Energy Storage and Delivery

Storage – All forms of energy are either potential energy or kinetic energy (thermal energy). Examples for potential energy are chemical, gravitational or electrical energy. A battery stores readily convertible chemical energy to power our lap tops for example. A hydroelectric dam stores energy as a gravitational potential energy. Chemical fuels such as coal, gasoline, diesel fuel, natural gas are form of energy storage. However, these produce greenhouse gases when used. Carbon-free energy carriers, such as hydrogen, or carbon-neutral energy carriers, such as cellulosic ethanol, biodiesel, are needed to reduce greenhouse gas emissions. Some of the Storage Methods are:

Chemical: Hydrogen, Biofuels
Electrochemical: Batteries
Electrical: Capacitor
Mechanical: Hydroelectric energy storage
Thermal: Solar Pond

Hydrogen is the most abundant element on earth. But it doesn’t occur naturally as a gas. It’s always combined with other elements. Hydrogen can be produced from a wide variety of domestic resources and be burned as a fuel or converted into electricity. Hydrogen has very high energy for its weight, but very low energy for its volume requiring new technology for its storage and transportation. Fuel cells harness the chemical energy of hydrogen to generate electricity without combustion or pollution.

In 2002, the NASA Glenn Research Center awarded $31M grant to Florida State Universities over a 5 year period to carry out leading edge hydrogen research and technology development to support NASA’s space launch and in-space activities. The program was managed by UF and FSEC. Some of the research focus areas were Fuel Cells, Hydrogen Production Processes, Cryogenic Transport, Storage and Cryofuels, and Hydrogen Leak Detection via Distributed Micro-sensors and Laser Instrumentation. The links below provide more information:

Renewable Energy Delivery – One of the challenges facing the electric power industry is harnessing the renewable energy and delivering them in a useable form. Many renewable energy resources such as solar, wind, and ocean energy are intermittent. They are not available on a continuous basis. For example solar energy is available during day time but not at night. Having the capability of storing renewable energy sources off-peak and releasing it during on-peak periods allows supply to more closely match demand. For example, a storage system (batteries) attached to a solar panel could store energy captured during day time. The stored energy can then be utilized at night time making solar electricity to be used both day and night. Many of the potential renewable energy generation sites are located far from transmission facilities and connecting them to the grid is costly.

FESC has a demonstration project combining renewable energy generation with an advanced battery system to supply renewable energy during the power system peak. The project will implement a “Smart Grid” on a portion of Progress Energy Florida’s distribution system in St. Petersburg, Florida. The system will integrate the use of renewable distributed generation along with advanced sensors, communication and control technologies, and other technologies, along with two-way communication between the utility and electric loads within customer premises, to increase energy efficiency, reliability and security.

Lithium Ion Batteries

The goal of the Laboratory for Energy Conversion and Storage is to design and develop new materials for advanced energy storage and conversion applications. The development of new materials to improve upon current capabilities is a key technological challenge of the 21^st century. Advances will allow smaller more powerful batteries as well as allowing a greater ability to harness more sustainable energy sources. Some of the research areas are:

Materials Design for Advanced Portable Power Sources

Lithium ion batteries have become a key component of portable electronic devices as they offer high energy density, flexible lightweight design and a longer cycle life than other battery systems. More efficient batteries are required in the development of advanced transportation technologies in order to reduce the use of imported oil and the emission of greenhouse gas. Electrochemical energy storage has been identified as a critical enabling technology for advanced, fuel-efficient, light and heavy duty vehicles. New materials need to be designed to achieve higher energy/power densities, longer cycle lives and better reliability for such applications. The research focus is on synthesizing new multi-transition metal oxides with higher energy density, faster rate capability and better safety, as well as exploration of the exact ion transport mechanism and structural stability during the cycling of the battery.

Thermoelectric Materials – Convert Heat to Electricity

Oxides are intriguing for thermoelectric applications as they are relatively cheaper and stable at high temperature. One major application is to recuperate wasted engine heat to electric current, thus increase the engine efficiency. Determination of the stable structures and charge/magnetic ordering is one of the most fundamental steps in obtaining optimum thermoelectric properties of these functional ceramics. High quality oxide films are fabricated by pulsed laser deposition and their figure-of-merit is characterized for thermoelectric applications. The goal is to propose strategies to further enhance the thermoelectric properties in the family of the oxides.

Structure-Property-Processing Relations of Nano-scale Materials

Materials science emphasizes the study of the structure of materials and of processing-structure-property relations in materials. It is the physics and chemistry of real materials. To understand how the desired properties of a material can be modified, it is necessary to understand the relationships between structure and properties and how the structure can be changed and controlled by the various chemical, thermal, mechanical, or other processes to which a material is subjected during synthesis and in use. Such knowledge is still lacking in the design and development of nano-scale materials, which have generated tremendous interest in the last decade for energy related research areas. For example, in order to achieve high power in batteries nano-scale materials such as inorganic nanotubes and nanowires (TiS₂, TiO₂, MoS₂…) may offer a plausible solution due to their high surface reactivity: i.e. fast surface transport property for electrode designs in which mass transport is not rate limiting anymore. Through understanding how the thermodynamic and kinetic properties of these tubes/wires differ from the bulk with ab initio study, guesswork can be eliminated and candidate nano-scale materials for energy applications can be effectively prescreened. Modern synchrotron X-ray and analytical transmission electron microscopy is applied to explore the structure – property relation in functional nanotubes and nanowires.