With adaptive-grid computational methodologies and judicious use of compressible and low Mach number combustion models, we are carrying out three-dimensional, time-dependent direct numerical simulations of a laboratory-scale turbulent premixed methane burner. In the laboratory experiment, turbulence is generated by a grid located in the throat of a 50mm diameter circular nozzle; swirl is be introduced by four tangential air jets spaced uniformly around the circumference of the nozzle just above the turbulence grid. A premixed methane flame is stabilized above the nozzle in the central core region where a velocity deficit is induced7the swirling flow. The time-dependent flow field inside the nozzle, from the turbulence grid and the high-speed jets, to the nozzle exit plane is simulated using an adaptive-grid embedded-boundary compressible Navier-Stokes solver. The compressible calculation then provides time-dependent boundary conditions for an adaptive low Mach number model of the swirl-stabilized premixed flame. The low Mach model incorporates detailed chemical kinetics and species transport using 20 species and 84 reactions. Laboratory diagnostics available for comparisons include characterizations of the flow field just down stream of the nozzle exit plane, and flame surface statistics, such as mean location, wrinkling and crossing frequencies.

Community energy storage (CES) has been proposed to mitigate the high variation in output from renewable sources and reduce peak load on the electrical grid. Thousands of these systems may be distributed around the grid to provide benefits to local distribution circuits and to the grid as a whole when aggregated. CES must be low cost to purchase and install and also largely maintenance free through more than 10 years of service life to be acceptable to most utilities.Achieving the required system life time is a major uncertainty for lithium-ion batteries. The lifetime and immediate system performance of batteries can change drastically with battery temperature, which is a strong function of system packaging, local climate, electrical duty cycle, and other factors. In other Li-ion applications, this problem is solved via air or liquid heating and cooling systems that may need occasional maintenance throughout their service life. CES requires a maintenance-free thermal management system providing protection from environmental conditions while rejecting heat from a moderate electrical duty cycle. Thus, the development of an effective, low-cost, zero-maintenance thermal management system poses a challenge critical to the success of CES. NREL and Southern California Edison have collaborated to evaluate the long-term effectiveness of …

Characterized by a changing landscape and new opportunities, today's increasingly complex energy decision space will need innovative financing and investment models to appropriately assess risk and profitability. This report provides an overview of the current state of clean energy finance across the entire spectrum but with a focus on early stage investing, and it includes insights from investors across all investment classes. Further, this report aims to provide a roadmap with the mechanisms, limitations, and considerations involved in making successful investments by identifying risks, challenges, and opportunities in the clean energy sector.