Diesel generator From Wikipedia, the free encyclopedia Jump to: navigation, search A diesel generator of 500kVA in a tourist resort in Egypt. A diesel generator is the combination of a diesel engine with an electrical generator (often called an alternator) to generate electric energy. Diesel generators are used in places without connection to the power grid or as emergency power-supply if the grid fails. Small portable diesel generators range from about 1kVA to 10kVA, while the larger industrial generators can range from 8kVA 30kVA for homes, small shops & offices up to 2000kVA used for large office complexes, factories and power stations. These generators are widely used not only for emergency power, but also many have a secondary function for providing back up power to utility grids. Ships often also employ diesel generators, sometimes not only to provide energy for electric systems, but also for propulsion. The use of diesel generators for propulsion is actually becoming more common because in this arrangement the generators do not need to be close to the propeller and instead they can be placed in better positions, usually allowing more cargo to be carried. Such a diesel-electric arrangement is also used in some very large land vehicles. Power generators are selected based on the load they are intended to supply power for, and that load's "mission critical" needs (e.g. a hospital needs to have 100% redundancy and up-time, a backyard standby unit to keep a hot tub warm isn't nearly as critical) Contents [hide] 1 Power plants 2 Supporting main utility grids 3 Engine Damage 4 Ratings o 4.1 Typical operating costs 5 Popularity 6 See also 7 External links 8 References  Power plants Diesel generators can be operated together (in parallel). The use of parallel running generators provides the advantages of more capacity, efficiency and redundancy. A power plant driven by diesel generators will typically include between three and six machines. Generators can be connected together through the process of synchronization. Synchronization involves matching voltage, frequency and phase before connecting the generator to a live busbar. Failure to synchronize before connection could cause a high current short-circuit or wear and tear on the generator and/or its switch gear. The synchronization process can be done automatically by an auto-synchronizer module. The auto-synchronizer will read the voltage, frequency and phase parameters from the generator and busbar voltages, while regulating the speed through the engine governor or ECU (Engine Control Module). Load can be shared among parallel running generators through load sharing. Like autosynchronization, load sharing can be automated by using a load sharing module. The load sharing module will measure the load and frequency at the generator, while it constantly adjusts the engine speed to shift load to and from the remaining power sources. As the prime mover of a diesel generator runs at constant speed, it will take more active load when the fuel supply to its combustion system is increased, while load is released if fuel supply is decreased.  Supporting main utility grids Emergency standby diesel generators such as those used in hospitals, water plant etc, are widely used in the US and the UK to support the respective national grids at peak times. In the UK for example, some 2 GWe of diesels are routinely used to support the National Grid, whose peak load is about 60 GW. These are sets in the size range 200kW to 2 MW. Control of the National Grid (UK) This is extremely beneficial for both parties - the diesels have already been purchased for other reasons; but to be reliable need to be fully load tested. Grid paralleling is a convenient way of doing this. In this way the UK National Grid can call on about 2 GW of plant which is up and running in parallel as quickly as two minutes in some cases. This is far quicker than a base load power station which can take 12 hours from cold. Whilst diesels are very expensive in fuel terms, they are only used a few hundred hours per year, and their availability can prevent the need for base load station running inefficiently at part load continuously. The diesel fuel used is fuel that would have been used in testing anyway. The tone or style of this article or section may not be appropriate for Wikipedia. Specific concerns may be found on the talk page. See Wikipedia's guide to writing better articles for suggestions.(December 2007)  Engine Damage Diesel engines can suffer damage under certain conditions that are sometimes encountered when used in a generating set- namely internal glazing and carbon buildup due to prolonged periods of running at low speeds and/or low loads. Such conditions may occur when an engine is left idling as a 'standby' generating unit, ready to run up when needed, if the engine powering the set is over-powered for the load applied to it by the alternator, or if the generator set's maximum output is far in excess of the normal loads placed on it, causing the diesel unit to be under-loaded. This is a common problem in generator sets. For example, a diesel generator set powering the lighting circuit of a building would be designed to be able to cope with the load of every light in the building being on. However, this situation rarely occurs, so for the vast majority of its operating life the diesel engine in the set will not be heavily loaded (maybe as little as 10% of the maximum load). Ideally diesel engines should run at least around 60-75% of their maximum rated load, and at around 75% of their maximum speed (although the phasing requirements of engines in generator sets can make these speeds hard to achieve). Glazing occurs due to low combustion temperatures and pressures in the engine cylinder. When an engine is loaded correctly, the load resists the movements of the crankshaft and piston during combustion. This causes the combustion pressure to rise as the volume of the cylinder cannot increase directly in line with the increase in pressure during combustion. Running an engine under low loads low cylinder pressures and consequent poor piston ring sealing – these rely on the gas pressure to force them against the oil film on the bores to form the seal. Low initial pressure causes poor combustion and resultant low combustion pressures