Coffee-Making Tools from Solar-Powered Glass Tubes

The limited space and land in the Netherlands have influenced people's innovation to create environmentally friendly and sustainable tools. The phenomenon was initiated by Boudewijn Buitenhek, who later developed his idea to make solar-powered kettles and coffee bean grills. The project, which he calls "Living with the Sun," is also a dedication to his master's program in industrial design studies at the Koninklijke Academie van Beeldence Kunsten (KABK), The Hague.

(Boudewijn Buitenhek-designed coffee bean kettle and roaster)

In his experiments, Boudewijn Buitenhek decided not to use gas or electricity for one week and limited himself to utilizing the natural energy that supports his apartment needs. Boudewijn Buitenhek started experiments by designing flexible solar panels arranged around apartment balconies, and generators operated by stepping on the pedals. Still, both methods turned out to be ineffective for heating water.

(Boudewijn Buitenhek harnesses the sunlight from the balcony of his apartment)

Through this failure, Boudewijn Buitenhek learned about the use of glass tubes in the 18th century by a Swiss scientist, Horace-Bénédict de Saussure that harnesses sunlight. After exploring how glass tubes work, he obtained a certain amount of data that was subsequently applied to two layers of glass tubes of different sizes. It is a device that can convert solar radiation into thermal energy.

(Two layers of glass tubes to convert solar radiation into thermal energy)

The transparent glass tube with larger dimensions is arranged into Living with The Sun's outer shell, allowing sunlight to enter through minimal reflection. While the smaller tube is coated with solar film and installed inside a transparent tube. Solar film on the tube layer serves to convert sunlight into thermal energy. So that the water contained in the tube can be warm.

As a result, this glass tube designed by Boudewijn Buitenhek only takes 1-1.5 hours to achieve heat of more than 200 degrees Celsius. That way, this tool can not only boil water to brew a glass of coffee but can also function as a roaster for raw coffee beans that require a temperature of 180-250 degrees Celsius.

(These two layers of glass tubes can roast raw coffee beans)

Some people living in apartments may think that with a roof, they can apply solar photovoltaic panels as a source of electricity. However, Boudewijn Buitenhek's "Living with the Sun" project has proven that limited space in apartments that do not have direct access to the roof can still take advantage of natural energy.

(The result of roasting coffee beans using a glass tube for one month)