Tech Talks

CED Tech Talks focus on development technology and its application. They are a way to make CED’s internal technical knowledge available to our members and supporters, as well as potential members and others outside our organisation.

They consist of a 45-minute talk followed by about 30 minutes of questions and answers and subsequent discussion, recorded from the initial Zoom meeting. Contact us if you would like to attend future Tech Talks with us on Zoom.

Talks so far

Paul Darrall on Solar Power for Remote Locations (20 April 2023)

In the sixth and final TechTalk of the 2022-23 season CED member Paul Darrall speaks about small scale solar power projects in development contexts. He describes the different approaches that can be used: stand alone or mains commutated systems. He then discusses the practical problems that need to be considered when designing a system. The talk concludes with a question and answer session.

YouTube video

Paul Winfrey on Travel and Health in Developing Countries (16 March 2023)

This is the fifth TechTalk of the 2022-23 season. Guest speaker Dr Peter Winfrey gives general information about travel and health issues that CED members who are travelling overseas. Peter was medical superintendent at Kisiizi Hospital in Uganda with the Church Missionary Society. He opens his talk by highlighting the two biggest risks that overseas travellers to developing countries will face: malaria and road traffic accidents. He suggests how these risks should be minimised. He continues to discuss a range of other health related issues that people might encounter. The talk concludes with a question and answer session.

Note: CED is publishing this video in good faith. This talk represents Peter Winfrey’s general medical opinion on issues related to overseas travel. It should not be constituted as medical advice. For any queries about the content of the video please contact CED at

YouTube video

Stephen Burgess on Solar Water Disinfection (16 February 2023)

This is the fourth TechTalk of the 2022-23 season. Longstanding CED member Stephen Burgess tells us about the benefits of Solar Water Disinfection or SODIS for short. Stephen brings his experience from working with Christian Community Services within the Anglican Church of Kenya in Eldoret region. SODIS is a zero cost sustainable way to disinfect non-turbid water in clear clean PET bottles. Stephen shares the Eldoret community’s real-life experience with SODIS and then explains where people can find further information. The talk concludes with a question and answer session.

YouTube video

Mike Yallop on Different Water Pumps (19 January 2023)

This is the third TechTalk of the 2022-23 season. CED member Mike Yallop tells us about the variety of different water pumps that might be used in small community water supply systems. Mike is a retired Chartered Water Engineer with over 40 years experience and considerable knowledge of this subject. He opens by explaining why he started getting involved with CED providing clean water overseas. He then breaks down his talk into descriptions of positive displacement and rotodynamic pumps. He also explains the importance of handpumps in developing countries. His talk then ventures into design concepts, including the importance of ensuring a pump is correctly matched with its piping system.

YouTube video

Stephen Morris on Bagged Earth Construction (15 December 2022)

In the second Tech Talk of the 2022-23 season, Stephen Morris describes the advantages of bagged earth construction. This sustainable approach to construction uses locally available materials, whatever the quality of the soil, and requires little skill. Buildings constructed using bagged earth construction also have good resistance to seismic activity. The video ends with a question and answer session.

YouTube video

Paul Darrall on High Voltage Power Transmission (17 November 2022)

In the first of our 2022-23 series of Tech Talks CED member Paul Darrall gives a talk entitled “A Guide to High Voltage Transmission – What Every Civil Engineer should know”. CED is working on a range of hydro electricity generation projects, so some awareness of issues relating to HV power transmission in development contexts is likely to be useful.

YouTube video

Alan Chadborn on Sanitation in Developing Countries (28 April 2022)

In the sixth and final Tech Talk of the 2021-2022 season, Alan Chadborn, one of CED’s most longstanding members, shares his experience of sanitation in developing countries. He starts by explaining hygiene principles, then goes on to discuss the challenges associated with preventing contamination of clean water as it is transferred from a water source. He concludes by assessing and comparing the various options for sanitation at household and institutional level. The video ends with a question and answer session.

YouTube video

Rob Wakeling on Climate Change (17 March 2022)

In the fifth of our 2021-22 series of Tech Talks Rob Wakeling, one of CED’s executive directors, speaks about Climate Change and its impact on CED’s work. He explains how those in the majority world have been increasingly affected by Climate Change and then describes what steps CED has taken in response. Rob then poses a series of challenging questions which leads into a time of discussion.