and temperatures. This poor combustion leads to soot formation and unburnt fuel residues which clogs and gums piston rings. This causes a further drop in sealing efficiency and exacerbates the initial low pressure. Glazing occurs when hot combustion gases blow past the poorlysealing piston rings, causing the lubricating oil on the cylinder walls to 'flash burn', creating an enamel-like glaze which smooths the bore and removes the effect of the intricate pattern of honing marks machined into the bore surface. Hard carbon also forms from poor combustion and this is highly abrasive and scrapes the honing marks on the bores leading to bore polishing, which then leads to increased oil consumption (blue smoking) and yet further loss of pressure, since the oil film trapped in the honing marks maintains the piston seal and pressures. Un-burnt fuel leaks past the piston rings and contaminates the lubricating oil. At the same time the injectors are being clogged with soot, causing further deterioration in combustion and black smoking. This cycle of degradation means that the engine soon becomes irreversibly damaged and may not start at all and will no longer be able to reach full power when required. The problem is increases further by the fact that a lightly-loaded diesel engine may never reach its designed operating temperature. This can cause carbon build up from poor combustion, oil dilution and the formation of acids in the engine oil caused by condensed water and combustion by-products which would 'boil off' at higher temperatures. This acidic build-up in the lubricating oil causes slow but ultimately damaging wear to bearing surfaces. Under loaded running inevitably causes not only white smoke from unburnt fuel due to the engines failure to heat up rapidly, but over time as the engine is destroyed it is joined by the blue smoke of burnt lubricating oil leaking past the damaged piston rings, and the black smoke caused by the damaged injectors. This pollution is unacceptable to the authorities and any neighbours. In fact at the diesels at Weymouth’s Radipole pumping station, before Wessex Water took them over and before they were converted to load management, on more than one occasion the fire brigade were erroneously called out to a supposed fire as they suffered just such an eventuality. The thick white smoke was routinely reported as a traffic hazard. Now, however, whilst housing estates have subsequently been built close up to the station there are no complaints. With a fully loaded diesel there is only a very short puff of white smoke which rapidly disappears once the diesels warm up in a matter of seconds. Once glazing or carbon build up has occurred, it can generally only be cured by stripping down the engine and re-boring the cylinder bores, machining new honing marks and stripping, cleaning and de-coking combustion chambers, fuel injector nozzles and valves. If detected in the early stages, running an engine at maximum load and a high throttle setting for a long period, to raise the internal pressures and temperatures, might allow the piston rings to expand and scrape glaze off the bores and allow carbon buildup to be burnt off. However, if glazing has progressed to the stage where the piston rings have seized into their grooves due to glaze, this will not have any effect. In the 1987 storms, 50% of Thames Water generators failed to start or stay running due to the failure to undertake these regular full load runs.  Ratings There are internationally agreed definitions of the rating levels for diesel engines. Standby - Output available with varying load for the duration of the normal source of electrical supply. In essence it is the "prime overload" condition with no time limit for an engine which is normally not operated. Prime - Output available with varying load between 25% and 100% of the rating for an unlimited time. The unit can be overloaded to 110% of the rating for one hour in twelve. Continuous - Output available without varying the load for an unlimited time. If the standby rating were 1000 kW, then a Prime Power rating might be 850 kW, and the continuous rating 800kW. Wessex Water sets are sized initially on the standby rating for emergency use, but are run on Load Management at the Continuous rating level which is about 80% of the standby rating.  Typical operating costs Approx. £3k to fit the PLC to the set Paralleling and synchronising gear and G59 equipment (this allows grid connection) Approx £5k Tidying up set (noise, larger fuel tank) Approx another £5k So for a 1MW set…£13/kW 50 kW…maybe £260/kW Running costs - fuel 10p/kWh maintenance about 0.5p/kWh This is very cheap capacity considering power stations are about £350/KW) for a CCGT. A diesel set itself is about 150/kW fully installed and connected.  Popularity Wessex Water has 550 generators of capacity 110MW in the range 50 kWe to 1.2 MWe. Presently, it only uses 32 generators of the larger sets (greater than 250 kW) with 18MW total capacity for Load Management / Triads / Reserve Service. Many of the other smaller sets have started to be converted also. According to EA Technology nationally there are up to 20 GW of emergency diesels. With the right financial incentives and explanations of the benefits large numbers of these could be brought into the Reserve Service type of scheme. Over 20 years this practice and associated technology will probably become standard.  