Coffee parchment as potential biofuel for cement industries of Ethiopia

ABSTRACT

This study explores the biofuel potential of raw coffee parchment and its pellets to supplement the energy demand of the cement industries of Ethiopia by characterizing their combustion characteristics and ash qualities for clinker production. The raw and pelletized coffee parchments were characterized for ultimate and proximate composition, calorific value, heavy metals, and ash oxides. The ultimate analysis confirmed higher carbon (45.5%) and hydrogen (6.5%) content and lower nitrogen (0.4%) and sulfur (0.1%) content in the pellets as compared to the commonly used biomass fuels. The moisture content (11.2%) and ash content (5.97%) of the pellets meet the ISO standard for non-wood pellets (ISO 17225–6, 2014). Pelletization of the coffee parchment enhanced the gross heating value of the biomass. The ash analysis revealed that the ash may supplement a sufficient amount of oxides of calcium, silica, aluminum, and iron required for clinker production. Overall, the results signify that coffee parchment and its pellets have suitable properties to be used as cheap, sustainable and eco-friendly bio-fuel for the cement industries of Ethiopia.

KEYWORDS:

• Coffee parchment
• calorific value
• proximate analysis
• cement
• biofuel

Highlights

• The study was conducted to investigate the quality coffee parchment (estimated to be generated in the rate of 15, 576 tonnes per year and found in the radius of about 41 km) biomass fuel with respect to combustion properties and quality of the ash to be used in clinker production for suitability as a potential alternative energy source for the cement industry of Ethiopia.

• Ultimate analysis result confirmed higher C (45.5%) and H (6.5%) and lower N (0.4%) and S (0.1%) contents in the coffee parchment as compared to the commonly used biomass fuels and also meet the standards specified for non-wood biofuel.

• Pelletization of coffee parchment using molasses as a binding agent enhanced gross heating value (HHV) from 18.56 to 27.95 MJ/kg. The obtained values after pelletization are on par with common fuels such as wood and coal.

• CaO, SiO2, Al2O3 and Fe2O3 contents in the coffee parchment confirmed that the fuel ash may supplement sufficient amount of the oxides required for clinker formation and the low and low heavy metal contents not expected to pose significant concerns when sequestered in the clinker. During the clinker manufacturing process, use or recycling of construction or demolition waste.

• Overall, these results signify that coffee parchment has suitable property to be used as a potential alternative energy source, especially as cheap and eco-friendly biofuel for cement industries of Ethiopia.

Additional information

Funding

This study was fully funded and supported by Adama Science and Technology University, Ethiopia.

Notes on contributors

Eshetu Bekele Wondemagegnehu

Eshetu Bekele Wondemagegnehu is a citizen of Ethiopia who was born in 1979, completed his Ph.D  in Germany, Rosotck University and MSc at Addis Ababa University, Ethiopia in Environmental Science. He got his bachelor of science degree in Chemistry from Alemaya University. Currently working as assistant professor in the department of Applied Chemistry and as Associate dean for undergraduate program at Adama Science and Technology University. His research expertise focused on solid waste management technology,  treatment of water and waste water, soil ecosystem functions and remediation, and Environmental chemistry. So far published more than thirteen publication in the aforementioned area of research.

Neeraj K. Gupta

Neeraj K. Gupta is a citizen of India and his area of specialization is polymer chemistry. he worked as a senor research scientist in BAYOR company, England for ten years. he has been serving Adama Science and Technology university in the professor position since 2016. he has been published a number of research articles related to polymer chemistry, energy and material science and engineering.

Elias Habtu

Elias Habtu was born in Ethiopia in 1978. He got his Bachelor of Science Degree in Mechanical Engineering from Addis Ababa University, Institute of Technology in 1998. He attended Master’s Degree in Mechanical Engineering specializing in Mechanical Design (Applied Mechanics) from 2005 to 2007. He has since served in Adama Science and Technology University as Lecturer, head of department, coordinator of design stream and as associate dean for the Cement Technology Center. His research work focuses on the cement industry especially on energy and has been involved in a number of research and university-industry consultation projects.