School of Civil and Environmental Engineering

Ph.D. Thesis Defense Announcement

Implications of Hybrid Decentralized Energy Systems Composed of Solar Photovoltaics and Combined Cooling, Heating and

Power (CCHP) systems within Large Urban Regions

by:

Jean-Ann James

Advisor: 

Dr. John C. Crittenden

Committee Members: 

Dr. Valerie Thomas – Policy & ISYE, Dr. Godfried Augenbroe - COA, Dr. Susan Burns - CEE,

Dr. Yongsheng Chen - CEE

Date & Time: Tuesday July 14, 2015 at 9:00 am

Location:  Brook Byers Institute of Sustainable Systems Room 338

ABSTRACT:

Increasing urbanization places cities at the forefront of achieving global sustainability. Urban regions play a major role in the global economy

and are responsible for a majority of global resource consumption. Water and energy are the two main growth limiting resources of an urban

region and are highly interdependent. An increase in urbanization means increasing demand for water, energy, and their associated

infrastructure systems. Greater demand for provision of water and energy resources is associated with an increase in the emissions and wastes

generated to supply these resources. Therefore in order for urban areas to become more sustainable, they must meet the increasing demands

on resources through increased efficiency, resilience and sustainable alternatives. Decentralized energy systems have the potential to improve

the resiliency and efficiency of energy generation in an urban region while reducing the emissions created. Combined cooling, heating and

power (CCHP) systems are more efficient than conventional energy generation systems as they can simultaneously generate electricity, useful

heat and cooling. Adding solar photovoltaics to this system will further decrease the emissions and water consumption that result from the

energy generation process. The objective of this work was to determine the efficacy of implementing CCHP systems, with and without solar

photovoltaics, for five generic building types in the Atlanta metropolitan region, and the economic and environmental impacts of these

systems under various loading strategies. CCHP systems were modeled using air-cooled microturbines and absorption chillers to match the

thermal (heating, cooling, and hot water) load of the 5 building prototypes. The 5 prototypes consisted of 3 commercial and 2 residential

buildings. The CCHP systems were modeled to operate under various thermal loading strategies to determine the best strategy to minimize

costs, emissions, and water consumption for energy generation. The prototype buildings were then used to estimate the projected energy

consumption of residential and commercial buildings in the 13-county Atlanta metropolitan region and determine the emissions and water for

energy impact of conventional versus CCHP energy generation systems. Solar photovoltaics were then added to the CCHP system to

determine the optimum PV area required for a given building and feed in tariff. These investigations found that operating microturbines to

follow the hourly thermal load of a given building results in the greatest reduction in CO2 emissions, and operating the turbine constantly to

meet the maximum annual thermal demand results in the greatest NOx and water for energy reductions. A net metering policy will impact

which operational strategy best reduces emissions, water for energy, and cost. When applied to the 13 county Atlanta Metropolitan region,

CCHP systems can significantly reduce emissions and water for energy consumption. For all building types the economic feasibility of

implementing solar photovoltaic systems with microturbines is dependent on the discount rate of the system, the cost of the solar-pv system,

the feed in tariff rate assumed, and if various policies are implemented to provide benefits for the mitigation of CO2, NOx, and water

consumption. This study can serve as a platform by which the implementation of other decentralized energy systems can be evaluated.