An innovation that recycles rice husks into briquettes to replace fuelwood is promising rice farmers in Mwea extra income while cutting environmental pollution four fold, opening up possibilities of recycling the over 1.2 million tonnes of other agricultural residues available each year which are carelessly discarded.
The briquette making machine by Jomo Kenyatta University of Agriculture and Technology seeks to take the strain from the farmers and the environment, producing five 90kgs bags in an hour and as much as 40 bags in a day. “The briquettes business is currently at an all time high as consumers become aware of its health benefits and their cost effectiveness considered to other sources of energy and this is one area rice farmers have not given key market attention to with their rice waste. There is money to be made here,” says Ismail Onchoke a bio mechanic and environmental engineer from JKUAT.
In 2010 the average price of a 40 kg charcoal sack was Sh500 rising to Sh900 in just an year as demand soar. In the mean time 4 pieces of firewood, estimated to substitute 3.3 kg of charcoal, were sold for Sh60 with Sh1900 of charcoal expected to last 2 weeks, whereas Sh3000 LPG lasting for between 4 to 10 weeks, depending on the family size and cooking frequency. For the purpose of comparison, the assumption that briquettes can replace charcoal weight for weight means that Sh3000 could last for between 2 and 4 weeks.
Briquettes which can cost between Sh1,00 and Sh1300 for a similar 40 kg sack and often last longer than traditional charcoal makes economic sense for thousands of families who cannot afford modern sources of energy like gas. Rice farmers in Mwea, who supply 70 percent of the rice consumed in the country, with nowhere else to dispose the husks, burn them at the road side creating a massive environmental hazard and putting into grave danger the health of thousands of lives living near the roads.
“We have recorded many lung diseases in this area which we attribute to the fumes from the burnt husks. Infact after rice harvesting which is when we report most of these cases, we treat over 10 cases of lung related diseases daily, and the cycle goes on unabated,” said Dr Raymond Njiru who runs a health centre in the area.
Farmers are equally aware of the dangers the toxic fumes pose to the environment and other lives but “it has been hard to try and dispose these husks, you cant take them back to the fields, you cant feed them to the livestock, we dont have a place designated to dispose them, you just have to look for your own way of disposing them,” said Alphonse Muchina a rice farmer who on a good harvest gets 20 bags of rice in his two acre piece of land.
A 90kg bag produces a 90kg bag produces about 45kgs of husks. “So you can imagine a farmer like Muchina producing 900kgs of husks in one harvest. Add that to over 200 farmers in one locality and you understand while we are staring at an environmental crisis,” said Jedidah Kairu an officer with Kenya Forestry Services.
But the briquette making machine now transforms the mammmoth husks into environmentally safe source of fuel. After husks are gathered they are put into a biomass stove and lit from the top. As it burns it carbonises the husks to produce char, which can then be compacted into a briquette. Carbonisation which is the same process that creates charcoal from wood and is preferred particularly in urban environments for its superior burning, drives off volatile compounds and moisture leaving a fuel with a higher proportion of carbon remaining (char). Conversion to char in a controlled process also reduces the amount of harmful emissions compared to when raw biomass is burned.
The decision to carbonise depends on the application. In the next stage, the carbonized husks, now black in colour are mixed with a binder like clay or cassava wheat plus water. The mixture is then fed to the briquette machine for production of raw material. The briquette making machine which costs Sh100,000 is still being trialled on other waste materials and will soon hit the market.