With proper maintenance, a whole-house generator can last between 20 and 40 years. The specific lifespan depends on how often and for how long the generator is used, and some models may have their life expectancy rated in hours of operation. To maximize its lifespan, expect to spend around $150 to $300 per year for annual maintenance checks from a qualified technician. During these checks, a technician will inspect the engine filter, starting mechanism, fuel, lubrication, and coolant levels. Consulting your installer and choosing a low-impact fuel like natural gas or diesel can also help ensure your generator lasts as long as possible.

While diesel is relatively stable, it won’t last nearly as long as propane and you may have to replace it if it sits unused for too long. Diesel can sometimes struggle to work efficiently or start engines during especially cold weather, so it’s not the best choice for every climate. Compared to fuels like propane and natural gas, diesel generators tend to be noisier and create more exhaust, which isn’t always ideal for home use.

Natural gas and electricity rates vary significantly based on location, and pricing can change over time, too. It’s possible that in locations where natural gas is particularly inexpensive, it will cost less than grid-based electricity will. However, you should also factor in the generator’s initial costs and maintenance needs, as well as its noise level and if it can comfortably power all your home appliances.

In some situations, yes. Never try to put biofuel into any home generator without checking the specifics first. If a generator has the ability to run on diesel, it can also run pure biofuel (the clear kind made from seed oils, for example). But if you are using biofuel made from animal fats or vegetable oils, the generator will need significant modifications before it can handle a sludgier type of biofuel.