AuthorTopic: Renewable Energy Survey  (Read 21809 times)

Offline Palloy

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Re: Renewable Energy Survey
« Reply #105 on: June 13, 2016, 05:23:21 PM »
Quote
AG: Energy RETURN EQUALS work (as defined by physics) MINUS WASTE HEAT)

Wrong again.   :emthdown:
Waste Heat is what it says it is - waste, it doesn't do work by definition.
Instead of wasting electrons on this load of crap, you should learn some Physics first.
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Renewable Energy Survey: Cassandra's Legacy Parallel Thread
« Reply #106 on: June 13, 2016, 08:00:07 PM »
Ugo published his take on the results of the Renewable Energy Survey on Cassandra's Legacy.

My response to his article is below, he hasn't approved it yet.

RE

This is a REALLY difficult problem on so many levels that giving one "answer" to it is impossible.  As Gail indicated a few times in the discussion, the leading problem here is the Financial System and it's continued operation.  Obviously, with a failed financial system, making the necessary investments in Renewable Energy will be difficult if not impossible.

The difference in attitudes between the population Ugo sampled and the population I sampled are extremely interesting.  However, our sample wasn't strictly Diners, it came from numerous websites, including Cassandra's Legacy.  The really interesting sample we cannot get is that of the general population, say the readers of USA Today.  What does the average person think of this, and can Renewables be sold to these people, given it would be an extremely costly thing to do?

We also wanted to make some discrimination here between the high finance systems of large PV farms and Windfarms and the smaller more self contained systems that are not necessarily Grid Connected.  What I would like to see moving forward here is a financial and energy analysis of how large scale compares to small scale.

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Offline agelbert

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Re: Renewable Energy Survey
« Reply #107 on: June 13, 2016, 08:14:08 PM »
Quote
AG: Energy RETURN EQUALS work (as defined by physics) MINUS WASTE HEAT)

Wrong again.   :emthdown:
Waste Heat is what it says it is - waste, it doesn't do work by definition.


Instead of wasting electrons on this load of crap, you should learn some Physics first.

Palloy reaches for some of these, AGAIN:

I apologize for the confusing statement about waste heat. I was trying to say ENERGY RETURN should
EXCLUDE WASTE HEAT because WASTE HEAT doesn't contribute to Energy Return, but it came out a bit mangled. I suppose you will want me to study English too. ::)

So, let me fix the phrase so you can understand it: Energy RETURN MINUS WASTE HEAT EQUALS work (as defined by physics).

The old "dismissal" type fallacious argument technique, complete with aspersions to the opponent's level of intelligence and education is really tired, but thanks for the great laugh, Palloy.   

Here's to waste heat electrons  :icon_mrgreen:  :icon_sunny:

And as to your laughable claim to know what you are talking about, you just exposed yourself as being an abysmally, and embarrassingly, ignorant example of one BESOTTED (your adjective for me is far more applicable to you  ;D) with fossil fuel love. 

What you just said about WASTE HEAT is RIDICULOUS!

WHY? Because, although it is true that WORK excludes WASTE HEAT because WASTE HEAT DOESN'T DO WORK, ENERGY RETURN, as calculated by the fossil fuel industry cherry pickers, ASSUMES that WASTE HEAT CONTRIBUTES to the "HIGH" ENERGY DENSITY. You are trying to talk your way around that.  :emthdown:

It's just MORE science challenged BULLSHIT from Palloy, the biosphere math challenged mathematician. 

How stupid can you be to claim WASTE HEAT isn't figured in the ENERGY in ALL the enthalpy of formation tables known to thermodynamics?

ALL HEAT is ENERGY. THAT is where the fossil fuel ERoEI MATH gets it's BASIC DATA. 

ONLY when it cannot do MECHANICAL WORK is it CLASSIFIED as "WASTE", you ignorant, double talking fossil fueler.
 
When you figure out how Hess's Law works, THEN you can make some intelligent remarks about physics in general and thermodynamics in particular, instead of displaying your abysmal ignorance of science side by side with your brain dead bias for fossil fuels.

I have met some stubborn, hide bound, recalcitrant sophists in my day, but you take the prize for STRAW GRASPING DENIAL of reality.

Have a nice day.

THE FACTS Palloy wants to pretend do not exist:
If we are going to talk about how much MONEY to invest in an energy source, based on how much MONEY it will cost to DO THAT, and how much MONEY we can get in a RETURN on our INVESTMENT, it is customary (if you aren't Gail Tverberg or PALLOY doing the bidding of the fossil fuel industry) to SUBTRACT all the COSTS of said energy source.
 




« Last Edit: June 13, 2016, 09:01:23 PM by agelbert »
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Offline Palloy

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Re: Renewable Energy Survey
« Reply #108 on: June 13, 2016, 09:30:32 PM »
Quote
AG: What you just said about WASTE HEAT is RIDICULOUS! WHY, because, although it is true that WORK excludes WASTE HEAT because WASTE HEAT DOESN'T DO WORK, ENERGY RETURN, as calculated by the fossil fuel industry cherry pickers, ASSUMES that WASTE HEAT CONTRIBUTES the ENERGY DENSITY. You are trying to talk your way around that.

I'll try and decipher what you mean by that garbled nonsense.  Then you might learn something.

Energy Density is how much Energy a fuel contains per unit of Volume or Mass.  In the case of FFs, you extract that Energy by burning the fuel, producing Heat Energy.  After that, what you do with the energy is up to you - no doubt some of it will be wasted, and some will do work.  But Energy Density is a feature that the fuel has BEFORE it is burned, when there is no waste. 

The percentage of Energy that ends up doing useful Work via an engine, is called the engine's Efficiency.  An engine doesn't have to be a FF-to-mechanical engine - a solar panel is a sunlight-to-electricity engine.

