Author Topic: EPA Now Looking at Shuttle SRB Perchlorate Oxidizer--again...  (Read 16808 times)

Offline randomly

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I'm sure you're quite right about current LH2 production not being the greenest process; however, NASA or UAL could buy wind energy contracts for electrolysis of hydrogen--like the New Belgium Brewery in Colorado.

http://www.newbelgium.com/sustainability

That would be counter productive and actually cause more pollution, not less. Electrolysis is only about 50% efficient, reforming methane is 80% efficient. Your wind power electricity will always be better spent displacing electricity generated by hydrocarbon fueled power plants than generating Hydrogen by electrolysis. Generating hydrogen by electrolysis only makes sense when you've eliminated all the hydrocarbon power generation.

Offline Lee Jay

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I'm sure you're quite right about current LH2 production not being the greenest process; however, NASA or UAL could buy wind energy contracts for electrolysis of hydrogen--like the New Belgium Brewery in Colorado.

http://www.newbelgium.com/sustainability

That would be counter productive and actually cause more pollution, not less. Electrolysis is only about 50% efficient, reforming methane is 80% efficient. Your wind power electricity will always be better spent displacing electricity generated by hydrocarbon fueled power plants than generating Hydrogen by electrolysis. Generating hydrogen by electrolysis only makes sense when you've eliminated all the hydrocarbon power generation.

What you said above is generally correct, but it also depends on which hydrocarbons it's displacing.  Natural gas plants average 41% efficiency, with a wide range from 25% (IC) to 60% (advanced combined cycle), and they produce far less CO2 per unit of energy than the average 33% efficient coal plants.  Comparing 80% efficient SMR with 50% efficient electrolysis against hydrocarbon displacement on-grid, as the wind might otherwise be displacing hydro or nuke - you just can't tell right away.

Offline kevin-rf

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as the wind might otherwise be displacing hydro ...

Considering how flat florida is, I guess we can rule that one out..
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Offline randomly

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What you said above is generally correct, but it also depends on which hydrocarbons it's displacing.  Natural gas plants average 41% efficiency, with a wide range from 25% (IC) to 60% (advanced combined cycle), and they produce far less CO2 per unit of energy than the average 33% efficient coal plants.  Comparing 80% efficient SMR with 50% efficient electrolysis against hydrocarbon displacement on-grid, as the wind might otherwise be displacing hydro or nuke - you just can't tell right away.
Wind always displaces Hydro if hydro is available, it doesn't ever displace nuclear. Displacing hydro allows hydro to conserve it's limited water supply and hydro has a very fast response time so it can accomodate the power fluctations from wind. There is no advantage in displacing nuclear since fuel costs are negligible (<0.5 cents/kwh), the costs are in operations and maintenance (1.3 c/kwh) and capital costs (~6.0 c/kwh). Nuclear costs almost as much whether it's producing power or not, that's why they are run at 100% 24/7/365. Nuclear is also very slow responding and can't change power levels rapidly.

No it doesn't matter which hydrocarbons it's displacing. 80% efficiency in reforming natural gas to hydogen is still better than 60% efficiency of electrical generation from a combined cycle power plant. Plus you are forgetting that electrolysis is only 50% efficient which makes the trade off twice as bad.

 If you use electrolysis to generate your hydrogen instead of using that electricity to displace hydrocarbon generated electricity you will end burning nearly 3 times as much methane as you would have if you just reformed natural gas to make your Hydrogen.

This is one of the aspects of the proposed hydrogen economy that make it largely unfeasible. Generating hydrogen from electricity is only 50% efficient. Fuel cells recover that energy at only 50% efficiency for an overall energy tranport efficiency of just 25%. This is very poor compared to batteries with 90%+ overall transport efficiency, and if you can run wires you are even better off. There will almost always be a better use for your electrical power until all hydrocarbon generated power is eliminated than wasting it on hydrogen generation.

Other than reforming natural gas there is no source of hydrogen that makes economic sense other than the potential of Very High Temperature Nuclear reactors coupled with the Sulfer-Iodine cycle which is 20 years away at least.

