Bush has killed a bill that would have required reduction of CO2 emissions at power plants. How can CO2 emissions be reduced? What could they do with the CO2 to prevent its escaping into the atmosphere?
- use less fuel (i.e. more efficient conversion of fuel to electricity, or use the waste heat from the conversion process, or convince people to use less electricity).
- use less carbon-intensive fuel (gas instead of coal, biomass or renewable energy instead of fossil fuels).
For hydrocarbons, the lower the carbon-to-hydrogen ratio in the fuel, the less CO[sub]2[/sub] will be released for each MJ burned.
- the exotic option: capture the carbon dioxide and sequester it in the deep ocean, in caves or the like. This one is difficult and energy intensive, so options 1 and 2 are favoured.
- Build more nuclear plants.
Also, I think there are additives that can be added to fuel (for a slightly higher price) that can help it burn cleaner.
CO[sub]2[/sub] is the natural result of complete combustion of carbon. Thus, it has already burned as clean as it possibly can.
hibernicus, of course, has the correct answers. Damn him for being 6 time zones ahead of me so he could answer the question first!
An interesting note - the Sierra Club had a “technical paper” on their wesite for a week or so last year that claimed it was possible to burn carbon, and use the electricity generated from that to run a process that would capture and “decompose” the CO[sub]2[/sub] back to C, thus allowing not only for 100% CO[sub]2[/sub] reduction but also unlimited, free energy!
But, since this was in fact impossible, they took it down with no announcement as to why. :rolleyes:
to reduce CO2 - here’s my thoughts:
remove emission controls - they cause energy loss and thus more fuel to be burnt (and they will allow more CO instead of CO2 but the CO will become CO2 naturally anyway)
use nuclear/solar/wind/water power
use biomass fuels - they will release CO2 but that CO2 was in the air naturally anyway and must be converted back (into plants) at the rate they are released for combustion to be a steady state power source.
put a factory in the middle of a forest… plants (of the vegetation variety) thrive on CO2, and produce oxygen… why would you want to reduce the gas that benefits the environment? (as long as you have enough plants to deal with the CO2)
(or am I waaayy off base?)
CO2 is only a benefit to the current ecosystem if it’s in balance with the current ecosystem’s requirements. At some point, whatever that may be, too much CO2 becomes a hazard.
Also note that forests are being quickly destroyed pretty much everywhere. So, we are increasing CO2 output but reducing one of the primary CO2 sinks. Smart, eh?
Not trying to be alarmist, but them be the facts. Sure, we don’t know the extent to which other sinks will compensate to keep CO2 within acceptable levels…but are we willing to bet our future on it? Apparently the majority answer so far is “yes” or “I don’t care”.
Hey, how did this soapbox get under my feet? Sorry about that.
Well, the real problems that the emissions controls are there to solve on most power plants are particulates, SO[sub]2[/sub], and NO[sub]x[/sub]. Extremely few plants have any controls for CO, although Selective Catalytic Reduction systems used for NO[sub]x[/sub] control will also catalyze a large amount of the CO into CO[sub]2[/sub].
The coal plant I work at uses anhydrous ammonia to convert NOx into CO2.
That must be some coal plant - to convert nitrogen into carbon and all.
I think you meant “NO[sub]x[/sub] into NO[sub]2[/sub]”, my friend. So it sounds like you are using Selective Non-Catalytic Reduction - do you work at an AEP plant, or Southern Company? Or somewhere else?
But these controls do cause more fuel to be burnt and that leads to more CO2. I was stating CO to point out that I am not considerng making CO as a way of reducing CO2. Just saying that emission controls cause inefficencies that result in more CO2 being produced.
Ok how does one sequester carbon? I have been at seminars where a Chem E. type said this wasn’t all that hard but he offered no explanation beyond that.
As for deep cave storage unless you can compress (freeze?) the gas you:
*Fill up available caves really quick
*Run the risk of the CO2 escaping back to the atmosphere during an earthquake etc.
*Kill off any life forms in said caves
For an ocean dump, are we suggestion carbonation of the world’s oceans, or am I missing something?
Yes, that is true. I guess one has to weigh what causes the greater problem to the environment - a pound of SO[sub]2[/sub] or a pound of CO[sub]2[/sub].
For an example - let’s take the output from a coal power plant in the East (unnamed) that has a wet limestone flue gas desulfurization system. Let’s look at some vital statistics:
With its typical coal that is burned, under typical base-load conditions, we have the following data:
Gross MW: 550 Net MW: 515 Auxiliary Power: 35 MW MW*hr of Gross Generation per Year: 4,600,000 MW*hr MW*hr of Net Generation per Year: 4,300,300 MW*hr MW*hr of Auxiliary Power per Year: 299,700 MW*hr MW*hr of Scrubber Power per Year: 19,600 MW*hr MW*hr of Scrubber Additive Prep Power per year: 3,700 MW*hr Mw*hr of Scrubber Booster Fan Power per year: 34,000 MW*hr Total Scrubber Power required per Year: 57,300 MW*hr
So, each year the plant uses 299,700 MWhr to operate itself, or about 6.5% of its gross power generated. The scrubber and its related equipment takes 57,300 MWhr per year to operate, or 1.25% of the plant total.
The plant burns a coal at 1.65% sulfur content by mass. The plant burns 1,640,000 tons of coal in a year, thus it takes in about 27,060 tons of sulfur in the coal. During this year, the scrubber will remove 24,576.1 tons of sulfur, at a removal efficiency of 90.8%. This 24,576.1 tons of sulfur forms 24,576.1*1.997 = 49,078 tons of SO[sub]2[/sub] per year.
OK…now how much CO[sub]2[/sub] is emitted by the plant? Well, over the year, the plant will produce 4,255,636 tons of CO[sub]2[/sub]. Thus, per MWhr gross, it emits about 4,255,636/4,600,000, or 0.925 tons of CO[sub]2[/sub] per MWhr gross.
Now, since we know the scrubber takes 57,300 MWhr of the gross, the CO[sub]2[/sub] contribution due to the scrubber is 57,3000.925 = 53,010 tons CO[sub]2[/sub] per year.
So…the srubber removes 49,078 tons of SO[sub]2[/sub], at a “cost” of 53,010 tons of CO[sub]2[/sub].
Now here is the question that I cannot answer with any basis other than a gut feeling: which harms the environment more? My guess is…the SO[sub]2[/sub].