See also motor-generator 3 phase loads  External links California Air Resources Board (CARB) - Verification Classifications for Diesel Emission Control Strategies California Air Resources Board (CARB) - Verified Technologies to Reduce Emissions from Diesel Generators [http://www.dieselgenerator.co.za/generators.html Diesel generator specifications and diagrams Why Should I Choose a Diesel Powered Engine or Generator? In today's world, where fuel prices are increasing as a consequence of spiraling demand and diminishing supply, you need to choose a cost effective fuel to meet your needs. Thanks to the invention of Rudolph Diesel, the diesel engine has proved to be extremely efficient and cost effective. Diesel fuel is priced moderately higher than gasoline but diesel has a higher energy density, i.e. more energy can be extracted from diesel as compared with the same volume of gasoline. Therefore, diesel engines in automobiles provide higher mileage, making it an obvious choice for heavy-duty transportation and equipment. Diesel is heavier and oilier compared with gasoline, and has a boiling point higher than that of water. And diesel engines are attracting greater attention due to higher efficiency and cost effectiveness. How Does a Diesel Engine Work? The distinction lies in the type of ignition. While gasoline engines operate on spark ignition, diesel engines employ compression - ignition for igniting the fuel. In the latter, air is drawn into the engine and subjected to high compression that heats it up. This results in a very high temperature in the engine, much higher than the temperature attained in a gasoline engine. At peak temperature and pressure, diesel that is let into the engine ignites on account of the extreme temperature. In a diesel engine, air and the fuel are infused into the engine at different stages, as opposed to a gas engine where a mixture of air and gas are introduced. Fuel is injected into the diesel engine using an injector whereas in a gasoline engine, a carburetor is used for this purpose. In a gasoline engine, fuel and air are sent into the engine together, and then compressed. The air and fuel mixture limits fuel compression, and hence the overall efficiency. A diesel engine compresses only air, and the ratio can be much higher. A diesel engine compresses at the ratio of 14:1 up to 25:1, whereas in a gasoline engine the compression ratio is between 8:1 and 12:1. After combustion, the combustion byproducts are removed from the engine through the exhaust. For starting during cold months extra heat is provided through 'glow plugs'. Diesel engines can either be two cycle or four cycle and are chosen depending on mode of operation. Air-cooled and liquid-cooled engines are the variants to be chosen appropriately. It is preferable to use a liquid-cooled generator as it is quiet in operation and has evenly controlled temperature. Advantages of a Diesel Engine The diesel engine is much more efficient and preferable as compared with gasoline engine due to the following reasons: Modern diesel engines have overcome disadvantages of earlier models of higher noise and maintenance costs. They are now quiet and require less maintenance as compared with gas engines of similar size. They are more rugged and reliable. There is no sparking as the fuel auto-ignites. The absence of spark plugs or spark wires lowers maintenance costs. Fuel cost per KiloWatt produced is thirty to fifty percent lower than that of gas engines. An 1800 rpm water cooled diesel unit operates for 12,000 to 30,000 hours before any major maintenance is necessary. An 1800 rpm water cooled gas unit usually operates for 6000-10,000 hours before it needs servicing. Gas units burn hotter than diesel units, and hence they have a significantly shorter life compared with diesel units. Applications & Uses for Diesel Engines Diesel engines are commonly used as mechanical engines, power generators and in mobile drives. They find wide spread use in locomotives, construction equipment, automobiles, and countless industrial applications. Their realm extends to almost all industries and can be observed on a daily basis if you were to look under the hood of everything you pass by. Industrial diesel engines and diesel powered generators have construction, marine, mining, hospital, forestry, telecommunications, underground, and agricultural applications, just to name a few. Power generation for prime or standby backup power is the major application of today's diesel generators. Check out our article on the various types of engines and generators and their common applications for more examples. Power Generators Diesel powered generators, or electrical generator sets, are used in countless industrial and commercial establishments. The generators can be used for small loads, such as in homes, as well as for larger loads like industrial plants, hospitals, and commercial buildings. They can either be prime power sources or standby/back-up power sources. They are available in various specifications and sizes. Diesel generator sets rating 5-30KW are typically used in simple home and personal applications like recreational vehicles. Industrial applications cover a wider spectrum of power ratings (from 30 kW to 6 Megawatts) and are used in numerous industries throughout the globe. For home use, single-phase power generators are sufficient. Three-phase power generators are primarily used for industrial purposes. There are several types of fuels that can be used for generators. It is however seen that the diesel generator is normally the choice of the commercial generator user. This is due to their ability to be both very portable and powerful making them suitable for a wide range of uses. In addition to these features there is also the added benefit of being dependable. The typical diesel generator is run at 1800RPM and is water cooled. This makes them great work horses as they are able to run for longer periods of time when compared to the gasoline generator and without much maintenance work required. They are also cheaper to operate due to the low fuels costs as compared to the other types of fuels such as gasoline and propane as well as the lowered maintenance costs due to there being no spark plugs and carburetors. The diesel generator operation is similar to that of the diesel engine. There are two types of diesel engines. The 2-stroke and the 4-stroke operation are the two types. The 4stroke operation is the one that is typically used in diesel generators. This process as the name implies uses four strokes. The first stroke is the power stroke where a fine mist of diesel is sprayed on top of the piston in the hot compressed air space. The fuel is then ignited and the air on top of the piston expands. This pressure then causes the piston to move down and this motion is converted to a rotary motion by a rod that drives the crankshaft. The next stroke is the exhaust stroke which is initiated by the momentum of the crankshaft turning and the piston then moves up. The next stroke is the suction stroke and this is when the piston reaches the top and the momentum continues so that the piston reverses in direction. The piston then moves down and the compression stroke is next where the