Final Report Summary - SOLHYCO (Solar-Hybrid Power and Cogeneration Plants)
The scientific and technological objective of the SOLHYCO project was to develop and test a highly efficient, reliable and economic solar-hybrid cogeneration system based on a 100 kW microturbine, able to operate in parallel on varying contributions of solar power input and fuel.
As key component, an innovative solar receiver should have been developed based on an innovative Profiled multi-layer (PML) tube concept. This technology would enhance the heat transfer from the irradiated tube wall to the gas and allow for reduced temperature differences on the circumference of the tube, thus reducing stress and leading to higher life time. During the course of the project, the manufacturing of such tubes was developed and first samples and test tubes up to a length of 1.3 m were tested in a laboratory setup. It could be shown, that the temperature difference on the tube circumference could be reduced from 73.7 degrees Celsius to 14.1 degrees Celsius or 80.9 %, respectively. Although a great success, it was also noted that the durability of the intermetallic connection was not yet sufficiently withstanding temperature cycling. Due to time delays in the development of the manufacturing method for the solar receiver it was decided to build the receiver for the prototype microturbine system from mono-layer tubes. The receiver has the same design as with PML tubes, such allowing a later replacement of the tube.
To elaborate the use of bio-diesel for 100 % renewable operation of such plant, a study was realised and necessary modifications for a turbine system developed. The operation with biodiesel was then implemented in the former SOLGATE test setup consisting of a 250 kW airborne gas turbine with three solar receivers. During this project the solar hybrid operation had been successfully demonstrated in 2003, but with kerosene as backup fuel. Now this system was modified and equipped for biodiesel operation. In the test phase from March 1 2008 until 13 March 2009 approximately 100 hours of turbine operation were achieved, of which 57 hours of solar operation could be accumulated. The system was successfully operated at 100 % power from renewable energy sources. Tests were accomplished with even higher receiver air outlet temperature (843 degrees Celsius) than planned and electric power generation reached almost 220 kW. Data evaluation showed that the performance of the system did not significantly change between kerosene and biodiesel operation. The control system worked very well, solar hybrid operation was successfully demonstrated.
The design of the Turbec T100 microturbine had to be modified from the original cogeneration unit since the operation conditions as solar-hybrid unit are quite different. The solar receiver adds additional volume and acts as heat sink during start-up which requires modifications of the control system. The flow paths had to be improved and pressure losses in the system optimised. The combustor had to be modified due to the different cooling necessities stemming from higher temperatures due to the solar receiver. The solar receiver for the Turbec T100 microturbine was manufactured in spring 2009. The test bed in the CESA-1 tower was prepared and a test plan defined. The receiver cavity was designed, manufactured and assembled. In summer 2009, the complete system could be built up in the test facility. Electrical wiring was completed and the flux measurement system prepared. A data acquisition system had to be installed and programmed. First system tests started in autumn 2009 showing still major initial problems with the turbine operation and control which could not been solved before spring 2010. Then, the system was successfully tested through a period of more than 165 hours of turbine operation whereof 100 hours were solar operation. The system was operated at design conditions of 800 degrees Celsius receiver outlet temperature. Unfortunately, the receiver efficiency could not been measured with the desired accuracy, since the receiver cavity showed defects already after a few testing hours. This led to major heat leaks which could not been precisely determined.
Nevertheless the complete system behaved very good and solar hybrid operation could be demonstrated successfully. Also the first solar-only gas turbine operation worldwide of two hours of operation was achieved. Additionally, it could be shown that a receiver window has a positive effect on the system performance, especially for setups with receivers not facing vertically downwards.
The Mediterranean market was studied in detail to elaborate the market potential for the SOLHYCO technology. The market assessment showed that in most countries the market for hybrid systems is not very well prepared since feed-in regulations, if existing, prefer storage against hybrid solutions. However, the Algerian market, providing also a great solar resource, is offering adequate feed-in regulations for hybrid systems and is identified as the preferred actual market in the Mediterranean. This is especially valid for the big CC plants, since the generation cost and such the profitability is advantageous. If the above mentioned CC plant of 21 MW is operated with a 25 % solar share, the LEC is 0.085 EUR/kWh and thus close to be profitable in the Algerian market.
