Skip Navigation

Energy Conservation in Coffee Processing

Coffee shrub with ripe (red) coffee cherries and green cherries.High electricity costs in the Caribbean Area create unique challenges for producers, but also offer unique solutions and opportunities. For many coffee processors, energy costs dictate whether they operate or not. The amount of energy needed to dry coffee using traditional, inefficient drying methods can be huge and costly. However, new technology is available and Caribbean Area NRCS has developed new scenarios to provide financial assistance for these more efficient methods. New energy-efficient coffee production equipment can save producers up to 80% and 70% in propane and electricity consumption, respectively.

Through the EQIP Energy Initiative, NRCS can help coffee processors save energy by switching to high-efficiency equipment, reduce fossil fuel use (and costs), and improve air quality (reducing greenhouse gas emissions and global warming). The initiative can also help processors decrease their power consumption to lower production costs and increased profits.

Coffee Processing Overview

Step 1

Coffee processing begins with picking the ripe (red) coffee cherries (above right). The cherries must be processed within 24 hours after picking to avoid fermentation and compromising coffee quality.

Ecological Wet Mill, 1 - depulper, 2 - separator & 3 - desmusilaginadora
Ecological wet mill - depulper (1), separator (2) & desmusilaginadora (3

Step 2

The coffee bean then needs to be removed from the cherry. This is where the first conservation innovation comes in: the ecological wet mill. An ecological wet mill includes:

  1. A de-pulper or machine to remove the exterior skin of the coffee cherries,
  2. A separator to separate green and ripe coffee and
  3. A “desmusilaginadora” or machine to remove the mucilage - the gel that lies between the coffee bean and the exterior skin of the coffee cherry.

After separation, the pulp is composted and the waste water goes to an infiltration ditch or storage pond.

An ecological wet mill saves water because it washes the coffee using friction, which also reduces the potential for water contamination. It conserves energy by using one motor to run multiple operations, and saves space because it is more compact than traditional systems.

Step 3

Bateas at a PR coffee processing facility
Bateas at a PR coffee processing facility.

Now the coffee beans are ready to dry. This step usually uses lots of energy. Farmers have traditionally used "bateas" or rotational ply dryers for this step.

A Batea is a homemade coffee bean dryer. It is built from scrap truck parts and metal. It uses a truck transmission, engine and differential. Some bateas use an electric motor instead of a diesel engine.

A batea has two engines, one to move the beans and another that powers a blower to force hot air through the slotted floor at the bottom of the dryer. The engine that moves the beans is connected to a truck transmission to slow down belt speed, and then is connected to the differential to turn the top arm that moves the beans.

These engines are typically oversized and waste a lot of energy. For example, most blowers used are designed for big deep silos, but bateas only have a shallow layer of beans (about 2 feet) so a third of the power supplied may suffice. Not only is the electricity consumption of the system high, but the amount of propane gas or diesel used as a heat source to remove moisture from the beans is also very high. 

Another area of concern is the quality of the drying. In coffee processing, the rate and temperature at which the coffee is dried is very important. With most bateas the temperatures are hard to control and usually too high, which roasts the coffee before it dries.

Instead, Energy Auditors recommend silo-type dryers to replace the bateas. The silo dryers are engineered machines with motors that are properly sized for the driers capacity. There are several benefits of the silo dryer:

  1. It uses only one motor for the blower, reducing electricity consumption.
  2. It has a pre-dryer bed on top which uses (recycles) the excess heat released from the main drier bed.
  3. The air flow can be inverted from over or under each bed to have a uniform dryer characteristics throughout the bed.
Industrial-scale coffee silo dryer operating in Adjuntas.
Left: Industrial-scale coffee silo dryer operating in Adjuntas. Right: 300kg-Capacity coffee silo-dryer, Adjuntas, PR.
300kg-Capacity coffee silo-dryer, Adjuntas, PR

Use of silo dryers can provide coffee processors with huge energy savings. According to energy audits performed by a certified TSP, a silo dryer can reduce electricity consumption by 69% and propane gas consumption by 80%!

NRCS Assistance Available through EQIP

Compact fluorescent (CFL) light bulbs. LED light bulbs Linear fluorescent light bulbs (T-5, T-8)

The ecological coffee wet mill addresses two resource concerns, energy efficiency and water quality. Therefore, financial assistance for the ecological module could be recommended by one of two practices: by the Farmstead Energy Improvement (Practice 374) which requires an energy evaluation or by Reduced Water and Energy Coffee Conveyance System (Interim Practice 737) which addresses water quality by reducing the amount of waste water. Financial assistance for the dryers requires an energy evaluation. The Reduced Water and Energy Coffee Conveyance System (Interim Practice 737) was developed to provide technical and financial assistance to Beneficiados to install a coffee processing device that was validated and demonstrated by Prof. Miguel Monroig and collaborators at the University of Puerto Rico Agricultural Experiment Station in Adjuntas.

NRCS offers coffee processors opportunities to save energy and money in a number of components of their operations:

Phase I of the NRCS EQIP Energy Initiative provides financial assistance for Energy Audits:

  • To study the client’s energy usage (electric & gas bills) and equipment efficiency, identify and recommend energy-saving opportunities.
  • Audits are conducted by NRCS-certified contractors (TSPs – technical service providers).
Ecological Coffee Processing Equipment
Ecological coffee processing equipment (Café beneficiado ecologico).

Phase II replaces old equipment with high energy-efficient equipment:

  • High efficiency equipment must first be recommended in the audit for producers to qualify for this phase.
  • Incentive payments are based on the EQIP Cost List.
  • The equipment has to operate for a minimum of 10 years. If not, NRCS will initiate cost recovery, with interest.
  • EQIP payments are made after new equipment is installed and NRCS staff certifies that the equipment is functional and meets the standards and specifications of the agency.

More Information

Contact

Engineer Alberto Atienza, 787-817-2473 x. 113