direction of the piston is again changed after the lowest point. This cycle continues for the operation of the diesel generator. Although the diesel generator is by far the cheaper generator overall it can cost a lot more to set up initially and this can be a deterrent to many generator users. The generators are also not as clean burning as the other fuel generators although this has improved much in recent times. The diesel generators may also require a larger store of fuel but this is much safer to store than gasoline. Another disadvantage of the diesel generator is that it can be a lot more noisy compared to their counterparts. Many persons however believe that the savings that can be derived from an investment in the diesel generator are indeed well worth the disadvantages. The savings in fuel and maintenance are immense and the hassle free maintenance is a great plus. This is the reason many commercial generator users opt for the diesel generator. Diesel generators are available in mainly larger designs but can also be found on occasion in smaller units. Generators on the Market Today » How a Diesel-Powered Generator Works Ads by Google Make Your Car Burn Water Run Your Car Using Water Now Drive Your Car On Water Fuel CarHydrogen.leading-world.com Diesel-powered generators are used to provide electricity in a variety of situations. Many families use large diesel units to supply electricity to their home during power outages. Smaller diesel generators can even be brought on camping trips or placed on jobsites. These handy power providers use simple principles in order to provide precious energy. Understanding how they work is simple. The energy from the combustion engine is converted into electricity by the generator. How this happens requires a little more explanation. The Diesel Engine Large trucks, passenger trucks, and even some cars on the market today have diesel engines. Of course, these engines are best known for their use in tractor-trailers. Industrial shipping would not be the same without the use of diesel combustion engines. Diesel is a derivative of crude oil that is less refined than gasoline. Until recent spikes in the price and demand of crude oil, it was cheaper than regular gasoline. A diesel engine differs from a gasoline because it uses compression in order to ignite the fuel. Pistons compress the air and fuel in the combustion chambers and it self-ignites. Gasoline engines use a spark plug to achieve the same result. The resulting reaction creates the energy necessary to propel the vehicle forward or, in the case of a generator, turn a wire coil. Diesel engines are preferred in industrial applications because they are more efficient and provide more power than other combustion engines. This is in part due to the way fuel is injected into the combustion chamber. The engine measures the right amount of fuel for the amount of air, creating better conditions for combustion. The fuel itself also contains more energy by volume than gasoline. Though the engines have to be bigger than those that use gasoline, they are overall more productive. The Electric Generator As combustion occurs inside the diesel engine, the energy is used to drive pistons. The mechanical energy of the pistons is designed to rotate a rod going into the generator. The sole responsibility of the generator is to convert this mechanical energy into electric energy. Usually this is achieved by spinning a small arm attached to a coil of wire. The wire spins inside magnets of opposite charges. This forces electrons through the wire and creates a current. Soon the electricity is flowing, and the outlets located on the unit have power. Uses and Considerations Diesel is used almost exclusively as the fuel for large industrial generators. This is because it is able to provide more power with less fuel. Additionally, it can be purchased from distributors without a highway tax added onto the price. Most diesel-powered generator will even run off of biofuel. The combination of a diesel engine and generator can be package into smaller units that are more portable than industrial models. Even though they are small, the engines in these products still give off heat and dangerous emissions. These generators need to be kept outdoors away from flammable material. It is also a good idea to learn how to properly store extra diesel fuel. Many families choose to buy a generator for unexpected power outages. A professional electrician can connect large generators directly to a home. They can wire a transfer switch to the electrical system in order to avoid feeding power back into the outside line. There are also natural gas and propane generators available for this type of project. Diesel options are the most expensive, but also the most efficient. Portable diesel units can be transported to job sites and camping grounds. Though these units provide less power than permanent installations, trailer units can run several large appliances at a time. The unit will not only have to be able to handle the running wattage of the item, but also its starting wattage. It is not good to overload a generator, but it can be especially easy to damage smaller ones. Lastly, diesel generators need to be allowed to warm up upon start-up and cool down before fueling. Letting the generator warm up will assure it will run more smoothly and be able to handle appliances rated up to its capacity. Turning the generator off before refueling will let the heat dissipate and reduce the risk of fire. Diesel-powered generators are cost-effective and efficient machines. Handling them correctly and performing proper maintenance will guarantee many years of service. About Author: Why Pick Diesel: Diesel powered portable generators remain the number-one choice for standby and emergency power systems worldwide. You rely on many appliances and systems in your home or business for your health, comfort and security. Most depend completely on utility supplied electricity. It makes sense to have a backup diesel generator system that will keep your family comfortable and your home safe in a power failure. Our diesel generator sets are rugged dependable and reliable with excellent mechanical and electrical performance. Careful preparation is essential to select, buy and install a backup system. Don't leave it to the