Residential fuel cells now being developed combine hydrogen from natural gas or propane with oxygen from the air to produce electricity. Homeowners might be able to meet all of their energy needs with a residential fuel cell and, in some cases, even sell excess energy to a utility. Currently, PTC 50, an ASME standard, is used to measure fuel cell system performance, but it does not take into account either seasonal changes in heating and cooling requirements, or a residence's quickly changing demands for electricity.
To bridge the gap between the PTC 50 standard and the information that consumers will need to make economic decisions on installing a fuel cell, NIST researchers have published proposed test and rating methods* that will help consumers assess the economic feasibility of four different types of residential fuel cells under different climate conditions in six different geographic locations. The rating will provide the annual electrical energy produced, fuel consumed, thermal energy for domestic water heating and space heating delivered, and water used by the residential fuel cell system.
The four fuel cell types studied include systems that operate independent of the power grid with all generated power used by the residence itself; systems connected to the grid, in which electrical power output remains constant and excess electricity is sold to the utility; systems for thermal space and domestic water heating similarly connected to the grid to supplement the fuel cell power when needed; and similar but smaller systems used primarily for water heating.
The NIST test methodology and performance rating procedure uses building energy simulation results for three days, one each for winter, spring/fall, and summer for a prototypical house located in a representative city within six Department of Energy (DOE) designated climate zones, including Jacksonville, Fla.; Charleston, S.C.; Memphis, Tenn.; Pittsburgh, Pa.; Minneapolis, Minn.; and Astoria, Ore.
The NIST researchers expect to present their test methodology and performance rating procedures to standards organizations this summer. Several manufacturers have provided input on the rating methodology.
John Blair | EurekAlert!
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Controlling electronic current is essential to modern electronics, as data and signals are transferred by streams of electrons which are controlled at high speed. Demands on transmission speeds are also increasing as technology develops. Scientists from the Chair of Laser Physics and the Chair of Applied Physics at Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) have succeeded in switching on a current with a desired direction in graphene using a single laser pulse within a femtosecond ¬¬ – a femtosecond corresponds to the millionth part of a billionth of a second. This is more than a thousand times faster compared to the most efficient transistors today.
Graphene is up to the job
At the productronica trade fair in Munich this November, the Fraunhofer Institute for Laser Technology ILT will be presenting Laser-Based Tape-Automated Bonding, LaserTAB for short. The experts from Aachen will be demonstrating how new battery cells and power electronics can be micro-welded more efficiently and precisely than ever before thanks to new optics and robot support.
Fraunhofer ILT from Aachen relies on a clever combination of robotics and a laser scanner with new optics as well as process monitoring, which it has developed...
Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.
A warming planet
Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.
The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...
Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...
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