On a typical day, when you return home from work and turn on the air conditioning, this action will force the electricity grid to provide the energy needed. That energy was not available before and is generated upon demand. In the UAE, 98% of this energy is provided by natural gas that is burnt in gas turbine engines. Fast forward 30 years from now – this energy source will be completely different. According to the UAE’s National Energy Strategy for 2050, one of the main objectives is to diversify the total energy mix in order to allow an increased contribution from renewables. The energy basket of the UAE in 2050 will consist of 44% renewables, 38% gas, 12% clean coal and six per cent nuclear.
Dr Elias Tsoutsanis
Today in the UAE, 98% of electricity is produced from natural gas that is burnt in combined cycle power plants, which are governed by gas turbines. A modern, heavy-duty, industrial gas turbine, which has the equivalent size of a bus, is capable of generating 400MW of power, which satisfies the energy demand of half a million people. To make a natural gas-fired power plant profitable and efficient, the gas turbines have to operate at full-load continuously. This performance characteristic is inherited from their jet engine counterparts, as they are more efficient when the aircraft is at cruise conditions of 40,000 ft. When it comes to the operation and maintenance of these machines, any unplanned outage or downtime can have a substantial economic impact. Managing the performance of gas turbines can make them strong support partners in renewable energy schemes, writes Dr Elias Tsoutsanis For example, unscheduled downtime for an LNG facility and an offshore platform costs USD 25 million and USD 7 million per day, respectively. Gas turbine manufacturers have addressed these challenges by equipping the gas turbines with sensors that are capable of monitoring their behaviour in real[1]time conditions.
However, the condition monitoring systems of these plants can only provide an indication of what’s going on with the engine. Further investigation has to be carried out in order to interpret engine data into customer value. A popular tool used for the above purpose is called engine performance diagnosis, which is the process of analysing data and identifying the health condition of engine components. Accurate and reliable diagnosis has a strong impact on the operation and maintenance of the plants, as they allow plant operators and managers to schedule, in advance, any maintenance action that each engine needs in order to minimise the risk of downtime and ensure the safe and reliable operation of the plant. With the impending energy transition that the UAE is targeting for 2050, several technical challenges will arise. One of these challenges is imposed by the intermittent nature of renewables, which will have a large contribution to the energy mix. When the sun is not providing enough radiation to the solar panels, or when the wind speed drops, both solar and wind farms will have a reduced capacity.
This problem will have to be solved by the gas turbines, which will be in stand-by mode and ready to respond quickly in order to fill the energy gap. Any delay or mismatch between demand and generation will affect the stability of the electricity of the grid. From the gas turbine perspective, this will mean that an engine will have to operate under dynamic and flexible conditions, characterised by fast acceleration and deceleration. To bring things into an operational perspective this is similar to taking an Airbus A380 and enabling it to engage in air combat with high manoeuvrability. Although this is something that gas turbines were not initially designed for, they have been equipped with technologies that empower them to cope with such scenarii. Nevertheless, the engines will experience accelerated rate of degradation, which means that the useful life of their components will be consumed faster than the current norm, and this will increase significantly the operational and maintenance costs of such assets.
Therefore, it is of crucial importance to redesign diagnostic and prognostic algorithms that will be able to predict accurately the performance of an engine that has a supporting role in the electricity mix. The slightest inaccuracy in the performance prediction of engines will affect the stability of the grid and can lead to blackouts. The above challenge motivated Dr Moussa Hamadache (University of Birmingham, UK), Professor Roger Dixon (University of Birmingham, UK) and I to investigate the effect of this transition. Our study proposes a new methodology that has the potential to diagnose the health of gas turbines engines when working in conjunction with renewable sources. We presented a paper on the subject at the American Society of Mechanical Engineers Virtual Turbo Expo in 2020. It was awarded the Best Paper by the Committee of Instrumentation, Control and Diagnostics. The study gives an insight into the challenges that the UAE will have to address in the future in order to enable a seamless transition to a diversified energy mix by 2050.
Dr Elias Tsoutsanis is Head of Research and Lecturer in Mechanical Engineering at the University of Birmingham Dubai. He specialises in gas turbine performance simulation, control, diagnostics and prognostics. He may be reached at E.Tsoutsanis@bham.ac.uk.
