Thread: Should We Burn Wood or Gas

Originally Posted by Cruzi

Worked with the smurfs for some time, with Obsolete Drilling Equipment, went OS to few countries ended up in Sakhalin doing ERD work, did that till my head exploded, now a wood eating hermit

You escaped from Smurfonia too?? Good to hear.

Originally Posted by BRADFORD

All the firewood used in our area is from trees that have fallen naturally, so if it is not used for firewood than it decays naturally (takes many years in some cases)
This means we are not harvesting trees for firewood but using what is really a waste product.
As far as I know most firewood used in WA comes from this source.
So calculating firewood from the forest harvest would not be quite right, because a very large percentage would be from waste.
BTW at our place we use about 5 tonnes per year, which is less than 50% (much less as we also supply our daughter's household as well) of the trees and branches that fall on our 30 acre property.

thanks for that number

so based on your experience, 30 acres (~12 ha) of mature trees generates about 10 tonnes of deadfall per year, which is enough to heat 4 or 5 houses.

1 million houses would therefore need about 2.4 Million ha of mature forest

a tree that is getting larger is storing carbon as it grows , once it gets to a mature size it looses as many branches as it grows , so it no longer stores any more carbon ,

when the branch hits the ground microbes feed off it and emit methane , and carbon dioxide , the methane has about 10 years in the atmosphere before UV light smashes it into carbon dioxide , methane is 100x worse as a green house gas than carbon dioxide

burning only dropped branches is bad because of the nitrogen in the branch is removed from the eco system ,most of the nitrogen comes from the air , but takes a long time to build up in the soils , since most of the air (60%) is nitrogen , the rain holds a lot , thats why watered grass (town water) is never as green as after 2 weeks of rain

best policy would be to remove the largest fully grown trees in the forest , the smaller trees will race to fill in the opening , storing carbon quicker than leaving the fully grown tree standing , but mature trees have hollows needed for animals homes ,

most people dont know how much carbon dioxide comes from oil , if you burn 100kg of petrol in a car , it will make 1.6 ton of carbon dioxide

In the area that I live the only trees that drop limbs of any significance are white gums and they would be lucky to be 10% of all the species and as fire wood they are useless because it does not give off very much heat and just smolders and smokes so we don't use it.

The eucalyptus trees that grow here eventually die of natural causes and these are the ones we cut down for firewood after they have been dead for at least 10 to 15 years and this isn't long enough to develop many hollows for wildlife.

The main species we use for firewood here are Yellow Box, Red Gum, Stringy Bark and New England Peppermint.

Originally Posted by SawDustSniffer

most people dont know how much carbon dioxide comes from oil , if you burn 100kg of petrol in a car , it will make 1.6 ton of carbon dioxide

???
can you please explain

Originally Posted by ian

???
can you please explain

100lt of petrol is mixed with 1500lt of air ,

hydro carbons are made up of hydrogen atoms bonded to a carbon chain , each carbon to carbon link uses 2 bonds , each hydrogen to carbon link uses 1 bond , carbon must bond with 4 links , oxygen needs 2 bonds per atom

...H H H H H H H H
H C C C C C C C C H
...H H H H H H H H

hydrogen is number 1 on the periodic table , with a "weight" of 1
carbon is number 6 on the table , with a "weight" of 12
oxygen is number 8 on the table with a "weight" of 15.99

during combustion the hydrogen is burnt and produces water vapour H-0-H ( H2O)
every carbon atom bonds with 2 oxygen atoms O-H-O , carbon DI oxide

swapping the light weight hydrogen (2x for long chain fuel, 4x for methane ) for the heavy oxygen , makes the carbon dioxide weigh +16x the weight of the original fuel (new tax $30 per ton = $30 per tank )


burning Methane ( LNG ) is a lot better than burning long chain fuel
methane has 4 hydrogen atom for every 1 carbon

...H
H-C-H
...H
so methane( LNG ) can burn 4 hydrogen atoms to make energy , producing only 1 carbon dioxide 4:1


propane( LPG ) has 3 a carbon chain with 8 hydrogen's

...H H H
H-C-C- C-H
...H H H
so when you burn propane the 8 hydrogen's produce the energy and 3 carbon dioxides are made

the chains on petrol are too long to type out , and diesel is even longer so the 2 extra hydrogen's on the ends of the chain dont matter much

you burn 2 hydrogen's for each carbon dioxide , almost 2x as much carbon dioxide than methane (LNG)

hope that is understandable , ken

,

swapping the light weight hydrogen (2x for long chain fuel, 4x for methane ) for the heavy oxygen , makes the carbon dioxide weigh +16x the weight of the original fuel (new tax $30 per ton = $30 per tank )

Er, hang on, it would be a carbon tax, not a carbon dioxide tax and at $12-$15 per tonne that would add say 50 cents to a tank of petrol. Anyway I am rigging up a steam boiler on my old jalopy and I'm gonna run it on firewood, all carbon neutral.

problems with hydrogen fuel

using hydrogen as fuel would be the best but there re a few problems

1) liquefying hydrogen use's more energy than the finished product gives as energy ,

