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Basics of Engine Generators

backup power generators Engine generators are a familiar accessory to off-grid homes and villages, as well as hospitals and other businesses who need reliable standby power. While a traditional generator may not fit into our definition of an "alternative energy" source, they are still a valuable addition to a remote power or grid back-up system.

Engine Generator Basics
How Generators Fit in a Renewable Energy System
Types of Combustion Generators
Using Engine Generators in Alaska
Benefits of Combustion Generators
Related Product Information

Engine Generator Basics

Like wind and water turbines, generators produce power from an electrical alternator. Of course, rather than using a renewable resource to spin the alternator, they rely on a diesel, propane or gasoline powered engine. This means they aren’t silent or emission-free, but they can be relied on when alternative power sources can’t meet your electrical needs, or whenever grid power fails. This eliminates the inconvenience (or in some cases, danger) of being without power for any significant amount of time.

How Generators Fit in a Renewable Energy System

One of the primary ideas behind a remote alternative energy system is to avoid the expense of fueling a generator. Another is to avoid the air and noise pollution caused by traditional combustion power sources. Considering these factors, suggesting the inclusion of an engine generator in an alternative energy system may seem odd. However, traditional generators can play a vital, part-time role in a renewable power system.

For individuals relying on a renewable power source, such as a solar, wind or hybrid power system, there may be times when the renewable source will not produce enough output to meet current electrical needs. A solar system during an Alaskan winter for example, a wind turbine on a calm day, or a water generator during fall freeze-up. During these times the engine generator can be configured to start automatically when storage battery charging is needed and shut down as soon as the batteries are charged, meeting short-term power needs while minimizing generator run-time.

Since the generator can be turned on and off, unlike a renewable power source, no dedicated charge controller is necessary. The generator can be hooked into the system through either an inverter with generator auto-start features, or a generator auto-start battery charger. Either of these methods will detect when the batteries are dangerously low, and will start the generator for as long as needed to charge the storage battery bank.

Types of Combustion Generators

Most engine generators run on either gasoline, diesel fuel or propane. Besides the relative cost difference between the three fuel types, the operating principles between them are the same. The primary difference between various generators is their output capacity.

Very small portable generators are available, which would not produce enough power to effectively support a household electrical system but are perfect for operating single pieces of equipment. It may be that the renewable energy system doesn’t have sufficient capacity to simultaneously power the house and a specific piece of equipment or machinery. It wouldn’t be cost effective to expand the alternative system if the equipment in question is rarely used, or it may be that a specific piece of equipment needs to be operated for a short time at a remote location. A portable generator would fit perfectly into such a situation.

A mid-sized generator that may be too small to power a full household electrical system operating at capacity can still provide supplemental power to charge batteries when the alternative system is under-performing. Such a generator could be attached only to specific essential power circuits, allowing non-essential loads to go without power until the batteries are recharged. This allows for reliable back-up power with a much smaller investment than a stand-alone capable generator would require, although the electrical system may not be fully operational at all times.

For systems where partial-capacity operation is not a viable (or desirable) option, engine generators are available at very high output capacity. While the alternative system may provide sufficient power under most conditions, with a full-capacity backup generator there is no concern about losing power in any situation. These large generators are also commonly found in hospitals, where vital life-support and other medical equipment must be operational even when grid power fails.

Using Engine Generators in Alaska

As a testimony to their practicality, generators have been used to power remote homes and villages for quite some time in northern climates. The only serious functional concern with using generator power in arctic climates is winterization.
Like an automobile engine, an engine generator must be installed in such a way that the engine itself stays warm enough to start in any weather. Making sure the generator enclosure is well insulated will not only reduce heating needs for the engine, but will also minimize generator noise. This is particularly important when the generator shed is attached to the house.

If the generator is set to start before or within minutes after other electrical power is lost, using standard automobile winterization heating pads may prove useful, as the heating pads will not be without power long enough before generator start-up for the engine to lose its heat. If the generator is not equipped to auto-start and may be sitting for some time after power is lost, arranging the generator shed in such a way that it takes advantage of a non-electric heating stove would be the most reliable idea.

Benefits of Combustion Generators

While engine generators do not have the environmental benefits of renewable energy sources, and their noise levels can be a nuisance, they can provide vital reliability that mother nature cannot promise. Alaska is short on sunlight during winter, can be short on wind during summer and river-mounted water generators must be taken out of commission for a short time twice a year. In addition to the variations in renewable power sources, the best-designed electrical system may occasionally demand more power than the weather permits, or may include occasional-use appliances that overtax renewable sources.

In all of these situations, as well as when grid power fails, a properly maintained and winterized engine generator will provide almost fail-proof backup power. When used in a backup capacity, generator noise will be occasional, and fuel use and emissions will be minimized. While it still may not qualify as an environmentally friendly power source, the peace of mind a generator’s reliability provides can be priceless.