For <1MW capacity which is better for electricity generation

This is a very vague question because selecting a proper power plant is open ended.

Im not a plant operator, however, I have worked on case studies for both types. In my experience, both plants operate in the same way, with the exception of the steam plant where steam does the work in the turbine.

So as you can see, a steam plant has an added step in which a fuel is combusted to heat up water to superheated steam levels which is then sent to a turbine where it produces work.

Capital costs for each basic plant overall probably run around the same, so the major concern is the fuel and water costs.

Maybe someone else can fill in the numbers but this is for a basic plant.

There are many add ons that can be utilized to save energy though. To increase overall efficiencies, heat exchangers can be implemented which can be used to heat up inlet streams with the outlet streams from the turbine. This is why it's very open ended because many design varities exists. Also, blowdown may need to be considered if you are using a steam plant with a boiler.

So I would prefer a gasifing plant becuase there are less steps. Steam plants have more areas for losses in efficiencies since you have a "middle man" doing the work.

Gas where abundant is the way to go, they can be on stand by to generate for exess demand and because they run up quickly and can be stopped fairly fast they are now the prefered way forward. they are also less poluting. Cheaper over all to run.

On the other hand,A solar operated steam generator can produce the needed steam flow to turn the generator during the day and use your bio mass at night. Best of both worlds. Don't forget we may be short on gas from petrolium sorces in the near future.

Sorry sir, I am talking the context of "Biomass energy" please see this site

http://www.zenithenergy.com/faqs.HTM

See question number 3

Dear Sarvesh

I agree with ChemE119. To get a picture of which would be better solution, you have to specify whole lot of factors, including but not limited to fuel availability ( gasifiers run on biomass, I think you know about it, hence availability and cost ), consumption whether for captive or sale to utility/electricity board, capital cost, operation and maintenance cost etc. Furthermore if there is any byproduct coming out after gasification, then that changes the economics completely. There are not very many gasifier based power plants of approx 1 MW with proven track records. Thus Each method of generation has its plus points and limitations.

Thanks

Ashok Toshniwal, Bangalore, India

Here's a dumb question. Has anyone ever tried to find a way to harness the gaseous byproducts of beer and Mexican food as a source of fuel?

Dear Guest

Clearly your knowledge is limited. You have given an example of beer & Mexican food. While I donot know if there is any power plant running on beer or its cousins and Mexican food, but there are power plants running on biomass which includes waste wood etc. Max. capacity of power plant based on gasification technology, which I know of, is 1 MW installed in South India. This has been functioning for atleast 5 years now. Coconut shells & wood is used as a feedstock& gas produced in the gasifier is fed to an engine which is coupled to alternator for power generation. There is another distillery which is extracting methane from the effluent discharge. This is gas is fed to a gas engine/steam turbine to produce electricity

Do you still think this is a dumb question?

Thanks

Ashok Toshniwal, Bangalore, India

Considering that we have invented machines to milk cows, it ought to be possible to build machines to accumulate the CH₄ and aromatic hydrocarbons expelled by flatulance. Design would be simple... but getting society to cooperate?? That would be a totally seperate problem.

In my view there is no doubt - gasification is the better and much more efficient way to go. Indeed I believe gasification is better even for much higher outputs than 1MWe. I say better because form an engineering perspective as well as commercially the system is more efficient and that is nothing more than basic physics really. The size of plant is much less, you do not have the same issues with moisture content as you do for simple combustion and you do not have the same inefficiencies using an IC engine as making steam and driving a turbine - for the reasons already explained earlier in the thread. Take a look at www.iti-energy.co.uk where you will find details of our techncial partners technology. The latest version of the unit will produce 1.7MWe net for export and 1.5MWth for export assuming you use 300KWth for drying feedstock - which would not be necessary in India possibly. The unit will consume about 1.5Te per hour of woodchips to produce this ammount of energy. You can also use RDF, coconut shells, straw pellets etc etc so long as you have a homogenous fairly dense fuel medium. Thats a very high efficiency. This technology is probably the most efficient in the world today. Installed cost is about US$3M per MWe output based on current exchange rates. You can also take a look at http://www.schmitt-enertec.com/cogeneration/home.htm where you will find details of a German technology provider who makes a 200Kw unit.

Link FYI:

http://www.dynamotive.com/en/technology/westlorne.html