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November 10th, 2010
Back in the Salt Palace near the Chenected booth, I found myself in the Sustainable Electricity: Generation and Storage Session. As issues centering around renewable energy production and its fluctuating supply arise, one can’t help but talk about energy storage. Massive Energy Storage Design for Renewable Electricity Generation Systems presented by Benjamin P. Omell of the Illinois Institute of Technology was a great way to lead off the session. Omell touched on a few of the energy storage options that have drawn the most attention recently: Large scale battery, compressed air, flow battery, flywheel, thermal energy storage and pumped hydro-storage. In his presentation he discussed the variable constraints that accompany energy storage and showed several models of hybrid coal, gas turbine and renewable energy production toward optimization. Alexandre F.T. Yokochi of Oregon State University followed up with his presentation on Sizing of Electrical Energy Storage for Large Scale Renewable Energy Penetration in the Grid and Implementation of a Lab Scale Grid for Experimental Validation. The sizing and control of energy storage system is extremely important as renewable sources of energy such as wind and solar are subject to fluctuations in intensity. The importance of forecasting accuracy in a method of hybrid electricity production is vitally important to having constant and consistent electricity available in the grid—storage is one way to even out the fluctuations. With Yokochi’s Lab Grid, we see on a small scale that improved forecast accuracy and co-function of electricity producers could lead to a much smoother electrical supply with minimal storage needs (the more accuracy demanded, the more vital storage becomes). A Steady-State Model of a Sub-Scale Flow Battery System presented by Arun Pandy of United Technologies Research Center was the next presentation—looking into a particular method of electricity storage. Boasting characteristics of both fuel cells and batteries, flow batteries are an attractive option for energy storage. Two different types of flow batteries are the Vanadium Redox Battery (VRB) and the Polysulphide Bromide (PSB) battery (these batteries have different cations moving across the membrane). The performance of these batteries is influenced by kinetic losses, ohmic losses and mass transport losses. Understanding the contributions to performance, Pandy developed a model to help analyze how the performance can be improved by looking at the electrode, the electrolyte, the electrolyte flow and the properties of the membrane itself. Up next was Frank Zeman of the New York Institute of Technology presenting Renewable Energy Storage Using Hydrated Lime discussing a chemical storage method. Zeman asked the audience to rethink “why electricity?” Yes, electricity is necessary to run certain processes in the home, but when you think about heating a home, we take a fuel source (electricity, natural gas, heating oil etc) and use it to produce heat. This hydrated lime chemical storage method is really a method of heat storage. Instead of inputting electricity into the system and trying to get electricity out of the system, electricity is input to drive the initial reaction and heat is the product that could be distributed to homes or locally produced within the home (thereby cutting out the furnace middleman). Additionally when using Quicklime as the raw material, this process yields an estimated material cost of $0.22/kW hr. The Sustainable Electricity: Generation and Storage session was extraordinarily well put together painting a narrative picture of what is going on in the research field at this time. As the Chair of the session, Alex Yokochi said in his closing remarks, this is definitely an area of research that is growing and we should look forward to another dynamic session next year.