uu.seUppsala University Publications
Change search
ReferencesLink to record
Permanent link

Direct link
Kaffesump som substrat i biogasanläggningar eller som bränsle i fjärrvärmeverk: en studie av effekter på växthusgasutsläpp och kostnader
SLU, Institutionen för energi och teknik.
2013 (Swedish)Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesisAlternative title
Ground coffee waste as substrate for biogas or as fuel in a heating plant : a study of effects on greenhouse gas emissions and economical costs (English)
Abstract [en]

Each year, the coffee machines at Ericsson in Kista produce around 100 tons of ground coffee waste.

The companies Coor Service Management, Löfbergs Lila and Selecta are all responsible for different

stages in the logistical chain in delivering coffee and, together with Ericsson, they want to increase

their environmental benefit. The plan is to produce biogas through anaerobic digestion instead of

incinerating the coffee waste in a heating plant. The results are to be presented as different business

cases in which different biogas plants are compared with the reference case (heating plant),

comparing costs and environmental impacts.

There are two major environmental benefits from producing biogas; reduced carbon dioxide

emissions from when fossile fule is replaced by carbon neutral biogas, and reduced emissions from

returning digestate from the bio reactor to farmland instead of using industrial fertelizer.

In order to determine the biogas potential in coffee waste, a couple of properties had to be

determined in a laboratory. Properties such as the dry substance content, heating value, moisture

content and ash content. The results show that 100 tons coffee waste could produce around 16 500

Nm3 biogas which would contain 163 MWh.

The biogas reactor and upgrade plant both need energy gas to function and uses around 14 MWh of

the produced gas. In the end, the resulting upgraded biogas contains 149 MWh energy. Such an

amount of gas can replace 15,1 m3 of diesel and thus reduce carbon dioxide emissions by 39,4 ton.

The emissions from running the reactor and upgrade plant, combined with methane leakage

amounts to 4,8 ton carbon dioxide.

All of the biogas plants that were examined returns digestate and nutrients to farmlands which

reduces the need for industrial fertelizer. The production of fertelizer uses alot of energy, and by

returning digestate a reduction of 58 GJ energy and 3 ton CO2 can be achieved. This is not the case

with the heat plant which instead has to place some of its produced ashes in landfills.

If the exergy content in the biogas is compared to that of the heat it shows that there is a point to

making gas instead of incinerating the waste. The biogas has about 50 % higher exergy content than

the heat has and therefore it is possible to utilize the substrate more efficiently.

Transporting coffee waste from Ericsson to different biogas plants will result in increased carbon

dioxide emissions. The three plants investigated in this thesis are Henriksdals sewage treatment

plant, the Himmerfjärd plant and Uppsala biogas plant. For each plant, drivning distance, pre

treatment requirements of the coffee waste, and related costs were determined. Using methods

from the Network for transportation and enviroment, the emissions for each case were calculated.

The results show that the Henriksdal case will increase carbon dioxide emissions by two tons per

year, and the other cases will increase emissions by four tons.

The result from combining laboratory work, simulations and calculations show that the case where

Henriksdal recives the coffee waste will reduce carbon dioxide emissions by 15,1 ton at a cost of

72 000 kr per year. The case with the Himmerfjärd plant will reduce emissions by 13,8 ton at a cost of

74 000 kr per year. The final case with Uppsala biogas plant will reduce emissions by 13,7 ton at the

cost of 107 000 kr per year. And thus there are environmental benefits from producing biogas from

the coffee waste, but they do come at a cost.

Place, publisher, year, edition, pages
2013. , 44 p.
UPTEC ES, ISSN 1650-8300 ; 14003
Keyword [sv]
Kaffesump, biogas, förbränning, transporter, koldioxidutsläpp, ekonomiska kostnader
National Category
Energy Systems
URN: urn:nbn:se:uu:diva-217116OAI: oai:DiVA.org:uu-217116DiVA: diva2:692035
Educational program
Master Programme in Energy Systems Engineering
Available from: 2014-01-31 Created: 2014-01-29 Last updated: 2014-01-31Bibliographically approved

Open Access in DiVA

fors_e(1141 kB)96 downloads
File information
File name FULLTEXT01.pdfFile size 1141 kBChecksum SHA-512
Type fulltextMimetype application/pdf

Other links

Examensarbetet är tidigare publicerat på SLU
Energy Systems

Search outside of DiVA

GoogleGoogle Scholar
Total: 96 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Total: 251 hits
ReferencesLink to record
Permanent link

Direct link