Sandia and an Albuquerque roaster test solar heat stored in rocks for a drum roaster
An experiment in New Mexico asks a question I had not thought about: can an ordinary drum coffee roaster run on solar energy stored as heat? Daily Coffee News reports that Sandia National Laboratories tested the idea with Albuquerque roaster Michael Thomas Coffee.
The setup works like this. Photovoltaic panels make electricity, which is converted to heat and stored in a bed of rocks. When needed, the stored heat is released into the roasting drum, a process Sandia systems engineer Ken Armijo calls indirect solar heating. The system roasted light, medium and dark coffees, with temperatures reaching as high as 600 degrees Celsius, and trimmed a few minutes off a dark roast.
Owner Michael Sweeney pointed to faster turnaround, since the system lets the roaster preheat and cool more quickly between batches, which could raise daily output. The rock bed can hold heat for a long time, potentially days, so roasting could continue when the sun is not shining. Albuquerque was chosen for its roughly 300 sunny days a year.
The long-term goal is a bolt-on kit for existing natural gas roasters, so shops would not have to replace machines. Sandia describes the project as a proof of concept that could greatly reduce natural gas use. Earlier work in 2022 used concentrated sunlight to roast green chile and, according to Sandia, halved the roasting time.
The project is funded through New Mexico's Technology Readiness Gross Receipts Initiative and runs under a cooperative research agreement, using Sandia thermal storage technology under a US patent. I am curious how it handles roast profile control, which the article does not detail.
Source: Daily Coffee News
The setup works like this. Photovoltaic panels make electricity, which is converted to heat and stored in a bed of rocks. When needed, the stored heat is released into the roasting drum, a process Sandia systems engineer Ken Armijo calls indirect solar heating. The system roasted light, medium and dark coffees, with temperatures reaching as high as 600 degrees Celsius, and trimmed a few minutes off a dark roast.
Owner Michael Sweeney pointed to faster turnaround, since the system lets the roaster preheat and cool more quickly between batches, which could raise daily output. The rock bed can hold heat for a long time, potentially days, so roasting could continue when the sun is not shining. Albuquerque was chosen for its roughly 300 sunny days a year.
The long-term goal is a bolt-on kit for existing natural gas roasters, so shops would not have to replace machines. Sandia describes the project as a proof of concept that could greatly reduce natural gas use. Earlier work in 2022 used concentrated sunlight to roast green chile and, according to Sandia, halved the roasting time.
The project is funded through New Mexico's Technology Readiness Gross Receipts Initiative and runs under a cooperative research agreement, using Sandia thermal storage technology under a US patent. I am curious how it handles roast profile control, which the article does not detail.
Source: Daily Coffee News
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