Cutting GHG by Replacing Coal by Natural Gas plants

by Ginosar  

A practical approach to cut US GHG by 19%

by replacing coal plants with natural gas combined cycle (NGCC)



Our electrical system was designed to supply reliable electricity at the lowest cost, which most of the time was done well. Without blaming, utilities and regulators concentrated mostly on low costs and did not give priority to our national long term needs, especially global warming (GW). But, GW demands a change in this approach: National considerations must be primary concern, not just costs. With limited increase in generation costs we can cut greenhouse gases (GHG) significantly. And since the benefits are national, the costs should be borne nationally too.

Goal: cut GHG as much as possible, as quickly as possible, at acceptable costs

Replacing Coal power plants by NGCC can reduce US GHG by 19%. This is a proven, readily available technology to use in larger quantity.

Several key ways available to cut GHG, first is conservation and energy efficiency.

Here only coal generated electricity is discussed since it is the largest GHG emitter.


Electricity generation emits 35% of US total GHG.

Coal plants emit 80% of that = 28% of all US GHG.

Replacing coal plants with NGCC would cut GHG to 1/3 of coal; a reduction of 19% of total US GHG emissions!


Approach: Mandatory laws, with compensation to customers, workers and owners

1. Reduce use of gas and electricity for winter heating nationally by intense conservation: result 50% cut in older structures, 80% reduction in new structures.

2. No new coal plants allowed - (until Sequestration of CO2 is proven reliable)

3. Only NGCC permitted from fossil fuels - or plants with same low GHG emissions

4. Start with replacing old coal plants with low remaining life, say 5 to 7 years

5. Even higher energy efficiency: Use smaller NGCC plants closer to industrial sites to use the waste heat for industry by combined heat and power (CHP)

6. Reduce PUC ability to hinder CHP with a national authority

Because NGCC plants have fast response they can work well with higher percentage of wind and solar thermal energies to supply base power.


Note: In summer 2009 - 28 new coal plants were under construction, 7 near constructions, and 13 permitted, a total new capacity of 26,000 MW. Plus 47 coal plants are in early stages.



1. Low NG plant usage: The average capacity factor, actual utilization compare to the maximum possible, of coal power plants is 74%, but that of existing NGCC is only 42% in the US, partially because the fuel cost of natural gas (NG) is higher by 3c per kWh.

At a cost increase of 3 c/kWh we can immediately cut GHG significantly with current equipment even before we start this program.


2. Some major questions raised by this proposal:

A. Why depend on another fossil fuel and not go directly to green technologies?

B. Where will we get the NG?

C. What will it cost?

D. How long will it take, or, how complex is it?

E. Note about energy waste and remedy by CHP


A. Why NG and not wind or solar?

Power generation relying on nature, such as wind, solar (and even hydro power), fluctuate and their fluctuations are also unpredictable. Cloudy days effect solar; changes in precipitation change dam storage, and winds are unpredictable and may be more so with increase in GW. Therefore, we must have solid, human-controlled power sources that emit the lowest GHG possible. The only proven technology we now have is nuclear power.

As much as I wish we did not need nuclear power, we will have to use it also in our mix of limited-GHG energy sources. The probability of severe global damage by GHG is much larger than the possibility of damage from nuclear power. However, due to great misconceptions and fear of nuclear power, it will take too long to overcome political resistance and public fear to install sufficient nuclear power plants.


The only currently proven, readily available technology that we can use at reasonable cost, I believe, is NGCC. We can not wait for the ideal, we must do what is possible and fast. And we must have reliable electrical power to sustain an industrial, electricity-based society while cutting drastically our GHG.

Geothermal has limited sources of energy at current technology and costs. Biomass should be tried soon with a large scale setup. Coal Sequestration is not a proven technology, and may not have low enough probability of CO2 escape.

Note: Germany with intense effort for green energies for years, is adding some 50 new coal plants.