Hydrogen powered vehicles make great environmental PR points, but don't expect them to ever be deployed in any significant sense because the economics of it just don't add up.
« Last Edit: 08/24/2009 04:55 pm by randomly »

Offline kevin-rf

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randomly, That is an excellent summary on the myths of the Hydrogen Economy, thankyou for taking the time to post it.
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Offline joema

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....if perchlorate from SRM exhaust grounds vehicles using solids the Air Force can rely on Delta IV-Heavy for assured access to space...

There are not significant perchlorates in SRB exhaust. The major components are  water, carbon dioxide, hydrogen chloride, and a metal oxide (typically aluminium oxide): http://en.wikipedia.org/wiki/APCP

The source of perchlorate contamination is being researched. Vast amounts of perchlorates were used in certain agricultural fertilizers.  Only recently has technology existed to detect perchlorate contamination at low levels.

The relationship (if any) between solid rocket fuel and perchlorate contamination is in the manufacturing phase, not the usage phase.

Ammonium perchlorate propellant used in human spaceflight does produce HCl (Hydrogen chloride), but the quantity is insignificant relative to coal-fired power plants and waste incineration.

Solid propellant obviously has some environmental impact, but economic and engineering factors limit the flight rate, hence overall impact. Solid fuel is simply not scalable to extremely high flight rates, but has certain advantages at lower flight rates.

Concerns about environmental impact at high flight rates which are unachievable from an economic and engineering standpoint seem misplaced.

Offline edkyle99

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The source of perchlorate contamination is being researched. Vast amounts of perchlorates were used in certain agricultural fertilizers. 

Exactly.  Before pointing an accusing finger at solid rocket motors, we should contemplate that bag of fertilizer in our shed.

 - Ed Kyle

Offline Antares

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This is very interesting.  I heard this torpedo was in the tube many, many months ago, like before the TO bug bit.  It's interesting to see the outer doors are open.
If I like something on NSF, it's probably because I know it to be accurate.  Every once in a while, it's just something I agree with.  Facts generally receive the former.

Offline MP99


I'm sure you're quite right about current LH2 production not being the greenest process; however, NASA or UAL could buy wind energy contracts for electrolysis of hydrogen--like the New Belgium Brewery in Colorado.

http://www.newbelgium.com/sustainability

That would be counter productive and actually cause more pollution, not less. Electrolysis is only about 50% efficient, reforming methane is 80% efficient. Your wind power electricity will always be better spent displacing electricity generated by hydrocarbon fueled power plants than generating Hydrogen by electrolysis. Generating hydrogen by electrolysis only makes sense when you've eliminated all the hydrocarbon power generation.


Perhaps the carbon from the reforming plant could be sequestered? Lots of (apparently relevant) google hits on methane reforming + carbon sequestration.

cheers, Martin

Offline kevin-rf

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I'm sure you're quite right about current LH2 production not being the greenest process; however, NASA or UAL could buy wind energy contracts for electrolysis of hydrogen--like the New Belgium Brewery in Colorado.

http://www.newbelgium.com/sustainability

That would be counter productive and actually cause more pollution, not less. Electrolysis is only about 50% efficient, reforming methane is 80% efficient. Your wind power electricity will always be better spent displacing electricity generated by hydrocarbon fueled power plants than generating Hydrogen by electrolysis. Generating hydrogen by electrolysis only makes sense when you've eliminated all the hydrocarbon power generation.


Perhaps the carbon from the reforming plant could be sequestered? Lots of (apparently relevant) google hits on methane reforming + carbon sequestration.

cheers, Martin

Why reform, it is an industrial gas that has much comercial value. Worse case convert it to carbon fiber to be used in composites. Waste not want not.
If you're happy and you know it,
It's your med's!

Offline Warren Platts

Good points WRT wind-powered electrolysis. Natural gas as a source for LH2--I'm for it. (I'm biased though, since I'm in the natural gas business.) :D

As for perchlorates released in SRB rocket exhaust, I can't find an actual empirical study. Nor can I find studies on perchlorates within the nearby National wildlife Refuge (MINWAR). However, perchlorates definitely spike after fireworks displays--this has been well documented. Arguably, the fireworks spikes result from fireworks that later fall back to Earth and have some residual perchlorates; arguably, some of the perchlorate is from incomplete ignition during launching processes.

