Biogas Production in Abu Dhabi : An Evaluation based on Energy and Economy (Comparison of two plant designs)

Abstract: Abu Dhabi, which is the capital city of the United Arab Emirates, is known for its fast and advanced development in a short period of time. The city however generates a large amount of waste on a daily basis and a large amount of this is dumped or landfilled. Landfilling of the organic fraction of municipal solid waste (OFMSW), contributes to greenhouse gas (GHG) emissions and circa 80 % of the OFMSW is landfilled in Abu Dhabi. However, Abu Dhabi has shown its commitment to reducing GHG emissions by aiming to generate 7% renewable energy by 2030, improving waste management, and developing a strategy for green economy. In this study the approach evaluated is the waste-to-biogas system which utilizes anaerobic digestion of the OFMSW. Modules based on the Aikan® and REnescience® plant designs were simulated using SuperPro Designer® where energy and economic values were obtained and used for the evaluations. Excel was used to make a cash-flow analysis for both modules. A SWOT analysis was conducted to compare the strengths, weaknesses, opportunities and threats between both modules. Energy Returned on Investment is an approach that calculates the efficiency of a fuel by dividing the energy acquired by the energy required in a process. Both modules give an energy returned on investment (EROI) ratio for biogas of slightly below 2:1, in regards to electricity which is considered relatively low when compared to other fuels. Three methods were used for calculating the profitability of the modules, internal rate of return, pay-back period and net present value (NPV). However the net present value (NPV) was found most reliable and showed an NPV of $500 000 and $3 000 000 for module one and two respectively and calculations show that module one has more risks while module two could result in a bigger risk monetarily. The results show that implementing such a system will have a minimal contribution to the city’s aim of 7 % renewable energy generation. However, it will contribute to the city’s target of reducing GHG emission, improve waste management, and lead to a green economy.