last minute. You should have time to learn how to use the system in advance. During a power failure, you may not be able to find suitable, reasonably priced equipment, fuel, and/or installation. Keep the system simple, so you and your family can operate and maintain it. Your emergency system must work reliably when needed. A backup power system should power most efficient appliances. We carry a wide range of products perfect for home, construction and emergency standby power. Simple operation with wireless remote starting and warranties that help protect you in the future. We remain a leader in the Industry and are a proud member of the Better Business Bureau. Portable Generators: Picking a generator that is right for you will depend on your power needs. Portable generators are the most popular because of their ease of use. Portable generators are often kept protected in a shed or garage until needed and then wheeling them outdoors. You have the ability to move them from one location to another. Portable generators cost less to operate and maintain then larger fixed type. Permanent Installations: These require professional installation and permits. Some jurisdictions require that the fuel tank be barred underground and with the special hookups required. The extra work involved is often not worth the costs associated with it. You can purchase two smaller generators at the fraction of the cost and get the same amount of power. How much power do you need? The silent type diesels are one of the largest you can get for residential use. Consequently this is more then enough power for the average homeowner. You can run a a fridge, freezer, pumps, television, microwave and lights. It is the most popular unit for home owners. Often large heating and air conditioning units require a lot more power then a portable generator can provide so in order to remain cost effective and not over spend on a larger more expensive unit most will use a spare window air conditioner that uses far less power then a whole home air is far less expensive to purchase then a second generator. You can also save power by switching your light bulbs to energy efficient florescent fixtures. Install one or two ceiling fans. Noise Levels: There are two type of portable generators. Open frame and closed frame. The closed frame are also known as "silent generators" The larger closed frame units have much larger mufflers and sound insulation to make them no louder then the level of two people taking to each other at 7 meters away. Diesel or Gas Generators: Why diesel-power instead of gasoline? Unlike gas engines, diesels have no spark plugs to replace, or carburetors to rebuild and service. Diesels generally burn less than half the fuel that gas engines do to do the same amount of work. Diesels regularly outlast gas engines ten-to-one. For example, the average gas engine powering a generator will run for around 1000 hours before needing replacement or a complete overhaul. And that’s an average. Many don’t make it past a few hundred hours. The average diesel engine will run 20,000 hours before needing any service beyond routine maintenance, but many make it to 50,000 hours, and some a lot longer than that. At four hours a day, even 20,000 hours works out to nearly fourteen years. Fuel Savings: The fuel-efficiency alone is a good reason to buy diesel, plus off-road diesel fuel is cheaper than gasoline. It’s also a lot safer to store. It’s flammable, but not explosive like gasoline. And although diesels sometimes produce more visible exhaust, it is less toxic than the emissions from a gasoline engine. A well-tuned diesel, by the way, produces no visible exhaust except briefly, under severe load-changes. Diesels sound scary to some people who are unfamiliar with them, but they are actually simpler in design and construction than gas engines. If you can service a gas engine, you can service a diesel. And it requires less service. The only maintenance generally required is changing the oil, and changing the fuel, air, and oil filters. This much is the same as on a gas engine. What you won’t have to deal with is tune-ups. No carburetor adjustments, no distributor or magneto to burn out, and no spark plugs to need periodic cleaning and replacement. Oil changes done on schedule are critical and make the difference between an engine that wears out prematurely and one that runs nearly forever. Diesel generator power is a sensible choice especially when integrated into the total system By Skip Thomsen Diesel Power? What about solar? What about the environment; don’t diesel engines use fossil fuels and create pollution? What about political correctness? I would never suggest that anyone who has the capability of using solar power do anything but. Powering your homestead with free, non-polluting power from the sun or from a hydroelectric system is the ideal way to go. But for some of us, solar isn’t feasible. Some folks live where the sun rarely shows its face throughout the four or five coldest months of the year, coincidentally when we need the most power. Others operate home workshops and/or businesses that require more power than any affordable solar array could possibly develop. For those folks, diesel power can be a viable and efficient option. Utilizing a generator to power the homestead doesn’t have to be an environmental disaster. A generator can be a very efficient component of your independent energy system. The key is to observe a few basics: make the generator part of the system instead of a sole source of power. Making the generator “part of the system” means that it is always working in conjunction with the rest of the system. If at all possible, operate the generator only when lots of power is required, as on the days of the week you do your laundry, vacuum the house, operate your shop, pump irrigation water or any other heavy use. And during those times, the difference between the power you are actually using and the full potential of the machine should be going into your battery bank. There are few solar installations that don’t require some generator backup occasionally. A generator is available in some of the best of solar homes for those times when the sky is grey for weeks at a time, and in many cases, for heavy-duty power needs. A lot of well-designed solar homes are planned