The price of gasoline fell again on Monday to $2.47 per gallon, after falling nearly 10 cents at the end of last week.
It was also the lowest level since April 2015.
However, prices have rebounded in recent weeks, with gas prices rising more than 5% over the last year.
On Tuesday, U.S. gasoline prices dropped again, to $3.16 per gallon.
Gasoline prices are the main factor in the continued decline in prices, but other factors such as the cost of renewable energy sources such as wind power, solar, and geothermal have also contributed.
According to the Energy Information Administration, solar photovoltaic panels accounted for about half of the decline in gasoline prices in 2016, and solar power increased its share of the power mix to 37.6% in 2020.
Wind energy increased its percentage share to 21.3%.
Wind power is still the cheapest source of power in the United States.
In 2020, wind power cost $1.85 per kilowatt hour.
The solar panel price decline has been a factor in reducing solar capacity, with the number of panels installed decreasing from 2.4 GW in 2014 to 1.6 GW in 2020, according to Solar Energy Industries Association.
This has led to an increase in prices of natural gas and oil.
The price of gas, on the other hand, has remained largely unchanged since 2015, and the energy industry is confident that it will stay that way, said Steven B. Davis, an analyst at Bernstein Research.
The U.N. Environment Program, a U.K.-based nonprofit group that monitors the environmental impacts of energy production and uses that information to help governments develop policies, predicts that U.s. energy mix will remain fairly stable in the coming years.
According a U, the U. S. energy infrastructure is also in good shape.
The cost of energy from the fossil fuel industry is low, with natural gas being the cheapest, and wind energy and solar panels being the most affordable.