Solar powered irrigation for developing country growers. Testing and development taking place at CAT.

by Nick Jefferies

In poor rural communities around the world, one of the only ways of earning extra income is by growing vegetables and fruits to sell at the local market. The key to growing these crops is irrigation. Most current irrigation methods use either labour intensive manual pumps or expensive, carbon-emitting diesel engines. While undertaking my Masters at CAT in Renewable Energy, I came across a small-scale solar thermal technology being developed that offers an alternative method for irrigation pumping.

The system uses a parabolic dish to focus the sun’s heat onto a boiler to produce steam power that drives a simple type of reciprocating engine pump. Having contacted the inventor, I travelled to Holland to see the pump in operation and determine whether I could contribute to further development. This led me to travel to Ethiopia last September where I spent two months monitoring the engineering performance and socioeconomic issues related to pumps installed on ten farms around the town of Ziway.

Data indicated that the system could produce 2,500-5,000 litres/day from a depth of 5-13m, allowing for a cultivated area of 500-800 sq m. If good growing practices are followed, this means the cost of the pump could be paid back in less than one year. Monitoring also showed that the equipment was simple enough to allow farmers to operate the system independently. One key finding was that the overall efficiency of the system, calculated by comparing incoming solar energy to hydraulic energy output, was about three times less than expected. The main reason for this under-performance was identified as an incorrect sizing of one of the steam engine components.

This issue will be addressed in the next development stage, leading to a large increase in daily pumped volume, and thus directly improving the income potential and marketability of the solar steam pump.

The Ashden Awards: CAT wins leading environmental award for training the green workforce of the future

At a prestigious awards ceremony in London on Thursday 16 June CAT was awarded the Ashden Award for Training in Sustainable Technologies. The Ashden Awards are the world’s leading green energy awards and CAT won for its achievement in training and inspiring people to work in green technologies through a range of postgraduate and professional courses.

The Ashden Awards showcase practical solutions to combat climate change, rewarding outstanding and innovative low-carbon schemes in the UK and developing countries. CAT received the Award from Grand Designs presenter, Kevin McCloud and £10,000 to be spent on expanding their sustainable energy work.

The world-leading centre for practical learning on sustainable energy and architecture is among five UK winners, all of whom are leading the way to a low-carbon society.

CAT, which was established 35 years ago, impressed judges with its range of innovative short courses and postgraduate degrees. Its courses are unique in combining hands-on experience with top-grade academic teaching, and their work is crucial in consolidating the skills and know-how required for a green economy.

Nearly 4,000 students have already benefited from the hands-on experience offered by on-site technologies such as hydro, wind, solar and biomass; the access to leading practitioners in their fields; and the inspiring community that has evolved at CAT.

The recently completed award-winning WISE (Wales Institute for Sustainable Education) building provides accommodation for students, but it also serves as a practical example of sustainable architecture and is used by students for practical elements of their courses.

Over the past five years, CAT has educated over 1,400 MSc students and had over 2,100 people attend short courses in sustainable energy, including 370 for accreditation in the installation of renewable energy technology.

Sarah Butler-Sloss, Founder Director of the Ashden Awards, said:
“To transform the UK into a low-carbon nation we need vision, investment, skills and infrastructure. CAT’s training and education programmes are helping bridge the gaping skills gap that we face in the green technology sector if we are hoping to address climate change and energy security. The challenge now is to step up our game, and replicate approaches like this in every corner of the country, to create a better future for us all.” Zero Carbon Britain

Commenting on receiving the award, Paul Allen, External Relations Director at CAT said:
“We are thrilled to receive such prestigious recognition from the Ashden Awards and very proud of the work we do at CAT. Many students go on to work in the green sector as consultants, public sector specialists or some set up their own businesses. Our approach is helping create experts with the skills and knowledge the UK needs to speed the transition to a low carbon economy.”

CAT plans to develop its educational work and continue to promote its Zero Carbon Britain strategy to increase its profile. The Centre’s Graduate School for the Environment recently launched a new MSc course, MSc Environmental Change and Practice: Buildings, and is working to increase student numbers on all its courses.

Open Source Digital Fabrication

A few weeks ago a project was started here at CAT to research and develop open source digital fabrication methods.   Digital fabrication tools allow us to build precise parts for everyday useful objects; and have been used for rapid prototyping in industry for many years.  The focus of this project is to make such tools accessible at a community level, a bit like having access to a master craftsman in your local town or village, but in digital form.

A key aspect of this project is that all software source code and hardware designs are available freely under the GNU General Public License.  Open sourcing allows a horizontal transfer of technology, gives greater autonomy for local communities to build the technology they need, and enables them to tap into a global knowledge base. It often gives rise to greater modularity in design (easier to fix, maintain and integrate), and thus in many cases better re-use of materials and components: leading to a cradle-to-cradle lifecycle.

Our initial focus is the RepRap 3D printer: a fabricator that can self replicate many of its component parts, thus the technology can be easily passed on to other communities. Documentation can be found at www.reprap.org .  A RepRap can print using a variety of plastics (such as starch based biodegradable PLA).  Other materials will also be investigated, such as ceramic extrusion and wood milling. An analogy for this project is like the symbiotic relationship between bees and flowers. In the same way bees pollinate flowers in return for nectar, humans will assemble machines in return for useful objects. In this way, both parties mutually benefit and human creativity and innovation can still evolve.

Local manufacturing itself should give rise to ‘just in time’ ‘pull-type’ production as opposed to a centralised ‘push’ approach with its associated inefficiencies of storing and distributing goods (naturally there will always be energy/ecological/social trade offs between the two methods).  Digital fabrication is just one of many tools for localised production and living; other aspects are still to be explored within the open source eco-system, such as energy production, material extraction, transportation and agriculture.

At CAT one focus will be the application of these tools for building parts for our displays and renewable energy systems such as molds for wind turbine aerofoils, pelton wheels, mechanical cogs, connectors, jigs and fixings. The project is open to discussion on what the best approaches might be for given situations, and also to explore the infinite realm of ideas on what we can build!

To follow progress of this work, please visit the blog www.digitalfabcat.blogspot.com and feel free to share your findings, links, experiences and thoughts for applications in this collaborative project.