B. Where to get the added NG?

Total US yearly natural gas consumption is 23 Tera cuft (10^12), for electricity generation: 6.6 Tera cuft; residential: 5 TCF; Commercial: 3 TCF; industrial: 7 TCU. US imports negligible amount of natural gas beyond our imports by pipelines from Canada and Mexico. We export an insignificant amount to Japan from Alaska (via LNG, i.e., liquefied natural gas). Some 20% of US electricity is generated by NG and it consumes 20% of US NG. During the summer when residential and commercial heating drops drastically, electricity generation from NG doubles to some 40%. Industrial use does not change much by season. It may be lowered by 10% to 20% by additional conservation and efficiency, since it is mostly for material and processing. Industrial use went down over time to cut costs, and because US industrial production has declined. Residential and commercial NG use is mostly for space heating and can be cut significantly by conservation and efficiency. In  addition to reducing NG by conservation and efficiency, electrical use is also cut down during winter, in most parts of our country. Many homes in low electrical cost zones, with hydro or coal generation, use electric space heating, which consume substantial amounts of electricity. This could lower need for new NGCC.

Conservation can cut heating consumption in existing homes by over two to one. This saving in NG will be available for electricity production which would allow almost doubling current use of NG for electricity. Additional NG could be extracted from within the US if the demand and higher prices are there to support it, as demonstrated in the last few years with price fluctuation of NG.

Recent technology innovations increased US natural gas reserves by some 50%. In addition the NG industry is starting to exercise its political muscles to use more NG for electricity production.


In case this is not enough over time, we may need to import LNG for expanding use of energy into the US if our conservation and efficiency are not done with sufficient intensity. Canada and Australia can be our major sources for our imports.


C. What will shift to NG cost?

NGCC have higher efficiency and half the emission, thus 1/3 of emission per kWh of coal.

The increase fuel cost is $50 per ton of CO2 reduced, compared to coal. (In comparison Photovoltaic is more than $600 per ton of CO2 under favorable future conditions.)

For the electricity market, coal is $2.00/MMBtu (million Btu) [2c/ 10,000 Btu] and NG is $7.00/MMBtu [7c/ 10,000 Btu]. At 10,000 Btu/kWh for coal and 7,000 Btu/kWh for NGCC the increase is 3 c/kWh above coal. NGCC plants have lower cost than new coal. NGCC has up to 50% efficiency, existing coal is 31%. New NGCC plants cost about $1,200 per kW, are faster online, and there is a tremendous environmental damage from coal plants in addition to high GHG. Coal plant cost is higher because of the higher complexity of the coal input system and the extensive air pollution control required.

If the total increased cost is distributed nationally the price of electricity may rise by 2 c per kWh.


D. How long will it take, and how complex is it?

This proposal is a massive undertaking; it involves up to 700 coal facilities (often more than one plant at a site) in many states with yearly income in the order of $60 B. Political resistance to phasing out coal plants is massive. It may take 20 years to fully accomplish and must be done in conjunction with mandatory national conservation and efficiency drives to reduce the amount of NGCC needed. But the environmental benefits are also considerable, more than can be obtained by partial approaches.



(Ballpark calculations.) Capital investment in electricity generation (of some 1000 billion watt total,) is very large: To replace the 70% of total current electricity generation that is generated by fossil fuels, with "Green" technologies will cost over two trillion dollars, if cost drops to $2/watt, (it does not include the "smart grid".) Note, capacity factor of green energy is less than half of NGCC. Our hope for future low cost green technologies is not likely to reduce this estimate. Moving a technology from R&D to full market penetration is a very long and costly process.

IT WILL COST MORE: US investment in our current electrical system is in the order 1.5 to 2.0 trillion dollars. With depreciation, it is worth less than half this amount. All new "green" technologies, from wind, solar thermal electric--let alone the very expensive photovoltaic technology--are considerably more expensive than current coal and natural gas systems. Over time the elimination of input fuels to coal and NG systems will level the expenses; however,  the vast initial investment would not easily come from private capital unless the legal and economic uncertainties are reduced and stabilized.


E. Note about our energy waste and remedy by CHP.

We waste 60% of our input energy during central station electricity generation. This wasted heat is often cooled by scarce fresh water. Typical efficiency now is 33% while two thirds is wasted. Combined Heat and Power (CHP), or cogeneration, is the use of this wasted energy. In some countries in Europe it is used to a much higher level (possibly 40%) than the US (around 8%). This is a critical waste of energy resources, and we must use this throw away heat to reduce our energy use and imports. Note that only about half of this wasted energy can be practically used.


A third of all our energy input, now wasted, is recoverable.

Utilities and the Department of Energy must spend intense effort to use this wasted energy! It could have major impact on our GHG, energy development, importation, and use!

Utilities should be rewarded for cutting its wasted energy. This is not the case in many states.




No feedback yet

Form is loading...