Comments for Efficiency

Comment on What is the numerical energy efficiency for wind energy, passive solar energy, and active solar energy? by Alexander

Alexander — Tue, 09 Mar 2010 23:30:30 +0000

Wind power companies like to claim ~35% efficiency with their systems but the best recorded in operation is a maximum of 20%
Solar panels are incredibly inefficient with efficiency ratings of less than 2% of energy emitted adsorbed into energy.
Ambient /Reflective solar energy systems believe it or not are more efficient around 10% in adsorbing energy but the turbines used to turn the energy into electricity are only around 20% efficient so the number is only 2%

The trick with solar is to use the energy collected by the reflectors for heating something to get the efficiency of the heat created. that’s why they make good water heaters.

By the way gas and diesel piston engines are only 20 to 30 % efficiency, Gas turbine engines are around 50% but if used as a co-gen unit where both the engine created energy and heat are utilized their efficiencies go into the 90% level.
It’s part of the reason gas turbine power plants are so comon.

Comment on What is the numerical energy efficiency for wind energy, passive solar energy, and active solar energy? by Nata T

Nata T — Tue, 09 Mar 2010 23:30:30 +0000

You need to define the efficency, as compared to what?

Wind turbines can only put out about 35% of their rated capacity, again based on location. Some may achieve 40% while others located in areas with little wind may only make 5%.

Active and passive solar efficency is based on the number os watts that hit them that are saved. I’d guess passive might reach 40% and active 50%, depending on location. On a daily average, including night, its about 8% and 10%.

Comment on What is the numerical energy efficiency for wind energy, passive solar energy, and active solar energy? by Kenny P

Kenny P — Tue, 09 Mar 2010 23:30:30 +0000

12, 6 and 9.

Comment on I'd like to know the energy efficiency difference between a one story home and two stories. Cost savings????? by Raymond H

Raymond H — Sun, 07 Mar 2010 23:31:58 +0000

I worked for a number of years in New Orleans, La. It was starting to grow rapidly on the west bank of the river and I ran into a number of 2 story houses that had one 5 ton A/C system for the whole house. The top story was nearly unlivable in the afternoon sun. The lower story was so cool it was uncomfortable. I remember one job in particular where we modified the duct system so that the upstairs was blocked off from downstairs. Then we installed an air handler upstairs and split an A type evaporator coil and installed two condensing units. Every room in the house was quite comfortable but it certainly was not efficient. Electricity was rather inexpensive then too. Other jobs we did used thermostatically controlled powered dampers. They did not work as well as the first fix I described, but the house was livable on the top floor. Fact is, heat rises and in central Texas I do not think there is any great lack of heat to rise. I agree with your first answer and would add that you should check that one story dwelling’s attic for proper insulation and ventilation. I would go with the one story.

Comment on I'd like to know the energy efficiency difference between a one story home and two stories. Cost savings????? by Merlin

Merlin — Sun, 07 Mar 2010 23:31:58 +0000

You’ll save energy by not having to run up and down stairs in a two story home!
Seriously, as long as the one story has efficient insulation, I would it is more cost effective.

Comment on Energy and efficiency questions about a ball? by Heliumcool

Heliumcool — Fri, 05 Mar 2010 23:30:23 +0000

4J
3J
1J
It has been converted into other forms of energy like sound.

Comment on Comparing different refrigerators’ energy efficiency online?? (10 Points to best answer!!)? ? by Ryan D

Ryan D — Wed, 03 Mar 2010 18:41:57 +0000

Here’s the best site. List of hundreds of Energy Star Qualified Refrigerators and Freezers. All you do to find the cost for 10 years is multiply the Kwh/year column provided by the price you pay per kwH and then by 10 for 10 years.

Comment on Comparing different refrigerators’ energy efficiency online?? (10 Points to best answer!!)? ? by Dominic

Dominic — Wed, 03 Mar 2010 18:41:57 +0000

http://www.energystar.gov/index.cfm?c=refrig.pr_refrigerators

Comment on Energy Efficiency for new house? by Bob C

Bob C — Mon, 01 Mar 2010 13:56:59 +0000

Austin is probably the "Green" capitol of the US. Look around the phone book (or call the CofC) and ask for the "Green Council" or something to that effect. They award points to energy efficient builders and offer all kinds of info on what works in Central Texas.

Comment on What is the energy efficiency of natural gas? by EnviroDude

EnviroDude — Sat, 27 Feb 2010 13:58:22 +0000

The amount of energy that is obtained from the burning of a volume of natural gas is measured in British thermal units (Btu). The value of natural gas is calculated by its Btu content. One Btu is the quantity of heat required to raise the temperature of one pound of water of 1 degree Fahrenheit at atmospheric pressure. A cubic foot of natural gas on the average gives off 1,000 Btu, but the range of values is between 500 and 1,500 Btu.

Energy content of natural gas is variable and depends on its accumulations which are influenced by the amount and types of energy gases they contain: the more non-combustible gases in a natural gas, the lower the Btu value. In addition, the volumic mass of energy gases which are present in a natural gas accumulation also influences the Btu value of natural gas. The more carbon atoms in a hydrocarbon gas, the higher its Btu value.

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