for scheduled generator usage. Perhaps one day a week, all the heavy-power-demand chores are done. On this day, the generator is run all day long, and any surplus power (the difference between what the generator will produce and what is being used), gets sent to the storage batteries. Operating a generator at near its full potential is the most efficient use of the machine. So since a generator will be required in just about any beyond-the-grid installation, why not have it be a machine that’s designed for serious use instead of a home-handyman unit that’s specifically designed for light-duty, intermittent use? Why a diesel? Why diesel-power instead of gasoline? Unlike gas engines, diesels have no spark plugs to replace, or carburetors to rebuild and service. Diesels generally burn less than half the fuel that gas engines do to do the same amount of work. Diesels regularly outlast gas engines tento-one. For example, the average gas engine powering a generator will run for around 1000 hours before needing replacement or a complete overhaul. And that’s an average. Many don’t make it past a few hundred hours. The average diesel engine will run 20,000 hours before needing any service beyond routine maintenance, but many make it to 50,000 hours, and some a lot longer than that. At four hours a day, even 20,000 hours works out to nearly fourteen years! Diesels are built to last. They’re built to produce their rated output for years on end. Most gasengine generators are built specifically to be used for intermittent or emergency power. Almost all gas-engine generators run at a self-destructing speed of 3600 RPM. Most diesels run at half that speed. The fuel-efficiency alone is a good reason for a diesel, plus off-road diesel fuel is cheaper than gasoline. It’s also a lot safer to store. It’s flammable, but not explosive like gasoline. And although diesels sometimes produce more visible exhaust, it is less toxic than the emissions from a gasoline engine. A well-tuned diesel, by the way, produces no visible exhaust except briefly, under severe load-changes. Diesels sound scary to some people who are unfamiliar with them, but they are actually simpler in design and construction than gas engines. If you can service a gas engine, you can service a diesel. And it requires less service. The only maintenance generally required is changing the oil, and changing the fuel, air, and oil filters. This much is the same as on a gas engine. What you won’t have to deal with is tuneups. No carburetor adjustments, no distributor or magneto to burn out, and no spark plugs to need periodic cleaning and replacement. Oil changes done on schedule are critical and make the difference between an engine that wears out prematurely and one that runs nearly forever. The bad news What about initial cost? Yep, diesels cost more initially than gas engines. But if you do the math on how the costs compare over a few years’ time, the diesel always comes out way on top. Plus, if you compare the initial costs of small diesel generators to premium-quality gas generators, the differences start to fade. Sure there are cheapo generators available, but these units just cannot be depended upon for any kind of constant service. They’re not built for it, and they won’t take it. I’ve had neighbors who’ve bought those garden-variety generators for $4-500, and they used to tell me about how great the guarantees were. They smoked another generator every couple of months, and all they had to do was to haul it back to the dealer and he’d give them another new one. Now doesn’t that sound just like how you would like to spend your time? Not to mention being without power every time another generator died. At the same time, we had our little diesel putt-putting away for years and years, without a single problem. The throw-away gas generators were screaming their little overworked hearts out, burning nearly a gallon per hour of gasoline, and our diesel was producing twice the power and running for five hours on a gallon of diesel. OK, so what’s available? Well, like gas-powered generators, small diesel generators come in various grades of durability, too. Unfortunately, the general theme is this: the bigger the machine, the better it’s built. For example, most of the smaller machines, like up to about 6 KW (kilowatts), use engines that run at 3000 to 3600 RPM (revolutions per minute). I don’t know why manufacturers choose to design a generator that requires such a high engine speed, unless it’s to be able to use smaller engines. Engines develop more horsepower at higher engine-speeds (RPM), so a smaller engine running at up to 3600 RPM can produce the same amount of power as a bigger one running at 1800 RPM. Two problems result from the higher RPM: shorter engine life and, in most cases, much more noise. Fuel consumption is usually higher on the higherRPM machines, too. OK, for you folks who are serious about homestead power and maybe have a shop or business that will depend on a totally dependable source of clean, stable power, there’s a jewel of a machine being offered by Onan. It’s their Model Number 8.0HDKAQ. This is a specially developed 1800 RPM, water-cooled, 8KW single- and three-phase generator that’s designed for continuous duty applications. It also has a lot of installation flexibility, with cooling-air discharge that rotates to either side- or bottom-discharge, and multiple oil-check and fill locations. All connections and controls are waterproof and sealed for safe and trouble-free installation even in harsh environments. I just talked to somebody who has had one of these machines running for years with no repairs at all. His is the older-model unit, but the only difference between it and the new one is the better noise-control on the new one. This genset (generator set) uses the proven Kubota three-cylinder diesel engine, and at about a 75% load, it runs four hours on a gallon of fuel. OK, you were going to ask sooner or later: it costs around $7000. Yes, that’s a lot of money, but if you look at the long-range picture, it still looks pretty good. In the first place, if you need a machine of this capability, a serious-duty gasoline-engine generator is going to cost at least $2000, and most are higher. (The consumer-brand machines that boast of even 5KW and are available for under $2000 