Energy efficiency has become very important of the rising cost and decreasing of fossil fuels. Consequently, modern technology been working to develop methods of oil and gas more economically. One of research and development has been engines. Cars that can travel farther a lesser amount of fuel are great demand today. Another area of is the huge amount of fossil used to provide heat. In addition developing other energy sources for this , scientists and engineers have been improving efficiency of heating systems that use traditional fuels.