Then there is all the HCl that is produced. No one denies that. I hear that's what most of the white smoke that is produced consists of. HCl is a health hazard. Not the most daunting one ever, yet nevertheless it is rightly regulated. Limited googling can't find a study on the effects of potential acid rain within MINWAR either. In sum, the arguments for the environmental benignness of Shuttle seem to be mainly based on theory, rather than actual empirical effect. That's just how it looks to a former wildlife biologist.

There are alternative solid fuels out there, e.g., there is a solid propellant based on ammonium nitrate and magnesium that potentially delivers more Isp than Al/perchlorate rockets. It's easier to manufacture, easier to handle--you can touch it with your bare hands--and there's no HCl or perchlorate in the exhaust.

http://www.wickmanspacecraft.com/psan-i.html

So why isn't NASA checking out this promising new technology that's potententially cheaper and more powerful? Here we are at a major crossroads in the choice of architecture for HSF. It appears to me that the environmental design dimension is not on anyone's radar screen. I think that should change.
« Last Edit: 08/25/2009 03:34 pm by Warren Platts »
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Offline robertross

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So why isn't NASA checking out this promising new technology that's potententially cheaper and more powerful? Here we are at a major crossroads in the choice of architecture for HSF. It appears to me that the environmental design dimension is not on anyone's radar screen. I think that should change.

Easy, ask ATK.

I'm sure they'll come up with a good many reasons, most notable being continuity of their production capabilties for not just the SRB, but the many other rocket motors they manufacture. IF DOD & NASA demanded change, I'm sure they would do so and simply pass on the costs to the customer.

Offline madscientist197

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The combustion of a firework is going to be nowhere near as complete as in a high pressure rocket engine, but it's not an unreasonable comparison.

With respect to the HCl, there are claims of regular fish die-offs in the KSC area due to water polution (I have no idea of the authenticity). It is also important to remember that pumping huge amounts of Chlorine high into the stratosphere is going to damage the ozone layer. Remember that it was Chlorine being released from CFC degradation that resulted in CFCs being banned. While I don't honestly think human spaceflight has a particularly big impact on this, it is still an issue that could result in substantially negative publicity and later costs.
John

Offline joema

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With respect to the HCl...While I don't honestly think human spaceflight has a particularly big impact on this, it is still an issue that could result in substantially negative publicity and later costs...

Human spaceflight's impact is miniscule at current flight rates.

Global HCl emissions from coal-fired power plants is roughly 6,000,000 metric tons per year. Waste incineration adds another approx. 2,000,000 metric tons per year.

By contrast each shuttle launch releases about 240 tons of HCl. At a flight rate of four times per year, this would be 960 tons per year, or 0.00012 of annual HCl emissions.

At vastly expanded flight rates, it would have more impact, but SRBs aren't scalable to that flight rate based on economic and engineering factors. You can't reach the point where HCl emissions from SRBs would be a significant problem, because nobody could afford to fly that many.

At hypothetical future very high flight rates, economic and engineering factors would mandate a totally different booster design, e.g, H2/O2 fully-reusable SSTO.  As a side benefit, that will automatically solve the environmental emission problems.

Part of engineering is being pragmatic and setting priorities. Otherwise you end up squandering effort on areas with little payback, which can prevent reaching your goal. E.g, if you want to limit HCl emissions, you stack rank the top emitters and focus on that. Human spaceflight is not in the top 1,000.

Offline Warren Platts

Politically, this could sink Ares for good.
"When once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been, and there you will always long to return."--Leonardo Da Vinci

Offline madscientist197

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With respect to the HCl...While I don't honestly think human spaceflight has a particularly big impact on this, it is still an issue that could result in substantially negative publicity and later costs...

Human spaceflight's impact is miniscule at current flight rates.

Global HCl emissions from coal-fired power plants is roughly 6,000,000 metric tons per year. Waste incineration adds another approx. 2,000,000 metric tons per year.

Yes, that's true but coal fired power plants don't release HCl directly into the ozone rich part of the atmosphere -- which does have a substantial multiplicative effect. The shuttle SRBs are responsible for around a tenth of a percent of the total amount of stratospheric Chlorine. That is not insignificant. And if some green group starts screaming 'NASA is destroying the atmosphere', I'm not sure how much the truth matters (sadly, IMHO).
John

Offline joema

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...shuttle SRBs are responsible for around a tenth of a percent of the total amount of stratospheric Chlorine. That is not insignificant....

