Wood Chip or Wood Pellet

Quack13

I am currently beginning to research what type of heat source we will use in our house.

I am thinking of going down the Solar/Wood Burner route.

I was speaking to a guy last night (who is a sustainability expert) about various issues.

He seemed to suggest to me that he thought that Wood Chip systems are better than Wood pellet systems.
He did say however that they can be harder to obtain for domestic use as they are usually quite large systems and are used more in industrial settings.
He wasn’t knocking wood pellet systems, he just felt the wood chip was a smarter buy.

I notice on here most people speak of the wood pellet systems with little or no mention of Wood Chip.

Does anyone here use a wood chip system for domestic use, if so how do they find it?

Does anyone have an opinion on how the 2 types compare in terms of cost/performance?

Carlow52

do u have room for the necessary (irish damp weather proof ) storage for either as well as access for bulk delivery?

WC is more industrial than WP.

Before deciding on the heat source have u got the best airtightness/insulation standards possible within your budget?

The best form of sustainable energy is the energy u dont use/need

Quack13

Hi Carlow,

To answer your questions:

Yes we have room for the necessary (damp proof) storage.
We also have access for bulk delivery.

Yes we believe we will have the best insulation/airtightness within our budget. (starting to build in a few weeks)

What do you mean WC is more 'industrial' than WP.
I just mentioned that I was told it tended to be used more in industrial settings. Are you simply re-affirming that?

Q

Carlow52 wrote: »

do u have room for the necessary (irish damp weather proof ) storage for either as well as access for bulk delivery?

WC is more industrial than WP.

Before deciding on the heat source have u got the best airtightness/insulation standards possible within your budget?

The best form of sustainable energy is the energy u dont use/need

Carlow52

Yes as WC is bulkier.
there is a page somewhere on www.sei.ie site showing the different cost/kW net output for different fuels

Evergreen

I have worked with both WP and Wc boilers during the last 4 to 5 years and the systems we have worked with go from 20kW up to 200kW so there are options out there for domestic wc boilers.

With a WCB the issues relating to fuel and moisture are far less of a problem than in the case of pellets. The boilers I have worked with have a lambda probe that allow the boiler to determine the moisture content of the fuel and modify the burning process to suit. As a result the WCB can handle fuel with up to 40% moisture content while having only a small reduction in output.

If you need any more information just send me a PM and I can contact you direct with information on boilers installed.

Carlow52

Evergreen wrote: »

I have worked with both WP and Wc boilers during the last 4 to 5 years and the systems we have worked with go from 20kW up to 200kW so there are options out there for domestic wc boilers.

With a WCB the issues relating to fuel and moisture are far less of a problem than in the case of pellets. The boilers I have worked with have a lambda probe that allow the boiler to determine the moisture content of the fuel and modify the burning process to suit. As a result the WCB can handle fuel with up to 40% moisture content while having only a small reduction in output.

If you need any more information just send me a PM and I can contact you direct with information on boilers installed.

This not true for the simple reason that the water has to be boiled off.

see table 4 in section 2.2.1 of
www.sbsa.gov.uk/archive/pdf/FinalReportResearchintotheStorageofWoodyBiomassFuel.pdf

The NCV goes from 16 to about 9 as MC goes from 10 to 40

The yoke may be able to handle the wet stuff but at a cost

PeteHeat

Hi,

One of the reasons wood pellet sells well in the domestic market over wood chip is there is very little maintenance on a pellet boiler compared to most chip boilers.

To buy a decent quality wood chip boiler it is best looking at the top end of the market because many systems start out in life with three phase motors, some companies changed the motors to suit our standard electricity supply.

The wood chip systems tend to work better from a financial point of view if you have access to a lot of fuel locally preferably from a supplier who is force drying the chips down to better than 20% moisture content.

An option that may be worth looking at is a boiler capable of burning pellet with a wood gasifier combined.

They give the homeowner all of the benefit of a gasifier with the back up of wood pellet boiler, they can work in either format or you can set it to have the pellet take over from the gasifier to continue providing heat.