won’t last long enough to even consider as an option.) Figure then that most gas engines need an overhaul (or replacement) after about 1000 hours of operation. But the diesel is good for at least 20,000 hours, and quite possibly twice that. Then factor in the fuel-consumption. Even a five-KW gas generator will burn a gallon per hour. This 8 KW diesel goes four hours on a single gallon. For the sake of a comparison, let’s assume four hours a day of use for a year. That’s 1460 hours. At a comparative figure of $1/gallon for off-road fuel, the gas unit will have used $1460 worth of fuel. The diesel, in the same amount of time would have burned $365 worth of fuel. So just the fuel savings alone would be $1100/year. Add to that the fact that the diesel will continue to faithfully produce dependable power for 13 years (figuring a 20,000 hour overhaul time), while the gas unit will likely need an overhaul at the end of its first year. The savings become obvious, don’t they? There’s another contender in about the same price range, too. It’s the “CLC Certex” series from Power Systems Engineering, and it is available from Northern Hydraulics of Burnsville, MN. This one’s for folks who need serious power, like 20 KW. The machine uses a Detroit Diesel Engine and is built for full-time operation. It’s way bigger than any basic homestead could ever use, but if you have a shop or business that needs this kind of power, this is a good machine. An alternative to the above generators, most of which use imported (mostly Japanese) diesel engines, are the gensets using engines made in China. Known generally as the China Diesels, these machines are notably cheaper, run at 1800 RPM (or less), and have an amazing life-expectancy. They also use less fuel for the same output of power than any other generators I’ve found. I’ve personally seen some of these little engines with well over 20,000 hours on them, still chugging dependably along. I even wrote a book about the China Diesel I used to run my homestead for years (see end of this article). However, the China Diesels seem to be happiest in the hands of owners who have a certain amount of mechanical savvy. Although I ran one for many years without a glitch, I have interviewed lots of owners who haven’t been so fortunate. In many cases, there had been problems, but most were easily solved with a bit of ingenuity. In almost all of these cases, once the bugs were worked out, the machines performed well from then on. If you need a machine that you can just plug in and forget about (except for routine maintenance, of course), the name-brand commercial units are a safer, if more expensive bet. But buyer beware: for the generators with the high-speed (3000-3600 RPM) diesels, I’ve heard time-before-overhaul figures ranging from 1000 to 3000 hours, and fuel burn promises of two hours per gallon. To me, that’s unacceptable. Maintenance = long life As with any internal combustion engine, proper maintenance is essential. Diesels are no exception, and the most important maintenance is oil changes. An oil change every 100 hours of operation is normal operating procedure for a diesel engine, and it will assure a long and trouble-free life. Regular air- and fuel-filter maintenance is also essential, and fuel filtering is one area where diesels are more demanding than gas engines. Diesels use precision fuel injectors that are ultimately dependable as long as they are kept clean. Even a tiny speck of debris can clog a fuel injector nozzle, so it is essential to keep a good-quality fuel filter in the system. The normal setup is to have a large, paper-element fuel filter somewhere in the fuel line between the fuel tank and the engine, and another filter, usually the canister-type that comes with the engine or genset, right on the engine itself. The first filter, available at most auto/truck supply stores, can be mounted on the wall of the generator shed. An outside location is usually preferred because of accessibility and the propensity to spill a splash or two of fuel when changing the filter element. If your generator shed has a wooden floor, spilled fuel (or engine oil) can create a serious fire hazard. Operating tips There are two things to remember to keep your diesel healthy as long as possible: The first is that these engines do not like to be started up for short runs. In other words, don’t start your generator for a 10-minute project. Ideally, the generator should be started and allowed to reach normal operating temperature before any big loads are applied, and it should again be allowed to run at a light load for a few minutes before shut-down. The reason is to avoid rapid temperature fluctuations. One secret of long life (of any engine, actually) is to allow it to make its necessary temperature fluctuations gradually. Shutting down an engine after it’s just been running at full load for a while means that it will cool more rapidly than is healthy for it. The second thing to remember is that diesel engines like to work hard. Matter of fact, they don’t do very well when they’re not working hard. Running a diesel engine at a fairly high load ensures enough combustion pressure to keep the piston rings seated firmly against the cylinder walls, and this is important to the long life of the engine. Running a diesel for long periods of time with only light loads can cause the rings and cylinders to form a glaze, which then keeps the rings from doing their job when the engine is next expected to work hard. The trick, then, is to run the generator only when you’ll be using a large portion of its potential power. Sometimes, this requires scheduling high-power-use operations for the same day of the week, or organizing your workday to do the power-tool chores while the generator is online. What I did for all the years I ran my diesel-powered homestead was have a small, very portable 1800-watt gas generator handy for those times when I just needed a little bit of power for a few minutes, especially somewhere out of reach of extension cords. I used this little machine for pumping water out of our creek, for field-repairs, and any time I needed more short-term power than I wanted to subject my inverter to. That’s the kind of service these little gas generators are designed for, by the way. Never operate your generator without a properly