The electric bill of your small chemical company is $110,000/year. Your company operates only during the normal business day, when the cost of electricity is highest. Consider this scheme to reduce the electric bill: install rechargeable batteries that will be charged from midnight to 6 am (when the cost of electricity is lower) and will be discharged during the day to power the plant. The capital cost of this scheme (batteries plus installation) is $65,000. The batteries are expected to last 5 years. The cost of maintenance and inspection of the batteries is expected to be $4000/year. With these batteries, you predict your electric bill will drop to $80,000/year. Calculate the ROI for this scheme to install batteries. You may assume a straight-line depreciation on the batteries.