Re: GAS-L: Gas-L: Energy Yields - Anaerobic digestion

["MINI WELL SYSTEMS [PVT] LTD" <mwsys@slt.lk>]

At 12:27 PM 9/29/02 +1000, you wrote:
>For vegetable matter where retention time is not an issue, we use a rule of 
>thumb of 2.5GJ/t dry mass completely digested. Currently for an Australian 
>potato scrap digester, the design figure was closer to 1.4GJ/t of dry matter, 
>because although potatoes are an excellent digester fuel, cost dictated that 
>our loading rates and retention times were reduced to keep the size of the 
>digester in check. This digester will produce 3.6GJ/h and cost around US$75k 
>(without pumps, CAF unit etc etc which are part of the associated water 
>recycling/treatment process). That amount of gas will run a 300kW gas 
>reciprocating engine, which in a cogeneration configuration would cost around 
>US$180k, so I guess if you were shooting for a total waste to electricity 
>figure, this unit works out US$850/kW installed power output, of which 2/3 is 
>the power plant (which would be the same for either gasifier or digester).
>
>Hope this is useful and would appreciate any comments from others.
>
>Mike Westerman



Mike,

Reference the above, 
In the figure of US$850/KW 
what will be the cost of the digester in  US$ per KW and 
the cost of the power unit in terms of in US$ per KW       
       
Also why did you say the retention time was not an issue.

At 1.4 GJ/t and 22MJ/cu m for the gas the yield will only be 65 cu m/t.
Is this correct or have I missed out a few naughts or hours.

For bio fertiliser a dry batch process has been introduced here. 
The gas yield is about 0.8 cu m /tonne/day for the digestion period of 120 days.
This gives a total of about 96 cu m/t. Rice straw and market/vegetable waste 
are the usul feed material. Like a land fill, 
once the digester is loaded and sealed there is no attendance required

 
        
Thanks

Tharu







>
>


V.Tharumaratnam
Mini Well Systems (Pvt) Ltd
161/1 Colombo Rd, Hewagama,
Kaduwela, Sri Lanka
e-mail: mwsys@slt.lk


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