Texmart is a locally owned “big-box” retail store chain in Texas with 75 stores, primarily located in the Dallas–Fort Worth area. In order to compete with national big-box store chains, Texmart is planning to undertake several “sustainability” (i.e., “green”) projects at its stores. These national chains have been heavily publicizing their sustainability efforts, including the reduction of greenhouse gas (GHG) emissions, which has had a positive effect on their sales. They have also demonstrated that sustainability projects can have a positive impact on cost (especially energy) savings. The projects Texmart is considering include installing solar panels at some or all of its stores, installing small wind turbines, replacing some or all of its 165 trucks with more fuel-efficient hybrid trucks, and implementing waste reduction programs at its stores, including recycling and reducing the use of plastic bags in stores. The costs for these projects (per store or truck), the resulting reduction in GHG emissions, the energy savings, and the annual costs savings are shown in the following table:

Sustainable Projects Solar Power Wind Power Shipping/

Vehicles Waste/

Recycling Plastic Bags Cost ($) $2,600,000 950,000 38,000 365,000 175,000 GHG reductions

(metric tons per year)

17,500 8,600 25 1,700 900 Cost savings ($) 220,000 125,000 26,000 75,000 45,000 Energy savings (kWh) 400,000 150,000 34,000 1,200 55,000 Units 75 75 165 75 75 Texmart has established the following four goals, in order of importance:

(1) It doesn’t want to exceed is program budget of $30 million for sustainable projects.

(2) It wants to achieve GHG emission reductions of at least 250,000 metric tons per year.

(3) It wants to achieve annual cost savings of at least $4 million.

(4) It wants to achieve annual energy savings of at least 5 million kilowatt hours (kWh).

a. Formulate a goal programming model to determine the number of each type of project to undertake to satisfy the goals.

b. Solve the model by using the computer. LO.1