What everyone has been searching for is a simple power generator that operates using a common inexpensive fuel source. Under some circumstances it can provide your entire home electric power, heating and hot water requirements. The system is simple, reliable, has a long life and requires minimal maintenance. Many renewable energy sources such as solar, wind or micro-hydro partially offer some of these features but they do not work well in all areas of the country.

     The WOODGEN25 is a residential sized power plant that was designed to provide electric power and heat where ever stick wood is currently burned and is in fact a miniature version of a larger steam power plant. It is the first product of its kind to be made commercially available to the general public. In summery it burns wood, produces electric power, hot water and it is fully automated requiring only the addition of wood, removal of ashes and occasionally a small amount of water. It was designed to fit in the back of a pick up truck or on a small trailer for transportation to a remote site if necessary.  The product is very similar in appearance to an outdoor wood fired hot water system, except it is slightly longer to accommodate the steam turbine and generator. The basic size and appearance is as shown in FIGURE 1. The various parts are explained later in the specification section.

 

                                                                                 FIGURE 1

Legend
1. Firebox door
2. System status indicator/control
3. Ash removal
4. Water to air heat exchanger (water radiator).
5. Circulation coolant and turbine reservoirs.
6. Turbine and generator as well as auxiliary pumps.

    The WOODGEN 25 is about 36" at the lower legs and a maximum of 44" at the sides with an overall length of less than 80" and height of less than 60", though the height may be increased to simplify installation.

 BLOCK DESCRIPTION

                                                                         FIGURE 2

      Referring to Figure 2, a firebox is used to create steam to drive a small high-speed turbine coupled to a brushless DC generator. The steam is then passed to a condenser where it is condensed back to water and as well heats the cold water coming from the home. The reheated water is then sent under pressure back to the home. The freshly condensed water passes through a pump and back to the boiler to repeat the cycle. All the main pumps and alternator are directly driven from a single common turbine shaft. This configuration allows the system to generate power efficiently and cleanly from almost any biomass source though the firebox is optimized for stick wood. The eternal hot water leaves the condenser at about 170F  (76C) and is piped to the home or hot water storage tank. The temperature of the return flow and rate of flow will determine the maximum power available. An optional cooling radiator with fan is available to operate the system as a stand-alone generator only.

 INSTALLATION

Contact the factory for mounting details prior to installation. Many different mounting techniques are available.  For example the unit can be mounted using anchor bolts set in post-holes filled with cement. The unit is fully insulated to operate outdoors. The firebox is slightly pressurized so it may be possible to install it in a open structure if State or Provincial laws permit. As these laws are constantly changing you need to consult with the local building inspector etc. for applicability for your area.

 PRELIMINARY SPECIFICATIONS


Output Power  2.5kW @48Vdc (optional 24V)
kW hour per month 1500kWh, enough for 5 homes using battery backup for peak power demand.
                                   Assumes continuous operation, and average home usage of 300kWh/month. 
Battery Charging Connect generator output to existing battery charge controller.
AC OutputRequires customer supplied DC to AC Inverter for AC Power

System Control Microprocessor monitors and controls all critical parameters.
Service requirements Replace water, coolant etc. as required.
Service Life >40,000 hours at full power, bearing grease life.
 Typical Ball bearing life rated at over 100,000 hours with grease replacement.

Auxiliary Heating output up to >20kW, >60,000BTU per hour
System Overall Efficiency 60%, electric power + heat output, 10% estimated, electric only 

Size Fits in the back of a full sized pickup truck.
Length 6.7 feet (2.0m), Width 3.7feet (1.1m), Height 5.0 feet (1.5m)
Weight 1000lbs (estimated)

Firebox capacity 25 cubic feet (hardwood typically equivalent to 18 gallons fuel oil.)
Log length 39 inches, (1.0m) 
Burn time >24 hours estimated, depends on wood quality, power requirement etc. 
Water circulation Internal pump operates from turbine shaft.

 FUEL COMPATIBILITY

       Every attempt has been made to ensure long operational life of the firebox. The firebox uses a two-stage combustion process that will greatly reduce smoke as well as improve the operating efficiency. Using fuels, such as coal hasn't been approved as well requires special care to prevent overloading of the firebox and screen burnout. Low Sulfur hard coal has almost the same energy density as fuel oil so it offers much longer operation between loading.  The system can burn methane from sources such as the decomposition of manure etc. however, these units will require a special gas burner, still under development.

CAUTION: Do not burn materials that have been contaminated with metal, such as pressure treated lumber, wood containing staples, paper waste, wood scrap with nails, waste engine oil, plastics, garbage etc. The ash residue from these fuel sources as well as the smoke may contain toxic metals that are toxic to the environment as well they could cause premature failure of the firebox or pressure tubes. Consult local regulations concerning burning restrictions applicable to your area Please respect the environment by ensuring that your fuel source is safe and clean.

 RELIABILITY

         The WOODGEN25 has been designed to provide a long low maintenance life. There are no messy oil changes or spark plugs to be replaced. Cleaning of air filters or removal of ashes from the firebox is the principal maintenance requirement.

         The main turbine shaft drives a high-speed brushless alternator as well as the circulation pumps. This removes external pumps as well as other components that could be subjected to failure. The reduction in the total number of parts simplifies the complete system. High-speed ball bearings are used in the turbine with an extended grease reservoir having a projected life in excess of 40,000 hours, while operating at full power. Standard bearings are rated for over 100,000 hours with regular grease replacement. Replacement of grease is recommended after 30,000 hours or 5 years which ever comes first. The system has been designed to be resistant to damage during a freeze up, check with factory for optional kits to simplify the thawing out of the system after freeze up.

            Stainless Steel has been used in all critical areas of the system to ensure a long life without the need for replacement of critical components. The firebox and major turbine components are corrosion resistant alloys to give a long life to those parts subjected to extreme heat or corrosive conditions. Operating stress levels of critical components have been kept to an absolute minimum to ensure long life without failure.