Clean Energy

Things to be considered seriously while building Zero Energy Cold Store

I got a chance to design and undertake project to build “Zero Energy Cold Store” (ZECS) in pocket areas for oranges in Syangja District, Nepal. After the visit of two sites of ZECS in two districts of Nepal , One successful  in Bharatpokhari, Kaski and the other one a failure in Fedhikhola ,Syangja. I found technical factors are prime to make a project successful but technical factors are not everything, social and socio-economic factors also play equally important role to make a project sustainable. More on to say, an engineer has to blend technical and social factors in “state of art” way to make projects (especially rural projects) successful.
I first visited a successful enterprise, ZECS in Bharatpokhari, Kaski where I was guided by Mr. Khagendra Adhikari, a local stakeholder. ZECS in Bharatpokhari had several reasons to work successfully, or may I say it was built with a big experience and conscience by Nepal Farming Institute (NFI) in this sector. ZECS is simple in principle, “Evaporation causes cooling”. For this, we need to build two walls with cavity between walls filled with the fine sand and water is dripped in sand. The challenge to build a ZECS is here,
  •   If water is to be dripped between walls, water carries the power to destruct the wall structure so NFI has seriously considered flow control of water through outer wall (which is made of mud and stone) and used “Z” connectors to bind two walls strong enough.
  •   Inside wall is built with concrete and stone. (Remember water breaths through this wall).
  • Water may also leak inside the cold store which can ruin total harvest, so structure has included a canal in four sides of cold store. Now, water seepage may not run to the harvest areas.
  •  A small angle slope is made just above the foundation, below inner wall and cavity to drain the water towards inner canal and to protect the outer wall from the flood created by water at the base.
  • The northern side wall (the front wall) has windows and ventilation, made from wood. If the water is dripped in wall above ventilation, it will apparently decay the wood used in ventilation and windows. Wisely, this cold store at Bharatpokhari, has considered the fact and water is dripped in only wall areas which do not have ventilation below.
At my second visit of ZECS  site at Fedikhola, Syangja I found all above points were not seriously considered by the project team so the project became technically fail and the  farmers has to bear a loss in one harvest of potatoes .
The other most challenging factor in ZECS is to maintain proper relative humidity. RH plays a vital role in deterioration of agro products. Agro products needs to be stored in controlled temperature and controlled RH. Most of the fruits and vegetables need to be stored in high relative humidity, generally above 85 %. With the appropriate RH, good air flow is needed to keep the fruits and vegetable fresh and respiring. Fruits are prone to different diseases due to damp condition inside the storage. Inadequate ventilation may result in fermentation and rotting of the products as a result of increased CO2 levels and inadequate supply of atmospheric oxygen.
Like I have mentioned earlier too, a technology needs to be technically sound as well as socially acceptable and adoptable too. When technology expects the human involvement, then there is a high chance of project failure. My point is, less the human dependence, more the chance to sustain projects. Human cannot be seriously committed to public projects every time and one delay in operation may totally ruin the project. For example, in the second site local were not too serious about closing and opening ventilation during day and nights respectively which apparently caused damp inside the store and potatoes got fungal diseases which led to ruin all harvest. So, what if we automate the windows. Yes, it’s possible and simple too by using solar energy. Probably this simple idea can sustain the whole project.


Prakash Acharya is an entrepreneur from Nepal, passionately working to substitute fossil fuels with clean energy technologies. He co-founds Mukti Energy, a solar energy company providing a one-stop solution in the sector. He is also a big believer in change so he advocates and works for creating impact in society. His topics of interest spans from sustainability, zero energy, poverty reduction, sociology to smart city. He graduated from Institute of Engineering, Thapathali Campus on Industrial engineering. He is also a former assistant lecturer in IOE, Thapathali . Prakash is a fellow for Social Entrepreneurship Outreach Program 2014, Social Entrepreneurship Forum Sweden.

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