From http://www.faqs.org/faqs/ozone-depletion/stratcl/ :

Subject: 4.5) Space shuttles put a lot of chlorine into the stratosphere.

Simply false. In the early 1970's, when very little was known about
the role of chlorine radicals in ozone depletion, it was suggested
that HCl from solid rocket motors might have a significant effect
upon the ozone layer -  if not globally, perhaps in the immediate
vicinity of the launch. It was immediately shown that the effect
was negligible, and this has been repeatedly demonstrated since.
Each shuttle launch produces about 200 metric tons of chlorine as
HCl, of which about one-third, or 68 tons, is injected into the
stratosphere. Its residence time there is about three years. A
full year's US schedule of shuttle and solid rocket launches injects
725 tons of chlorine into the stratosphere. The European Space Agency's
Ariane rocket makes a similar contribution, with 57 tons of HCl deposited
in the stratosphere for each launch.  These inputs are negligible
compared to chlorine emissions in the form of CFC's and related
compounds (~ 1.0 million tons/yr in the 1980's, of which ~0.3 Mt reach
the stratosphere each year). It is also small in comparison to natural
sources of stratospheric chlorine, which amount to about 75,000 tons
per year. [Prather et al.] [WMO 1991] [Ko et al.]

Offline madscientist197

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Subject: 4.5) Space shuttles put a lot of chlorine into the stratosphere.
Simply false.

Simply math:

725t * 100% / (0.3 * 1,000,000t + 75,000t) = 0.193%

Which overestimates the amount of Chlorine put into the atmosphere due to including other launches. So 0.1% is probably about correct.

Your point? Are we having an argument over whether 0.1% is significant or not? If people are worried about the ozone hole, they can still blame STS and NASA still gets the negative publicity. From your figures NASA might as well phase CFC based spray on insulation back in -- but do you think that would go down well with a post-Montreal protocol public? If any organisation is dependent on goodwill, NASA is.

EDIT: Is that article actually measuring Chlorine mass or the mass of the Chlorine containing CFCs? That has a rather large effect because CFCs can take awhile to break down and only part of the mass is chlorine. If it is CFC mass, then the HCl has a much more significant effect.

Human spaceflight is not in the top 1,000.

Might want to revise this... at least as far as the Chlorine that matters goes.
« Last Edit: 08/26/2009 01:26 pm by madscientist197 »
John

Offline tamarack

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Politically, this could sink Ares for good.

And in the process, ban all perchlorate used by NASA and DoD. This would cause a tremendous amount of money, far eclipsing any savings we'd get by discontinuing AresI. If you don't like AresI, give a good reason instead of spouting political BS that would cause immense collateral damage.

[Sarcasm] While you're at it trying to save trees, why not point out every launch through the ionosphere harms it. With any luck, you could put an end to all space programs for decades. Maybe you'd like us to ban plastics, fuel, medicine and other oil-derived products because of the harm done during their production. With any luck, you could send us back to the Bronze Age. [/Sarcasm]

Offline MP99


I'm sure you're quite right about current LH2 production not being the greenest process; however, NASA or UAL could buy wind energy contracts for electrolysis of hydrogen--like the New Belgium Brewery in Colorado.

http://www.newbelgium.com/sustainability

That would be counter productive and actually cause more pollution, not less. Electrolysis is only about 50% efficient, reforming methane is 80% efficient. Your wind power electricity will always be better spent displacing electricity generated by hydrocarbon fueled power plants than generating Hydrogen by electrolysis. Generating hydrogen by electrolysis only makes sense when you've eliminated all the hydrocarbon power generation.


Perhaps the carbon from the reforming plant could be sequestered? Lots of (apparently relevant) google hits on methane reforming + carbon sequestration.

cheers, Martin

Why reform, it is an industrial gas that has much comercial value. Worse case convert it to carbon fiber to be used in composites. Waste not want not.


I'm not sure I understand the question. The reforming is done to extract the H2 from the gas, resulting in waste CO or CO2. The issue is whether that gas is released to the atmosphere.

However, if the question is "why sequester", then conversion to carbon fibre sounds like it might be energy intensive? Would CO/CO2 normally be a feedstock for carbon fibre production?

cheers, Martin

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