Pris­ons with a Green So­lu­tion

Southern Innovator - - CONTENTS -

An in­ge­nious so­lu­tion is help­ing Rwanda to re­duce the cost of run­ning its burst­ing pris­ons while im­prov­ing con­di­tions for the pris­on­ers and help­ing to pro­tect the en­vi­ron­ment.

The coun­try’s prison pop­u­la­tion soared to a peak of 120,000 sus­pects await­ing trial for their role in the 1994 geno­cide in which 800,000 Tut­sis and mod­er­ate Hu­tus were killed. The tra­di­tional court sys­tem, gacaca, is be­ing used for na­tional rec­on­cil­i­a­tion, but the process is slow and costly for a coun­try where 90 per cent of the pop­u­la­tion ex­ists on sub­sis­tence agri­cul­ture and where food pro­duc­tion has dropped be­low 70 per cent of the lev­els needed for self-suf­fi­ciency (USAID).

But thanks to enor­mous, bee­hive-shaped hu­man ma­nure di­gesters, a steady sup­ply of bio­gas is on tap for cook­ing and light­ing at pris­ons – Rwanda is the first coun­try in Africa to do this. Five of the coun­try’s largest pris­ons – two in Gi­tarama and one each in Butare, Ki­gali and Cyan­gugu – now have bio­gas plants pro­duc­ing 50 per cent of the gas needed to cook for pris­on­ers. It has also saved half of each prison’s Us$44,000-a-year fire­wood costs.

Bio­gas is pro­duced from the fer­men­ta­tion of house­hold or agri­cul­tural waste or an­i­mal or hu­man fae­ces and has be­come a vi­able al­ter­na­tive when tra­di­tional gas sources be­come more ex­pen­sive. The waste is placed in a 150 cu­bic me­tre bee­hive-shaped di­gester and fer­mented un­til a gas is pro­duced. Ac­cord­ing to lead engi­neer on the pro­ject Ainea Ki­maro, 100 cu­bic me­tres of waste are turned into 50 cu­bic me­tres of fuel by bac­te­ria de­vour­ing the ma­nure in just four weeks.

The di­gesters are a pro­ject of the Ki­gali In­sti­tute of Science, Tech­nol­ogy and Man­age­ment‘s Cen­ter for In­no­va­tions and Tech­nol­ogy Trans­fer.

“Bio­gas kills two birds with one stone,” Ki­maro told the BBC. It gets rid of all the hu­man waste and cov­ers the costs of feed­ing so many pris­on­ers.

Many would think that this is a smelly af­fair, but in fact the whole process isn’t that pun­gent. Most of the di­gester is un­der­ground and the gas pro­duced burns a clean, blue, smoke­less flame. It is much cleaner than the smoke from fire­wood. The re­main­ing sludgy residue is used as an odour­less com­post for soil. This is used in the prison gar­dens to grow maize, man­gos, bananas and toma­toes. – (Fe­bru­ary 2008)

Bio­gas plant un­der con­struc­tion at Ki­tarama prison, Rwanda.

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