The problem of both FFs and solar panels (and every other kind of engine) is that the engine's manufacture itself takes Energy.  So in an increasingly energy-constrained world, building NEW engines is not a solution, even if they are more efficient.  This is NOT an argument in favour of FFs.

Got it now?
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Re: Renewable Energy Survey
« Reply #109 on: June 13, 2016, 11:12:03 PM »
\

The problem of both FFs and solar panels (and every other kind of engine) is that the engine's manufacture itself takes Energy.  So in an increasingly energy-constrained world, building NEW engines is not a solution, even if they are more efficient.

That's not entirely true.

If you could make solar panels just utilizing the energy from previously produced solar panels and still have a surplus of energy to use for other purposes, then building more solar engines IS a solution.  It becomes a self-replicating system.  It is in fact then only limited by the amount of material you have available to make the solar panels, which is quite large for the straightforward silicon based ones.  You could keep churning them out until they covered the entire Sahara Desert and Gobi Desert and all of Death Valley.  You could pave every road with them and roof every house.  They could line the sides of a rail track along the right of way and power your trains.

However, as of yet nobody has demonstrated making new solar panels just using energy from already produced solar panels.

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Offline agelbert

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Re: Renewable Energy Survey
« Reply #110 on: June 15, 2016, 01:22:52 PM »
Quote
AG: What you just said about WASTE HEAT is RIDICULOUS! WHY, because, although it is true that WORK excludes WASTE HEAT because WASTE HEAT DOESN'T DO WORK, ENERGY RETURN, as calculated by the fossil fuel industry cherry pickers, ASSUMES that WASTE HEAT CONTRIBUTES the ENERGY DENSITY. You are trying to talk your way around that.

I'll try and decipher what you mean by that garbled nonsense.  Then you might learn something.

Energy Density is how much Energy a fuel contains per unit of Volume or Mass.  In the case of FFs, you extract that Energy by burning the fuel, producing Heat Energy.  After that, what you do with the energy is up to you - no doubt some of it will be wasted, and some will do work.  But Energy Density is a feature that the fuel has BEFORE it is burned, when there is no waste. 

The percentage of Energy that ends up doing useful Work via an engine, is called the engine's Efficiency.  An engine doesn't have to be a FF-to-mechanical engine - a solar panel is a sunlight-to-electricity engine.

The problem of both FFs and solar panels (and every other kind of engine) is that the engine's manufacture itself takes Energy.  So in an increasingly energy-constrained world, building NEW engines is not a solution, even if they are more efficient.  This is NOT an argument in favour of FFs.

Got it now?

That you are as arrogantly insulting as ever is what I get from your post. You are the one that doesn't get the fossil fuel favoring "high" energy density con. I'll try again for the benefit of readers here.

Quote

Palloy:  This is NOT an argument in favour of FFs.
:emthdown:

Yes it is. You cannot arrive at efficiency assumptions without FIRST starting out with an energy density figure. THOSE energy density calculations FAVOR fossil fuels because the false equivalence between gross high energy density and  "high" FF ERoEI is peddled by the fossil fuel industry.

Although the subject of engine design is appropriate BECAUSE our entire civilization routinely replaces most engines manufactured in a 20 year cycle, there are more significant factors at play here. Your claim that the high thermal processes required by industry requires fossil fuels ignores the fact that electric arc furnaces can be powered quite well by electricity, at least the last time I checked. There is nothing in industry that beats electric arc furnaces at rapid heat increase and easily controllable temperatures for smelting metal alloys. PV and wind can supply that electricity quite well. No combustion is required to make PV and wind infrastructure, even though we stupidly still do a lot of that, to the joy of the fossil fuel industry. But that is a political/corporate issue, not one that has beans to do with thermodynamics or energy density.

I am referring to the fact that enthalpy values are based on scientific measurements of EXTERNAL combustion, not INTERNAL combustion.         

Energy density is a function of the total amount of energy in a chemical compound that will be released when combusted.  You are the one that does not get Hess's Law flaws.

Hess's Law is used to determine, in energy units per mass units, the thermodynamic release (for exothermic reactions) or absorption (for endothermic reactions) of energy in the form of heat energy (enthalpy).


Hess's Law DOES NOT differentiate between WASTE HEAT ENERGY and USEFUL HEAT ENERGY. The Hess Law ASSUMPTION that the total CHANGE in ENTHALPY (sum=Σ of changes=Δ  in enthalpy=H°f in intermediate reactions= Σ ΔH°f )  can be used to arrive at an enthalpy value ASSUMES that WASTE HEAT  is USEFUL HEAT.

Yes, HEAT IS a form of energy. But Hess's Law LOWBALLS the enthalpy of LOW WASTE HEAT biofuels like ETHANOL because they have LESS waste heat than hydrocarbons.

In a sane world of thermodynamics calculations on chemical compound combustion, the WASTE HEAT should be SUBTRACTED from the figure arrived at using Hess's Law.

BUT, it is NOT subtracted. Therefore, oxidized (i.e. combusted) compounds with LOW waste heat like ETHANOL appear ERRONEOUSLY to have LOWER enthalpy values than compounds with HIGH waste heat (i.e. ALL HYDROCARBONS - i.e. fossil fuels). This Hess Law ERROR is reflected in the published tables in chemistry texts for the Enthalpy of Combustion of chemical reactants AND makes its way to ERoEI values.

The following table is factual, though the reasonable facsimile of Agelbert  ;D saying "NO WAY" is also accurate. 


If we used fossil fuels exclusively to boil water, the above table is accurate BECAUSE the "work" of boiling water (or running a steam engine) makes them the winners.

But if you combust the above compounds in the above table in an INTERNAL combustion engine, ETHANOL is the WINNER. You cannot understand that, for some reason.

As to the energy density of PV and Wind, they are far and away above that of fossil fuels and even ethanol, regardless of what you wish to believe.

