english issue
and wind speeds of up to 126 km / h . The Shams Power Company is 80 % -owned by Masdar and 20 % -held by Total . Masdar is also leading a bid for Dubai ’ s first CSP tower plant . CSP developers are being urged to improve plant performance
in the ramp up years to lower the risk margins which impact competitiveness . The Shams 1 plant achieved a 99.5 % reliability rate in 2016 and generated a total of 232 GWh , some 9 % above expected output levels , Alobaidli told New Energy Update . Output at Shams 1 was boosted by modifications during the initial production phases which reduced morning start-up times , Alobaidli said . “ When we started operating Shams 1 it took us two hours to start up the plant .... Today it takes one hour and sometimes less ,” he said . Modifications included a pre-warming line to extract steam from the turbine to warm the plant , Alobaidli said . “ We utilize the steam in the system to pre-warm the plant and avoid having a big difference between the hot and cold status of the plant later . You must keep the solar-field and steam cycles as close to each other as possible in terms of temperature ,” he said . The Shams Power Company also improved plant reliability by erecting a perimeter wind fence to protect components from high wind levels and shifting dust . The fence protects the parabolic troughs from wind gusts and prevents the persistent movement of sand which can enter the solar field and cover components . A similar fence at DEWA ’ s planned CSP tower project would protect heliostats from performance degradation . “ I think a wind fence will be needed because it has huge benefits to the plant ,” Alobaidli said . “ Distances in tower plants can reach two kilometres whereas in trough plants they do not exceed three metres . So , the dust impact is much bigger on tower technology ,” he said . Shams Power Company is also currently testing a modification to cleaning trucks to make them more efficient and reduce water consumption . “ We ’ re planning to pilot this modification in one of our cleaning trucks in 2017 and if the results are positive we will upgrade our trucks in 2018 ,” Alobaidli said . Innovative heliostat designs , smart software , and pre-assembly installation methods are helping to reduce the cost of CSP towers . DEWA has specified that its first CSP plant must have a minimum of eight hours storage and the utility has tendered for a pair of 100 MW towers as this layout represents a cost-effective solution at this stage of global CSP development , Inaki Perez , Solar Team Leader at Mott MacDonald DEWA ’ s Technical Advisor , said at the MENA New Energy 2017 conference in April . DEWA ’ s tender specifications also provide design flexibility , allowing developers to optimize the solution within the tender requirements , Perez noted . The attenuation of solar rays from heliostat to tower due to dust and aerosols is the « biggest technological challenge » for developers in the UAE , Georgio Akiki , Middle East business development manager at EPC contractor Sener , told the conference . Sener has been involved in 29 CSP plant projects globally and is a partner in one of the DEWA CSP tender bids . More research is required into the impact of attenuation on plant performance so that companies can engineer ways to minimize the risks , Akiki said . One option to reduce attenuation is to construct a higher density solar field closer to the tower but this layout would also need to minimize shading and blocking , he noted . Going forward , design solutions to mitigate attenuation could change tower designs in the Middle East , Alobaidli said . « The solution is to think about multi-tower technology , because this will reduce the distance between the heliostat and tower ,” he said .
By Heba Hashem
OIL & GAS business / NUMÉRO 27 / juillet-août 2017 / 59