July 19, 2024

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Preserving Lake Kivu: The Monitoring of Methane Gas Extraction

The Rwanda Environment Management Authority (REMA) has stated that the methane gas extraction in Lake Kivu has not caused any damage to the lake, based on constant measurements taken. Lake Kivu, which reaches depths of up to 450 meters, contains vast amounts of methane gas.

Due to the shifting tectonic plates at its depths, gases like methane (CH4) and carbon dioxide (CO2) are released and collect in the lake water, similar to active volcanoes. CO2 is particularly hazardous, as it is odorless and lethal in high concentrations. The methane gas is contained deep within the lake by water pressure and is utilized by a pumping station to generate energy.

The process of methane gas extraction and monitoring in Lake Kivu was discussed during the “Environment Restoration at 30” tour, which commenced on May 25 and will continue until June 5.

As part of the “Environment Restoration at 30” tour, REMA also organized five-day tour, from May 27 to 31, highlighted Rwanda’s accomplishments in land restoration and sustainable agriculture, bringing together students from universities, media personnel, and members of civil society to explore rehabilitated landscapes.

This initiative coincides with National Environment Week leading up to World Environment Day on June 5, with this year’s theme being “Land Restoration, Desertification, and Drought Resilience.”

Dieudonne Tuyisabyimbabazi, Site Plant Monitoring Specialist at Rwanda Environment Management Authority (REMA), a methane gas extraction operator in Lake Kivu, explained a lot of gas in the groundwater of Lake Kivu as the reason for the monitoring of methane gas extraction in the lake.

He said, “We have 300 billion cubic meters of CO2 dissolved in the water and 60 billion cubic meters of methane gas dissolved in the water; without monitoring those gases, Gisenyi and all other areas around the lake could have destroyed life. That is why the Government of Rwanda started the method of extracting and electrifying the water that was stored and returned to the lake at its former depth.”

Tuyisabyimbabazi noted that since 2018, an agency has been set up to monitor whether the methane gas extraction is affecting the ecosystem in Lake Kivu and that it has not caused any damage since they started the inspection.

He said, “Currently, there are no significant changes to the lake and its organisms because there has been no decrease or increase due to the extraction according to the standards we take. It appears that the organisms are in good condition, and there are no negative effects due to the methane gas extraction being carried out.”

He revealed that although there are no visible effects, researchers have shown that Lake Kivu increases the temperature by 0.05 degrees Celsius so that the gas extraction area can increase the temperature due to the inclusion of water mixed in the gas.

In the process, the water is sucked out of the depths, and the gases are extracted. Gas and water separate automatically as soon as the pressure drops on the way to the surface; methane separates at a depth of 120 meters and carbon dioxide at 15 meters. The system directs CO2 back into the water and methane through a pipe to the shore. There it is burned; the hot air drives a turbine to produce electricity.

“Water taken from deep waters to extract methane gas is then re-injected deeply to preserve lake stability. Water taken from the biozone for the ‘washing’ of the gas is also injected at the bottom of the biozone. Uptakes and re-injections have to follow the Management Prescriptions (MPs),” Tuyisabyimbabazi said.

He added that monitoring re-injected waters is an important component to ensure that the integrity, stability, and ecology of Lake Kivu are well preserved and that gas resources are not diluted.

He continued to collect deep vertical profiles of temperature, PH, turbidity, and salinity—oxygen in the biozone—near gas extraction plants regularly to localize the re-injected waters and detect any impact on the stratification of the lake and in the biozone.

Lake Kivu methane gas was extracted and used for the first time in Rwanda by Union chimique de Belge with a gas pilot plant at Cape Rubona in 1963 to supply the Bralirwa brewery.

Until 2004, extraction of the gas was done on a small scale, with the extracted gas being used to run boilers at a brewery in Gisenyi. Since then, the government of Rwanda has prioritized the production of electricity from this unique resource to address the growing electrical energy deficit.

The US-based company Contour Global anchored in 2015 a 50 by 30-meter production platform in the middle of the lake, which currently produces around 26 MW of energy. It plans to increase capacity to 100 MW in the future with three more platforms.

According to Rwanda Energy Group (REG), Lake Kivu holds enough methane gas to provide 700 megawatts for 55 years and could supply all of Rwanda and neighboring countries with electricity.

Rwanda’s primary energy use is dominated by biomass, which accounts for 86.3% of the total. Rwanda has one of the lowest electricity consumption per capita in the region, and generation capacity is low. 83.3% of Rwandan households use wood for their cooking fuel, followed by charcoal (15.2%), crop waste (0.8%), gas or biogas (0.2%), and the other 6%.

At a national level, the use of electricity for lighting changed from 11% in 2010/11 to 20% in 2013/14. Of the 14% of non-biomass primary energy, petroleum products account for 11% (used mainly in the transport sector) and electricity for approximately 3%.

The REMA department responsible for monitoring the quality of Lake Kivu shows that the changes in Lake Kivu are closely controlled, with the help of standards and modern laboratories to control these standards, to establish the status and trend of the lake water quality and lake stability during methane extraction.

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