In closing, I recommend your "erudite mathematical highness" to be sure and tell Richard Heinberg he does not "get it" and needs to go study physics.

How We Get to a 100% Renewable Energy Future

Richard Heinberg | June 15, 2016 12:20 pm

I spent the last year working with co-author David Fridley and Post Carbon Institute staff on a just-published book, Our Renewable Future. The process was a pleasure: everyone involved (including the twenty or so experts we interviewed or consulted) was delightful to work with and I personally learned an enormous amount along the way. But we also encountered a prickly challenge in striking a tone that would inform but not alienate the book’s potential audience.

As just about everyone knows, there are gaping chasms separating the worldviews of fossil fuel promoters, nuclear power advocates and renewable energy supporters. But crucially, even among those who disdain fossils and nukes, there is a seemingly unbridgeable gulf between those who say that solar and wind power have unstoppable momentum and will eventually bring with them lower energy prices and millions of jobs and those who say these intermittent energy sources are inherently incapable of sustaining modern industrial societies and can make headway only with massive government subsidies.

We didn’t set out to support or undermine either of the latter two messages. Instead, we wanted to see for ourselves what renewable energy sources are capable of doing and how the transition toward them is going. We did start with two assumptions of our own (based on prior research and analysis), about which we are perfectly frank: one way or another fossil fuels are on their way out and nuclear power is not a realistic substitute. That leaves renewable solar and wind, for better or worse, as society’s primary future energy sources.

In our work on this project, we used only the best publicly available data and we explored as much of the relevant peer-reviewed literature as we could identify. But that required sorting and evaluation: Which data are important? And which studies are more credible and useful? Some researchers claim that solar PV electricity has an energy return on the energy invested in producing it (EROEI) of about 20:1, roughly on par with electricity from some fossil sources, while others peg that return figure at less than 3:1.

This wide divergence in results of course has enormous implications for the ultimate economic viability of solar technology. Some studies say a full transition to renewable energy will be cheap and easy, while others say it will be extremely difficult or practically impossible. We tried to get at the assumptions that give rise to these competing claims, assertions and findings, and that lead either to renewables euphoria or gloom. We wanted to judge for ourselves whether those assumptions are realistic.

That’s not the same as simply seeking a middle ground between optimism and pessimism. Renewable energy is a complicated subject and a fact-based, robust assessment of it should be honest and informative; its aim should be to start new and deeper conversations, not merely to shout down either criticism or boosterism.

Unfortunately, the debate is already quite polarized and politicized. As a result, realism and nuance may not have much of a constituency.

This is especially the case because our ultimate conclusion was that, while renewable energy can indeed power industrial societies, there is probably no credible future scenario in which humanity will maintain current levels of energy use (on either a per capita or total basis). Therefore current levels of resource extraction, industrial production and consumption are unlikely to be sustained—much less can they perpetually grow. Further, getting to an optimal all-renewable energy future will require hard work, investment, adaptation and innovation on a nearly unprecedented scale. We will be changing more than our energy sources; we’ll be transforming both the ways we use energy and the amounts we use. Our ultimate success will depend on our ability to dramatically reduce energy demand in industrialized nations, shorten supply chains, electrify as much usage as possible and adapt to economic stasis at a lower overall level of energy and materials throughput. Absent widespread informed popular support, the political roadblocks
to such a project  [/color]will be overwhelming.

That’s not what most people want to hear. And therefore, frankly, we need some help getting this analysis out to the sorts of people who might benefit from it. Post Carbon Institute’s communications and media outreach capabilities are limited. Meanwhile the need for the energy transition is urgent and the longer it is delayed, the less desirable the outcome will be. It is no exaggeration to say that the transition from climate-damaging and depleting fossil fuels to renewable energy sources is the central cause of our times. And it will demand action from each and every one of us.

You can help by visiting the Our Renewable Future website, familiarizing yourself with the issue, sharing your thoughts and spreading the word with friends, family, colleagues and allies.

http://ecowatch.com/2016/06/15/our-renewable-future-heinberg/

Rob Brown: Great column. To have a future, humanity has to embrace renewable energy. We may never get to 100% renewables but, unless targets are set, progress will not be made. A number of countries have reached the 50%+ barrier on renewable power. These countries have been steadily reducing CO2 emissions and other types of pollution for decades. Sweden is a good example.

https://sweden.se/society/ener...
 
agelbert > Rob Brown

"To have a future, humanity has to embrace renewable energy. "

Exactly right. 

And Amory Lovins has shown how to do that. The Post Carbon Institute's insistence that a 100% Renewable Energy powered civilization, in order to be sustainable, requires a lower energy use is true. BUT, their attempt to equate a lower total energy use to an obligatory lower standard of living is flawed because, as Amory Lovins painstakingly proves in his peer reviewed work titled Reinventing Fire, Renewable Energy plus energy use efficiency improvements can shave over 80% of current energy demand off of our civilization without any lowering of our standard of living.

Richard Heinberg portrays this 'type of energy use' argument as two sides of a polarized, and irrational, debate. It's not. Those defending unsustainable dirty energy have conclusively been proven to be, not just wrong, but an existential threat to our biosphere.

Richard Heinberg fails to point out the fact that political roadblocks to 100% Renewable energy have zero basis in science, both from an energy density happy talk for fossil fuels point of view, and climate cause and effect. It is those vested interests in a dirty energy status quo who don't want to hear the facts, not those advocating a 100% Renewable Erengy transition.

This is not, as Heinberg claims, about what "people want to hear" about the transition to Renewable Energy. This is about, as he points out without sufficient emphasis, the FACT that any dirty energy scenario is not optional to a 100% Renewable energy scenario, PERIOD.










