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Bulb efficiency chart is here The range for LED looks a little low to me; I think in theory they should eventually be able to get up to around 100 lumens per watt, which means they still will never beat a high pressure sodium lamp for efficiency. (White LED bulbs themselves can get up to 150 lumens/watt, but apparently there are some losses in converting the 120VAC to 5VDC to drive the LED.)

The places that allow you to go net negative buy your power back at wholesale rates, which is far lower. If you think about it when you sell power back to the power company you're not competing with the power company, you're competing with the power generators. Why should the power company give you an unfair advantage there?

While it may be true that you sell at wholesale rates in many locations, it's not in my area.

First, I am in the utility's green power tomorrow [PDF warning!] program. That means that I pay $0.01 extra per kWh to fund renewable energy. The utility promises that they will purchase enough renewable energy to cover every kWh that is paid at the higher rate, in addition to the legally mandated 1.73% minimum renewable energy they buy. 99.9% of that comes from wind farms in 3 areas, the other 0.1% comes from local solar generation. That puts my total rate at about $0.14/kWh for last month (it goes up and down by a few pennies quite regularly).

For those that have solar arrays, the local power company will buy all your solar-generated electricity for $0.25/kWh, and then sell it back at the regular electric price, plus a $0.01 charge per kWh to be part of the same green power program that I am. So if you're using 5 kW and producing 5 kW, you're still getting paid! (Caveat: I believe the program is currently full, they have a cap on the total capacity.)

The way they can afford to do this is through the extra penny others are choosing to pay. Renewable power generally costs more than the coal, natural gas, or nuclear plants they replace. So they collect this extra amount, and buy more expensive electricity. It's worth noting that there are charges assessed per-day (around $11/month for me), so it's not exactly a brilliant money-making scheme. I also don't know if some of the other charges (like the charge for distribution service, paying for the wires between my house and the power plant) are counted as credits when selling power, if they are not assessed at all, or if they charge you for the distribution service no matter which way the electricity is traveling.

Anyway, I applaud the local utility, MG&E, for encouraging growth of renewable energy by providing programs both for buying and selling renewable energy.

The places that allow you to go net negative buy your power back at wholesale rates, which is far lower. If you think about it when you sell power back to the power company you're not competing with the power company, you're competing with the power generators. Why should the power company give you an unfair advantage there?

While it may be true that you sell at wholesale rates in many locations, it's not in my area.

First, I am in the utility's green power tomorrow [PDF warning!] program. That means that I pay $0.01 extra per kWh to fund renewable energy. The utility promises that they will purchase enough renewable energy to cover every kWh that is paid at the higher rate, in addition to the legally mandated 1.73% minimum renewable energy they buy. 99.9% of that comes from wind farms in 3 areas, the other 0.1% comes from local solar generation. That puts my total rate at about $0.14/kWh for last month (it goes up and down by a few pennies quite regularly).

For those that have solar arrays, the local power company will buy all your solar-generated electricity for $0.25/kWh, and then sell it back at the regular electric price, plus a $0.01 charge per kWh to be part of the same green power program that I am. So if you're using 5 kW and producing 5 kW, you're still getting paid! (Caveat: I believe the program is currently full, they have a cap on the total capacity.)

The way they can afford to do this is through the extra penny others are choosing to pay. Renewable power generally costs more than the coal, natural gas, or nuclear plants they replace. So they collect this extra amount, and buy more expensive electricity. It's worth noting that there are charges assessed per-day (around $11/month for me), so it's not exactly a brilliant money-making scheme. I also don't know if some of the other charges (like the charge for distribution service, paying for the wires between my house and the power plant) are counted as credits when selling power, if they are not assessed at all, or if they charge you for the distribution service no matter which way the electricity is traveling.

Anyway, I applaud the local utility, MG&E, for encouraging growth of renewable energy by providing programs both for buying and selling renewable energy.

MG&E in Wisconsin has been offering this as a voluntary service for a while: http://www.mge.com/home/services/power_cntl.htm

The idea is you get a $25 credit for having this installed and then $8/hour of shutoff time and they specific times when they will not shut off your AC. I've seriously thought about it since the possible shutoff times are pretty much while I'm at work.

No it isn't. Water vapor is the most significant. If you eliminate water vapor, than it is the most significant but not by far.

Ok, yes, but we don't usually consider water vapor when we're talking about greenhouse gasses from human activity.

There are a few other good energy sources. Nuclear for example. US has a problem with storing nuclear waste, but it is political, not practical problem. Can you point me to a working "clean coal plant" or is it another piece of vaporware? It does not reduce the CO2 emissions, at best you will be able to store temporarily some of them underground. And I have heard of even crazier ideas of pumping the CO2 deep in the ocean.

On clean coal, yes, it's a matter of not letting the carbon into the atmosphere. Here are the basic options for clean coal. And there are other ways to make much cleaner, more efficient conventional power plants. Here is an example from my city.

That said, I couldn't possibly be more in agreement with you on the subject of nuclear power. It's a political problem, and a classic "NIMBY" problem. The energy production per mass input and per output of managed waste is something that can't be touched. I wish the US was even more involved with ITER than it is. In fact, I've often wondered what would happen if the US could muster the kind of public and political will it would take to devote the kind of resources we're able to collectively justify for wars - no matter one's opinion of a particular war - but could never justify for, e.g., full-scale fusion research.

If you burn natural gas at the home then you can use the excess heat generated to heat the house. When the power plant burns natural gas(or coal) the waste heat usually ends up getting dumped in a lake which is great for the ducks but not so efficient.

My local university and power company recently teamed up to build a cogen plant that burns natural gas and uses the excess heat to heat campus buildings. They figure that this new plant is 70% efficient vs 30-35% for most existing natural gas power.

US Electricity production in 2003 was 3800 Billion KWh (=3.8 PWh =13 Quad); 21% nuclear (.76 PWh=2.6). For comparison, hydro was 7%; solar, geothermal, and other alternative sources about 1%.

Total energy consumption, however, is about 100 Quad, once you include all energy use ("petroleum, dry natural gas, coal, net hydro, nuclear, geothermal, solar, wind, wood and waste electric power").

Since nuclear energy is used exclusively for electricity generation (neglecting the effect of a few floating cities), it would not be impossible to replace nuclear power with an expanded coal program, especially given the vast proven US coal reserves. However, coal-fired plants have arguably greater drawbacks-- coal ash is radioactive, and burning more coal would release more CO2.

Replacing nuclear power with an expanded alternatives program (wind or solar) would require an order of magnitude increase in generation capacity. It would also result in a cost increase; wind energy costs around .

According to the State of Wisconsin, wind power costs 9 cents versus 4 cents for standard fuels. Of course, this is still cheaper than what people are paying here on the east coast (10-12 cents I would imagine).

if the whole world converted to wind power in 15 years, the amount of power being extracted from the atmosphere would be more than the increase in greenhouse gas atmospheric energy

Awesome.

when we run out of oil we will convert coal to synthetic fuel.

I doubt it. The Germans did this in the 1930's, and it was pretty expensive.