2) liquefied hydrogen is very hard to store , the hydrogen atoms under pressure will travel straight through the metal of a storage bottle and over time the bottle will empty unless the bottle is kept extremely cold , ( more energy )

hydrogen can be used if wind and solar generation are expanded to run peak load electricity , at off peak the excess electricity can be used to brake water apart , and cool and compress the hydrogen , the oxygen would be released into the atmosphere

using oil products to get hydrogen uses less energy than using water to get the hydrogen ,but we run into a huge problem if its allowed to happen

water is a very stable compound , in nature not much will brake it down , lightning will , so water is very long lived unlike carbon dioxide where green plants will brake it down ,
so if hydrogen is allowed to be made from oil , it will use oxygen in the atmosphere to produce water , as it do's today burning oil , reducing the oxygen levels in the atmosphere , a tiny problem today but over time it will be a problem

so hydrogen has to be split from water , the oxygen produced is released into the air , and recombined with the hydrogen in combustion

another idea is to use electric motors in cars , and instead of replacing the battery's at the servo , replace the acid , drain out the used acid , solar panels on the servo recharge the acids , and the fresh acid is used to refill the battery ,
i believe a test program has been set up on an island in "Bass Straight" ???King island ?? by Melbourne university , using a system with 2 acids , one + one - , when the acids are introduced to the battery ( kept separate by a membrane ) electricity can be used , the used acid is drained into 2 "spent" acid tanks allowing more fresh acid into the battery

SDS, thanks for your sensible, succinct and unemotional explanations.

Originally Posted by AlexS

SDS, thanks for your sensible, succinct and unemotional explanations.

Yep well, I've long since stopped being the chemistry nazi so I'll keep my mouth shut save one thing. 100kg of petrol burnt in a modern IC engine produces around 230kg of carbon dioxide, give or take, not 1600kg. The mistake is that combustion in an IC engine is not complete.

Originally Posted by SawDustSniffer

1) liquefying hydrogen use's more energy than the finished product gives as energy

This is not a problem if waste energy is used. There are new designs of nuclear reactors that will safely make hydrogen directly from the waste heat involved while they make electricity.

2) liquefied hydrogen is very hard to store , the hydrogen atoms under pressure will travel straight through the metal of a storage bottle and over time the bottle will empty unless the bottle is kept extremely cold , ( more energy )

Have you heard about the Perth Hydrogen bus trial - just google "Perth Hydrogen bus trial". The bottles are not kept cold, just high pressure and they last for months. The big problem with hydrogen in steel pressure vessels was that H would embrittle the tanks but this problem has more or less been solved with using the right steels. New ally and carbon fibre composite bottles have been designed that also reduced the bottle weight problem but they currently cost a lot more than steel but the prices will drop if enough are produced.

Originally Posted by SawDustSniffer

100lt of petrol is mixed with 1500lt of air ,

hydro carbons are made up of hydrogen atoms bonded to a carbon chain , each carbon to carbon link uses 2 bonds , each hydrogen to carbon link uses 1 bond , carbon must bond with 4 links , oxygen needs 2 bonds per atom

...H H H H H H H H
H C C C C C C C C H
...H H H H H H H H

hydrogen is number 1 on the periodic table , with a "weight" of 1
carbon is number 6 on the table , with a "weight" of 12
oxygen is number 8 on the table with a "weight" of 15.99

during combustion the hydrogen is burnt and produces water vapour H-0-H ( H2O)
every carbon atom bonds with 2 oxygen atoms O-H-O , carbon DI oxide

swapping the light weight hydrogen (2x for long chain fuel, 4x for methane ) for the heavy oxygen , makes the carbon dioxide weigh +16x the weight of the original fuel (new tax $30 per ton = $30 per tank )

hang on Ken, would you like to check your sums?

if we assume that a molecule of petrol contains twenty carbon atoms, when it's burnt we'll get twenty molecules of carbon dioxide.
So in terms of mass, petrol with 240 "weight" units of carbon (20x12=240) becomes 880 "weight" units of CO2 (20x(12+16+16)=880), a 3.67 times "weight" gain.
so 100kg of petrol will generate about 360kg of carbon dioxide, not the 1.6 tonnes suggested earlier.

most people dont know how much carbon dioxide comes from oil , if you burn 100kg of petrol in a car , it will make 1.6 ton of carbon dioxide

Originally Posted by ian

hang on Ken, would you like to check your sums?

if we assume that a molecule of petrol contains twenty carbon atoms, when it's burnt we'll get twenty molecules of carbon dioxide.
So in terms of mass, petrol with 240 "weight" units of carbon (20x12=240) becomes 880 "weight" units of CO2 (20x(12+16+16)=880), a 3.67 times "weight" gain.
so 100kg of petrol will generate about 360kg of carbon dioxide, not the 1.6 tonnes suggested earlier.

as I said earlier, in practical terms it's about 230kg CO2 per 100kg petrol.

Originally Posted by mic-d

as I said earlier, in practical terms it's about 230kg CO2 per 100kg petrol.

So this would represent about 63kg of carbon (using others maths, not mine)
Assuming a carbon price of $30 per ton, 100kg of petrol (more than the average tank would hold) would cost about $1.90 extra with a carbon tax.
This would mean about $1.00 for an average tankfull, or something in the order of 1 to 1.5 cents per litre.
BTW I'm not pushing for a carbon tax