The Forestry Forum

General Forestry => Sawmills and Milling => Topic started by: Cedar Eater on April 09, 2002, 09:36:19 PM

Title: Steam Power
Post by: Cedar Eater on April 09, 2002, 09:36:19 PM
Does anybody make steam from wood waste to generate electricity? I've been wondering how much wood waste it would take to run a mill or a house or both. :P
Title: Re: Steam Power
Post by: Frank_Pender on April 10, 2002, 08:12:53 AM
I have been thinking the very same thing, Cedar Eater. :P  I guess great minds run in the same direction. 8)  I have a couple of friends that live within just a mile or two, that I have been talking with and they seem to feel that it can be done.  The major jurtle is the State and the Fed due to regulations,  >:(as steam under pressure is a bomb.   :'(  I know I sure would have to have some speail help in the design and set up.  I believe that the steam turns a small turbin or a pelton wheel of some sort for the generation for energy.
Title: Re: Steam Power
Post by: splinters on April 10, 2002, 12:28:20 PM
Hi Guys.  Around here there are some big outfits with steam powerplants.  To big for an individual. The buzzword seems to be biomass. You might check antique and steam engine associations. Iv'e found that these guys are as eager to talk old steam and uses as we are to talk trees and sawing.  I'd try for old technology rather than new because of simple and tried and true.  Steam ran most of the world until the 50's and they found out how to ship high voltages long distances.  Good luck and keep us informed.
Title: Re: Steam Power
Post by: Ron Scott on April 10, 2002, 06:00:34 PM
There are a number of Consumers Energy etc. cogeneration plants around the state. They burn wood chips to generate steam to generate electricity.

Cedar-Eater, have you visited the Hillman Cogen Plant near Lincoln? I guess they are in the process of getting a permit from DEQ to burn tires also, though the one here in Cadillac was denied a tire burning permit.
Title: Re: Steam Power
Post by: Scott_R on April 10, 2002, 07:58:09 PM
Woodmiser is in partnership with External Power LLC to develope a shipping version of the sterling cycle generator that external prototyped. Direct conversion of heat to electricity!! The prototype has very few moving parts and uses gas bearings. No oil to change. It is expected to go for ten years before neediing any servicing. I would love to have one especially if a large 3 phase version were available. GO ORANGE!  Scott_R
Title: Re: Steam Power
Post by: Cedar Eater on April 10, 2002, 10:00:03 PM
Wow, so there's some interest in this topic. I've done some digging :P and learned some particulars. There's an interest in home-sized and farm-sized systems among people who desire independence from "the grid" (survivalists, dairy farmers (ever tried to milk 200 cows by hand? :o), people who can't get 3-phase power >:(, etc....).

I think the plant in Lincoln that you're referring to is called Tractebel and they've been burning tires, sawdust, woodchips and who-knows-what for a while now. They're currently trying to get their permit upped to burn more tires. I have some background in industrial turbine generators from 600KVA up to 10MVA, but for a small operation, the rules are vastly different.

Roughly speaking, assume that 1KVA = 1hp (746 watts = 1hp, but there are losses in the systems) ???. So if your mill is 25hp, you need probably a 50KVA generator with a steam turbine or piston engine and a big flywheel to help your motor overcome it's startup current. Of course, there's always the option of running your mill with a steam turbine instead of an electric or gas motor, but then you have live steam in your work environment and that really increases the risk.

The key would be to keep the genset within the limits of low pressure systems (<250 psi) and to keep the heat output of the boiler below the radar for Fed and State environmental regs. Low pressure steam is much safer and less stringently regulated than high pressure. I'm not sure about this, but I think a 100 KVA system also falls just under the EPA limit. If you have employees, there's also some OSHA and other impacts.

Overall, this suggests that you could run a small mill and your household with the electricity and heat kilns, barns, homes (and even hot tubs) while condensing the turbine or engine "exhaust" (so that it can be recirculated into the boiler feedwater). Unfortunately, a 10KVA system costs about $10,000 and scaling it up to 100KVA could easily approach $50,000. Finding ways to decrease the cost or boost the efficiency of a cheaper system is something I would have to tackle.

The problem I'm hoping to find some expertise with is determining whether moving wood into the boiler would become a full time job. I wouldn't want to work full time just to be able to say goodbye to Consumers Power. ;D There's a logger/sawyer nearby who heats his home and a 30MBF kiln from an outdoor wood furnace that he supposedly only loads wood into once per day, but there's a big difference between letting the power company circulate the hot water and pouring in enough heat to produce a decent amount of electricity.

If anybody can conservatively estimate the heat content of a cubic foot of waste wood, I can probably track down a btu/hp ratio for steam turbines and steam engines. That would give me some handle on the scope of this.
Title: Re: Steam Power
Post by: Frank_Pender on April 10, 2002, 10:10:24 PM
Ceder Eater, that is what I do, I have two hot water systems (Taylor's)  that I use;  One for the home and one for the kiln.  I would sure love to convert both to being able to generate electircity with them.  I have on hand about a 150 yards of sawdust and chips right now.  I know where I could even get more if-need-be, in the future.  I can also get my hands on hundreds of gallons of used oil to burn, also  :P I just have to find the right comnbinations of people to help them come to pass. 8) 8)
Title: Re: Steam Power
Post by: splinters on April 11, 2002, 06:47:49 AM
I did some searching last night and it seems that one of the problems is going to be size. small 10-25 hp boilers would need a lot of attention. Small firebox. In this case bigger is better. You would be looking for a horozontal firetube boiler at least 50 hp. Fuel feed on a shaker grate. Thats like a cast iron pizza oven chain but set to feed down into the firebox. runs over excentrics to bounce. forced draft from behind the grate. Whole thing fed by a belt from supply. Wood fired boilers need cleaning often because of ash in the tubes and heating surfaces. This was from an Old Guy who was a fireman on a powerplant in a wood mill.  Personally, I'd use the wast to heat the kiln and make power with a diesel gen- set running on waste grease from mickey d's