.

Evergreen

Carlow52 wrote: »

This not true for the simple reason that the water has to be boiled off.

see table 4 in section 2.2.1 of
www.sbsa.gov.uk/archive/pdf/FinalReportResearchintotheStorageofWoodyBiomassFuel.pdf

The NCV goes from 16 to about 9 as MC goes from 10 to 40

The yoke may be able to handle the wet stuff but at a cost

I'm afraid that this simply is true

Becuase the boiler knows what the moisture content of the fuel is it is able to adjust the amount oxygen available to the burning chamber in both primary and secondary jets. There is some fall off in output but not as dramatis as can be seen in most of the cheap and nasty stuff that you can see on the market.

This has been proven by the testing authority in Austria, BLT Wiesenburg. I can get you copies of the certificates if my word is not good enough.

Quack13

PeteHeat wrote: »

Hi,

One of the reasons wood pellet sells well in the domestic market over wood chip is there is very little maintenance on a pellet boiler compared to most chip boilers.

To buy a decent quality wood chip boiler it is best looking at the top end of the market because many systems start out in life with three phase motors, some companies changed the motors to suit our standard electricity supply.

The wood chip systems tend to work better from a financial point of view if you have access to a lot of fuel locally preferably from a supplier who is force drying the chips down to better than 20% moisture content.

An option that may be worth looking at is a boiler capable of burning pellet with a wood gasifier combined.

They give the homeowner all of the benefit of a gasifier with the back up of wood pellet boiler, they can work in either format or you can set it to have the pellet take over from the gasifier to continue providing heat.

.

Do you know of any good examples of this type of model? Feel free to PM me any links/companies. Thanks.

Carlow52

Evergreen wrote: »

I'm afraid that this simply is true

Becuase the boiler knows what the moisture content of the fuel is it is able to adjust the amount oxygen available to the burning chamber in both primary and secondary jets. There is some fall off in output but not as dramatis as can be seen in most of the cheap and nasty stuff that you can see on the market.

This has been proven by the testing authority in Austria, BLT Wiesenburg. I can get you copies of the certificates if my word is not good enough.

EG: I am not for a moment doubting your word here and there was no intent to do so.

Please by all means provide the performance certs.

My issue is very simple:

I dont have time to dig out the math but the energy required to convert the moisture into either water vapour or steam has to come from somewhere and can be calculated based on moisture content.

So on the face of it the performance has to decrease the wetter the fuel

Air is typically 21% oxygen so increasing the Oxy supply means introducing more air which reduces the efficiency of the combustion due to the presence of the other 79% which is in the way so to speak and needs to be heated also.

Combustion is simply a chemical reaction that happens fast and for wood chip the its the carbon C that is burned with Oxy O2

eg C plus O2 = CO2 plus heat.

Cheeble

Doesn't it depend on whether the energy used to heat the water is subsequently recovered?

Ok, it takes energy to heat the moisture out of the fuel, but you then have hot water vapour/steam from which it's relatively easy to get the energy back. If the equipment operates this process, and does so efficiently, you could still stand to recover most of the calorific value of the original fuel?

Don't really know what I'm talking about here btw, just thinking out loud.

Cheeble-eers.

Gurgle

Quack13 wrote: »

I was speaking to a guy last night (who is a sustainability expert) about various issues.

He seemed to suggest to me that he thought that Wood Chip systems are better than Wood pellet systems.

Anyone trying to sell either system isn't an expert, he's a sales rep. Get a wood burning stove if you want to burn wood.

Quack13

He wasn't actually trying to 'sell' me anything. He's a friend of a family member.

His job is offering advice to corporations on how to be more energy efficient. He was simply offering me impartial and independent advice which I was after.

And also it's only his opinion which I was putting out there.

It seems to be bringing up some good points and generating some interesting discussion though, which is great!

Carlow52

Quack13 wrote: »

....
It seems to be bringing up some good points and generating some interesting discussion though, which is great!

exactly:)


I am just looking at the basic thermodynamics and trying to ensure we dont have too much Green 'fool's gold'

mahoney.john

Quack13 wrote: »

I am currently beginning to research what type of heat source we will use in our house.

