PTC-Assisted ORC System with Greenhouse Heating Supported by Condenser Waste Heat and Heat Pump

The effective use of renewable energy sources is of great importance in meeting the growing demand for energy, reducing dependence on fossil fuels, lowering greenhouse gas emissions and ensuring sustainable development. In this context, Parabolic Trough Collector-supported (PTC) Organic Rankine Cycle (ORC) systems and the utilisation of waste heat from the condenser for greenhouse heating offer a noteworthy solution for both increasing energy efficiency and reducing environmental impacts. In this study, a hybrid greenhouse heating system integrated with a CSP-based ORC is examined. In the system design, thermal energy obtained from CSP is used for electricity generation via ORC, while waste heat released at the turbine outlet and condenser unit is utilised for greenhouse heating. The greenhouse heat demand is assumed to be 32 kW, and analyses are being conducted for PTC areas of 100 m2and 200 m2. The results show that greenhouse demand cannot be met at low irradiance levels in a 100 m2PTC area, but is fully met at approximately 500-600 W/m2irradiance. On the other hand, in a 200 m2PTC area, greenhouse heat loss is completely eliminated from 200-300 W/m2radiation onwards, and additional energy production is achieved. In terms of electricity generation, the net electricity production for 100 m2of PTC at 1000 W/m2irradiation was approximately 12 kW, while the electricity fed into the grid was approximately 10 kW. In the 200 m2PTC scenario, under the same irradiation conditions, net electricity production is approximately 25 kW, while electricity fed into the grid reaches levels of 20-25 kW. At low radiation levels, the heat pump consumes an additional 2-4 kW of power, but in a scenario with a 200 m2PTC area, the heat pump shuts down at lower radiation levels, thereby increasing the reliability of the system. These findings demonstrate that the proposed hybrid approach not only enables the efficient use of renewable energy sources, but also reduces energy costs in greenhouse heating and provides additional electricity supply to the grid. Furthermore, this integration is expected to reduce environmental impacts and contribute to sustainable agricultural production.