YouTube video

Angus Armstrong on Zanzibar Spice and Why Cathedrals don’t Fall Down (17 February 2022)

In the fourth of our 2021-22 series of Tech Talks Angus Armstrong, one of CED’s executive directors, describes how he participated in the restoration of the historic Christ Church Cathedral in Zanzibar. He gives and overview of the history, geography and geology of Zanzibar, then explains the structural problem that the cathedral was facing. A solution to tie the walls together was developed and then installed as part of the cathedral restoration programme. Angus’s talk gives a fascinating glimpse into a simple, but effective project that will secure the stability of the structure for many years hence. You can find out more information about the project here. The talk concludes with a question and answer session.

YouTube video

Nigel Heeler on the Clariwash Self-Washing Filtration System (20 January 2022)

In the third of our 2021-22 series of Tech Talks Nigel Heeler, the inventor of the Clariwash filtration system, talks about his design. Clariwash filters a water supply until it becomes clogged – then it automatically reverses its flow to wash itself out. It needs no power supply and works entirely from the flow of the water. Nigel says: “I have attempted to develop an appropriate low cost community water treatment system. It has no complex parts and no moving parts, so it can be constructed locally. It can be easily transported to where it is needed and requires little or no maintenance”. The talk concludes with a question and answer session. You can find out more about the Clariwash filtration system at Nigel’s website

YouTube video

Rob Brighouse on the who, what how and why of CED (16 December 2021)

In the second of our 2021-22 series of Tech Talks Rob Brighouse, Chair of CED’s non executive committee goes back to first principles to explain the who, what, how and why about CED? Rob starts by explaining CED’s philosophy and what it has achieved. He goes on to explain how CED works in practice and how people can get involved. He concludes his talk with a case study of the Kagera Rainwater Harvesting project which demonstrates how CED works in partnership with the local community to deliver sustained benefits. The video ends with a question and answer session.

YouTube video

Dick Waller on Community Water Supply Systems (18 November 2021)

In the first of our 2021-22 series of Tech Talks Dick Waller, one CED’s longest standing members shares the breadth of his experience about water supply systems in majority world contexts. The title of his talk is “Compare and Contrast Water Supply Systems in and for the Developing World”. Dick describes the types of water supply system that might be used, how the water is transported and the practical considerations that are involved. He also gives an overview of the factors that are involved in planning and designing new facilities.

YouTube video

Jonathan Appleby on Engineering in Disasters (8 March 2021)

In the last our our 2020-21 series of Tech Talks, CED’s Chair of Directors Jonathan Appleby shares his experience working with a Tearfund team in Kashmir in the aftermath of the 2005 South East Asia earthquake. His talk brought home the challenges of working with relief teams from different NGOs as well as the human cost of natural disasters. His presentation also addressed some structural design challenges that remain outstanding today.

YouTube video

Philip Tibenderana with A Ugandan Perspective on Development (8 February 2021)

In our fourth Tech Talk, CED’s part-time engineer Philip Tibenderana brings us “A Ugandan Perspective on Development”. Philip compares the UK and Uganda in terms of development, before sharing his extensive experience from working with CED in Uganda. He reflects upon the positive outcomes that he has witnessed and concludes by highlighting some common project delivery challenges. There is a Question and Answer session after the end of Philip’s presentation.

YouTube video

Jonathan Cox on Micro Hydro Technology and Opportunities (11 January 2021)

In the third of CED’s Tech Talks, CED member Jonathan Cox spoke about “Micro Hydro Technology and Opportunities”. He discussed the processes for generating power from water (both from an energy and a practical perspective). He then discussed some common design problems that he has experienced, before briefly considering today’s context including the impact of climate change.

YouTube video

Stephen Morris on Rammed Earth Construction (14 December 2020)

In CED’s latest Tech Talk Stephen Morris speaks about rammed earth construction : why it is beneficial and how it is done.

YouTube video

Ian Rankin on Rainwater Harvesting (9 November 2020)

In the first of CED’s first season of Tech Talks, CED’s former Chair Ian Rankin speaks about the construction and use of ferrocement pumpkin tanks for rainwater harvesting. The talk is introduced by another of CED’s directors, Mike Beresford.

YouTube video