Why doesn't the united states use 100 renewable energy

there are not enough sources of renewable energy

renewable energy producers don't qualify for tax incentives

fossil fuels are still relatively inexpensive compared to renewable energy

The most obvious and widely publicized barrier to renewable energy is cost—specifically, capital costs, or the upfront expense of building and installing solar and wind farms. Like most renewables, solar and wind are exceedingly cheap to operate—their “fuel” is free, and maintenance is minimal—so the bulk of the expense comes from building the technology.

The answer is that anaerobic respiration is used commercially in the production of beer, wine, bread, yogurt, and cheese.