By Robert Walker
As part of the BBC's Fuelling the Future season, Rob Walker looks at plans in Rwanda for exploiting methane from the bottom of a lake in order to boost the country's faltering electricity supply.
Rwandans are struggling to make ends meet in the energy crisis
Rwanda is gradually shaking off the horrors of the genocide in 1994 which shaped the image of the country for years.
The economy is being rebuilt but recovery is slow as daily life reveals.
Trade is brisk in Felix Akiba's barber shop in the centre of the capital, Kigali.
A line of customers chat and read newspapers while waiting their turn under the expert clippers of Felix and his fellow barbers.
But suddenly the electricity is cut, and Felix's clients have to wait while he coaxes a small and ancient generator into life.
"It is difficult to make a good profit. We have to pay for the fuel to run the generator, buy oil, it is very expensive."
Rwanda has made strides in rebuilding infrastructure after the devastation of the genocide in 1994.
Lake Kivu may offer a solution to Rwanda's energy woes
Kigali is expanding rapidly with multi-storey buildings and new housing estates springing up.
But just as the country needs it most, hydro-electricity production has crashed, resulting in frequent power cuts over the past 18 months.
The cause of the crisis lies north of the capital, among lush green hills and extinct volcanoes wreathed in cloud.
Here, the reservoirs which are the source of Rwanda's hydro-power are drying up.
A dip in rainfall in recent years means less water flowing into the reservoirs at the same time as power stations have been sucking more out of them to meet the spiralling demand for energy.
Now water levels have reached a critical point, and power stations are only able to run at half capacity.
Construction is springing up all over the place in the capital
"As demand has grown, we have operated the machines for too much of the time until now we are at a situation where we have to reduce generation so we match water coming in," said Brian Allan, Director of Electricity at the national electricity company, Electrogaz.
But now there are hopes of a solution and it comes from a surprising source - the bottom of Lake Kivu, a huge inland lake running along Rwanda's western border with the Democratic Republic of Congo.
Three hundred metres below the surface are an estimated 55 billion cubic metres of methane gas.
The Rwandan government has signed an $80m deal with an international consortium, Dane Associates, to start exploiting the methane.
The aim is to double Rwanda's electricity supply within two years.
But in the longer term, the potential is even higher. Methane could increase Rwanda's energy production by more than 20 times.
"We are talking of more than 700 megawatts of energy supply which goes far beyond what our country needs. It could be used for export purposes, or regional sharing," said Albert Butare, Minister of Energy.
The technology required is already available.
A brewery next to Lake Kivu has used methane from a pilot plant to power its boilers for more than two decades.
It could even turn Rwanda from a net importer of electricity to a source of power for the whole region
And the process of extracting the gas is surprisingly simple.
Pipes suck up water rich in methane from the bottom of the lake. Then the gas is separated out and dried, leaving almost pure methane.
The length of time taken to start exploiting the gas on a meaningful scale has provoked scepticism among Rwanda's long suffering consumers about whether an end to power cuts and high electricity bills is really in sight.
But if the new project succeeds, it could finally offer businesses like Felix Akiba's barber shop more reliable power and higher profits.
And it could even turn Rwanda from a net importer of electricity to a source of power for the whole region.