I am thinking of going down the Solar/Wood Burner route.

I was speaking to a guy last night (who is a sustainability expert) about various issues.

He seemed to suggest to me that he thought that Wood Chip systems are better than Wood pellet systems.
He did say however that they can be harder to obtain for domestic use as they are usually quite large systems and are used more in industrial settings.
He wasn’t knocking wood pellet systems, he just felt the wood chip was a smarter buy.

I notice on here most people speak of the wood pellet systems with little or no mention of Wood Chip.

Does anyone here use a wood chip system for domestic use, if so how do they find it?


Does anyone have an opinion on how the 2 types compare in terms of cost/performance?

hi, wood pellet are the best they offer you an alternative way to heat your home.

Pellets have the following advantages over other types of wood fuel:- * Less volume to transport and store (due to higher energy density)
* Fewer deliveries
* Consistent size and moisture content
* Versatility - can be used in stoves and boilers
* Less ash
* Lower emissions CO2 neutral
* Exempt from CO2 tax
* Pellets are dry and can be stored without degrading
* Flow like a liquid and can be used in automatic machinery
* Easier to handle
* Easier to igniteclick here to download

Evergreen

mahoney.john wrote: »

* Less volume to transport and store (due to higher energy density)
* Fewer deliveries
* Consistent size and moisture content
* Versatility - can be used in stoves and boilers
* Less ash
* Lower emissions CO2 neutral
* Exempt from CO2 tax
* Pellets are dry and can be stored without degrading
* Flow like a liquid and can be used in automatic machinery
* Easier to handle
* Easier to igniteclick here to download

Interesting list, but you could come with just as impressive a list for wood chip, with a lot of the same items applying to woodchips.

* Less volume to transport - is that the home owners problem?

* Fewer deliveries - surely this is solely down to the size of fuel store for both options

* Consistent size and moisture - for decent wood chip boilers this is not an issue, this is why there are standards for both pellets and woodchip. If the fuel meets the standard set for it then it will work fine in a boiler designed to burn it.

* Versatility can be burned in stoves and boilers - you can burn wood chip in a multi fuel stove.

* Less ash - this is purely down to the amount of bark and contaminants in the fuel whether it is pellet or chip. I have seen pure ship with no bark produce less ash than some of the low quality imported pellets from the Far East.

* Lower emissions, Co2 neutral - are we not taking about the same material in different formats? At the end of the day the emissions are more down to the boiler than they are to the fuel.

* Exempt from carbon tax - what carbon tax, did I miss something in the Budget? And even if they do bring in a carbon tax do you believe that they will tax chips differently than pellets? In fact there is a lot more carbon used to produce pellets than what is used to produce chips.

* Pellets are dry and can be stored without degrading - that really depends on the pellet store, I would say that woodchips are easier to store than pellets. A leak of water on wood chips just makes them a little wetter whereas the same thing will destroy pellets.

* Flow like a liquid and can be used in automatic machinery - most wood chips are used by automated boilers, in fact I have yet to see a manual one.

* Easier to handle - Supplier puts fuel into fuel store, boiler takes fuel from fuel store, what handling are you talking about?

* Easier to ignite - Lighting woodchips is no more difficult to light than wood pellets once they are within the standards.


At the end of the day this does not address the reall issues facing sombody considering both options. I deal in both pellet and wood chip boilers day-in day-out and here are the real issues that people have to consider when choosing

* Extra capital investment for woodchip boiler
* Extra space for larger fuel store
* Some boilers require 3 Phase electrciity, some do not
* Some boler use G30 chip others use G50, what does your nearest supplier have?
* What kind of delivery system does your local supplier have? This affects the type of fuel store required
* Will the lower fuel costs be enough to justify the extra expendiure up front.

My advice is talk to lot's of people who have experience of the different boilers you are interested in - whether it is pellet or chip - and be aware of installers only offering relatives as reference sites.