Group items tagged

A novel form-stable phase change wallboard (PCW) was prepared for low-temperature latent heat thermal energy storage by incorporating eutectic mixture of capric acid and stearic acid and gypsum wallboard. Thermal properties of form-stable PCW were measured by DSC analysis. The form-stable PCW has good thermal reliability with respect to the changes in its thermal properties after accelerated thermal cycling.

This paper is focussed on thermal storage technologies using phase change materials (PCMs) in the temperature range of 120-300°C for solar thermal power generation and high temperature process heat. As the state-of-the-art reference system a steam accumulator is described, which typically has a volume-specific thermal energy density of 20-30 kWh m-3.

The storage of cold with ice slurries - a special type of thermally multi-functional fluids or phase change slurries (PCS) - is discussed. At first an example of a calculation of a thermal energy storage tank in an ice slurry system with a peak load demand is presented.

Batteries have to contain all of the chemicals on both sides of their energy releasing equation. The very best batteries available today can store about 0.4 MJ/kg (0.05 kw-hr/lb) including the cases and safety systems. In contrast, gasoline carries about 46 MJ/kg (5.7 kw-hrs/lb).\n\nEven with a 20% efficient IC engine, a gasoline tank stores 20 times as much energy as a battery of equal weight. As the vehicle is moving it gets rid of some of that weight. Battery powered vehicles must carry the full weight of their energy source.\n\nThe energy density difference also plays a key role in the time that it takes to put more energy back on the vehicle once a fuel load is consumed. A two minute fill-up of a 12 gallon tank puts the equivalent of 87 kilowatt-hours into the vehicle, again, taking into account the 20% thermal efficiency.\n\n87 kilowatt-hours in 2 minutes works out to 2.6 MegaWatts. Even with a 220 volt connection, that would require about 11,800 amperes of current. Just imagine the size of the electric cables for that current.\n\nThere are certainly places and applications where electric vehicles have a role, but it is worth remembering that at least five or six generations of engineers have looked very hard at trying to meet transportation needs and they keep coming back to the same fact - when you want to move a vehicle, you need power, (energy per unit time).

NV Energy deal, legislation in Congress could help state develop solar power SolarReserve, a California energy company, is planning to build a 100-megawatt solar thermal power plant near Tonopah, and on Tuesday it announced that NV Energy had agreed to buy power from the plant. As Stephanie Tavares reported on the Las Vegas Sun's Web site, the plant is designed to use heat storage technology that will allow its steam turbines to run at night. The Crescent Dunes Solar Energy Project is being vetted by the Bureau of Land Management. The company says it could break ground by 2011 and expects construction to last two years.

This is Part 3 in a series on Passive Solar Design by Will Stewart, a Systems Engineer in the energy industry and longtime reader of theoildrum.com. As a new administration considers how best to make future infrastructure investments, it seems like some of the lowest hanging fruit is better utilization of the daily solar flux, not only directly with photovoltaic and hot water, but also in building construction and placement. I encourage our readers to further their understanding of passive solar concepts by reading/bookmarking this series.