As key component, an innovative solar receiver should have been developed based on an innovative Profiled multi-layer (PML) tube concept. This technology would enhance the heat transfer from the irradiated tube wall to the gas and allow for reduced temperature differences on the circumference of the tube, thus reducing stress and leading to higher life time. During the course of the project, the manufacturing of such tubes was developed and first samples and test tubes up to a length of 1.3 m were tested in a laboratory setup. It could be shown, that the temperature difference on the tube circumference could be reduced from 73.7 degrees Celsius to 14.1 degrees Celsius or 80.9 %, respectively. Although a great success, it was also noted that the durability of the intermetallic connection was not yet sufficiently withstanding temperature cycling. Due to time delays in the development of the manufacturing method for the solar receiver it was decided to build the receiver for the prototype microturbine system from mono-layer tubes. The receiver has the same design as with PML tubes, such allowing a later replacement of the tube.
To elaborate the use of bio-diesel for 100 % renewable operation of such plant, a study was realised and necessary modifications for a turbine system developed. The operation with biodiesel was then implemented in the former SOLGATE test setup consisting of a 250 kW airborne gas turbine with three solar receivers. During this project the solar hybrid operation had been successfully demonstrated in 2003, but with kerosene as backup fuel. Now this system was modified and equipped for biodiesel operation. In the test phase from March 1 2008 until 13 March 2009 approximately 100 hours of turbine operation were achieved, of which 57 hours of solar operation could be accumulated. The system was successfully operated at 100 % power from renewable energy sources. Tests were accomplished with even higher receiver air outlet temperature (843 degrees Celsius) than planned and electric power generation reached almost 220 kW. Data evaluation showed that the performance of the system did not significantly change between kerosene and biodiesel operation. The control system worked very well, solar hybrid operation was successfully demonstrated.
The design of the Turbec T100 microturbine had to be modified from the original cogeneration unit since the operation conditions as solar-hybrid unit are quite different. The solar receiver adds additional volume and acts as heat sink during start-up which requires modifications of the control system. The flow paths had to be improved and pressure losses in the system optimised. The combustor had to be modified due to the different cooling necessities stemming from higher temperatures due to the solar receiver. The solar receiver for the Turbec T100 microturbine was manufactured in spring 2009. The test bed in the CESA-1 tower was prepared and a test plan defined. The receiver cavity was designed, manufactured and assembled. In summer 2009, the complete system could be built up in the test facility. Electrical wiring was completed and the flux measurement system prepared. A data acquisition system had to be installed and programmed. First system tests started in autumn 2009 showing still major initial problems with the turbine operation and control which could not been solved before spring 2010. Then, the system was successfully tested through a period of more than 165 hours of turbine operation whereof 100 hours were solar operation. The system was operated at design conditions of 800 degrees Celsius receiver outlet temperature. Unfortunately, the receiver efficiency could not been measured with the desired accuracy, since the receiver cavity showed defects already after a few testing hours. This led to major heat leaks which could not been precisely determined.
Nevertheless the complete system behaved very good and solar hybrid operation could be demonstrated successfully. Also the first solar-only gas turbine operation worldwide of two hours of operation was achieved. Additionally, it could be shown that a receiver window has a positive effect on the system performance, especially for setups with receivers not facing vertically downwards.
The Mediterranean market was studied in detail to elaborate the market potential for the SOLHYCO technology. The market assessment showed that in most countries the market for hybrid systems is not very well prepared since feed-in regulations, if existing, prefer storage against hybrid solutions. However, the Algerian market, providing also a great solar resource, is offering adequate feed-in regulations for hybrid systems and is identified as the preferred actual market in the Mediterranean. This is especially valid for the big CC plants, since the generation cost and such the profitability is advantageous. If the above mentioned CC plant of 21 MW is operated with a 25 % solar share, the LEC is 0.085 EUR/kWh and thus close to be profitable in the Algerian market.
