Micro CoGen.

I'm looking at various options for the most fuel efficient natural gas engines I can find. My conclusion is that all of the modern and most fuel efficient engines are very expensive and use some sort of lean burn technology, which is highly computer controlled.

It is possible for me to convert a standard, old school spark ignited natural gas engine with a simple carb/mixer and low pressure gas to run on a highly lean mixture? Lets say I take a naturally aspirated engine and add a turbocharger, doubling the air intake, but do not increase the fuel rate. Would I have problems running the engine? Can this be done without a modern computer system to control everything?

The idea/hope is to use an engine that is larger than necessary with a small fixed load for longevity, while still keeping the throttle near wide open to reduce pumping losses, just like a diesel.

Can this be done by a backyard mechanic or is this just for university studies and high dollar computer controlled gensets?

I am interested in putting together a large-ish inverter generator that would generate 60v using an ST head modified as described elsewhere on the forum, and then feed the 60v into an inverter. The engine speed would vary depending on load.

What I am curious about figuring out, is what happens when you over speed or under speed an ST generator head modified for 60v output? Obviously the frequency would be all over the place, but that's not a problem if I rectify into DC. What happens to the voltage when you spin an 1800 RPM head faster than 1800 RPM? Or slower than 1800 RPM? Does the head still maintain the same or similar voltage?

And will an 1800 RPM head survive if you ever spin it much faster than that?

I am attempting to find a good liquid cooled engine in the 30hp range to run from natural gas. I am trying to find something that will have the lowest BSFC. I expect to either increase the engine compression or add a turbocharger to increase efficiency and take advantage of the high octane of NG.

In this power range, I have found 3 major engine types to choose from:

1. Briggs and Stratton or Kawasaki aluminum block V-twin.
2. Geo/Suzuki 3 cylinder 1.0L aluminum block inline 3.
3. Briggs and Stratton .7L cast iron block inline 3.

I'm leaning towards #3, mainly because it has a cast iron block. Is an engine of the same design with an aluminum block going to have a higher BSFC due to the aluminum losing more heat? Or can that be controlled as long as the engine has a proper thermostat? Also, the Briggs engine is a converted diesel, so it should be able to handle turbocharging quite well. (turbo diesel is a factory option)
http://www.ebay.com/itm/131797201535

My other concern is number of cylinders. I think two is better than three. Is a two cylinder engine likely to have a better BSFC than a three cylinder of the same displacement?

Are there any other engines I should consider? I would also think about the Kubota 3 cylinder gas engines, much like the Briggs, but I can't find anywhere to buy one that is new.

I am interested in playing with the idea of CO2 enrichment in a greenhouse for increased plant growth. A lot of people use propane burners for this, mostly just a torch in a box. I would like to instead experiment with using the exhaust gas from a propane powered engine to generate the CO2. Unfortunately a lot more than CO2 comes out, and I need some sort of catalytic converter to convert the CO to CO2.

Does anybody know a source of a small catalytic converter that would work on an engine running in the 2-5hp range? I've found a bunch of industrial "scrubbers" for small engines through a google search, but no actual sources to buy them, or $500+. Are there any cheap OEM cats I might be able to find a modify that would work on an engine that small? Would anything from a small car engine be too large? (not enough exhaust heat?)

I'm looking for an engine to use for a larger cogenerator setup. To me it seems like choosing something that was used as a marine motor, and has water cooled exhaust manifolds available is a good idea. Unfortunately most of these motors are gasoline, not diesel, and too big for my use.

I want to collect as much waste heat as possible into my water system. With the exhaust manifold being the hottest part, it seems like the best place to collect heat energy. It's also really hard to create a custom water cooled exhaust manifold for a motor that was never used in a boat.

Lets say I made a simple shell heat exchanger around the exhaust pipe, after the manifold on a 3-4 cylinder motor. Now I wrap the exhaust manifold in insulation. Maybe some thermal barrier coatings. Would I still lose a lot of heat through the exhaust manifold? Is it going to be less efficient if I start collecting waste heat AFTER the manifold?

I am considering moving to a location off grid. If so I will probably be building a large diesel cogenerator (trigenerator?) system. My desire is to use some percentage of WMO, mixed with #2 diesel, and also some propane injection to hopefully increase burn efficiency and clean deposits formed from WMO. (minimal propane, it would be the most expensive fuel) I plan on having at least two generators, one for small loads, under 5KW, and another for larger loads.

I know using WMO is a controversial topic. Some people report great success, while others warn of immediate failure. My intention here is to use an engine that is really cheap to replace, or has cheap cylinder liners, and expect that waste motor oil will cause an increase in cylinder wear, and replace as needed.

I have a desire to use the GM/Detroit 6.2L diesel for several reasons:
- It's cheap and common, I can have a stack of spare long blocks on hand.
- I can buy water cooled exhaust manifolds meant for marine use.
- It's indirect injection should work well with WMO.
- It gets really good fuel economy in the 1200-1800 RPM range when fully loaded. Best economy at 1200.
- They have a really heavy flywheel for an automotive engine (more than 50lbs)

I found some detailed BSFC graphs for this engine based on JP8 and JP8 with WMO as fuel for military vehicle use. I have determined that it gets best fuel economy fully loaded from 1200 to 1800 RPM. At 1200 RPM I can get 50HP, 1800 RPM about 90HP. It gets really good economy in this range, .375-.425 lbs/hp/hr.

One big problem: That's a little more horsepower than I need. I would like a machine that gets good economy at 15KW electric power output and less. That's about 50% load at 1200 RPM.

