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March 4, 2010 at 6:42 am #36648
I’d like to know the comparison of hybrid, off-grid, diesel generator and conventional generator,technically.
Could anyone do me a favour?March 5, 2010 at 5:24 pm #40731
The normal off grid system contains a battery bank and some kind of backup charging system. The backup charging system can be diesel, biodiesel, propane, or gas powered motor/generator. The solar/wind reduces the frequency of the backup generator run and its time. The combination of a generator, battery bank, and inverter is called a Genverter system.
Every off grid power setup is a Genverter system PLUS free charging sources like wind, sun, and hydro. So for example, comparing a straight diesel only power system to a diesel powered Genverter system is easy. The generator only solution must be run, just to power a 20W light when needed, and all the excess power is wasted. When the other equipment for a Genverter is added, you only run the generator to charge batteries, otherwise power is available 24/7.
Hope this helps clarify things for you.
MarshallMarch 6, 2010 at 12:44 am #40732
Hybrid off-grid diesel generator? Generally speaking the term hybrid is used with respect to propulsion systems as in ‘hybrid cars” It has also been misused in referring to multi-fuel internal combustion engines but neither term really makes sense when speaking about off-grid applications of generators. regardless of what they use for fuel.
Hybrid vehicles recapture energy by regenerative braking as when the momentum of the vehicle causes the wheels to keep turning while applying a drag that turns the electric motor backwards and recharges the battery a little bit. Although it is not specifically mentioned hybrid engine systems run at variable speed.
Conventional generator sets run at a constant speed to produce a fixed frequency and a steady voltage. Some generators are multi fuel where they can switch from one fuel to another such as regular diesel to vegetable oil fuel and at times this has also been labelled as ‘hybrid’ by non technical journalists who really should not write about technical subjects they are not qualified to comment on. They tend to quote experts but lack the insight to accurately quote a complex subject in fewer words.
One generator that comes to mind is the Honda EU2000i which is variable speed but as far as I know it does not run on multiple fuels only gasoline.
Any generator is capable of being used in an application that is off-grid. In fact if you are connected to the grid why would you bother to run a generator and pay more for power. If the utility power fails because the grid wires broke then you are already ‘off-grid’ and you now need the generator as a back up. You have to watch these marketing people and non technical journalists. They tend to confuse even simple technical subjects.March 6, 2010 at 3:42 pm #40734
Win your question asking for a comparison of hybrid, off-grid, diesel generator and conventional generator,technically has many possible interpretations and as many answers. A complete answer would fill a book. Especially when you ask for a technical answer. Diesel versus conventional generator. The obvious answer is the kind of fuel used but diesel engines tend to last three times as long between service intervals than comparable power gasoline engines. However Gasoline engines are convertible to run on propane, natural gas, or methane. All of the gaseous fuelled engines have spark ignition and thus run at lower compression compared to diesel which is compression ignition. Diesels can be converted to run on vegetable oil derivatives. Both diesel and gasoline engines are capable of running a fuel mixed with ethanol. Perhaps this is where you got the ‘hybrid”label from.
One difficulty with diesel engines especially those running vegetable derived fuels has to do with low ambient temperatures. When cold such fuels tend to reach a gel point at much higher temperature than gaseous fuel ‘gasoline’ type engines. At that point the fuel does not flow and you see engine stoppages or not even starting.
It is common procedure to have electric fuel heaters on diesel engines. In fact most road vehicles include a glow plug start sequence for cold weather starts and my ford truck had heaters in both fuel filter and the pipe inline between lift pump and the injection pump. The electrical energy required for this heating may be too much for a limited capacity off-grid system with a depleted battery bank. My recommendation would be to use a gasoline engine for cold weather starting. However since gasoline is relatively expensive this fuel option may not be as economical in the long run. Much depends on your location and climate. Where I live we see -30 C temps sometimes for a week or more on end and diesels are really hard to start. Now you need to consider an insulated generator building or else other means of pre-heating the diesel for a cold start. Propane suffers from a similar issue. The vapor point of propane at which it volatizes is -34 C but above that there is a point where the vapor cannot develop enough pressure in the tank to get a motor going. Natural gas is okay that way but you may find it difficult to get natural gas in an off-grid location.
I’m still not sure where the ‘hybrid’ label comes into play. Are you asking to compare ‘hybrid’ with off-grid? Or hybrid generators with conventional generators?October 27, 2010 at 6:22 am #41071
jamesraynor79ParticipantOctober 27, 2010 at 10:48 am #41072
Off-grid users who acquire a back up generator should keep something in mind.
If they have a charger capable of charging at 100 Amps into a 12V battery bank only consumer 1200 watts plus about 10% for conversion losses. A 24V bank charging at 100A is 2400 watts and so forth. In many cases this is a small percentage of the total output most gensets are capable of and as a result the generator runs at a very wasteful fuel burn rate.
Marshall has the right idea with his genverters concept wher a very small generator is used that is just large enough to drive the available chargers.
The other thing that is rarely discussed by people wanting to go off grid is the fact chargers must be matched to the battery bank size or you are likely to end up with battery problems. The cure is likely to be expensive.April 10, 2012 at 9:12 pm #42533
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