(630f) Sustainabilty Assessment and Design of Centralized and Decentralized Energy Solutions

Healthy economic growth in developing countries combined with increasing population and affluence are resulting in significant increase in total energy consumption.  At the same time, growing concern about environmental problems such as air pollution, global warming and depletion of fresh water resources is encouraging efforts for supplying this increasing energy demand in an environmentally friendly and sustainable manner. Depletion and price fluctuation of fossil fuels also mandates finding alternative technologies to satisfy this energy demand.

Especially in rural areas of developing countries, the burden of energy poverty reduces opportunities for enhancing their quality of life.  This poverty is due to factors such as absence of electrification or inconsistent availability.  Utilization of inefficient energy sources like cow dung, kerosene or biomass residues causes local environmental problems such as indoor smoke further triggering health problems and related healthcare costs.   Consequently, many efforts are focused on introducing decentralized and cleaner energy solutions.  Such solutions are also being adopted by the developed world due to the desire for enhanced sustainability.

  Given these reasons, it is essential to design energy systems consisting of centralized and localized options which create the optimum energy mix to meet energy demand in a manner that is environmentally, socially and economically feasible.

In this study, we evaluate the environmental and energetic performances of different energy technologies utilizing thermodynamic methods such as ecological cumulative exergy consumption or emergy analysis. These technologies are two centralized coal gasification technologies (conventional and calcium looping technologies) implemented with CO₂ capture, decentralized multi-crystalline solar cells, biomass gasification, and floating drum biogas power plants.  Furthermore, using a multi-objective mixed integer linear programming (MILP) framework and setting environmental, economic, social and thermodynamic objectives, we plan to find optimum energy mix for the selected society. This framework is applied to Rampura, a village in Central India, which is representative of a developing society.

Based on our preliminary results based on data from Rampura, biogas power plant is most attractive from a life cycle thermodynamic point of view, followed by solar power plant and coal technologies.

For rural biogas plant, we calculate its renewability index to be around 75 % for only biogas production and slightly lower for electricity generation from biogas because of machinery and maintenance requirements. A quality corrected thermodynamic return on investment is calculated to be around 5 for both biogas and electricity.   A sensitivity analysis identifies manure and brick (for construction) to be the most important resources. The photovoltaic solar power plant is found to be much less attractive than the biogas plant, with the most dominant inputs being resources for open ground mounting, inverter, maintenance inputs.   Not surprisingly, coal gasification is least attractive from an environmental point of view, but may be essential for satisfying energy needs.

Life cycle assessment of these technologies, including land use, water use, global warming potential and economic assessment are the next steps in this work.  The optimization problem is being formulated to identify the “optimum” energy mix while accounting for multiple objectives.  This framework will be relevant to choosing combinations of centralized and decentralized options in developing and developed economies.