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Parabolic greenhouse solar dryers have been developed to overcome product quality and postharvest loss problems. It uses solar energy, a renewable source of energy. Due to their high investment costs, economic feasibility and the potential of carbon dioxide (CO2) mitigation were investigated. Owners and managers of 17 enterprises, producing several varieties of herb products, investing in different sizes of solar dryers and using various traditional drying methods before investing in solar dryers, were interviewed in depth to create a data set. The net present value (NPV), internal rate of return (IRR), payback period and CO2 mitigation were evaluated. The enterprises with annual production capacities higher than 1,200 kg or the annual revenues higher than solar dryer investment costs tended to have positive NPV indicating that the investments were attractive. Most enterprises showing CO2 mitigation higher than 130 tCO2e over 15 years had positive NPV. The annual production capacity, annual revenue and the amount of CO2 mitigation could be used to assess investing in greenhouse solar dryers.

According to the needs of sustainability, a new sustainable banana chip value chain, which is a combination of the traditional banana chip value chain and the banana waste value chain, was designed. Scenarios were created assuming that an anaerobic digester would be implemented to produce biogas—which can act as a substitute for liquefied petroleum gas (LPG) used in banana processing—from banana wastes. The values of banana residues throughout the value chain were determined depending on farm gate tree price, transportation cost, and the final value of LPG substitution. The value chain was optimized using two objective functions: total chain profit maximization and factory profit maximization. The tree price at the farm gate was determined and assumed to be between USD 0.067 and USD 0.093 per tree, and the transportation cost of tree transportation was assumed to be between USD 0.31 and USD 0.39 per km. Different tree prices and transportation costs affected the profits of all stakeholders throughout the chain. The scenarios that maximized total chain profits showed superior environmental performance compared to the scenarios that maximized factory profits. The proposed sustainable value chain will lead to an increase in farmers’ profits of 15.5–17.0%, while the profits gained by collectors and factory will increase between 3.5 and 8.9% when compared to business as usual.