Hello
Some comments to this calculation.
There is nothing wrong with it. The important thing in it is that the value
of wood turned into pellets or into liquid fuel is set by the market price
of the cheapest alternative and that is different in different countries. In
Sweden fossil fuels and electricity are heavily taxed. Originally the taxes
were mostly fiscal but during the last 15-20 years or so they have been
raised to curb the consumption. What the taxes will be in the future is not
easy to forecast but imagine a general tax level that is high enough to
force a change over to fueling our cars with liquid fuel produced from wood.
If this will come it will probably also set the price level on wood for
heating. The market for private and public transportation of people and gods
might be willing to pay much more for the raw material wood than those who
are heating their homes. We know nothing about the future willingness to pay
but we can guess. We already know that those who are heating their homes and
the district heating companies are sometimes willing to pay more for the
wood than the pulp and paper industry. 
Bjorn Dahlroth
Sweden 




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Today's Topics:

   1. pellets vs electricity ([email protected])


----------------------------------------------------------------------

Message: 1
Date: Wed, 08 Dec 2010 22:11:05 +0100
From: [email protected]
To: Discussion of biomass pyrolysis and gasification
        <[email protected]>
Subject: [Gasification] pellets vs electricity
Message-ID: <[email protected]>
Content-Type: text/plain; charset=ISO-8859-1


Hello, this is an interesting post found on TheOilDrum.com (by Paul Nash )
the original is there : http://www.theoildrum.com/node/7214#comment-749914

"You quantify it by running the numbers, which I have done before.

We had a discussion about wood pellets coal etc on RR;'s site last week,
including how much you can grow per acre per year. Turns out there is more
money
in pellets than corn!;
http://www.consumerenergyreport.com/boards/renewables/coals-two-year-hig...

A dry kg of wood has about 20Mj energy content.
The current best commercial energy return for a wood to liquid process,
gasification and Fischer Tropsch, would give you 10MJ liquid fuel, but at
quite
some cost. You would also receive about 1MJ as electricity from the process
heat.
Wood to methanol will give slightly better energy yield, up to 60%, but no
one
is doing this.

To make pellets, you use about 10% of the energy, so 18MJ, and then get 90%
of
that from the pellet stove/furnace/boiler, so 16MJ of heat.

We can also use the woodchips for electricity, by gasifier-then ICE (25%
eff)
and you will get 5MJ electricity PLUS 10MJ of waste heat from the engine
(5MJ
exhaust, 5MJ coolant) which you can use directly.
The 5MJ of electricity can be used to run a heat pump, and with CoP of 3:1,
you
will turn the 5Mj into 20MJ of heat, for a total of 30MJ.

The real question is the $$. Turning wood to liquid fuel is very expensive,
and
needs large scale plants - which means transporting the wood a long way. You
can
densify it first by pelleting, or torrefaction, which incurs more energy
loss
but saves on transport.

Wood to liquid yields 10MJ fuel, or 0.08gal, worth about 16c, and 1MJ elec
(0.28kWh) worth about 2.8c, for a total of 18.8c

Wood pellets sell wholesale for $160/ton, and that is 8% moisture, so they
are
$174/ton, but you have used 10% of the energy to make them, so $157/ton, or
15.7c/kg - a better return. For the ton of pellets (8% moisture) you get
18.4GJ
of energy, and 90% of that, from your furnace is 16.6GJ (16.3MMBTU), so you
are
paying near enough to $10/GJ - close to a residential NG rate.

Doing gasification-electricity route yields 5MJ electricity, worth 14c, plus
10MJ of heat, which we'll value at using what we get with pellets,
$10/GJ=1c/MJ.
So, the total is 14c+10c=24c/kg, or $240/ton.

Just for reference, the current futures market for 2x4 lumber is about
$270per
thousand board feet, or about $207per ton. But you need good straight wood
for
lumber, and some of the wood (20%) as energy to mill and kiln dry it. A ton
of
wood in the field yield 2/3 a ton of lumber, using the remainder as energy

So, a (dry)ton of wood, is worth;

$139 as lumber
$140 as electricity only
$174 as wood pellets
$188 as liquid fuel plus some energy
$240 as electricity and heat

What is wood being used for today?

The lumber industry is barely profitable, and is shrinking.

There are some stand alone wood to electricity plants, but they are only
marginally profitable, and same for the cost of getting wood to co-fire with
coal, unless subsidised.

The world pellet market has doubled in volume, twice, in the last decade, to
ten
million tons/yr. It is the fastest growing and most profitable wood products
market. The equipment is simple, and any sawmill can be adapted to make
them. It
is even profitable to ship them from Vancouver through the Panama Canal to
Europe!

There are a couple of demo wood to liquids (FT) plants in Europe, and one
being
built in Edmonton, Canada. They are VERY capital intensive, and seem to need
to
be paid to take wood (wood waste)

Doing electricity plus heat, needs a use for the heat. One of the largest
consumers of wood pellets, Sweden, makes extensive use of CHP plants with
district heating systems, and is building more of them.

I am working on a project to do wood CHP at a local commercial greenhouse -
you
can see the difference in value for an electricity project when there is a
beneficial use for the heat!

The capital cost for wood to liquids is a big hurdle, as is the scale
problem
and even if there is a (new) cellulosic ethanol process, I doubt its
economics
will be much better.

Wood to electricity can be done at any scale, from as low as 10kW, and thus
at
any place. If you can do it anywhere, you can take it to a place that needs
a
lot of heat.

Does that answer the question ? "



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