[Gasification] Small steam systems plus gasifiers for electricity

Tom Miles tmiles at trmiles.com
Sun Dec 1 17:20:14 CST 2013



In most cases that we have looked at you need about US$0.25/kWe for power and low cost fuel to make a gasifier CHP system work. In the case of the California gasifiers they are using waste fuels, generating at peak electricity rates (~$0.18/kWh), and selling biochar as a co-product at $0.75/lb. There is no market for recovered heat. 


It is very difficult to be a small power producer in the US because there is opposition from the utilities that buy the power. Small systems are usually charged very high fees (demand charges, connection fees) and offered low prices for the power. It often takes political persuasion to make a small plant into a commercial position.    


In our Alaska projects high energy prices (~$0.65/kWh) provide an incentive to generate power but running a gasifier is a lot of work. Fuel oil might be expensive but it is convenient so there is less enthusiasm for it. Often the heat load is residential. Buildings and housing are small and disperse  which means that you have to build an extensive district heating system to offset high fuel oil costs. There are always challenges. 


Gasification is a new management activity for remote communities or small business. They should always start with a boiler or heat demand. The best place for a boiler or gasifier is where you are already handling biomass fuels and can fully benefit from combined heat, power and biochar.  




From: Gasification [mailto:gasification-bounces at lists.bioenergylists.org] On Behalf Of Thomas Koch
Sent: Sunday, December 01, 2013 2:56 PM
To: Discussion of biomass pyrolysis and gasification
Subject: Re: [Gasification] Small steam systems plus gasifiers for electricity




It is real pleasure to participate in a debate there are contributions like this.


First Stirling – look here --  http://ing.dk/artikel/stirling-dk-om-vaekstfonden-solgte-et-ufaerdigt-produkt-158574 - run through Google translate. The company got over 30 million € and produced a total of less than 15000 hours operation – but employed an army of business developers – big headed incompetent greedy venture capitalist investors combined with too optimistc predictions for the performance of the technology.


Hjordkjær – heavily supported by public funds would never have worked In a competitive environment. 


Our ORC poultry friend. Lets assume he operates 4000 hours pr year (probably optimistic) and produce (25 kWe*4000 hours) 100.000 Kwh. The plant lasts for 10 years and he spends 10 % of the investment in O&M and the interest on the investment Is 5 %. 

If he invest 280.000 $ the yearly costs are (10%+10%+5%)*280.000 = 70.000 $ = 0,7 US$/kWh  -- if he spends 1.000.000 the electricity price is 2,5 $/kWh. 

And there are potentially a risk that the “cooling agent” will escape to the atmosphere and be a very potent greenhouse gas


Gasifiers – I think it a good idea to ask you selves why it might be a good idea to build a gasifier. I personally try to maintain the idea that it is my work – and thus I should earn money.

Here in Denmark there has been a change in the price structure in the energy market. Electricity is traded internationally – heat is more local. 

In 2002 I started building a 2,3 MW (700 kWe) biomass gasifier. At that time the electricity price was (or at least we where dreaming about it would be) approx. 20-25 UScent/kWh. And the heat was much less. But as the electricity marked liberalized the price on electricity dropped to 10,5 UScent/kWh (0,6 DKK) and the heat became much more expensive.

The fundamentals of the economy of a biomass gasifier for CHP is that you bye a cheap fuel (eg wood) you produce 20-30 % expensive product – electricity -  and 50-60 % cheap waste heat at a temperature level where it is saleable. 

But when I had to start the gasifier (and had spend 3 mio $)  the prices structure had turned the business model upside down making it MUCH more expensive to produce heat by a well working gasifier (that does not exist as far as I know) than by a wood chip boiler. 

My conclusion was to stop developing risky technology and become a consultant for some years. 


I am very interested to see the business plan that – According to the rules for getting public funds have to follow an application – was made to support the  DTU-Weiss gasification project. 


If anybody is interested there is a 2,3 MW 3 stage TK Energi gasifier for sale – if we can get 5000 $ more than scrap value we are happy . Never operated in this size – but 18.000 hours on a 400 KW pilot gasifier.



