UT Austin Center for Electrochemistry Conference

I spent this weekend attending an electrochemistry conference at UT Austin called “Challenges at the Electrode/Electrolyte Interface”. Electrochemistry is involved in a number of systems that could play a role in helping address the world’s energy needs. This includes batteries, fuel cells, and photoelectrochemistry. These systems could play a role in vehicle propulsion via plug-in hybrid, electric, or fuel cell vehicles, load leveling for large scale renewable energy infrastructure via fuel cells or flow batteries, or fuel or electricity production via photoelectrochemical systems such as dye-sensitized solar cells, artificial photosynthesis, or photon driven water electrolysis for hydrogen production.

One of the poorly understood and critical areas of research for fuel cells and other electrochemical systems is electrocatalysis. Despite decades of research, catalysis and what makes certain materials better catalysts than others is still not well understood. (A catalyst is a material that increases the rate of a chemical reaction. Catalysts are required to drive the reactions needed to generate electricity in fuel cells). Much effort is being put into trying to identify other materials to replace the costly platinum catalyst in fuel cells. Some promising alloys include Pd-Co, Pt-Co, and Pt-Cu.

A number of theories exist as to what leads to the improved performance of a Pt-Co (platinum cobalt) alloyed catalyst over a pure Pt catalyst. These theories include bifunctional effects, electronic effects, and geometric effects (the quantum mechanical details of which are way beyond the scope of this blog post). Because these factors all generally act in concert, it becomes very difficult to separate out the contribution of each. Better understanding the relative contributions can aid in the search for better alloyed catalyst materials, a process that currently involves much trial and error over the wide space of potential alloyed material combinations.

Jeff Greeley, who presented at the conference, is trying to help in this process by using quantum mechanical computer modeling to pre-screen for materials that are both active catalysts and stable catalysts (1) . Another researcher, Peter Strasser, finds that by creating particles containing a copper core and a platinum surface layer, catalytic activity can be increased due to increased compressive strain on the surface platinum (2). By controlling the composition, annealing process, and de-alloying process, this strain and corresponding catalytic performance changes can be tuned.

Other cool energy research at the conference included studying the degradation mechanisms of lithium ion batteries and biologically inspired improvements to electrochemical systems. Battery durability is a major concern for automotive applications and an issue that must be resolved for plug-in hybrids to be feasible on a large scale. Laptop batteries generally only last a few years, but that certainly wouldn’t be acceptable for a vehicle which needs to stay running for at least a decade without needing a $10,000+ replacement battery pack. Robert Kostecki investigated battery degradation after repeated cycling and found that degradation mechanisms include loss of conductivity due to both changes to the conductive carbon coating and particle separation in the cathode (3)

It will be interesting to see what happens with the new administration and stimulus spending in terms of funding for energy technology research. Certainly much work still needs to be done at both the basic science level and system design level for a number of electrochemical and other energy systems.

1. Greeley, Jeff, and Jens K. Nørskov. “Large-scale, density functional theory-based screening of alloys for hydrogen evolution.” Surface Science 601.6 (2007): 1590-1598.

2. Strasser, Peter, Shirlaine Koh, and Jeff Greeley. “Voltammetric surface dealloying of Pt bimetallic nanoparticles: an experimental and DFT computational analysis.” Physical Chemistry Chemical Physics 10.25 (2008): 3670-3683.

3. Kerlau, Marie et al. “Studies of local degradation phenomena in composite cathodes for lithium-ion batteries.” Electrochimica Acta 52.17 (2007): 5422-5429.

Vehicle-to-Grid (V2G) Technology Aims To Help Electricity Grids Use Renewable Generation

Newly elected President Obama just unveiled his 'American Reinvestment and Recovery Plan'. Part of this plan is a push for renewable energy, including a promise to double it in three years. Possibly more telling and exciting is the inclusion of a commitment for “3,000 miles of new or modernized transmission lines and 40 million 'Smart Meters' in American homes.” The reason this is important is because the current system cannot handle significant increases in renewable energy.

Our nation's industrialization and subsequent use of fossil fuels has given our society access to a switchable utility system. That is, when steam engine train conductors or coal plant operators wished to alter a supply of energy, they could simply add fuels to burn and convert to energy at any time they wished. Because of this, our electric grid is designed to simply deliver peak-load supply, i.e. the grid is built to have the necessary capacity for the maximum energy use on a hot day in the summer. If users are pulling more Watts from the system, grid operators can just switch the system to deliver more Amperes.

Renewable generation technologies including photovoltaic (PV) modules and wind turbines do not follow this model. These sources of energy cannot be controlled such as those provided by fossil fuels. These sources require the sun to shine and the wind to blow, respectively. For grid operators, increasing the use of these sources adds undesirable fluctuations of available energy. This is especially true for localized distributed generation sources such as solar panels on residential homes. Connecting these sources to the grid changes the makeup of the grid in unpredictable ways that make grid operators unable to properly evaluate system load requirements and locate system faults. Additionally, energy consumers cannot be expected to utilize renewable generation at the instant it is most abundant. Consumers are unlikely to dim their lights until the sun is bright or to complete their most power intensive computing when an impeding storm causes high wind speeds. Clearly, our electric grid will need to be updated in order to use more renewable energy.

Vehicle-to-Grid (V2G) technology is one possible way researchers hope to improve the stability and reliability of our grid when incorporating renewable generation. The idea, originating from University of Delaware Professor Willett Kempton, is that the electrification of our transportation fleet goes hand-in-hand with the inclusion of renewable energy in our grid. He and other researchers argue that the Lithium-ion batteries on fully electric and partially electric vehicles can be used to temporarily store and redistribute energy to and from the grid. This means that your future Prius may come with a two-way connection to the grid. Professor Kempton argues that because 95% of vehicles are parked at any given time, a significant number of electric vehicles could potentially end reliable concerns of variable energy supplies.

An analogy with a different technology that you are using as you read this post may help illustrate how this works. Imagine that our information superhighway was changed to where there was no storage involved. Each bit and byte had to be available at all times so it could be delivered instantaneously upon request by the consumer. This is how our energy system works today. However, due to Internet protocols and storage technology, we do not have those requirements. As you access this post you are utilizing storage components within the Internet structure, and as you read this post you are utilizing storage on your personal computer. In fact, one crucial component of a V2G system is information technology that tells the grid when and where to pull and deliver energy.

The city of Newark, Delaware, is now testing a demo V2G system. Professor Kempton envisions a situation where consumers will be compensated by energy companies to enable V2G to pull from their vehicles. The Smart Meters necessary for V2G could also be used to give energy prices that correspond to the demand. This would encourage the public to buy into V2G systems because they could opt to sell energy when the price was highest.

Of course, problems still need to be clarified and researched further including the impact of V2G on the life-cycle on the Lithium-Ion batteries currently installed on electric vehicles. However, hope is increasing for V2G as politicians accept the need to modernize our electric grid as we increase our use of renewable energy.