« Last Edit: June 15, 2016, 01:29:42 PM by agelbert »
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Offline Palloy

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Re: Renewable Energy Survey
« Reply #111 on: June 15, 2016, 04:14:17 PM »
Quote
AG: Hess's Law DOES NOT differentiate between WASTE HEAT ENERGY and USEFUL HEAT ENERGY.

True.   :emthup: :emthup: :emthup:

As I said before:
Quote
Palloy: Energy Density is how much Energy a fuel contains per unit of Volume or Mass.  In the case of FFs, you extract that Energy by burning the fuel, producing Heat Energy.  After that, what you do with the energy is up to you - no doubt some of it will be wasted, and some will do work.  But Energy Density is a feature that the fuel has BEFORE it is burned, when there is no waste.

There is definitely no inefficiency in Hess's Law - Thermodynamics wouldn't work if there was.
CH4 + 2O2 => CO2 + 2H2O (steam) + energy
∆H: -74.81 + 0 = -393.5 + 2*( -241.8 ) + X
X = 393.5 + 2*241.8 - 74.81
X = 802.29 kJ/mol

A mol of Methane has a Mass of (12 + 4*1) = 16 grams
So Methane has an Energy Density of 50.143 kJ/gram
This differs from your quoted figure of 55.496 kJ/gram because that assumes burning Methane produces liquid water, not Steam (they have different ∆H: -241.8 and -285.8 ).  If liquid water remained in the furnace, it would eventually flood the reaction, so the furnace output (not the boiler) MUST be steam.  The difference between your figure and the correct one is the energy it takes to turn the liquid H2O to steam.
Isn't Hess's Law neat?

Quote
AG: But Hess's Law LOWBALLS the enthalpy of LOW WASTE HEAT biofuels like ETHANOL because they have LESS waste heat than hydrocarbons.

In a sane world of thermodynamics calculations on chemical compound combustion, the WASTE HEAT should be SUBTRACTED from the figure arrived at using Hess's Law.

No, that is wrong.   :emthdown: :emthdown: :emthdown:
Hess's Law describes the chemical reaction - it doesn't say anything about what you are going to do with the heat after you've got it.

OK, so now you have your heat, 50.143 kJ/gram of Methane, what are you going to do with it? - boil water to produce steam.  Try as you might, that process is going to be less than 100% efficient because some heat will always be lost through the walls of the boiler to the atmosphere.  That Energy is Waste Heat, but it is NOT the fault of Hess's Law, it is the fault of the boiler's efficiency (an engine).

Then you are going to take that steam and run it through a steam turbine (maybe several in cascade).  That is another engine and it will have an efficiency of less than 100%.

Then you are going to take the Energy of the spinning shaft and couple it to an electrical generator, another engine, again with an efficiency of less than 100%.

So the complete process is:
(Mass of Methane * Energy Density) = Fuel Energy
and Fuel Energy * efficiency of boiler * efficiency of turbine * efficiency of generator = Electrical Energy
and (Electrical Energy / Fuel Energy) is the efficiency of the whole system.

Now the amount of Methane entering the system is known, and the amount of electrical energy leaving the system is known, so the efficiency of the whole system is known, and that is what is used in ERoEI calculations.

I can't see what your problem is, except that your 55.496 figure is wrong, it should be 50.143.
Hess's Law and its table of ∆H values is 100% correct and is nothing to do with waste.



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Offline Eddie

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Re: Renewable Energy Survey
« Reply #112 on: June 15, 2016, 06:09:34 PM »
Quote
AG: Hess's Law DOES NOT differentiate between WASTE HEAT ENERGY and USEFUL HEAT ENERGY.

True.   :emthup: :emthup: :emthup:

As I said before:
Quote
Palloy: Energy Density is how much Energy a fuel contains per unit of Volume or Mass.  In the case of FFs, you extract that Energy by burning the fuel, producing Heat Energy.  After that, what you do with the energy is up to you - no doubt some of it will be wasted, and some will do work.  But Energy Density is a feature that the fuel has BEFORE it is burned, when there is no waste.

There is definitely no inefficiency in Hess's Law - Thermodynamics wouldn't work if there was.
CH4 + 2O2 => CO2 + 2H2O (steam) + energy
∆H: -74.81 + 0 = -393.5 + 2*( -241.8 ) + X
X = 393.5 + 2*241.8 - 74.81
X = 802.29 kJ/mol

A mol of Methane has a Mass of (12 + 4*1) = 16 grams
So Methane has an Energy Density of 50.143 kJ/gram
This differs from your quoted figure of 55.496 kJ/gram because that assumes burning Methane produces liquid water, not Steam (they have different ∆H: -241.8 and -285.8 ).  If liquid water remained in the furnace, it would eventually flood the reaction, so the furnace output (not the boiler) MUST be steam.  The difference between your figure and the correct one is the energy it takes to turn the liquid H2O to steam.
Isn't Hess's Law neat?

Quote
AG: But Hess's Law LOWBALLS the enthalpy of LOW WASTE HEAT biofuels like ETHANOL because they have LESS waste heat than hydrocarbons.

In a sane world of thermodynamics calculations on chemical compound combustion, the WASTE HEAT should be SUBTRACTED from the figure arrived at using Hess's Law.

No, that is wrong.   :emthdown: :emthdown: :emthdown:
Hess's Law describes the chemical reaction - it doesn't say anything about what you are going to do with the heat after you've got it.

OK, so now you have your heat, 50.143 kJ/gram of Methane, what are you going to do with it? - boil water to produce steam.  Try as you might, that process is going to be less than 100% efficient because some heat will always be lost through the walls of the boiler to the atmosphere.  That Energy is Waste Heat, but it is NOT the fault of Hess's Law, it is the fault of the boiler's efficiency (an engine).

Then you are going to take that steam and run it through a steam turbine (maybe several in cascade).  That is another engine and it will have an efficiency of less than 100%.

