Using wood pellets in coal powered electricity generating stations

probe

http://online.wsj.com/article/SB124691728110402383.html

robtri

if all the coal stations start to use pellets, have we the capabilities to support these without depleting natural resources???

zod

robtri wrote: »

have we the capabilities to support these without depleting natural resources???

we have capability to grow enough trees.

are we likely to ? .. probably not .. we don't do forward planning

greener&leaner

zod wrote: »

we have capability to grow enough trees.

are we likely to ? .. probably not .. we don't do forward planning

Can I see some calculations to back that up?
Area of trees required, availability of suitable land, that sort of thing.

Thanks.

bladespin

zod wrote: »

we have capability to grow enough trees.

Are you sure about that? From what I understand we'd need pretty much the whole country covered for years before we could substitute.

Nukem

Honsetly dont think this is as easy as it makes out in that report. Dont coal and wood pellets have completely different properties for the infamous combustion three T's (Time, Temperature and Turbulence).

Surely there is a large difference between the amoount of time required to burn coal and biomass? Temperature and flue gas components may give rise to fly ash and other nasties which may be worse than CO2 to local areas.

I reckon this needs to be looked at in way more detail per plant rather than the knee jerk reaction that report is on about.

PeteHeat

Hi,

I believe the original 8mm wood pellets manufactured by Balcas were used in the coal fired generating stations in the UK.

As far as I know the pellets were mixed with other fuels to generate electricity, I expect there are possibilities although forward planning would be essential.

.

ART6

Wood pellets used in conventional power station boilers are like rocket fuel. They release their energy too rapidly, so they can only be used in small quantities in a mix with the fossil fuels the plants were designed for. Equally, they can't be used in oil or gas fired stations as there is no means of introducing them into the furnaces.

Some big plants burn wood chip, but they are generally fast recirculating fluid beds that can burn anything. I am not aware that we have any of them in Ireland.

truerenew

Do Bord Na Mona not have a fluid bed for coal and peat?

truerenew

Taught so...see the link below. Says it only uses peat but I heard coal was been tested in it last year with peat...not sure if it went ahead.

http://www.edenderrypower.ie

rayh

The following is taken from the Governments White Paper "Delivering a Sustainable Energy Future for Ireland" Strategic Goal 4 which is relevant to the trials at Edenderry.

Bord na Móna, as well as delivering on its existing core business, is developing new strategic directions with full Government support including renewable energy, waste to energy, energy research and development and power generation. Bord na Móna will play a key role in delivering national bioenergy/biomass goals up to 2020 including appropriate strategic partnerships with the private sector.

derry

It was interesting to look the technical info from Edenderry

http://www.edenderrypower.ie/inside.asp?id=5

It needs 1,000,000 tons of peat a year to gve 120MWper day
about 330 days a year and efficency approx 35%.If we factor in that there is energy to produce and ship and dry out suitable peat to the Edendery power station this might bring the true global energy efficiency below 30%.

The last info I had on wood pellets was its requires twice as much weight of pellet fuel to equal a fossil fuel like oil or 2 kilos of wood pellets will equal one kilo of oil.
This make transporting wood pellets any distance a uneconomic enterprise so the wood pellets have to be localy sourced to be economic as in grown and made in ROI

Now another factor is that a oil power or gas power station could expect to use 500,000 tons of fuel to make 120Mw and the power station would expect to get closer to 70% effiency from the fuel used

However oil for example will often require a 30% energy input to get the fuel to the power station as in for every 7 tons of oil used in the power station another three tons was consumed extracting the oil from the ground refining it and transporting it .This mean the global effiency from the electric power station could drop below 50% effiency when all global factors are counted in.

What is likely over time is as more and more oil feilds and gas feilds get older and require more energy inputs for extraction ratios as they move towards thrird stage or final stage extractions processes this means that that the long term output of these power stations could over time drop down to lower than 30% global effeciency when all global factors are factored in .
However that would be more likely to be the case after 2050 than sooner but even as early as 2020 we can expect 35% ratios for fossil fuel extractions or 5% over todays ratios.What is certian is the energy input extraction ratios for fossil fuels like oil and gas wil most likely increase incrementaly every year .

Given that most Oil and gas isnt from the ROI and extraction of these fossil fuels requires huge capital inputs over many years and has serious risks for the envioremnet both ouside ROI and inside ROI if there are oil spills or large gas leaks helps makes this form of power production for the ROI a bad deal.Throw in the fact that most of the money leaves the ROI economy if we import oil and gas this it makes this an even worse deal.

However Bio mass although renewable as in repititiive for ever it will impact the country in that large regions would have to grow bio mass fuels.Being realistic assuming the 15% of the land in ROI is marginal land suitable for Bio mass production still might not be enough to provide all the power the ROI would need.It more likely that a acheivebe target of 20% of the power requirements for the ROI isnt impossible but technically difficult.
Bio mass energy production would also be able to buffer the ROI from interuptions from imported oil and gas and help get the ROI away from its its 90% energy imports to something less more like 60% imports .

What has to be figured with all bio fuels is the energy ratio returns are very low as in nature would give us back 1% of the energy that natures supplies to the process from solar power.

This translates into needing large tracts of land to get energy.A example a tall pine tree after twenty years could weigh maybe one ton in wood.Just to run the Edenderry station would than require 1,000,000 trees per year so 20,000,000 trees in total in twenty year cycle

This makes older larger trees less interesting compared to fast grow tree and cropping every 5 years where maybe you need twenty trees to get one ton of fuel and therefore 400,000,000 smaller trees using the about same amount of land in acreage .Soil exhastion would also be a factor to look at where some land might have to let fallow a few years in between crops

Properly done where some Bio mass went to power stations and some went to directly to fuel sources like making gas energy or bio fuels like alcohol or bio deisel we might with ROI fast growinging climate support 30% of our energy demands without impacting food farming land

At least bio fuels could supply more perminant employment than fly by night offshore companies .


But its not so easy the bio fuel route and requres a long term plan that ensures th bio fuel isnt ditched when oil prices drop for a few years in a row.
Thats where Governments with a five year election window lose interest in the promises of riches in twenty years hence just isnt a concept they relate to when its the votes in the next election they look at.
If there is votes in growing trees then you will see you local TD up dem hills planting trees:D

Derry

PeteHeat

Hi,

Just to clarify :

When Balcas first made wood pellet it was 8mm and of industrial quality, basically they were using the pellets as a means of using the saw dust in a practical way.

I agree with Derry wood pellet or wood products are not the answer when it comes to generating electricity, there are many forms of biomass available however using them commercially takes a lot of forward planning.

.

rayh

derry wrote: »

It was interesting to look the technical info from Edenderry

http://www.edenderrypower.ie/inside.asp?id=5

It needs 1,000,000 tons of peat a year to gve 120MWper day
about 330 days a year and efficency approx 35%.If we factor in that there is energy to produce and ship and dry out suitable peat to the Edendery power station this might bring the true global energy efficiency below 30%.


Derry

Derry - just to add to your point - Electric energy is a higher order energy form, very versitile, but we must question very seriously our uses and application of this energy.
To add further to your point, transmission of the electrict energy to you losses a further 14%. Therefore for every unit you receive, it took 4 units to produce.
Just to add a small ponint to your comment about drying the peat. Harvested peat is air dyred - no mechanical energy except for operations which is another story