[Gasification] cost per kW, cost per kWh - was: Re: Ash to land? -separated ash fractions

[Ken Boak]

Peter and List,

Daniel has rightly identified the main costs of running a gasifier and 
generator system on a commercial basis, in an attempt to compete with 
existing power generation technologies.

Tom Miles has identified the real world costs of setting up a gasification 
plant based on components available today on the world market and following 
standard engineering practices.  There are many other costs that have to be 
factored into the overall project costs - not to mention the cost of the 
building to house the unit.

Both Daniel and Tom have taken their illustrations from commercial systems 
which exceed the 100kWe or even 1MWe power output, whilst you are clearly 
focussing on "village scale" power in the <10kWe class.  These systems 
clearly can be set up at much reduced costs, and are an attractive option 
for introducing small amounts of electrical power to local communities, 
workshops or agricultural processsing sheds, where other forms of power are 
non-viable on the grounds of cost.

However, whilst you have correctly identified the costs for setting up a 
small generator system in the order of $750/kW,  you have rather pinned your 
overall operating costs to the continued availability of  reasonably priced 
diesel fuel,  waste motor oil or other vegetable oil based fuel, and 
neglected the costs of setting up and running  a small scale gasifier to 
supply the gen-set.

With diesel fuel costing about $0.80 per litre,  you will be lucky to see 
this small scale power costing less than $0.40 per kWh. Of course cheaper 
fuels are available (kerosene, home heating oil etc).

It would appear to me, that in order to reduce the cost per kWhe, then the 
bulk of the fuel energy needs to be offset by a cheaper fuel, using a small 
gasifier (or possibly biogas generator) and running the engine in dual fuel 
mode.  This becomes particularly attractive if you have agricultural 
residues available locally that can be used as feedstock and a source of 
labour on site who can attend to the gasifier.

What still needs to be identified are the costs associated with putting 
together a practical gasifier suitably sized for the <10kWe market, complete 
with gas scrubbing, cooling and other associated equipment such as fuel 
preparation equipment.   Does anyone on the list have direct experience of 
this size of gasifier which could be applied to cost-sensitive village scale 
power systems?

Whilst this might add another $500/kWe  to the capital cost of the plant, if 
these small scale systems can be shown to work reliably in dual fuel mode, 
then the savings in fuel costs could bring the cost per kWh down to a more 
attractive  $0.10 to $0.20  per kWh.  With savings of fuel of nearly $10 per 
day (4kW x 12hours) then the payback for the extra costs of the gasifier 
could be in the order of 1 to 2 years.

As you have shown from your experiments with the Chinese built 195 engine, 
that when derated, a reliable  plant can be run, what is needed now is to 
show that success can be obtained from a low cost gasifier, such as those 
now available from China.

As a cautionary note,  if small scale gasifier/generator plant can be shown 
to be economically viable for village power, what are the environmental 
effects of having a multitude of  small distributed systems, opposed to a 
few large scale central plants?

Drawing a parallel with Mao's  "Backyard Blastfurnace" programme of the 
1950s, might the widescale adoption of vllage scale gasifier power, lead to 
innumerous sites polluted with tars and heavy metal toxins and a lack of 
environmental legislation to ensure that emmissions and pollution levels are 
controlled.




Ken