Power Plant Fueled By Nut Shells

sbszine writes "The Sydney Morning Herald is running an article about a green power plant that runs on the discarded shells of macadamia nuts. The power plant, located in Gympie, Queensland, is expected to reduce greenhouse gas emissions by around 9500 tonnes in its first year of operation."

Comments

Reduction in Co2?

[zefod]

My guess is that they would burn the shells of these nuts, right? This produces carbondioxide, so how does this reduce CO2?

Re:Reduction in Co2?

[spektr]

Just compare it to a closed system in a box with a plant and a device burning it's seeds; the plant will consume the CO2 a lot slower than the device can produce it

What makes you believe that? Are you assuming that the plant produces seeds at a diminishing rate, or that burning a seed releases more carbon than was put into building it? Because something doesn't add up here.

There are two coupled systems: the solid biomass in the soil and the CO2 in the atmosphere. CO2 is transported in both directions at a *slow* rate. Decaying biomass releases a modest amount of carbon into the atmosphere, while most of it is recycled directly by plants and microorganisms. In the same way the plants absorb a modest amount of CO2 back from the atmosphere.

If we burn biomass then we accelerate the transfer of carbon into the atmosphere. The transport from the atmosphere to the solid biomass is mostly unaffected by this instantaneously (though a higher CO2 concentration may let plants grow faster).

So, in a short frame of time, burning biomass has the potential to increase the CO2 concentration in the atmosphere. In the long run, the ecosystem will reach a new equilibrium. This equilibrium doesn't necessarily possess the same climatic properties of the equilibrium we experience today.

Re:Reduction in Co2?

[WolfWithoutAClause]

The atmosphere and biosphere is not a closed system, because the CO2 is removed from the atmosphere by weathering (CO2 and limestone forms carbonate rocks) and added to the system predominately by volcanic activity and only very much secondarily from human activity (by nearly two orders of magnitude). In addition CO2 is not the primary greenhouse gas, water vapour is far more significant.

Re:Reduction in Co2?

[gl4ss]

so what you're saying is that we should kill all the plants, stop them from growing, dying? or use fossil fuels instead of something available?

yeah. that's the ticket.

from your link:
" The most important points to draw out from this briefing are as follows:

* Fossil fuel consumption is the greatest source of greenhouse gas emissions.
* Deforestation in the tropics is the second most important source of greenhouse gas emissions.
* Forests are net absorbers of CO2 while they are growing (which is stored as carbon) but then release the accumulated carbon when they die.
* Young forests absorb more CO2 than old forests, but old forests have much greater stores of carbon.It is widely recognised that old forests are valuable storehouses of carbon and should be protected.
* Logging old-growth forests and replacing them with plantations intended for timber/paper production results in a net loss of carbon which is released into the atmosphere. This is especially relevant in Canada, Russia and the Baltic States where this is most widespread, and also in Scandinavia. "

however the whole text was fairly anti-paper industry disquised as something scientific and relevant(there's barely any logging of _old_ forests in finland anyways, and the total yearly growth is _more_ than what we cut down yearly).

sure the russians do log real old forests.. but they do lots of other stuff too(bad for the environment) that is seriously in need of more attention.

i've planted ~500+ trees myself(in last 2 years, double the amount for total during my life and i'm 22), so i'm not worrying too much about our forests being robbed as forests are seen as a source of income that needs to be taken care of, not just exploited silly. the worrying thing is that people in (for example) amazonia just burn down some area of forest and farm on it for few years and then just move on, to burn more forest to be used for farming.

anything to cut down on fossil fuels is good anyways, at least as an alternative. what the article says is that old forests bind more co2 than young forests, which has nothing to do with it 'coming from dimension x' or something.

nice prediction

[loraksus]

yes, this assumes that the grid is not already running at close to capacity. . . As we know, it is pretty rare to start up another power plant if there is no need for it. . .
So the "savings" is kind of like the recording industry's / BSA's claims of "losses", a great way to get rid of nuts though. Has anyone seen "Equilibrium" by the way? ;)

Granted, it beats burning coal or the many other alternatives, but I suppose gold plating it makes the 3 mill a lot easier to swallow.

Efficiency?

[brucmack]

It would be nice to know what the cost efficiency of this plant is... seeing as how this has always been the big problem with "green" power.

Also, is there any inherent advantage to using macadamia nuts rather than some other biomass?

Thats nothing

[mphase]

Watch this process turn your garbage into oil.

Hello, 1970?

[heironymouscoward]

This is the scene. I'm a young boy, 8 years old, in Dar-es-Salaam, capital of Tanzania. On the horizon sits a squat building with a tall tower, belching some kind of gray-white smoke.

"Mummy, what's that?"
"It's a power plant, Heirony"
"What does it burn, Mummy?"
"Caschew nut fruits, Heirony"

The caschew nut grows as a small nut on a huge fruit which is rich and oily. For each of those tiny caschew nuts, a fruit weighing perhaps 500gr is grown, harvested, and then discarded.

In Tanzania in 1970, and probably still today, these fruits were dried and then burnt for power. Glad to see that some third-world technology had finally made it to the rich west.

Re:Energy in/Energy out.

[deek]

• How much energy goes into getting the nuts out of the shells in the first place?

I've visited a macadamia farm, and seen the machine that they use to remove the shells. It resembles something like an engine, with rows of levers catching the nut and compressing it just a few millimeters. The shell is very brittle and cracks completely if you can compress it just a little.

• They had a prize of a lifetime supply of macadamias if you could get a nut out of a shell without using a saw. I tried smashing it with a rock with no luck. Apparently, no one had ever collected the prize.

I can't say I'm surprised. I regularly crack open macadamia nuts. Handheld nutcrackers are useless. I've actually broken the nutcracker before I've broken the nut. My method involves an irresistable force and an immovable object (who said that theoretical physics wasn't practical?! 8)) . But seriously, I use a hammer and a rock slab. I literally have to pound the nut a good three or four times with the hammer. And I mean serious swings ... with the kind of force you need to drive a nail. But the nut always gives way, and on rare occasion, the finger too (ouch!).

Whoever came up with the phrase "a hard nut to crack", obviously worked in the macadamia business.

DeeK

Other biomass/CO2 neutral examples

[Zog The Undeniable]

There are biomass power stations in Europe that use willow as a fuel. Willow trees grow very quickly and, as has been done for centuries, can be "pollarded" to remove the last year's growth for fuel without killing the tree. These plants are CO2 neutral. over the timespan of a year. Biodiesel, which works in the majority of new diesel cars, is also CO2 neutral because it comes from quick-growing crops such as soya beans.

All this makes more sense than GWB's hydrogen economy, which needs electricity to make the hydrogen. As electricity generation is about 30% efficient, there's not much point in using biomass to produce hydrogen for fuel cells - you might as well stick biodiesel straight in the car.