Development of a large-scale integrated solar-biomass thermal facility for green production of useful outputs

The present paper develops a new multigeneration plant to produce multiple commodities from two combined renewable energy sources, solar thermal and biomass and considers a specific case study administered for the city of Al Lith in Saudi Arabia. The plant generates power, heating, refrigeration, hydrogen, chlorine, concentrated sodium hydroxide, ammonia, urea, and fresh water, which are the commodities highly demanded in the area. The overall energy efficiency of the present system is determined to be 53 % with an annual generation of over 1036 GWh of power and cogenerated 858 GWh of heating, nearly 23 GWh of refrigeration effect, over 11,300 tons of ammonia, almost 1800 tons of urea, over 113,000 tons of concentrated sodium hydroxide and over 905,000 m3 of fresh water. The exergy contents of heating, refrigeration, power and commodity products represent a total of 45 % of the sources, which leads to a multigeneration platform's exergy efficiency. The system includes an integrated biomass gasification combined cycle with a biomass oxy-gasifier. The Aspen Plus simulations of the oxy-gasifier determined that the oxygen-to-biomass weight fraction should be set to 0.15, whereas the steam-to-biomass weight fraction is around 0.1. The exhaust gas recirculation is applied to enhance power generation rate and efficiency. The recirculation ratio of exhaust gas is found to be 0.21 if power generation efficiency is to be maximized and 0.28 if the power generation rate is to be maximized. Due to the fluctuating and intermittent nature of solar energy resource, there are two key options to overcome such challenges, namely incorporation of storage and hybridization with another renewable energy resource. The current paper demonstrates that the hybridization of solar and biomass energy together with integrated processes for multiproduct generation enhances the overall competitivity of the renewable energy system. To address this aspect, the objective of the paper is to develop and assess a new integrated flowsheet for hybrid renewable resource multigeneration.