Then you are going to take the Energy of the spinning shaft and couple it to an electrical generator, another engine, again with an efficiency of less than 100%.

So the complete process is:
(Mass of Methane * Energy Density) = Fuel Energy
and Fuel Energy * efficiency of boiler * efficiency of turbine * efficiency of generator = Electrical Energy
and (Electrical Energy / Fuel Energy) is the efficiency of the whole system.

Now the amount of Methane entering the system is known, and the amount of electrical energy leaving the system is known, so the efficiency of the whole system is known, and that is what is used in ERoEI calculations.

I can't see what your problem is, except that your 55.496 figure is wrong, it should be 50.143.
Hess's Law and its table of ∆H values is 100% correct and is nothing to do with waste.
Now I remember why I dropped PChem when I got accepted to dental school.
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Offline Palloy

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Re: Renewable Energy Survey
« Reply #113 on: June 15, 2016, 06:54:50 PM »
But it's BEAUTIFUL, what's more it's absolutely TRUE - always was, always will be, not just here on Earth but everywhere in the Universe, and in parallel Universes if they exist.  You can't do better than that.

What's more, Hess's Law is true for nuclear reactions as well - you have a separate table of ∆Hs for nuclear reactions of course.  In the simplest fusion reaction, Deuterium + Tritium forms Helium and a neutron and Energy:
2H + 3H => (4He + 3.5 MeV) + (1n + 14.1 MeV)
The Kinetic Energy of the Helium cannot escape the magnetic bottle, but the Kinetic Energy of the neutron can.  The 3.5 MeV is not "wasted", it just exists.
(Again, this is NOT a pro-fusion statement, it is just a fact.)

If AG just pursues his perceived fault with it one more step, his misunderstanding of it will be made clear to all.  I'm still not sure what he is thinking is wrong with it, but it definitely not Hess's Law.  This is the point where he will turn to his usual ad hom and "have a nice day", thus not exposing himself.
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Offline agelbert

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Re: Renewable Energy Survey
« Reply #114 on: June 15, 2016, 07:12:53 PM »
Quote
AG: Hess's Law DOES NOT differentiate between WASTE HEAT ENERGY and USEFUL HEAT ENERGY.

True.   :emthup: :emthup: :emthup:

As I said before:
Quote
Palloy: Energy Density is how much Energy a fuel contains per unit of Volume or Mass.  In the case of FFs, you extract that Energy by burning the fuel, producing Heat Energy.  After that, what you do with the energy is up to you - no doubt some of it will be wasted, and some will do work.  But Energy Density is a feature that the fuel has BEFORE it is burned, when there is no waste.

There is definitely no inefficiency in Hess's Law - Thermodynamics wouldn't work if there was.
CH4 + 2O2 => CO2 + 2H2O (steam) + energy
∆H: -74.81 + 0 = -393.5 + 2*( -241.8 ) + X
X = 393.5 + 2*241.8 - 74.81
X = 802.29 kJ/mol

A mol of Methane has a Mass of (12 + 4*1) = 16 grams
So Methane has an Energy Density of 50.143 kJ/gram
This differs from your quoted figure of 55.496 kJ/gram because that assumes burning Methane produces liquid water, not Steam (they have different ∆H: -241.8 and -285.8 ).  If liquid water remained in the furnace, it would eventually flood the reaction, so the furnace output (not the boiler) MUST be steam.  The difference between your figure and the correct one is the energy it takes to turn the liquid H2O to steam.
Isn't Hess's Law neat?

Quote
AG: But Hess's Law LOWBALLS the enthalpy of LOW WASTE HEAT biofuels like ETHANOL because they have LESS waste heat than hydrocarbons.

In a sane world of thermodynamics calculations on chemical compound combustion, the WASTE HEAT should be SUBTRACTED from the figure arrived at using Hess's Law.

No, that is wrong.   :emthdown: :emthdown: :emthdown:
Hess's Law describes the chemical reaction - it doesn't say anything about what you are going to do with the heat after you've got it.

OK, so now you have your heat, 50.143 kJ/gram of Methane, what are you going to do with it? - boil water to produce steam.  Try as you might, that process is going to be less than 100% efficient because some heat will always be lost through the walls of the boiler to the atmosphere.  That Energy is Waste Heat, but it is NOT the fault of Hess's Law, it is the fault of the boiler's efficiency (an engine).

Then you are going to take that steam and run it through a steam turbine (maybe several in cascade).  That is another engine and it will have an efficiency of less than 100%.

Then you are going to take the Energy of the spinning shaft and couple it to an electrical generator, another engine, again with an efficiency of less than 100%.

So the complete process is:
(Mass of Methane * Energy Density) = Fuel Energy
and Fuel Energy * efficiency of boiler * efficiency of turbine * efficiency of generator = Electrical Energy
and (Electrical Energy / Fuel Energy) is the efficiency of the whole system.

Now the amount of Methane entering the system is known, and the amount of electrical energy leaving the system is known, so the efficiency of the whole system is known, and that is what is used in ERoEI calculations.

I can't see what your problem is, except that your 55.496 figure is wrong, it should be 50.143.
Hess's Law and its table of ∆H values is 100% correct and is nothing to do with waste.

Don't you ever get tired of thumbs down? Talk about wasting electrons.

What, exactly, is your problem with the enthalpy of COMBUSTION table I just gave you?


My math comes from published tables. If you have a problem with them, argue with wikipeda, not me.

You can rant and rave about efficiency and there allegedly not being any "inefficiencies" in Hess's Law until the cows come home, but I never said beans about the Hess Law "inefficiencies". I merely stated that the experimental basis for obtaining the energy density values, WHEN THEY CAN OBTAIN THEM (which is simply impossible in some cases), is through measurement of EXTERNAL combustion.

What part of that is too difficult for you to understand?

