FAQ
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Here’s answers to Frequently Asked Questions about the GEK Gasifier and gasification in general. If you do not find what you’re looking for, see also the GEK wiki and GEK forum. You can also ask questions and get improved answers in the newbie Q&A section in the forum. If confusion persists, please contact us at gek or through the form on the contact page here.
1. Will the GEK run my car, truck, generator, lawnmower, tractor, boat, etc?
The standard GEK is delivered with an Imbert type downdraft reactor sized to run engines in the 5 – 40HP. The standard reduction bell and nozzle configuration will run 5-20hp engines. Changing these particulars can expand the gas rate to support up to 40hp engines, or a 20-25kw genset.
Most people like to start with small engines– Listers, China Diesels, Briggs and Stratten, Honda V-twins, 4cyl car engines, etc. But you can easily adjust nozzle size and position, as well as change out the reduction bell to an optional larger version to support larger gas flows. We find the GEK is large enough to run common 4cylinder engines in smaller cars. Here’s an elaboration on the basic GEK running a Honda Accord with a standard 1600cc 4 cyl engine.
2. Does the GEK produce clean tar free gas?
The GEK does not promise, nor does it guarantee, clean gas or turnkey hands off performance. There are too many variables of fuel size, shape and moisture content, in combination the variables of the operator to guarantee specific results. However, we know through our extensive experience, and you can confirm through the community of GEK users, that the GEK will produce very clean syngas and run an internal combustion engine, when the gasifier is properly operated.
The basic GEK comes with a variety of improvements on historic Imbert gasifiers units that will increase the liklihood of your success. Add to these basics the Hot TOTTI waste heat recovery and recyling components, and range of success expands dramatically. This heat augmentation system makes it possible for us to run the GEK down to 3hp or 1kw continuous without tar. This is an impossibly low rate for a traditional non-heat augmented gasifier.
We like to say there is a “Triangle of Dependencies” for successful gasification: the operator, the fuel, and the machine. The weakest link in this triangle is usually the operator. To help newbie operators along, we’ve developed the equivalent of a “speedometer” and “tachmeter” to guide your operation. You can use this a formal set of numbers to read temp and pressure gauges and know when things are good (or bad) in your gasifier.
3. What kind of biomass can I use in the GEK?
The best fuel for a downdraft gasifier is a chunky and dry, carbon dense biomass. Things like wood chips, chunks, nut shells, coconut shells. Fine materials, lawn clipping, grasses, hay, leaves and similar will usually not work (though I’m surprised regularly by people who do make them work).
The fuel needs to fill bed in a manner which leaves void space between the chunks. The void space is where the gas passes, and where the combustion and cracking takes place in the hearth. If you put fine material in the gasifier, the bed will pack, stopping gas flow, and the correct conditions for tar cracking will not be established.
The perfect fuel is a 1” wood sphere. Such would have fabulous void space and wonderful mechanical flow characteristics. As most do not have large supplies of 1” sphere, we approximate. Anything from 0.5” to 1.5” chunks will do. Common wood chips made on a disk chipper and screened to remove fines will work well. Wood chips are the fuel we optimize for as it is what is available for the most users. Wood pellets will work too, though they are pushing the minimum size limit, and they will often decompose from steam if left in the hopper post run. In general, a chunk of wood about 1″ on a side is ideal, for air flow and combustion.
We do a lot of testing on different fuels to see how they run. The formal tests and numbers are here. If you want to just see the clean air filter and no tar after days of running a genset, see here.
4. How long will the GEK run on one hopper load?
It depends on how much gas you are producing and/or the amount of power you are making. In general, the standard 30 gal open top hopper on the GEK is sized for 4-8 hour runs. On the Power Pallet we use a stainless steel 55 gal open top hopper, which should last around 7-14 hours. The exact run time will also depend on the density of your feed stock, and the amount of moisture in it. For more detailed calculations, see number 12 below.
5. What kind of generator would you recommend?
Here’s a detailed exploration of what one wants/needs for a good producer gas genset, and a full inventory of options you might build or buy. This documentation is mostly from the era of our exploring the options for the Power Pallet. After going through everything from Listers to China diesels, Briggs and Strattons to Hondas, we’ve settled on the specifics seen here in the current Power Pallet.
