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# Economic considerations for carbon reduction4

## Economic considerations for carbon reduction

(OP)
This thread is dependent on the assumption that there is a public interest in reducing carbon emissions here in the United States. That may be a big assumption for some. But, assuming it to be true, what is the most efficient way for that to be done?

To me we spend too much time arguing across political aisles about the severity and cause of global warming. I would prefer we spend more time talking about the "economics" associated with the solutions. Maybe we're wasting public funds to support projects that are intended to make us feel better, but are not particularly cost efficient if reducing carbon emissions is our goal.

My initial thoughts on the subject are the following:
1) Solar isn't all that cost effective. Expensive per kilowatt hour produced and government funding / subsidies may be better spent elsewhere.
2) Obviously Hydro power is essentially carbon free (after building the dams). But, there are only so many locations where these can be built.
3) Nuclear power is also essentially carbon free. Perhaps we need to reconsider our country's resistance to building new power plants (and forcing existing ones to decommission).

### RE: Economic considerations for carbon reduction

It's extremely hard to beat petroleum's 49 MJ/kg, both on the generation side and the storage side. Li-ion batteries come in at around 1.1 MJ/kg, so they have to last at least 100 or 200 complete discharge cycles to break even.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm

### RE: Economic considerations for carbon reduction

I hate to say it but reduction in energy demand may well be the cheapest way to make a significant difference both short and long term. If demand is reduced then whatever method is used to supply the enrgy, you still need less of it and less capacity. Solar and wind have their place as does , gas , nuclear and hydro along with several other less well known technologies. But if we are serious about reducing carbon emmissions we also have to accepot the fact that we must reduce demand across the board.

I am not talking about replacing light bulbs with more energy efficient types and driving hybrid SUVs but rethinking our whole approach to consumption. A smaller house uses less energy to construct , operate and maintain, less to air condition , heat and light. A smaller car uses less material to build and less fuel operate (regardless of source). Most of us could afford to eat less and walk more.And so on....

However this will be a bitter pill to swallow because our whole economy is based on endless growth and ever increasing consumption.

I wonder what the Easter Islanders said when they chopped down the last tree?

Regards
Ashtree
"Any water can be made potable if you filter it through enough money"

### RE: Economic considerations for carbon reduction

"Timber!" Or whatever the local equivalent was.

### RE: Economic considerations for carbon reduction

Our state (Washington) voted on an initiative to pass a carbon tax. It failed, but mostly (IMO) because there was little information available, nor written into the law, as to how the funds obtained from the tax would be spent. There will likely be some follow up of this in state congress next year.

### RE: Economic considerations for carbon reduction

Leaving aside the carbon tax issue, which raises more problems than it answers - Whatever happened to tidal power generation? At one point, it was the "next big thing". And now, it's not even discussed anymore.
GRANTED, it's also an intermittent source. However my (admittedly limited)understanding is that power can be generated off much of the tide in both directions, making it far more stable than wind or solar...

### RE: Economic considerations for carbon reduction

Sounds like a good question to post...but why ask it in the bottom of a thread on carbon reduction?

### RE: Economic considerations for carbon reduction

#### Quote:

Sounds like a good question to post...but why ask it in the bottom of a thread on carbon reduction?

Perhaps because it's directly relevant to the question in the original post?

I'd say the main reasons we don't hear much about it are:
1. There are limited sites with sufficient tidal range to make it economic.
2. It necessarily requires a huge initial investment in a single project with a long lead time.
3. Environmental effects are significant.

Doug Jenkins
Interactive Design Services
http://newtonexcelbach.wordpress.com/

### RE: Economic considerations for carbon reduction

It looks like I'd better do some reading on the subject. I had the impression that tidal range, while definitely a factor, wouldn't be so important as to limit placement to just a few sites.
While I can understand the cost/time/return factors would play a part, I also hadn't expected a huge environmental impact, unless talking about acres of the things. Unless you're referring to land-based installations, using channels to direct/amplify the tidal surge?
In any case, it's something interesting to look into, so I'll go do that.

### RE: Economic considerations for carbon reduction

JoshPlum:

#### Quote:

5) Coal burning power plants are the worst offenders. I've seen studies suggesting that the quickest and most efficient method to reduce carbon emissions would be to replace coal burning power plants with natural gas powered turbine generators. It's definitely NOT carbon free, but if it is a cost effective step in the right direction then why aren't we doing it?