Every time the subject of the higher ERoEI of ethanol than other hydrocarbons comes up, you have spasms of uncontrollable twitching, for some reason.

You have often gone into great detail about how much of this, that and the other is fossil fuel based to deny the cost effectiveness of SEVERAL Renewable Energy technologies, not just ethanol and other biofuels.

YET, when I point out peer reviewed studies  that prove ethanol beats hydrocarbon fuels, you pull out your down thumb smiley. LOL!

Hess's Law had its place in contributing to the Law of Conservation of Energy, but it is an inappropriate method of basing the start of ERoEI calculations. Even wikipeda agrees that ERoEI calculation should ONLY INCLUDE USEFUL ENERGY. Gross Energy density values include potentially useful and potentially useless energy known as waste. Deny it all you wish, but those are the thermodynamic facts.

Quote
In physics, energy economics, and ecological energetics, energy returned on energy invested (EROEI or ERoEI); or energy return on investment (EROI), is the ratio of the amount of usable energy delivered from a particular energy resource to the amount of energy used to obtain that energy resource.[1][2] It is a distinct measure from energy efficiency as it does not measure the primary energy inputs to the system, only usable energy.

A fuel or energy must have an EROEI ratio of at least 3:1 to be considered viable as a prominent fuel or energy source.[3][4]

The irony of the above quote is that wikipeda then proceeds to post all the Charles Hall fossil fuel and nuclear power happy talk ERoEI charts.

But, to their credit, they do admit that ERoEI calculations have no actual standard rigorous and required inputs. Therefore, ERoEI math is a fossil fuel industry cherry picking paradise.

Quote

Measuring the EROEI of a single physical process is unambiguous, but there is no agreed-upon standard on which activities should be included in measuring the EROEI of an economic process. In addition, the form of energy of the input can be completely different from the output. For example, energy in the form of coal could be used in the production of ethanol. This might have an EROEI of less than one, but could still be desirable due to the benefits of liquid fuels.

How deep should the probing in the supply chain of the tools being used to generate energy go? For example, if steel is being used to drill for oil or construct a nuclear power plant, should the energy input of the steel be taken into account, should the energy input into building the factory being used to construct the steel be taken into account and amortized? Should the energy input of the roads which are used to ferry the goods be taken into account? What about the energy used to cook the steelworker's breakfasts? These are complex questions evading simple answers.[28] A full accounting would require considerations of opportunity costs and comparing total energy expenditures in the presence and absence of this economic activity.

However, when comparing two energy sources a standard practice for the supply chain energy input can be adopted. For example, consider the steel, but don't consider the energy invested in factories deeper than the first level in the supply chain.

Energy return on energy invested does not take into account the factor of time. Energy invested in creating a solar panel may have consumed energy from a high power source like coal, but the return happens very slowly, i.e. over many years. If energy is increasing in relative value this should favour delayed returns. Some believe this means the EROEI measure should be refined further.

Conventional economic analysis has no formal accounting rules for the consideration of waste products that are created in the production of the ultimate output. For example, differing economic and energy values placed on the waste products generated in the production of ethanol makes the calculation of this fuel's true EROEI extremely difficult.

They also break down the three prominent ERoEI calculations, while ignoring the fact that the Charles Hall type SUNY "studies", whether they allegedly  ;) use 'point of use' or 'extended' (FORGET 'societal' - the dirty energy corporations don't DO 'societal') exclude inconvenient costs and include gamed dirty energy subsidies that artificially give fossil fuel and nuclear power "high" ERoEI and lowball Renewable Eenrgy ERoEI.

Quote
There are three prominent expanded EROEI calculations, they are point of use, extended and societal. Point of Use EROEI expands the calculation to include the cost of refining and transporting the fuel during the refining process. Since this expands the bounds of the calculation to include more production process EROEI will decrease.[21]

Extended EROEI includes point of use expansions as well as including the cost of creating the infrastructure needed for transportation of the energy or fuel once refined.[30]

Societal EROI is a sum of all the EROEIs of all the fuels used in a society or nation. A societal EROI has never been calculated and researchers believe it may currently be impossible to know all variables necessary to complete the calculation, but attempted estimates have been made for some nations.


https://en.wikipedia.org/wiki/Energy_returned_on_energy_invested




Things were simpler in the middle of the 19th Century

Hess's Law of the constant summation of heat was obviously a special case of the law of the conservation of energy, which had not yet been formally stated.

But that was then. NOW the polluters use Hess's Law to our detriment and their profit.
 
The REALITY of WASTE HEAT in fuels for internal combustion engines, as well as the ENERGY REQUIRED to ameliorate the POLLUTION those fuels produce when combusted, is excluded. This convenient fiction distorts the value of selected energy sources, resulting in the use of NEGATIVE ERoEI, inefficient and polluting, hydrocarbon fuels to run industrial civilization.

In the REAL world we live in called the biosphere, this is unsustainable because the balance of energy radiated to space versus that received from the sun is altered towards life destroying heat.

It IS a closed system. ALL factors must be computed. Hess's Law is an ABERRATION of the Law of Conservation of Energy because it reduces the concept of "energy" to heat, whether or not it is waste (i.e. USELESS for work and damaging to the biosphere) heat.

TODAY, Hess's Law is used BY THE FOSSIL FUEL INDUSTRY and the CHEMICAL MANUFACTURING INDUSTRY to arbitrarily to exclude inconvenient thermodynamic FACTS in order to downplay the value of Renewable energy based technologies that produce fuels, textiles, plastics, medicines, etc.

Hess's Law, because it is the most basic enthalpy step to obtain energy density values for chemical compounds that are subsequently used in Energy Return on Energy Density (ERoEI) calculations, has helped the Fossil Fuel Industry Perpetuate the following MYTH: It Takes More Energy to ­Produce Ethanol than You Get from It!


