Reducing Air Pollution by Geothermal Heating A geothermal power plant in Nevada is generating electricity using geothermal water extracted at 180°C, and reinjected back to the ground at 85°C. It is proposed to utilize the reinjected brine for heating the residential and commercial buildings in the area, and calculations show that the geothermal heating system can save 18 million therms of natural gas a year. Determine the amount of NO _{x} \text { and } CO _{2} emissions the geothermal system will save a year. Take the average NO _{x} \text { and } CO _{2} emissions of gas furnaces to be 0.0047 kg/therm and 6.4 kg/therm, respectively.