2014-17 – Human-Powered Shredder

appropriate technology / composting / mulching / small-scale farming / urban ag

The Participatory Design of a Human-powered Shredder for Urban Farmers in Soweto

Peter Harrison, MTech Industrial Design, 2014-2017, completed Cum Laude
Supervised by Angus D. Campbell & co-supervised by Dr. Naudé Malan.

Despite mankind’s technical achievements, broader illusive issues like climate change, rapid urban sprawl and food insecurity still remain. In Soweto, South Africa, it is historically marginalised emergent farmers who remain at the forefront of the fight against urban food insecurity, but despite their efforts, much urban farmland remains under-utilised. Lacking appropriate equipment emergent farmers struggle to either maintain or rehabilitate their available soil. Farmers’ current methods of reducing organic waste for composting and mulch materials are laborious and ineffective. Soils therefore often remain infertile, damaged or under-nourished and hence farmers’ are unable to optimise their urban small-holdings.

Hence, experienced Industrial Designer Peter Harrison undertook a participatory design process to develop a human-powered shredder for improving compost production with, and for, small-scale urban farmers in Soweto, South Africa. Harrison applied criteria from Appropriate Technology (AT) as a means of governing design decision-making, and employed Human-Centred Design (HCD) as a formal methodology for working with emerging farmers. Participatory HCD was utilised to develop appropriate agricultural processing equipment in collaboration with experienced farmers, composters and engineers. Harrison purposefully selected experienced experts from each of these three fields as the shredder study’s key informants. Consecutive semi-structured focus groups, observation and fieldwork facilitated data collection. Iterative prototyping, testing and design reflection formed the basis for monitoring product design development. Being human-powered, the design favours multiple operators. Human-power allows farming families to power shredders at will without incurring added running costs. Thus, encouraging greater ‘resilience’ by considering, local employment. The shredder use and maintenance has been found accessible by newcomers, and serviceable using three basic hand tools. Components were purposefully sourced from local suppliers where possible, thus favouring local manufacture. The shredder study aimed to ‘nudge’ an increase in the ease and frequency of compost production by farmers.


This work is based on research supported in part by the National Research Foundation (NRF) of South Africa for the Thuthuka, unique grant number 88030 held by Angus D. Campbell and titled, Designing Development: An Exploration of Technology Innovation by Small-Scale Urban Farmers in Johannesburg, and unique grant number 88059 held by Dr. Naudé Malan and titled, Innovation in the Soweto Food System: Engaging with Soweto Agriculture. Any opinion, finding, and conclusion or recommendation expressed in this material are that of the authors, and the NRF does not accept any liability in this regard.


Harrison, P.H. 2017. The Participatory Design of a Human-powered Shredder for Urban Farmers in Soweto. MTech: Industrial Design Dissertation. University of Johannesburg. (4Mb)

Harrison, P.H. 2017. Human-powered Shredder Open Source CAD manufacture and assembly files.

Campbell, A.D. & Harrison, P.H. 2015. A Framework for Socio-Technical Innovation: The Case of a Human-Powered Shredder. In Collina, L., Galluzzo, L. & Meroni, A (Eds). Proceedings of the Cumulus Conference, Milano 2015: The Virtuous Circle: Design Culture and Experimentation. Milan: McGraw Hill. pp. 211-230. ISBN: 978883869405 (Peer Reviewed).

Campbell, A.D. & Harrison, P.H. 2015. Socio-technical Innovation: The Case of a Human-powered Shredder. Paper presented at the Design Society Development DESIS Lab Seminar, University of Johannesburg. Johannesburg, South Africa, 6 March.