Most ethanol research over the past 25 years has been on the topic of energy returned on energy invested (EROEI). Public discussion has been dominated by the American Petroleum Institute’s aggressive distribution of the work of Cornell professor David Pimentel and his numerous, deeply flawed studies. Pimentel stands virtually alone in portraying alcohol as having a negative EROEI—producing less energy than is used in its production.

In fact, it’s oil that has a negative EROEI. Because oil is both the raw material and the energy source for production of gasoline, it comes out to about 20% negative.

That’s just common sense; some of the oil is itself used up in the process of refining and delivering it (from the Persian Gulf, a distance of 11,000 miles in tanker travel).

The most exhaustive study on ethanol’s EROEI, by Isaias de Carvalho Macedo, shows an alcohol energy return of more than eight units of output for every unit of input—and this study accounts for everything right down to smelting the ore to make the steel for tractors.

But perhaps more important than ERoEI is the energy return on fossil fuel input. Using this criterion, the energy returned from alcohol fuel per fossil energy input is much higher. In a system that supplies almost all of its energy from biomass, the ratio of return could be positive by hundreds to one.

Put your DOWN THUMB out there all you want, Palloy. You are wrong about high ERoEI for fossil fuels and low ERoEI for Renewable energy..
« Last Edit: June 15, 2016, 07:49:53 PM by agelbert »
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Offline Palloy

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Re: Renewable Energy Survey
« Reply #115 on: June 15, 2016, 08:33:11 PM »
Quote
AG: What, exactly, is your problem with the enthalpy of COMBUSTION table I just gave you?

I've already explained that - your table assumes the reaction produces liquid water, when in fact it produces steam.  The correct figure for Methane burning is 50.143 kJ/gram.  The problem is you just grab these "facts" without understanding them, or saying where you got them from so the context can be checked.

Just like you say that iron ore can be smelted in electric arc furnaces.  It can of course, but it uses up electrodes, and the electrodes are made of Carbon (in graphite form) so the reaction is still:
Fe3O4 + 2C + Energy => 3Fe + 2CO2
so it is still a CO2-producing reaction.
And producing pure graphite electrodes is an energy-consuming process itself, much more so than just digging up coal.  And building new electric arc furnaces is an energy-consuming process.  And making solar panels to power the electric arc furnace is an energy-consuming process.  And building the solar panel factory is an energy-consuming process.

It is true that there is no formal agreement on what items should be counted in the Energy Budget of a technology or not - the System Boundary problem.  The broadest of system boundaries is obviously best, but is the most difficult to do.  Dumping the CO2 into the atmosphere and forgetting about it (an externality) is a cheat that FF producers do, but solar-powered electric arc furnaces do it too.  The Energy required to undo the Entropy of Mixing is huge, which is why CCS is not a viable solution.
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Re: Renewable Energy Survey
« Reply #116 on: June 15, 2016, 10:18:03 PM »
Quote
AG: What, exactly, is your problem with the enthalpy of COMBUSTION table I just gave you?

I've already explained that - your table assumes the reaction produces liquid water, when in fact it produces steam.  The correct figure for Methane burning is 50.143 kJ/gram.  The problem is you just grab these "facts" without understanding them, or saying where you got them from so the context can be checked.

Just like you say that iron ore can be smelted in electric arc furnaces.  It can of course, but it uses up electrodes, and the electrodes are made of Carbon (in graphite form) so the reaction is still:
Fe3O4 + 2C + Energy => 3Fe + 2CO2
so it is still a CO2-producing reaction.
And producing pure graphite electrodes is an energy-consuming process itself, much more so than just digging up coal.  And building new electric arc furnaces is an energy-consuming process.  And making solar panels to power the electric arc furnace is an energy-consuming process.  And building the solar panel factory is an energy-consuming process.

It is true that there is no formal agreement on what items should be counted in the Energy Budget of a technology or not - the System Boundary problem.  The broadest of system boundaries is obviously best, but is the most difficult to do.  Dumping the CO2 into the atmosphere and forgetting about it (an externality) is a cheat that FF producers do, but solar-powered electric arc furnaces do it too.  The Energy required to undo the Entropy of Mixing is huge, which is why CCS is not a viable solution.

Palloy,
 :emthdown: (sorry, I couldn't resist  :laugh:).

Your post is not worthy of a response because you are engaging in false equivalences.

And since the "standard" for ERoEI is a cherry picked one so as to put the best face on dirty energy, people like you should stop trying to pretend you have a handle on fossil fuel ERoEI versus Renewable Energy.

I am going to ask RE a question about some Hess Law math. I would appreciate it if you waited for his answer before jumping in.
« Last Edit: June 15, 2016, 11:07:18 PM by agelbert »
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Re: Renewable Energy Survey : RE - I need your Columbia Chemist Brain
« Reply #117 on: June 15, 2016, 10:59:10 PM »
RE,
I am having some difficulties with Hess Law calculations. Even though I have performed them repeatedly, I get values that are inaccurate. Therefore, I must be doing something wrong. These calculations deal with the combustion of Hydrogen gas versus the combustion of the hydrocarbon methane. Since the water gas product, in a standard atmosphere, immediately goes to its lower energy state of a liquid, I am using the liquid water enthalpy value in both reactions.

I would appreciate the use of your Columbia University graduated Chemist brain.

This is what I have calculated:

Combusting the common hydrocarbon CH4 gas (methane), we get CO2 plus water. According to the Standard Enthalpy of Formation table, CH4 has a value of -74.81  kJ/mol, CO2 −393.509 kJ/mol and water (liquid) −285.8 kJ/mol.

CH4 + 2(O2) --> CO2 + 2(H2O) The enthalpy of the reactants is subtracted from the enthalpy of the products after accounting for the molar quantities.