6. Can I use the GEK to run a diesel engine?
Yes, you can run a diesel on wood gas in dual fuel mode. A little liquid fuel is still used for the pilot ignition. But about 90% of the fuel can be wood gas fumigated into the air intake of the engine. See here for more details.
7. Can the gas be compressed and stored for use later? If so, how?
Technically it can, but the economic returns and logistical hassles make it not really a good idea. The energy density is about 1/8th that of natural gas. It takes a very large amount of energy and/or very large storage vessels to store any reasonable amount. Pressurization and storage of natural gas is already a dubious proposition. Now make that 8x worse. Also, it is easy to get some oxygen mixed in with your made gas. mixing oxygen and fuel under pressure is a bad idea.
8. Will this be something I can use to feed energy back into the grid?
9. I want a bigger GEK to run a V-8 engine. Can you make me one?
This is easy in priniciple. The GEK Imbert is designed on a set of formal ratios for all vessel sizes and internal relationships, as well as the plumbing sizes for air in and gas out. You can see the steps for GEK upsizing here. The resulting new sheetmetal dimensions are easy to cut via the CAD design and CNC cutting method that produces the units currently.
In practice, however, the details of sourcing, logistics, information support, and unit testing make supporting multiple sizes simultaneously a challenge to our progress on the fundamentals. Thus we have tried to stay with the size the greatest number of users/developers want, and thereby optimize the potential for collaboration engineering and development on top of a common base. All the details we work out on the small units will transfer to larger units down the road. We will just get there faster by not forking the road from the beginning.
Nonetheless, if you have a more ambitious project and are interested in developing a larger GEK installation, write us and we can discuss the options.
10. All Stainless steel gasifiers look hot! Can I get the GEK in stainless?
We build GEKs in a motivated combination of stainless alloys and mild steels. Exotics are used only where required, thus minimizing price while maximizing longevity. For exceptional use situations, all stainless versions of the GEK are also available. Write us for details on the pricing.
11. Can I heat my house, cabin, garage, with the GEK?
(or)
Can I use the gas from the GEK in my existing boiler or water heater?
Yes the GEK will produce a flammable gaseous fuel that you can simple burn for heating. However, you will need to retrofit your heater/boiler with a new combustor that will properly burn producer gas. You can’t just put the producer gas into the same fuel line, as the mixture ratio of wood gas is very different than propane or natural gas. This retrofit or rebuild might be easy or difficult depending on your specific equipment and your building skills.
12. How much wood do I need to make (insert HP) or (insert KW)?
1 gal of gasoline or diesel will make about 15HP of shaft power for one hour. if driving a genset, this will produce about 10KWe.
1 gal of gasoline or diesel is equivalent to about 20lbs of biomass through a gasifier.
1 ton of biomass to power through a gasifier-engine system is equal to about 100gal of liquid fuel in a genset, or 1MW of electricity.
Thus, the main rule of thumb to remember:
1 kg of biomass ~ 2lbs biomass ~ 2m3/h woodgas ~ 1HP ~ 0.75KW
13. How much wood do I need to drive my car?
Here’s how to approximate how much power your vehicle requires at cruise?
60MPG = 1gal/hr or 15HP for one hour
30MPG = 2gal/hr or 30HP for one hour
15MPG = 4gal/hr or 60HP for one hour
Remember that wood gas contains carbon monoxide and thus should never be used indoors. It is not ok to run a wood gas heater, wood stove, boiler or otherwise inside an enclosed building, with or without ventilation.
14. What are the specs of the air compressor needed for start up?
The ejector venturi used to motivate the wood gas on start up runs off of compressed air. After the GEK gasifier is brought up to temperatures high enough to crack the wood tar, the air compressor is turned off and the engine motivates the wood gas through the gasifier throughout the duration of the run. The specs for the air compressor needed is about 6-8 CFM at about 90-120 psi.
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Not yet answered
- Can I burn coal in it?
-How much does it cost to ship a GEK to the UK, Canada, India, Australia, Germany, etc?
-If I get the current GEK version, will it be irrelevant after the next version comes out?
- How long does it take to get one delivered?
- What’s coming in the future.
- How hard is it to start?
- What are the maintenance needs?
