Coffee produces greenhouse gas emissions in different ways. At the front end, fertilizers used to enrich the soil with nitrogen emit nitrous oxide into the atmosphere. In later stages of production, some processes used to dry coffee beans emit carbon dioxide, such as when firewood is burned to fuel boilers.
Methane emissions are another factor. To extract the coffee bean—the inner seed that gives coffee drinkers worldwide that energy boost—the coffee cherry’s bright red skin and pulp must first be removed. The discarded pulp, which makes up around 40 percent of the total volume of coffee that is picked, decomposes and produces methane.
“If the pulp is not treated properly, it becomes a serious environmental problem. Right now, treating the pulp involves a significant investment of financial resources and logistical efforts on the part of the producers,” said Cindy Torres, a chemical engineer and researcher at the University of Costa Rica (UCR). Working hand in hand with the Costa Rican Coffee Institute (ICAFE), she has been experimenting with methods to efficiently convert that waste product into energy through gasification.
This project is a small piece of a much larger, multiyear effort Costa Rica is undertaking to reduce carbon emissions in the coffee industry, as a Nationally Appropriate Mitigation Action (NAMA). NAMAs are policies and measures designed and implemented by developing countries as part of their international commitment to tackle climate change.
In this case, NAMA Café Costa Rica brings together a range of national and international partners, with an expected total investment of $30 million over 10 years. The project to turn the waste pulp into energy is being funded with a $100,000 grant from the Inter-American Development Bank’s Multilateral Investment Fund, with matching funds from the University of Costa Rica and considerable staffing and in-kind support from ICAFE.
The seeds for this particular project were actually sown during a previous project funded by the U.S. State Department through the Energy and Climate Partnership of the Americas (ECPA). That initiative (see related story) focused on opportunities to use renewable energy such as solar and wind technologies in the coffee industry, but also included a preliminary study on the potential for turning coffee waste products into fuel.
Coffee pulp does have other purposes already. Many of Costa Rica’s coffee mills compost it and use it for organic fertilizer. The pulp has also been found to have high nutritional value for animal feed and is even being used in some flours destined for human consumption. (“It’s gluten-free,” one mill manager noted).
But Rolando Chacón, head of industrialization processes at ICAFE, said it makes sense to provide an alternative to use the discarded pulp for energy production. For one, composting takes several months, and in the meantime the piles of decomposing waste material are generating methane. Another selling point for energy production is that—depending on the results of economic viability studies—coffee mills could potentially bring down their electric bills by generating some of their own energy.
And anything the coffee sector can do to stand out from the competition is a plus, Chacón said, adding that Costa Rica produces only 2 percent of the world’s coffee. “We can’t compete on quantity. We have to differentiate ourselves—obviously without leaving aside the quality of the coffee,” he said.
A Complex Undertaking
It is no simple thing, though, to efficiently produce energy from coffee pulp. Some mills had tried doing this through a gasification process several years ago but encountered technical problems and abandoned the effort.
The research team led by Torres has been working on two parallel tracks: first to produce a consistent, clean-burning fuel, and second to refine the energy generation process.
Creating the fuel involves extracting moisture from the pulp, treating the material, and turning it into dense pellets that are about one third the length of a pencil. Once the material is in this dense pellet form, it no longer decomposes and can be stored and used as needed. “We can have energy on demand,” Torres said.
The pellets are fed into a gasification system modified to handle this particular type of biomass. At high temperatures, the material breaks down into gases that are then combusted to power a motor and generate electricity. Part of the energy produced could be used for the process itself, in a closed loop.
The research team spent several months experimenting with a range of variables, including the moisture content of the pellets, monitoring the pressure, temperature, and flow of gases in the chemical reactor. Based on that research, Torres has no doubt that it is technically feasible to produce quality, reliable energy from coffee pulp. “We engineers have to optimize the process to produce it as cheaply as possible,” she added.
It is not yet clear how affordable this could be on a small scale—a thorough economic analysis will be done later this year—but the potential for large-scale implementation is enormous, Torres said. Consider this, she said: Worldwide, last year’s coffee harvest alone produced some 19 million tons of pulp waste. Torres envisions scaling up the technology to accommodate the huge processing operations found in larger coffee-producing countries such as Brazil and Vietnam, which could generate power not in kilowatts but megawatts. But even on a smaller scale, this type of energy has “positive externalities,” as it would enable coffee mills to meet their environmental targets and reduce a major source of greenhouse gases, Torres said.
That has monetary value, as environmentally friendly coffee can command higher prices—although in today’s global, competitive market the premium is measured in cents per pound rather than dollars, said Roberto Mata, CEO of the Cooperativa de Caficultores de Dota R.L. (CoopeDota). At its mill in Costa Rica’s Tarrazú region, southwest of San José, the cooperative processes coffee grown by 850 producers at elevations ranging from 1,500 to 1,900 meters above sea level.
In 2011, CoopeDota became the first coffee producer in the world to be certified as carbon-neutral under the British Standards Institute’s PAS 2060 specification. While this certification has helped the company attract new clients and stabilize its market share, Mata said the environment was a stronger motivation than the bottom line for implementing carbon-friendly practices.
“We continue to do that because it’s worth it, thinking about the environment and the sustainable future of coffee growing,” he said.
Mata wasn’t familiar with the specifics of the gasification research project underway and expressed some skepticism about transferring laboratory findings to an industrial level. But he said he would welcome any new suggestions “with open arms”—especially since electricity is CoopeDota’s second-largest expense, after labor.
The cooperative has explored different ways to generate some of its own electric power, and it is planning to invest in a small (250 kW) hydroelectric plant on the Río Pirris. “The river hasn’t run dry in any year yet,” Mata said, with a wry chuckle.
While the mill burns a small amount of biomass in its coffee-drying process, the bulk of the waste pulp it generates is used for compost and animal feed. Mata said the company is planning to implement a faster composting method to reduce methane emissions. CoopeDota and other nearby coffee mills are also discussing the possibility of joining forces to find more efficient ways to handle the waste pulp on a larger scale.
That kind of joint arrangement might also make gasification an economically viable alternative for some small coffee mills, according to Torres. She said the University of Costa Rica will make all these research findings available free of charge to the entire coffee industry.
Every coffee mill has its specific characteristics, depending on its size and technological capacity, but in general the Costa Rican coffee industry has long strived to implement best practices—beginning with efforts more than 20 years ago to reduce the use of water in processing, according to ICAFE’s Chacón. He said many coffee mills are in the process of meeting the requirements for carbon-neutral certification, by reducing their greenhouse gas emissions as much as possible and planting trees or buying carbon offsets to make up the difference.
“This sector has been a pioneer in the environmental area,” Chacón said.
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