855,658 research outputs found
Solar Water Heating: Using the Sun's Energy to Heat Water
Key facts: - Solar water heating systems use the sun's energy to provide hot water, space heating, and air conditioning. - More than 1.5 million homes and businesses currently use solar water heating in the United States, representing a capacity of over 1,000 megawatts (MW) of thermal energy generation. Another 400 MW is likely to be installed over the next 3-5 years, according to the US Department of Energy. - Assuming that 40 percent of existing homes in the United States have sufficient access to sunlight, 29 million solar water-heating systems could be installed. Solar water heaters can operate in any climate. Performance varies depending on how much solar energy is available at the site, as well as how cold the water coming into the system is. The colder the water, the more efficiently the system operates. - Solar water heaters reduce the need for conventional water heating by about two-thirds and pay for their installation within 4 to 8 years with electricity or natural gas savings. Compared to those with electric water heaters, Florida homeowners with solar water heaters save 50 to 85 percent on their water heating bills, according to the Florida Solar Energy Center
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Energy use for urban water management by utilities and Households in Los Angeles
Reducing energy consumption for urban water management may yield economic and environmental benefits. Few studies provide comprehensive assessments of energy needs for urban water sectors that include both utility operations and household use. Here, we evaluate the energy needs for urban water management in metropolitan Los Angeles (LA) County. Using planning scenarios that include both water conservation and alternative supply options, we estimate energy requirements of water imports, groundwater pumping, distribution in pipes, water and wastewater treatment, and residential water heating across more than one hundred regional water agencies covering over 9 million people. Results show that combining water conservation with alternative local supplies such as stormwater capture and water reuse (nonpotable or indirect potable) can reduce the energy consumption and intensity of water management in LA. Further advanced water treatment for direct potable reuse could increase energy needs. In aggregate, water heating represents a major source of regional energy consumption. The heating factor associated with grid-supplied electricity drives the relative contribution of energy-for-water by utilities and households. For most scenarios of grid operations, energy for household water heating significantly outweighs utility energy consumption. The study demonstrates how publicly available and detailed data for energy and water use supports sustainability planning. The method is applicable to cities everywhere
Solar Energy Resource Potential in Alaska
Solar energy applications are receiving attention in Alaska as in
much of the rest of the country. Solar energy possibilities for Alaska
include domestic water heating, hot-water or hot-air collection for
space heating, and the use of passive solar heating in residential or
commercial buildings.
As a first analysis, this study concentrated on applying solar
energy to domestic hot-water heating needs (not space heating) in Alaska,
and an analysis of solar hot-water heating economics was performed using
the F-CHART solar energy simulation computer program. Results indicate
that solar energy cannot compete economically with oil-heated domestic
hot water at any of the five study locations in Alaska, but that it may
be economical in comparison with electrically heated hot water if solar
collector systems can be purchased and installed for 25 per
square foot.This work was made possible by a grant from the Solar Planning
Office, West, 3333 Quebec, Denver, Colorado. It was performed as the
Alaskan response to a western regional solar energy planning grant from
the U. S. Department of Energy.
The authors wish to acknowledge the support and cooperation of the
Alaska State Department of Commerce, Division of Energy and Power Development,
through whose efforts the grant was made available, especially
Clarissa Quinlan, Grant Peterson, and Don Markle
An innovative design and evaluation of a stratified hot water storage system - the Water Snake
The increase in energy prices and the demand to reduce carbon emission is attracting the attention to the implementation of diverse heating technologies such as heat pumps, solar energy, gas boilers, CHP and electric heaters. Heating applications for integrated technologies include district heating, domestic small scale applications and commercial large scale buildings. Thermal storage is likely to become key to energy efficient heating. A stratified hot water tank will play an important role in the integration of several heating technologies that operate efficiently at different level of temperatures with reduced implementation cost. This paper describes the concept and the assessment of the ‘Water Snake’, a novel low cost concept of a stratified hot water tank. The results show that the new concept could provide efficient stratification at a very low cost using this invention
Freeze protection in gasholders
In cold weather, the water seals of gasholders need protection from freezing to avoid compromising the seal. These holders have a large reservoir of "tank water" at the base which is below ground. At present freeze-protection is achieved by external heating of the seal water which is in a slotted channel called a cup. Electrical heating or circulation of heated tank water to the cup are examples of systems presently used.
The tank water has a large thermal capacity and National Grid wishes to investigate whether circulation of the tank water without external heating could provide sufficient energy input to avoid freezing. Only tanks in which the tank water is below ground are investigated in the report. The soil temperature under the reservoir at depth of 10m and lower is almost constant
Comparative performance of twenty-three types of flat plate solar energy collectors
Report compares efficiencies of 23 solar collectors for four different purposes: operating a Rankine-cycle engine, heating or absorption air conditioning, heating hot water, and heating a swimming pool
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use natural gas consumption in 201Scenarios to decarbonize residential water heating in California
This paper presents the first detailed long-term stock turnover model to investigate scenarios to decarbonize the residential water heating sector in California, which is currently dominated by natural gas. We model a mix of water heating (WH) technologies including conventional and on-demand (tank-less) natural gas heating, electric resistance, existing electric heat pumps, advanced heat pumps with low global warming refrigerants and solar thermal water heaters. Technically feasible policy scenarios are developed by considering combinations of WH technologies with efficiency gains within each technology, lowering global warming potential of refrigerants and decreasing grid carbon intensity. We then evaluate energy demand, emissions and equipment replacement costs of the pathways. We develop multiple scenarios by which the annual greenhouse gas emissions from residential water heaters in California can be reduced by over 80% from 1990 levels resulting in an annual savings of over 10 Million Metric Tons by 2050. The overall cost of transition will depend on future cost reductions in heat pump and solar thermal water heating equipment, energy costs, and hot water consumption
Relevance of Tidal Heating on Large TNOs
We examine the relevance of tidal heating for large Trans-Neptunian Objects,
with a focus on its potential to melt and maintain layers of subsurface liquid
water. Depending on their past orbital evolution, tidal heating may be an
important part of the heat budget for a number of discovered and hypothetical
TNO systems and may enable formation of, and increased access to, subsurface
liquid water. Tidal heating induced by the process of despinning is found to be
particularly able to compete with heating due to radionuclide decay in a number
of different scenarios. In cases where radiogenic heating alone may establish
subsurface conditions for liquid water, we focus on the extent by which tidal
activity lifts the depth of such conditions closer to the surface. While it is
common for strong tidal heating and long lived tides to be mutually exclusive,
we find this is not always the case, and highlight when these two traits occur
together.Comment: Submitted to Icaru
Performance of coloured solar collectors
The use of solar collectors with coloured absorbers for water heating is an area of particular interest when considering their integration with buildings. By matching the absorber colour with that of the roof or façade of the building, it is possible to achieve an architecturally and visually pleasing result. Despite the potential for the use of coloured absorbers very little work has been undertaken in the field.
In this study, the thermal performance of a series of coloured, ranging from white to black, water heating solar collectors is examined. Subsequently, the annual solar fraction for typical water heating systems with coloured absorbers is calculated. The results show that coloured solar collector absorbers can make noticeable contributions to heating loads. Furthermore, although their thermal efficiency is lower than highly developed selective coating absorbers, they offer the advantage of sensitive integration with buildings
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