A homeowner is purchasing a new dryer. The home is set up and wired so that it may use an electric dryer or a natural gas dryer. Electricity for this home is generated by a coal-fired power plant. The homeowner needs to decide which type of dryer to purchase based initially on cost. The following information is being used to help in the decision-making process.

The homeowner dries seven loads of laundry per week. There are 52 weeks in one year. On average, it takes one hour to dry each load. Prices for natural gas and electricity vary greatly around the world. For this exercise we will assume:

Natural gas dryer Electric dryer
1 hour of use = 0.25 therms of natural gas 1 hour of use = 6 kilowatt hours (kWh) of electricity
1 therm = $1.05 1 kWh = $0.1331
The homeowner also wants to take environmental impacts into consideration when purchasing a new dryer. Combustion of any fossil fuel, such as natural gas, releases carbon dioxide (CO2), a greenhouse gas, into the atmosphere. However, the homeowner knows that their house receives energy from a power plant that burns coal. The following information is being used to help in the decision-making process.

Natural gas

1 therm = 11.7 lbs of CO2 released

1 kWh = 1.1 pounds of coal burned

Electricity from coal
1 lb of coal = 2.86 lbs CO2 released

How many pounds of coal would be needed to power the electric dryer for one year?