from a copper Plant nearby to avoid additional fossil fuel-based heating supply is presented. It is, to date, the world largest (in volume) underground seasonal Thermal energy storage. The research in this paper proposes a modeling and simulation method to analyze the energy performance of the STES for two district heating system configurations. Several performance indicators are selected to assess the STES system performance. Results show that a lower STES discharge temperature leads to a better energy performance. A sensitivity analysis of the site properties illustrates that the soil Thermal conductivity is the most sensitive parameter among the chosen performance indicators. The long-term performance of the STES is also discussed in this paper to explore the time needed to reach a stable operation condition under different scenarios.