Gravity Lights!

I have a love-hate relationship with technology:  I love the fact that a small USB dongle plugged into my laptop enables me to publish this article for blog readers in a dozen countries on five continents.  I hate the fact that this dongle also allows me to be bombarded with requests to download endless software updates, virus threat warnings and emails offering me credit cards I don’t want.

The technologies which impress me most are the simplest.  When I served in the RN on multi-million pound warships filled with electronic wizardry, I soon learnt that they also needed tonnes and tonnes of fuel, stores of expensive spare-parts and even more expensive teams of engineers to keep them all working.  Personally, I’m more impressed with a sailing boat, which can sail right around the world with only one or two people, simply by harnessing the wind.  Similarly, although I love cars, I think the bicycle was the more significant invention, certainly for the millions of people in Asia and Africa (and Cambridge!) who use relatively cheap bicycles to multiply the range, speed and carrying capacity of the legs that God gave us for free.

Imagine my excitement when one of our home-church deacons, sent me an email about a company which had harnessed the power of gravity to make light!  I immediately contacted “Deciwatt” and asked if they were interested in having their project field-tested in the towns and villages of Kasese district, western Uganda, most of which lack electrical power, and some of which in the Rwenzori mountains, will probably never get power because they are so high and difficult to access.

A few months later I got two parcels containing 10 Gravity lights accompanied by 20 extra small lights called “Sat-lights”, which plug into the main gravity light unit.  The design is beautifully simple.  You cable-tie the gravity unit onto a roof beam, ideally over 2m above the ground.  Then you pass a white tape with holes punched all along it into the gravity unit.  On one end of the tape you hang a heavy bag, filled with 12kg of stones, and on the other a smaller bag with just 1kg of stones.  Then you lift the heavy bag as high as you can and let go of it.  Gravity takes over and pulls the heavy bag towards the ground.  As the holes in the tape pull through the unit there’s some form of ratchet mechanism which powers a dynamo and makes about a watt of electricity.  Years ago 1 watt of electricity would have been useless, most incandescent lightbulbs used 40 – 100 watts each.  However, with modern LED technology, this 1 Watt powers a main bulb in the gravity unit plus the two “sat-lights”.  The speed of fall/brightness can be adjusted with three settings so that you can have a bright light for 14-15 minutes, a medium light for 20 minutes, or a dim light for 25-30 minutes.  When the small bag reaches the top, or the heavy bag hits the floor, you simply lift the heavy bag up again and the light comes back on again.  Because there’s no battery required and LEDs last for years, the only limit to how many times you can use it is the strength in your arms – and most rural Africans who dig fields, pound maize and carry their water and firewood have very strong arms. 

If you’ve grown up with electricity all your life then a room with only a gravity light in it seems pretty dark.  However, if like much of the world’s population, you live without electricity and are reliant on kerosene which as well as being very dim, flickering and smoky, is also expensive, unhealthy, a fire-risk, and bad for the environment; then Gravity Light is a life-changer!

As many of you know, I have a passion for helping Ugandans to find alternatives to their reliance on fossil and wood-based fuels, hence the solar projects in churches and the charcoal-briquette making project to replace wood-fuels.  Therefore, I was excited to have this smaller light product to take to places which, for various reasons, had been ineligible for the solar project.  In order to conduct a useful trial for Deciwatt, we decided to trial the lights in a variety of contexts to see how they would be used.  Geographically this included Kasese town, Kayanzi fishing village (on the shores of Lake Edward), the typical rural villages of Kyaminyawandi and Kalehe, and the mountain villages of Kisabu and Ibweryakyona, which are high in the Rwenzoris and right on the border with DR Congo.  Each place had to be visited once to install the light and explain the trial, and then visited again a few weeks later to ask follow up questions.  Reaching the latter two was quite an adventure.  On my only previous attempt to reach Kisabu the Landcruiser had got stuck in mud and we’d turned back.  This time we made it, but only just, and I will never drive there ever again (the Pastor met us elsewhere to do the follow-up questions for the trial).  Ibweryakyona is the last village before the Rwenzori Mountains National Park boundary but you have to park a few kms beforehand and then climb the final steepest section on foot.

For social context the trial included three households, one primary school, two drug shops/clinics and three small Baptist churches (one of the 10 lights broke).  In all cases the Gravity light was greeted with amazement on arrival.  People were astounded that a bag of stones could produce electric light, one man even opened the bag to see if we’d hidden a battery and other wires there!  For households and small businesses, the cost of kerosene, (or lamp batteries or candles) is often 10% of their weekly income.  For churches and schools there is no budget for providing lighting, so they remain closed in the evenings, or have to rely on begging kerosene from their members, whereas Gravity light enabled them to open their doors for homework sessions/lesson-planning, bible-studies and evening fellowships.  Therefore, all 9 recipients are now saving money every week by using their Gravity light.  Furthermore, whereas a kerosene lamp provides a single light source, the addition of 2 Sat-lights to the gravity light enables it to either light three rooms in a house at once, or to light a larger space (such as a small church).  Uses of the Gravity light varied across the trial:  in a household in Kayanzi fishing village, they leave the house late every afternoon to go night fishing and return at 3 or 4 am in the pitch dark.  The gravity light therefore enabled this family to wash, change and eat together on returning from fishing.  For the health clinic in Kalehe and the drug shop on the edge of Kasese town, the Gravity light enabled them to see patients at night, which is common as people usually seek medical care after they’ve finished their working day.  For other households the uses were as you’d expect; children doing homework, parents cooking food and preparing clothes for the next day, and families sitting to eat their evening meal together.  One thing stood out from almost all of the respondents; whether collectively in a church, or individually in their houses or workplaces, people used their new free lighting to read their bibles.  Psalm 119:105 tells us that God’s word “is a lamp to my feet and a light for my path.”  Yet too many people in the world lack the physical light required to read God’s word and follow his spiritual light.  The clever people at Deciwatt, and their beautifully simple invention, Gravity Light, have harnessed the power of gravity to bring affordable and sustainable light into more places across the globe. 

This is a technology I can love.  Please see the "pictures 2014" for some pictures and Check out www.deciwatt.org if you love it too!