Sustainable Solutions:

Industrial Solar Coffee Drying Systems

Coffee Drying and Energy
Rapidly escalating energy costs throughout coffee producing regions is yet another variable beyond control of the producer. In Central America electricity costs have increased nearly 20% annually for the past decade. As the region becomes more reliant on fossil fuels for the generation of electricity, this trend is forecast to continue. As coffee processing is highly energy intensive, energy costs play a large role in profitability and sustainability for the coffee sector. After labor costs, energy is the most expensive component of coffee production. Nearly 84% of the energy required is consumed during the drying process.

According to the Costa Rican Coffee Institute (ICAFE) and our own regional surveys by the Institute, conventional mechanical dryers consume 10.5-kilowatt hours of electricity for every one hundred pounds of coffee dried. In addition, 0.12 cubic meters of firewood, or firewood equivalent, is consumed for every one hundred pounds of coffee dried.

This level of energy consumption seriously impacts the bottom line for the producer and has serious environmental impact as well. The impact of energy costs is strikingly apparent when analyzing the cost performance of solar industrial drying systems installed at Cooperative Montes de Oro in Miramar, Costa Rica, with conventional drying methods. These industrial solar drying systems use one-tenth the electricity as conventional dryers and eliminate the need for fuelwood entirely. The energy costs to dry ten thousand one hundred pound sacks of coffee with conventional mechanical dryers with today's energy prices would cost an estimated $20,400, versus $1,700 using the solar alternative. While drying on concrete patio requires no electricity or fuel, labor costs to patio dry the above-mentioned coffee are $29,500, versus $6,385 for solar, and $5,490 for conventional mechanical dryers. The dramatic reduction in operating costs through energy savings allows payments previously made to the energy utilities to be used instead to pay for the solar equipment, thus turning expenses into assets. Refer to Coffee Drying Metrics (under Additional materials) on this page for a Life Cycle Cost Analysis for drying alternatives.

Solar Coffee Drying and Quality
In addition to reducing production costs, the solar drying alternative allows for improvement in the drying process over conventional dryers and patios. The solar technology maintains a drying temperature of 45 to 50 degrees centigrade to avoid harming volatile oils. The solar technology avoids the prolonged drying intervals of five to fifteen days that are required to dry beans on cement or plastic patios, instead drying the beans in two days of solar operation, or in twenty four hours of continuous operation using coffee parchment as fuel during night operation. The prolonged drying intervals encourage the development of microflora - mold and bacteria that severely impact quality. For maximum quality, Montes de Oro exposes the coffee to sun for one day on a patio prior to loading it into the drying chamber to enhance the color and flavor characteristics preferred by the specialty coffee industry.

Coffee Drying and the Environment
In Mesoamerica, an estimated six thousand hectares of forest are used each year to supply wood to fuel conventional coffee dryers—this loss of forest is roughly equivalent to three square centimeters of forest for each cup of coffee we consume. The linkage of energy and environmental impact for the coffee sector have led to programs to support the introduction of the technology through the Global Environment Facility (GEF) and an energy conservation program now being developed with the Costa Rican Electrical Institute (ICE). The opportunity to modernize the aging coffee drying infrastructure faces many challenges including the lack of credit for capital investment for the sector as a whole, and overcoming the nearly one hundred years of experience with the current conventional drying equipment that has remained largely unchanged since the introduction of coffee as an agro-industrial product.