Electricity Generation and Delivery

Researchers at the California Institute of Technology (Caltech) and their partners will design and fabricate a new CPV module with features that can capture both direct and diffuse sunlight. The team's approach uses a luminescent solar concentrator (LSC) sheet that includes quantum dots to capture and re-emit sunlight, micro-PV cells matched to the color of the light from the quantum dots, and a coating of advanced materials that enhance concentration and delivery of sunlight to the micro-PV cells. In addition, the light not captured by the quantum dots will impinge on a tandem solar cell beneath the LSC sheet. The design of the LSC will focus on lowering the number of expensive micro-PV cells needed within the concentrator sheet, which will reduce system costs, but still maintain high efficiency. The design will also allow the module to be effective without any tracking system, making it potentially attractive for all PV markets, including space-constrained rooftops.

Carnegie Mellon will combine its expertise in additive manufacturing (AM) with Westinghouse's knowhow in nuclear reactor component fabrication to develop an innovative process for AM of nuclear components. The team chose to redesign nuclear reactor spacer grids as a test case because they are a particularly difficult component to manufacture. The role of spacer grids is to provide mechanical support to nuclear fuel rods within a reactor and reduce vibration as well as cause mixing of the cooling fluid. The team will alter the traditional AM process, including using nonstandard powders to optimize performance and reduce cost. If the project is successful, it could pave the way for other reactor components to be additively manufactured, enabling the rapid deployment of advanced reactors.

Case Western Reserve University is developing a water-based, all-iron flow battery for grid-scale energy storage at low cost. Flow batteries store chemical energy in external tanks instead of within the battery container. Using iron provides a low-cost, safe solution for energy storage because iron is both abundant and non-toxic. This design could drastically improve the energy storage capacity of stationary batteries at 10-20% of today's cost. Ultimately, this technology could help reduce the cost of stationary energy storage enough to facilitate the adoption and deployment of renewable energy technology.

Cogenra Solar is developing a hybrid solar converter with a specialized light-filtering mirror that splits sunlight by wavelength, allowing part of the sunlight spectrum to be converted directly to electricity with photovoltaics (PV), while the rest is captured and stored as heat. By integrating a light-filtering mirror that passes the visible part of the spectrum to a PV cell, the system captures and converts as much as possible of the photons into high-value electricity and concentrates the remaining light onto a thermal fluid, which can be stored and be used as needed. Cogenra's hybrid solar energy system also captures waste heat from the solar cells, providing an additional source of low-temperature heat. This hybrid converter could make more efficient use of the full solar spectrum and can provide inexpensive solar power on demand.

The Colorado School of Mines will develop a hybrid power generation system that leverages a pressurized, intermediate-temperature solid oxide fuel cell (SOFC) stack and an advanced low-energy-content fuel internal combustion (IC) engine. The custom-designed, turbocharged IC engine will use the exhaust from the anode side of the SOFC as fuel and directly drive a specialized compressor-expander that supplies pressurized air to the fuel cell. High capital costs and poor durability have presented significant barriers to the widespread commercial adoption of SOFC technology. In part, these challenges have been associated with SOFC high operating temperatures of 750-1000°C (1382-1832°F). This team will use a robust, metal-supported SOFC (600°C or 1112°F) technology that will provide greater durability, better heat management, and superior sealing over standard ceramic-supported SOFC designs. The modified diesel IC engine in a hybrid system provides a low-cost, controllable solution to use the remaining chemical energy in the fuel cell exhaust. The system will use the hot air and exhaust gases it produces to keep components running at the proper temperatures to maximize overall efficiency. The team will also develop supporting equipment, including a specialized compressor-expander and power inverter. The new system has the potential to enable highly-efficient, cost-effective distributed power generation.

Cornell University is creating a new software platform for grid operators called GridControl that will utilize cloud computing to more efficiently control the grid. In a cloud computing system, there are minimal hardware and software demands on users. The user can tap into a network of computers that is housed elsewhere (the cloud) and the network runs computer applications for the user. The user only needs interface software to access all of the cloud's data resources, which can be as simple as a web browser. Cloud computing can reduce costs, facilitate innovation through sharing, empower users, and improve the overall reliability of a dispersed system. Cornell's GridControl will focus on 4 elements: delivering the state of the grid to users quickly and reliably; building networked, scalable grid-control software; tailoring services to emerging smart grid uses; and simulating smart grid behavior under various conditions.

Cree is developing silicon carbide (SiC) power transistors that are 50% more energy efficient than traditional transistors. Transistors act like a switch, controlling the electrical energy that flows through an electrical circuit. Most power transistors today use silicon semiconductors to conduct electricity. However, transistors with SiC semiconductors operate at much higher temperatures, as well as higher voltage and power levels than their silicon counterparts. SiC-based transistors are also smaller and require less cooling than those made with traditional silicon power technology. Cree's SiC transistors will enable electrical circuits to handle higher power levels more efficiently, and they will result in much smaller and lighter electrical devices and power converters. Cree, an established leader in SiC technology, has already released a commercially available SiC transistor that can operate at up to 1,200 volts. The company has also demonstrated a utility-scale SiC transistor that operates at up to 15,000 volts.

City University of New York (CUNY) Energy Institute is working to tame dendrite formation and to enhance the lifetime of Manganese in order to create a long-lasting, fully rechargeable battery for grid-scale energy storage. Traditional consumer-grade disposable batteries are made of Zinc and Manganese, two inexpensive, abundant, and non-toxic metals, but these disposable batteries can only be used once. If they are recharged, the Zinc in the battery develops filaments called dendrites that grow haphazardly and disrupt battery performance, while the Manganese quickly loses its ability to store energy. CUNY Energy Institute is also working to reduce dendrite formation by pumping fluid through the battery, enabling researchers to fix the dendrites as they form. The team has already tested its Zinc battery through 3,000 recharge cycles (and counting). CUNY Energy Institute aims to demonstrate a better cycle life than lithium-ion batteries, which can be up to 20 times more expensive than Zinc-based batteries.

Det Norske Veritas (DNV GL) and Group NIRE will provide a unique combination of third-party testing facilities, testing and analysis methodologies, and expert oversight to the evaluation of ARPA-E-funded energy storage systems. The project will leverage DNV GL's deep expertise in economic analysis of energy storage technologies, and will implement economically optimized duty cycles into the testing and validation protocol. DNV GL plans to test ARPA-E storage technologies at its state-of-the-art battery testing facility in partnership with the New York Battery and Energy Storage Technology Consortium. Those batteries that pass the rigorous evaluation process will be adapted for testing under real world conditions on Group NIRE's multi-megawatt, wind-integrated microgrid in Texas. Testing will show how well the ARPA-E storage technologies can serve critical applications and will assist ARPA-E-funded battery developers in identifying any issues with performance and durability. This testing will also deliver performance data that buyers of grid storage need, enabling informed choices about commercial adoption of grid storage technologies.