OPTIMIZING A HYBRID RENEWABLE ENERGY SYSTEM WITH A FOCUS ON OFFSHORE WIND IN THE US NORTHEAST

Abstract

The objective of this research is to quantitatively assess the energy transition of a New England State, Rhode Island, to a renewable energy-based system that mainly relies on offshore wind resources. Rhode Island has currently planned a 1,000 MW offshore wind capacity as a major step toward fossil-free energy. It is not clear how the energy demand of the state can be met and what will be the realistic contribution of renewables in the future (e.g., 2030). In this study, at first, the electricity demand in Rhode Island at the present and future (e.g., considering electrification of transportation using electric cars) was assessed using the most recent published data. The time series of the hourly electricity demand for a year was predicted for several scenarios, and the base load, the peak load, and other load parameters were estimated. Further, the supply of renewable energy resources based on offshore wind and solar PV was predicted. Several electricity mix scenarios assuming various shares of renewable penetration and natural gas were created to assess how the demand can be met with a hybrid energy system. To optimize and assess each electricity mix scenario, HOMER (Hybrid Optimization of Multiple Energy Resources) was implemented. HOMER, developed by National Renewable Energy Laboratory, can optimize a hybrid renewable energy system based on minimum cost (i.e., Net Present Cost) while including constraints such as minimum renewable energy contribution/penetration. Several scenarios including the present energy mix, using 1000 MW of offshore wind, 100% renewable, and other mixes were simulated and optimized in HOMER. For the cost estimation, available published data were used. It was found that the transition towards renewable energy based on offshore wind is very challenging due to the peaks in electricity demand (e.g., August) in the summer when the offshore wind production reaches a minimum due to lower wind speeds. Natural gas or other resources would be still necessary to meet the demand in peak time. A possible solution to solve the intermittency is energy storage and solar energy which were assessed in HOMER as another scenario. Results were discussed and some recommendations for energy transition and possible percentage of each resource in the mix were presented.