[Gasification] Gasification Digest, Vol 30, Issue 1: ORC, gasifier, SRC systems at around the 2MWe level

[David Coote]

Hi Tom,

I'm doing a bit of work in this space at the moment. How did you define 
Btu's below for the Btu/kWh efficiency calculation?  Was it from the HHV 
or LHV of the original biomass fuel?

When you say steam + ORC is that off an existing boiler? The ORC vendors 
claim that you can get 20% electrical efficiency at the 2MWe system 
level using a biomass system heating thermal oil that would run at much 
lower temperatures and pressures than a similar SRC system. Hence 
cheaper operations and maintenance costs. I haven't managed to find data 
yet on the cost delta between thermal oil biomass systems and the more 
common biomass systems heating water/steam.

Regards

David

On 2/02/2013 7:00 AM, gasification-request at lists.bioenergylists.org wrote:
> Message: 20
> Date: Fri, 1 Feb 2013 09:04:09 -0800
> From: "Tom Miles"<tmiles at trmiles.com>
> To: "'Discussion of biomass pyrolysis and gasification'"
> 	<gasification at lists.bioenergylists.org>, 	"'stuart mather'"
> 	<kneebraceboy at yahoo.com.au>
> Subject: Re: [Gasification] mycoremediation of tarry water
> Message-ID:<00b601ce009e$27e317b0$77a94710$@trmiles.com>
> Content-Type: text/plain; charset="us-ascii"
>
> Except . . apparently when you do a detailed engineering feasibility study
> and get quotes from suppliers. In a recent 2 MWe project we found that
> gasifiers were 50% higher in capital cost than steam (turbines or engines)
> or steam + ORC. In the opinion of a couple of gasifier suppliers, for our
> economic circumstances, gasifiers could be more competitive in the 5 to 10
> MWe scale. At 10 MWe steam becomes more economic. We were interested to see
> that at the 2 MWe scale steam or steam + ORC could be competitive. There are
> about 200 ORC systems in operation on biomass but to use ORC you need a use
> for large amounts of low quality heat.
>
>
>
> We found that while a 5-10 MWe biomass plant may have a heat rate (fuel to
> power) of 14,500 Btu/kWh, the efficiency for the 2 MWe plant ranged from
> 18,500-22,800 Btu/kWh for small scale steam turbines; 28,000-55,000 Btu/kWh
> for ORC boiler-turbines and 24,000 Btu/kWh for gasifiers. In this 2 MWe case
> gasification did not demonstrate an advantage in capital and operating costs
> or fuel to power efficiency compared with steam or steam + ORC.
>
>
>
> Tom
>
>