The enthalpy of the reactants equals ONE mole of CH4 (ignoring the two moles of O2 gas because, according to Hess Law convention, elements in their standard state have an ARBITRARY VALUE OF ZERO) =  -74.81 kJ

The enthalpy of the products equals One mole of CO2 + TWO moles of H2O = 965.509 kJ.

−393.509 kJ + [2(-285.8 kJ) MINUS [(-74.81 kJ) + (2 (ZERO))] = -890.299 kJ/mole



That was pretty straightforward. :icon_sunny: Now for the combustion of hydrogen gas.

In the following reaction (Thermochemical Properties of selected substances at 298 degrees Kelvin and 1 atmosphere of pressure.), oxygen gas + hydrogen gas = water gas. WATER gas has an enthalpy of formation of −241.818 kJ/mol.

That means that an Exothemic (energy releasing reaction) sent out (a certain amount of) kJ/mole of ENERGY from two gases.

When hydrogen gas combusts with oxygen gas, we get water gas, which quickly turns into to liquid in a standard atmosphere.

2(H2) + O2 --> 2(H2O) The enthalpy of the reactants is subtracted from the enthalpy of the products after accounting for the molar quantities.

The total enthalpy of the reactants is, according to Hess's Law, ZERO.

The enthalpy of the products equals one mole of water (liquid) −285.8 kJ/mole.

-285kj - [(2 times ZERO) + ZERO] =  −285.8 kJ/mole

So, it appears that burning methane releases (890.299 kJ minus 285.8 kJ) 679.709 kJ/mole (about 76%) MORE ENERGY than burning hydrogen. This is inaccurate.  :(  :emthdown:

I did some checking and the more accurate figure for the energy given off by the combustion of one mole of methane is 802 kJ.

THE ENERGY FACTS:

Quote
"Since there are 500 moles of hydrogen gas in a kilogram, this means that burning a kilogram of hydrogen gas releases 500 times as much energy, or 121 MJ (million joules), assuming that the water comes out as a gas, as is usually the case in a combustion process."

"The energy given off by the combustion of one mole of methane turns out to be 802 kJ. The combustion of one kilogram of methane releases 50 MJ. Heavier hydrocarbons generally yield more energy per mole, but approximately the same energy on a per-kilogram basis. Gasoline, a mixture of hexane, heptane, octane, and various other hydrocarbons, yields about 44 MJ per kilogram."

http://physics.weber.edu/schroeder/eee/chapter4.pdf

NASA preferred Hydrogen over methane in their main space shuttle tank for a no bullshit thermodynamic higher energy release per unit mass reason. Yes, I know the fossil fuel industry peddles the "hydrogen is just an energy carrier, not a source" baloney 24/7. Bad mouthing Hydrogen as an energy source is right behind ethanol in the  fossil fuel propaganda fun and games.  :evil4:  But somehow they couldn't convince NASA of that  ;)

 
So, what am I doing wrong that I can't make Hess's Law math come out right for the chemical reaction of hydrogen gas with oxygen gas?

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It ain't OVAH 'till...
« Reply #118 on: June 15, 2016, 11:18:35 PM »
My latest reply to an Extinction Troll over on Ugo's Blog.  :icon_mrgreen:

Not up yet, waiting for approval from Ugo. lol.

RE

Quote from: RE

Don't forget the Zombies & Cannibals!

What about using the lard from Fat People?  It might not be Renewable, but it could be a very good extender!  Great EROEI, no deepwater drilling, no fracking necessary!  Just Liposuction!  A Beverly Hills doctor proved this works during the financial crisis when things were tight.

http://gizmodo.com/5115588/liposuction-doctor-powered-his-cars-with-human-fat

It Ain't OVAH till the last Fat Lady is Liposuctioned!


RE
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Re: Renewable Energy Survey : RE - I need your Columbia Chemist Brain
« Reply #119 on: June 15, 2016, 11:43:48 PM »
RE,
I am having some difficulties with Hess Law calculations. Even though I have performed them repeatedly, I get values that are inaccurate. Therefore, I must be doing something wrong. These calculations deal with the combustion of Hydrogen gas versus the combustion of the hydrocarbon methane. Since the water gas product, in a standard atmosphere, immediately goes to its lower energy state of a liquid, I am using the liquid water enthalpy value in both reactions.

For each bond you break through oxidation, burning H2 gas gives you more energy back than each bond you break in the oxidation of methane.  The bond energy for  H-H is 432 Kj/mole.  The bond energy for the C-H bond in Methane (and all the single bonded alkanes +/- a bit) is 410 Kj/mole.  So for an equal number of moles of H2, you have more energy stored in the Hydrogen than the methane.  However, in the Gas phase, methane is more energy dense than hydrogen, because each molecule has 4 C-H bonds to break, whereas each molecule of H2 only has one bond to break.  So it is almost 4X less efficient a store of energy in the gas phase, even though each individual bond holds greater energy.

This changes if you liquify the gas though.  In this case, an equal amount of liquid hydrogen to liquid methane would contain more energy and release it on oxidation.  For space applications, it is not that energy consumptive to keep these gases liquified, because space itself is so cold.  On earth, this is a much bigger problem.  So NASA for space uses Hydrogen, but on earth generally methane works better with a higher energy density in the gas phase.

Liquid Alkanes (basically pentane and up at normal earth temps) pack a lot more punch than both hydrogen and methane by volume, because they are liquid at normal earth temps.  To keep Hydrogen gas liquified at earth surface temps would itself expend tremendous energy, so it is not a practical alternative on earth.

You can't just apply Hess' Law without dealing with the Phase Change problems here between Liquids and Gases.

RE

Note: This assumes both Hydrogen Gas and Methane Gas operate according to the combined gas laws PV=nRT.  Both gases do operate very closely to that law except at very low temps or very high pressures.
« Last Edit: June 15, 2016, 11:56:38 PM by RE »
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