In the US we are. The wide availability of cheap fracked natural gas has enabled this transition to occur for immediate economic reasons alone. As a result, we have the most significant reductions of CO2 emissions over the last few years of any major country (from an admittedly high starting level).

### RE: Economic considerations for carbon reduction

in my ignorance ... why does burning natural gas reduce CO2 emissions ? 'cause energy/ton CO2 emitted is greater for natural gas than other FFs ? I has assumed all FFs were the same.

I have long wondered why propane is not more widely used.

### RE: Economic considerations for carbon reduction

Natural gas has the highest ratio of hydrogen to carbon of any fossil fuel -- mostly methane (CH4 at 4:1) and some ethane (C2H6 at 3:1). So the result of oxidation is more H2O and less CO2 per unit of energy. The longer the alkane "chain", the closer to a 2:1 ratio it comes.

Coal is much closer to "pure" carbon with very little hydrogen, so produces about twice the CO2 compared to natural gas per unit of energy. Combine this with the ability to use natural gas in "combined cycle" turbines that get 50-60% efficiencies in converting the thermal energy to electricity, compared to typical 35% for coal plants, and you get even greater resulting CO2 reduction. (The "supercritical" coal plants starting to come on line look to increase their thermal efficiencies to 45% or so.)

Propane's ability to compress to a liquid at ambient temperatures makes it very valuable for use where it is not feasible to pipe natural gas. It would be a waste to use it where natural gas would do.

### RE: Economic considerations for carbon reduction

Burning coal, all of the energy comes from converting C into CO2.

Burning hydrocarbons a large part of the energy comes from converting H to H20.

How far changing from coal to methane is a good idea, I'm not sure. A power plant built today is likely to be around for 40 years, so it might be more cost effective to switch to other (non-fossil fuel) sources, even if the total investment/kW was higher.

If there was a realistic price on GHG emissions, the market could sort out these things, but with so much of the cost hidden it requires subsidies and central regulation.

It does seem a bit surprising that it is the more conservative governments in the world who seem to be going for the latter route, but we just have to work within the politics as they are.

Doug Jenkins
Interactive Design Services
http://newtonexcelbach.wordpress.com/

### RE: Economic considerations for carbon reduction

If more hydrogen results in the hydrogen bonding to oxygen instead of carbon (very simplistically), then could it be feasible to add an onboard hydrogen generator to a vehicle, and expect to see CO2 emissions drop? Or would the chemistry not pan out that way?

### RE: Economic considerations for carbon reduction

No, the stoichiometry of the chemical reaction for burning dictates what's bonded

m*CxHy + n*O2 --> s*CO + t*CO2 + u*H2O

adding hydrogen does nothing to the carbon oxidation, except possibly cranking a truckload of CO and wasting another truckload of energy. The energy you would have gained in the water fusion process is negated by the energy required to crack water to get hydrogen.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm

### RE: Economic considerations for carbon reduction

no, but Hydrogen as a fuel is under consideration for aircraft ... probably a lead balloon. The operational problems are obvious. Hydrogen is the fuel in fuel cells which are "fabulously" expensive.

### RE: Economic considerations for carbon reduction

Hydrogen, as "fuel," is, energetically, a losing proposition, since it takes more energy to get hydrogen into a "fuel" state than you get back upon combustion.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm

### RE: Economic considerations for carbon reduction

I agree ... to cost to make a fuel cell probably exceeds the value of the energy stored for most applications but when you need it (like military and space) then you pay for it.

### RE: Economic considerations for carbon reduction

Re hydrogen as a "fuel" (strictly speaking, it is not). This article may be somewhat dated in some respects. The physics, of course, are not :)

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

### RE: Economic considerations for carbon reduction

A lot of that is semantic quibbling. By the same token, fossil fuels are likewise energy carriers, since they require sunlight and chemical reactions to produce, albeit, many eons ago, as opposed to cracking water in the immediate past. Additionally, hydrogen DOES naturally occur in nature, just not on Earth; obviously the Sun fuses hydrogen into helium, and didn't need to crack water for it. Of course, one could argue that the creation of the Sun's hydrogen in the Big Bang likewise was a possible net negative on energy. But, by the same token, the interstellar production of oxygen and carbon required massive amounts of energy and the fusing of hydrogen into helium,, etc., etc., in the first place as well.