What if I removed the pistons and push rods on four of the cylinders? Could I make an engine with half the displacement? Would it it be too unbalanced? Would it get bad fuel economy? I was thinking I could modify the connecting rods by cutting off the rod part and making two bearing caps. Then bolt this onto the crankshaft to keep oil pressure up from the missing cylinders.

Now, when the first 4 cylinders wear out from WMO, I could hook the other 4 cylinders up and run until they wear out. Think it could work? I know they used to make gas powered air compressors that only ran on 4 cylinders, and compressed air with the other 4. They still had the other 4 pistons for balance though. Could I compensate by externally balancing the flywheel? (6.2L is already externally balanced)

I'm sitting here bored out of my mind recovering from some surgery, googling stuff. I came across this article from the University of Wisconsin:
http://www.news.wisc.edu/16945

They claim to be running a modified Cat engine on a varying mixture of diesel and gasoline. They also claim to have achieved more than 50% thermal efficiency doing this. I'm wondering if any such idea could be applied to a generator?

I'm a little bit confused how they implemented the system. It says:

Quote"You can think of the diesel spray as a collection of liquid spark plugs, essentially, that ignite the gasoline," says Reitz, the Wisconsin Distinguished Professor of Mechanical Engineering. "The new strategy changes the fuel properties by blending the two fuels within the combustion chamber to precisely control the combustion process, based on when and how much diesel fuel is injected."

That makes it sound like a compression ignition engine. But then it says this:

QuoteIn addition, the system can use relatively inexpensive low-pressure fuel injection (commonly used in gasoline engines), instead of the high-pressure injection required by conventional diesel engines.

How would that work? Anybody else ever heard of this technology before? I thought maybe they were using gasoline in the same way some people use propane or natural gas to fog their diesel engine. But how could that work using "low pressure fuel injection"? The diesel pilot would have to be the normal high pressure system, wouldn't it?

I'm trying to research the running cost of a small natural gas engine. Can anybody help me find some rough average numbers for a single or twin cylinder engine? I am not able to locate a published fuel consumption on natural gas or propane for any small generator. I found a few giant ones, but that probably won't be the same. I found a very rough estimate of 10,000 BTU per horsepower, but that seems way high and a little too round.

I've wanted to setup a cogenerator for a very long time, but one of the biggest hurdles are permits and other rules from my power company. They of course allow standard net metering with solar panels, and other renewable energy sources, but they tell me specifically natural gas, propane, and diesel fuel are NOT included.

I would like to have a standard net metering setup with a generator instead of a solar panel. I can understand they don't want a homebrewed system connected to the grid. But what if I had a million bucks to spend and I bought a commercial natural gas cogenerator system? Maybe one of the ones made by Marathon, or Honda. I find it hard to believe something like that would not be allowed. I have a "smart" meter so I can't just run the meter backwards without permission like you could in the old days.

What I'm wondering is, are there any ways to grid tie a generator, WITHOUT ever feeding power back into the grid?

For example:
I have a 5kw generator and a 7kw power consumption. I can run the generator all day and still pull 2kw from the grid. If I turn off the load, I need the generator to automatically disconnect from the grid so as not to feed power back. Is this possible?

Also, is there any way to momentarily tie a generator to the grid, while you switch from one power source to the other? This way there is no loss in power for electronics.

I suppose I could generate DC power and use a grid tie inverter, but I'd like to generate AC power directly.

I'm looking hard for a small, single cylinder water cooled diesel engine that I can purchase legally in the US. About the only ones that I even know exist are Farymann diesel engines, I think they're used in sailboats. They show some interesting options on their website (http://www.farymann.com/) but where do you buy such a thing?

Are there any other small liquid cooled diesel engines I can buy? I realize it won't be cheap. I'm attempting to build something like the APUs they put on semi trucks, but sized for a pickup.

Hello everyone. I own a boat shop, recently we moved into a giant old fruit packing plant for a shop. I just got a $350 electric bill and I don't even have heat yet! We are burning around 3500 KWH per month. And it will go up. I want to set up a hydronic heat system, we have several odd little rooms that I want to heat scattered all around the building.

I've come across a source of lightly filtered WVO for $0.75 per gallon. I'd like to use this as fuel in the shop. Question is, am I better off simply burning this stuff in a boiler, or should I try to come up with a cogeneration setup?

Doing some very rough math, I'm thinking if I had a generator running from this stuff, I might get 10 KWH per gallon. That would be 7.5 cents per KWH, about 3 cents less than my utility - and free heat! Does that sound doable? Of course that does not count engine maintenance, or filtering of the oil. It wouldn't have to be a complicated grid tied sort of thing - I can easily move my lighting circuits to a generator, and it's no problem for me to turn on 10+KW of lights if I want some heat.

Or do you think that would be too much of a headache? Is it going to need constant maintenance to run 12 hours a day? I work on engines all day so a little tinkering is not a big deal, but I don't need another job. What engine should I be looking at? I know the choices are a bit limited by the EPA. I think I've seen some of the larger Chinese-type diesel engines on ebay recently.

If not, is there a sub $5000 commercially available boiler that will run on WVO?

Hello everyone. I am trying to setup a small generator that would keep some 12v batteries charged. I would like for the generator to sense that the batteries are low, automatically start and charge them, and then shut off. Is this possible? I would like to use an inverter generator that already has an electric start option. Does somebody sell any kind of controller that could start that generator for me?

I've found the Onan "Energy Command" system that basically does that, but I believe it only works with newer Onan generators. Is there a more generic system I could buy?