Fuzzy optimization of a waste-to-energy network system in an eco-industrial park

The Ulsan Eco-Industrial Park (EIP) in South Korea houses as many as 1,000 companies, which generate about 524,000 t/year of organic waste. Of this total, 34 % is recycled, 8 % is incinerated with energy recovery, and the rest (58 %) is disposed of by ocean dumping (45 %), landfilling (11 %), or incineration without energy recovery (2 %). Although 42 % of the total waste generated at Ulsan EIP is recycled for material and energy recovery, additional opportunities to recover energy from improperly disposed of or incompletely utilized waste are possible through existing waste-to-energy (WTE) networks. To find an optimal WTE network in the Ulsan EIP, a fuzzy mixed integer linear programming mathematical model was developed to meet energy supply and demand (in terms of both quantity and grade) while considering the satisfaction level of potential stakeholders (e.g., the EIP initiator and tenants). The developed model was applied to two different scenarios that considered the requirements of EIP tenants for waste treatment and energy recovery. Based on the satisfaction level of the stakeholders, the WTE networks were analyzed to establish an optimal WTE network with maximum energy production and a minimal payback period.