The bottom line is that whatever the genesis, the energy cost is reflected in the unit pricing of the "fuels." The cost of oil includes exploration, drilling, pumping, refining, and delivery of that fuel. Likewise, the cost of hydrogen includes the cost water, the cracking process, the generation of the power to do so, and delivery. No one wants to lose money in the hydrogen economy, so all the costs have to be captured and transferred to the end user. Once that process is valid, then hydrogen is a fuel.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm

### RE: Economic considerations for carbon reduction

Yeah, perhaps more accurate to say "not an energy source". However you state it the challenges are significant. Here is another old paper. Haven't read if thru recently, but if I recall correctly even the fuel cell guys aren't too excited.

The problem with sloppy work is that the supply FAR EXCEEDS the demand

### RE: Economic considerations for carbon reduction

IR it is you who is quibbling and it gets tiresome, sometimes. Is hydrogen a "fuel"? Sure, but not in any sense that is relevant to this discussion. It is not, and never will be, a source of energy for our society. This is what confuses people and you are contributing to this confusion, not to clarity. Fusion is a completely separate subject. It would be nice if you would take a moment to think about a topic before instantly replying with the first contrarian thought that pops into your head. You have a lot of knowledge to contribute here, but you seem to forget that there are thousands of people who read this site. It is not a private conversation between you and couple of others.

### RE: Economic considerations for carbon reduction

I do understand, and I think it confuses the non-technical people when we insist, pedantically, to call hydrogen a "non-fuel" because the average person sees it otherwise and sees it being used as fuel. For them, the main issues are the carbon footprint and the cost, not that it's not a "fuel."

It would be far more useful to detail and compare the precise carbon footprint of hydrogen; is it better or worse than petroleum? Because of cheap natural gas, the carbon footprint of hydrogen has gotten better.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm

### RE: Economic considerations for carbon reduction

(OP)
IDS -

One quick clarification. I didn't mean "sin tax" in any negative sense. It's just a term used to discourage certain unsavory behavior. Why have sin taxes on alcohol or tobacco? Well, aren't there other societal costs associated with them that are difficult to quantify? Increased health care expenses for both. Same concept for other "sin taxes" that might be proposed. Sugary drinks, pornography, et cetera. Some of these costs are easy to quantify, some are not. However, they're all associated with an attempt to discourage behavior that causes some ills in our society (or are perceived to cause ills).

One a different note, I would very much prefer for the cost of ones actions to be more closely associated with those actions themselves. The money spent on roads should entire come from gasoline taxes or car taxes or such. The money spent on government subsidies for clean power should entirely come from taxes on the less clean sources of power. I think that's essentially what you were saying before which I very much agree with.

### RE: Economic considerations for carbon reduction

Josh - thanks for the clarification, and all good points.

Doug Jenkins
Interactive Design Services
http://newtonexcelbach.wordpress.com/

### RE: Economic considerations for carbon reduction

I don't know what the official technical definition of a fuel is, but to me it means any substance that contains stored energy that can be extracted for some useful purpose. On that basis hydrogen is clearly a fuel.

On the other hand, it is reasonable to point out that there is a difference between natural fuels that can be extracted at comparatively low cost, such as coal, or natural gas, or wood, or rainfall stored at high altitude, and manufactured fuels, such as hydrogen, or batteries, or ethanol, or pumped water stored at high altitude. All of the latter have costs which should be taken into account, and depending on the source of the energy used to create them, may have significant associated GHG emissions.

Doug Jenkins
Interactive Design Services
http://newtonexcelbach.wordpress.com/

### RE: Economic considerations for carbon reduction

The on-board reformation of hydrocarbons to produce hydrogen to feed fuelcells has been studied and abandoned for good reasons. PEM fuelcells need absolutely pure hydrogen with a total of CO plus CO2 lower than 10 ppm. Even argon in the feed gas requires anode tailgas venting to avoid its accumulation. An onboard reformer is dead in the water in terms of cost, efficiency and the need for purification.

People continue to work on so-called direct methanol fuelcells, but they're not a thing for vehicles yet. Methanol is one of the easiest things to reform onboard as it falls back apart to CO and H2 fairly easily- but then you have to water gas shift the CO + H2O back to CO2 + H2, and then the purification etc. Not worth the bother.