My conclusion is that energy is too cheap to justify the CAPEX and OPEX of a gasification system unless it is VERY big. 


But it is still my hobby J 


But for work I only work with large pressurized entrained flow gasifiers.










Fra: Gasification [mailto:gasification-bounces at lists.bioenergylists.org] På vegne af Tom Miles
Sendt: 1. december 2013 20:58
Til: 'Discussion of biomass pyrolysis and gasification'
Emne: Re: [Gasification] Small steam systems plus gasifiers for electricity




We have seen four or five biomass fired Stirling companies fail in the last 15 years. Successful Stirling engine companies  supply the solar and recreational markets with very small systems and run mostly on LPG.   


Stirling DK had the potential to fill an important niche. I liked their 9 kWe and 35 kWe units. It seems likely that they failed for business reasons as much as technical reasons. They were very slow to get organized and capitalize on the early experience of the DTU units. It is not clear why they charged so much.


We have a few small scale 50 kWe Organic Rankin cycle (ORC) generators in operation in the US. They seem to work very well for clean waste heat like exhaust from diesel gensets or biogas. One of my clients is testing one on diesel exhaust. http://electratherm.com/

The owner of a poultry farm tells me that his ORC unit works fine but the heat exchanger from his poultry litter fired gasifier keeps plugging up. (We have been there before.)  He gets 20-30 kWe from the $280,000 machine. The gasifier and ORC system cost $1 million. There seem to be conflicting reports about how much the system is actually run. 


Steam systems suit district heat or industrial settings where much more steam is produced than needed for electricity otherwise load balancing is a problem. We have seen a 1 MWe wood boiler and steam turbine system fail at a prison due to the inability to balance heating and electrical loads. We saw many small turbines in the 250 kWe-1.5 MWe range installed in the wood industry in the 1970s and 1980s. It was common to see a sawmill generate higher pressure steam and use a 500 kWe backpressure turbine to reduce the pressure for distribution to a large number of lumber dry kilns. We have lost most of our sawmills in our region and electricity is cheap so we haven’t seen any new systems installed. I visited a 600 kWe Russian turbine at a district heating plant in Hjordkær, Denmark in about 2004. At the time they had been running since 1997 and were happy with it. They were serving about 700 homes and a chocolate factory. It seemed like a good match.  


In recent years we have seen a couple of small scale steam systems in the 250 kWe to 2 MWe range. One supplier will provide a 1 MWe modular fluidized bed steam system for $5 million. These need to be installed in industrial or utility setting for reasons cited by others. 


We were disappointed last year not to find more gasifiers with demonstrated performance in the 2 MWe scale for the Alaska project. Nexterra was just installing their 2 MWe Jenbacher system at University of British Columbia. Babcock Volund gave us a budget price but didn’t think putting a unit in Alaska was interesting to them. Kawasaki Heavy Industries seems to have abandoned their program that was based on the CarboConsult downdraft gasifier. Their principal proponent of the system retired. Etc. And we didn’t want a gasifier with a wet cleaning system. We did receive budget proposals from some companies that had 150 kWe to 250 kWe gasifiers but that didn’t have field performance data to demonstrate their production with multiple units.


We still need to demonstrate more viable small scale systems with any technology. 







From: Gasification [mailto:gasification-bounces at lists.bioenergylists.org] On Behalf Of Thomas Koch
Sent: Sunday, December 01, 2013 9:42 AM
To: Discussion of biomass pyrolysis and gasification
Subject: Re: [Gasification] Small steam systems plus gasifiers for electricity




Striling.dk just went banckrupt – and gasification gas is Dynamite.




Fra: Gasification [mailto:gasification-bounces at lists.bioenergylists.org] På vegne af Jeff Davis
Sendt: 1. december 2013 18:37
Til: Discussion of biomass pyrolysis and gasification
Emne: Re: [Gasification] Small steam systems plus gasifiers for electricity


I would have to agree with Steve. Steam is a lot like playing with dynamite. A gas producer and an off the shelf engine is the system to beat.

Too bad nobody is working on a Stirling engine for using excess heat.


On 12/01/2013 11:29 AM, sabbadess at aol.com wrote:

I found that small steam at the residential scale is just a bad idea.


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