For all their ecofriendliness or usefulness in niche applications, non conventional sources of energy face an uphill battle for success in the marketplace. Established energy sources such as coal and gasoline have their downsides, but they are economical, widely available and simple to use. They enjoy technical advantages over non conventional energy sources. Acceptance of new energy technologies takes decades, even when they have clear cut benefits (Reference 1, Page 3).
Some unusual devices cannot run on conventional energy and require a specialized power source. For example, a deep space probe may need electricity for several decades. Chemical batteries do not have enough capacity, and the probe travels too far from the sun for solar panels. The spacecraft's designers justify the high cost of a nuclear battery, as it fulfills the needs of the project and they have a multimillion dollar budget. You will likely never see nuclear battery powered TV sets or refrigerators, however, as the cost would be too high.
Low Energy Density
Environmentalists tout solar and wind power as they are renewable energy sources, and they produce no greenhouse gases. A solar or wind plant, however, produces a smaller amount of power per acre than a coal fired or nuclear plant. Full sunlight on a bright day delivers about 1,000 watts per square meter, less than a tenth the energy density of a frying pan. As solar harvesting technologies run 10 to 30 percent efficient, the 1,000 watt figure drops to about 200 watts. To make up for this, the solar plant must occupy a larger area. This means a solar plant must locate to a relatively rural area where land costs are cheap.
In the U.S., refineries mix gasoline with corn based ethanol to increase the amount of the mixture. Since the ethanol is renewable and the gasoline is not, the mixture conserves gasoline. Because farmers grow the corn locally, this reduces the need to import oil from foreign sources. Unfortunately, diverting some of the farmer's production has the effect of raising the price of corn for food. corn products find their way into many processed foods, so the price increase has been widespread.
Non conventional sources of energy can be technically immature compared to conventional sources. A hydrogen powered car, for example, must store its fuel as a compressed gas or in a material that releases hydrogen as you drive. Energy companies have not settled on a standard way to package hydrogen, so the design of cars and filling stations depends on the car maker. Although clear standards eventually emerge, early adopters risk losing out if their system does not prevail.