Solid oxide fuelcells might be an option for large vehicles (ships being one example), but they're high temperature devices best suited when you need both power and heat, i.e. stationary applications. They're not sufficiently higher in efficiency to merit the replacement of large diesels which are already quite efficient.

Hydrogen fuelcells for cars and small trucks sound appealing until you get into the details. If you're starting with either methane or electricity, about 70% conversion of methane LHV or electrical joules into hydrogen LHV is the best you're going to do. Storage at high pressure is about 90% efficient, i.e. eating about 10% of the energy in the hydrogen you've produced. Then the onboard fuelcell is about 50% efficient- you might stretch that to 60% but not without a fair bit of cost. That's 37% from energy source to wheels at best, forgetting about distribution losses. Battery EVs do quite a bit better than that- battery plus charger is about 90%, and the motor/inverter too are around 90%, so about 81% from energy source to wheels. Both would be subject to distribution losses etc. which you'd have to figure in if you were going to compare against gasoline/diesel which are, round numbers, about 80% efficient from well to tank. So the fuelcell vehicle's value proposition becomes one of roughly 2.4x as much energy (and hence 2.4x as much operating cost) to move a similar car the same distance, all in return for faster refuelling. Doesn't make sense to me, not even if electricity were to suddenly become very cheap- because we haven't talked about the refuelling infrastructure, its cost, and how it would be paid for (i.e you'd be charged for it at the pump). Hydrogen in California is $15 USD/kg retail, and that's only 1/3 renewable right now (2/3 is cheaper fossil-sourced hydrogen). That will take a Toyota Mirai about 320 miles. By the way, the Mirai is actually 200 pounds heavier than the Tesla Model 3 long range version which has a range of about the same- 312 EPA miles on a charge. ### RE: Economic considerations for carbon reduction (OP) Molten Metal - I'd love to get some better understanding of the different types of fuel cells. I did a quick lookup on wikipedia, so I'm not exactly an expert. But, it sounds like you're focused mainly on small / portable fuel cells of type that could be used for cars. Is that correct? There are other types of fuel cells that work fairly efficiently for small power needs (i.e. less than a MegaWatt). I did a bit of structural engineering work for a company that specializes in this a number of year ago. https://www.fuelcellenergy.com/ Now, I don't believe these are very scale-able for large energy needs. But, there appears to be a market niche for them. Customers who want their own power supply and don't want to rely completely on the grid. Maybe manufacturing, hospitals, utilities, or such. ### RE: Economic considerations for carbon reduction The high temperature units are either molten carbonate or solid oxide type fuelcells. They in a sense are "cheating", because they do thermal reformation of the feed fuel onboard. They are useful as mentioned in my post for stationary or large (think ships) mobile applications especially where the desire is combined heat and power. They're about as efficient as CCGT but available at lower scale. For smaller transport applications, the low temperature PEM fuelcell is the only game in town. And there's good reason there are already about 4,000,000 battery EVs on the world's roads and only about 10,000 fuelcell cars. ### RE: Economic considerations for carbon reduction To clarify a bit: the high temperature fuelcells use both H2 and CO electrochemically- they do not have a device which converts all the energy in the feed fuel to energy in hydrogen first, thereby avoiding both the energetic and purification losses that the PEM fuelcell endures if it is fed hydrogen derived from hydrocarbons. ### RE: Economic considerations for carbon reduction The majority of posts here seem to refer to the USA and perhaps thats understandable.. Moltenmetal makes reference to a possible$150 per tonne Carbon tax. Is there a carbon tax in place anywhere in the USA?? If so, how much and how socially accepted is it ?? Here in Alberta we have a $25 per tonne tax, scheduled to go up every year in the near future. It shows very clearly on your utility bill, its built into your gasoline / diesel costs at the pump ( but its not so blatant there) and every thing that is delivered by truck or rail, Im sure the extra costs are passed onto the consumer. Personally I resent the entire concept. Its just another tax grab with another level of bureaucracy built in. Is the average USA resident prepared for the increased cost of living that this tax carries with it?? ### RE: Economic considerations for carbon reduction Given that many/most/the majority of informed experts on the subject of global warming link carbon emmissions with the problem i would suggest that its not a matter of whether or not we can afford the extra cost of the tax but whether or not we can afford not to do something about carbon emmissions. I would suggest that we may well find out that$25,50 or \$150 /tonne was way under price in the long term.

Regards
Ashtree
"Any water can be made potable if you filter it through enough money"

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