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147 comments on A Visit to the New Choren BTL Plant

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hvacman on May 6, 2008 - 11:28am Permalink | Subthread | Parent | Comments top

My back-of-the-envelope calcs suggest this process turns 10 units of biomass energy into 3 units of diesel energy, which then would turn into 1 unit of shaft energy in a diesel engine. Not a very efficient use of biomass energy compared to direct biomass combustion at a conventional biomass cogeneration plant, which could turn 10 BTU's of biomass into 4 BTU's of electricity and 4 BTU's of process heat. If the gasification processes can produce sufficient high-quality waste heat usable by other industries or for space heat, it might make some sense.

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FrankRichards on May 6, 2008 - 12:57pm Permalink | Subthread | Parent | Comments top

You, and in fairness, Choren's summary box, are neglecting 365*24*45 = 394200 megawatt hours of electricity.

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Petrus on May 6, 2008 - 2:13pm Permalink | Subthread | Parent | Comments top

And this is substantial.
While it generates only 113,400 barrels of oil worth $13million,
It produces 394.2GWh of electricity worth 19.71million at the $0.05/kwh price of coal electricity.

So overall, the most profit is out of the gas, not liquid.

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hvacman on May 6, 2008 - 5:52pm Permalink | Subthread | Parent | Comments top

Thanks for picking up on the electrical power output. I completely missed it on the chart. Something doesn't quite add up, though, as my ballpark numbers now suggest that an efficient wood-burning power plant could produce at best about 139 GWh hours/year with 65,000 metric tons of dry wood. That would put the power value at about $6.9 million.

Assumptions:
65,000 mt = 65,000 x 2,200 = 143,000,000 lb wood/year
8,300 BTU/lb higher heat value
40% power plant thermal efficiency.

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Engineer-Poet on May 6, 2008 - 11:40pm Permalink | Subthread | Parent | Comments top

Something I haven't seen yet is an analysis of the inputs and outputs.

68,000 metric tons/year @ 17.4 GJ/tonne = 1.18 EJ
18 million liters diesel @ 38.6 MJ/liter = 695 TJ
45 MW * 8760 hr/yr * 3.6e9 J/MWH = 1.42 EJ

Whoops!  The claim is that more ELECTRICITY comes out than biomass energy goes in!  There is clearly an error in the figures given.

Could the electric output possibly be 4.5 megawatts, not 45?

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Petrus on May 7, 2008 - 12:53am Permalink | Subthread | Parent | Comments top

Good catch. I tought that the discrepancy is moisture in the wood. But even though having igh effect, it cannot account for it.

I would say that the 45MW would the Max Suppliable power that could be delivered in the peak hours, using perhaps stored gas and stored charcoal. Outside of peak hours it would perhaps deliver a fraction of it.

But that makes some economy calculations invalid.

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Robert Rapier on May 6, 2008 - 1:21pm Permalink | Subthread | Parent | Comments top

My back-of-the-envelope calcs suggest this process turns 10 units of biomass energy into 3 units of diesel energy...

While it's not quite as bad as that, this is the first area I pressed David on. I know about what GTL and CTL give, efficiency wise, so I knew that would be an area to explore. David said that out of all the recent visitors to come through, I was the only person to ask that. But I can't say exactly what he said, as I am covered by an NDA. But you can get to a ballpark number (which you did) by looking at wood in and fuel and electricity out.

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SwordsOfDamocles on May 6, 2008 - 2:00pm Permalink | Subthread | Parent | Comments top

How many units of diesel energy does it take to get 10 units of biomass?

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Petrus on May 6, 2008 - 2:49pm Permalink | Subthread | Parent | Comments top

That depends.

If you let it grow freely and burn it in place, you get all the heat with zero diesel energy input ;-)

That should be mostly determined by the mode of transportation. Cheapest would be using waterways. I assume that the seeding, is a negligible expense, considering the high plant/seed weight ratio.

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147 comments on A Visit to the New Choren BTL Plant

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