installed and serviced air cleaner. It doesn’t take much abrasive dust to dramatically shorten the life of an engine. Use only engine oil marked for service in diesel engines. Diesels run at much higher operating pressures than gasoline engines, and they need this grade of oil. The cheapest way to go on oil is to check with your favorite discount store to find what brand they carry, and then buy several cases at a time when it’s on sale. Which brand you use (as long as it’s marked for diesel service) is immaterial, but most mechanic-types recommend staying with one brand. I’ve always used Valvoline HPO 30W, as it is a high-quality diesel-rated oil and it always seems to be on sale somewhere. Safety equipment We’re talking safety of your generator here. We’ll get to your personal safety later. Any permanent generator installation needs to be protected with automatic shut-down equipment. Most manufacturers offer shut-down kits for excessive coolant (engine) temperature and oil-pressure loss, and some also have overspeed shut-down kits. I recommend all three. Having all the automatic shut-down capability in the world is no substitute for proper maintenance, however. It’s a good idea to do at least a cursory inspection of the machinery at every oil-change. Keep the engine clean so that any leaks are easily spotted, and should there be a leak, tend to it at once. The shut-down switch that’s supposed to protect your engine in the event of an oil-pressure loss may stop catastrophic damage, but it’s doubtful that any engine operating at a load will fully survive zero-oil-pressure for even the amount of time it takes for the switch to shut down the engine. Diesel engines are highly dependent on proper oiling at all times because of the high pressures on internal parts. Another important consideration is proper ventilation of the generator enclosure or shed. Even with a good cooling system on the engine itself, the entire machine needs to have substantial access to fresh, cooling air. The shed must have either a large enough screened opening for natural convective airflow, or if a smaller opening is dictated by the amount of noise you’d like to have escape from it, a blower must be installed. A blower that forces airflow through the enclosure can be plugged directly into the 110 volt power of the generator so that it will come on any time the machine is running. In very cold climates, you can connect the blower through a temperature-sensitive switch, so that the blower will operate only after the room temperature has reached 80 degrees or so. Temperature control is important to the long life of the electrical equipment as well as the engine. Excess heat is what ultimately kills alternators. One last piece of equipment I highly recommend is an hour-meter. Most commercial-duty generators already have one installed, but if not, it’s a convenient and inexpensive way to monitor oil-change and other maintenance intervals. Keep a notebook and pencil handy in your generator shed and make notations of all service and repairs done to the machine, too. Your safety If you’re not intimately knowledgeable on things electrical, remember that the current produced by your generator can kill you. Before making any connections, changes, or repairs that you are unsure of, please seek the help of somebody who is competent in these matters. Don’t remove guards that are designed to keep your fingers, clothing and what-not-else out of harm’s way. If you need to temporarily run your equipment without belt or other guards, be acutely aware of their absence. Belts and pulleys have a habit of locating and catching anything they can get, like shirt-sleeves, shirttail, rags, tools, fingers, and worse. An engine that is or has been running is hot. Some parts, like exhaust components, are hot enough to inflict serious burns. Be careful. Oil spilled on a wooden floor is a serious fire hazard. Best keep a suitable metal drip pan under your engine if your shed has a wooden floor. Never leave oily rags in the shed, either. Spontaneous combustion is a very real hazard. When designing your shed, leave enough room to get around the equipment, and place the equipment in the shed for best access to common maintenance areas. Protect the exhaust pipe with shielding to prevent accidental contact. Oil changes are best done when the engine is hot, or at least warm. Try to develop a system in which you can remove the drain plug without touching the engine or the hot oil with your hands. Have a 12-volt light (wired to the engine’s starting battery) in your generator shed so that you can see what you’re doing, even at night, with the generator off. Noise Noise is another consideration, of course. All diesel engines are noisy, and the noise must be controlled if the machine is within earshot of your home or your neighbor’s. The Onan machine mentioned above comes in its own sound-barrier enclosure, and it’s one of the best I’ve seen (and heard). Installing that entire unit in a well sound-insulated shed will make a quiet installation. Just make sure that you don’t impair the supply of cooling air in your quest for quietness. In conclusion, when you figure the long-term costs of operation, diesels always win out over gas engines, and commercial-duty equipment always wins out over the home-handyman variety. Once you acquire your diesel generator, install it carefully and thoughtfully and make sure it receives the proper maintenance. Keep your machine clean. Wipe it down at every oil change, and you’ll be able to spot any little leaks before they become a real problem. Clean equipment is also easier to service, and, well, haven’t you ever noticed how much better your car runs after you wash it? Your electrical system is going to be with you for a long time. It deserves to be thoroughly researched, thoughtfully designed, and carefully constructed. It should be built with dependability and permanence as the primary focus. Plan your electrical needs not only for right now, but for the foreseeable future as well. It’s a lot cheaper to build your system with the future in mind than to upgrade it later. Buying cheap components not intended for full-time use may save you a little at first, but you’ll pay more than the difference when you have to replace them.
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