ef4022976_si_001.pdf (264.2 kB)
Effect of the Type of Bean, Processing, and Geographical Location on the Biodiesel Produced from Waste Coffee Grounds
journal contribution
posted on 2015-12-17, 00:42 authored by Rhodri
W. Jenkins, Natasha E. Stageman, Christopher M. Fortune, Christopher J. ChuckWaste
coffee grounds offer a viable waste feedstock for biodiesel
production. Approximately 8 million tonnes of coffee are produced
globally each year and contain up to 15 wt % lipid, of which the glyceride
portion is predominantly made up of palmitic, stearic, oleic, and
linoleic acids. In this investigation, the variation in the oil content,
saponifiable lipids, and lipid profile according to the regional location
and processing or brewing techniques was assessed. A number of key
fuel properties were also investigated. The oil content for fresh
coffee grounds (FCGs) ranged from 11 to 15% across the range of coffees
examined. Spent coffee grounds (SCGs) had slightly reduced levels
of lipid, between 7 and 13 wt %, for the coffees under investigation.
The lipids contained between 0 and 40% unsaponifiable material, which
could not be processed to fatty acid methyl ester (FAME). For all
samples, with the exception of Vietnamese coffee, the FAME profile
of the resulting biodiesel was consistent; the oils contained between
35 and 40% palmitic acid, between 7 and 8% oleic acid, between 44
and 50% linolenic acid, and between 7 and 8% stearic acid, although
the fuel properties were reasonably variable across the data set.
The kinematic viscosity ranged between 4.0 and 5.5 mm2 s–1; the density ranged between 841 and 927 kg m–3; and the pour point ranged between −1 and
16 °C. This variation was also observed in previous reports,
suggesting that these fuel properties are not solely determined by
the FAME profile but other lipid-soluble biomolecules present in the
coffee biodiesel.