Terms of Reference
Engineering
Proposal – Solar Option
Inter-Basin Water Transfer to Lake Chad
Prepared for the
Lake Chad Basin Commission
This paper was presented at the The International Conference on Lake Chad Basin
held in Abuja, Nigeria Feb 26th-28th, 2018.
Consultant: Guy Immega, P.Eng.
Solar Option Group
Vancouver, BC, Canada
guy.immega@kinetic.ca
Introduction:
In 2011, CIMA International (Canada), under contract to the Lake Chad Basin Commission, completed a Feasibility Study of the Water Transfer Project from the Ubangi to Lake Chad. In broad terms, the study recommended a 360 MW hydroelectric dam on the Ubangi River in the Congo River Basin. Most of the power (250 MW) from this dam would be used to pump water to Lake Chad.
A dam on the Ubangi River would flood the waterway 200 km upstream, displacing villages and disrupting fishing and navigation. The dam is also costly, at $2.7 billion (2011 dollars). The Solar Option is an alternative power source to the dam. Sample Project Specifications for the Solar Option indicate it will pump 1.58 billion m3/yr to Lake Chad (50% of the rate of the hydroelectric dam) at an approximate cost of $267M (less than 10% of the cost of the hydroelectric dam).
The new proposal will consider the option of using solar energy to pump water from submerged intakes in the Ubangi River. This approach avoids the environmental impacts of a dam and is based on renewable solar energy. Initially, pumping will occur during daylight hours only, when solar energy is available. Later, grid-scale battery technology can provide nighttime pumping. Eventual solar power can be distributed to nearby towns and villages.
Although these Terms of Reference use information from the previous CIMA 2011 feasibility study, and also from the 1970-2014 Bonifica Transaqua proposals, the current concept for IBWT (Inter-basin Water Transfer) using solar energy (the Solar Option) is intended to have low environmental impact, reduced cost, and use sustainable renewable solar energy.
The scope of these Terms of Reference includes all the engineering information necessary for completion of IBWT to Lake Chad. This includes technology specifications and sources, infrastructure required (such as roads), milestone goals and schedules for staged construction, and budget.
Glossary:
CAR – Central African Republic
CIMA – CIMA International, engineering company in Laval, Quebec (previous study)
DRC – Democratic Republic of Congo
IBWT – Inter-Basin Water Transfer (from the Congo Basin to the Lake Chad Basin)
LCBC – Lake Chad Basin Commission
PV – Photovoltaic solar-electric panels to generate power from sunlight
Solar Option – the use of solar power (instead of hydroelectric) to pump water to Lake Chad
1.
Solar
Power
1.1. PV Power:
This project will be powered by PV technology (no dams or flooding). The
optimum size of the PV power station shall be calculated. Specific PV
technology will be selected, based on cost, reliability, maintenance
requirements, and projected lifetime. The PV power station shall initially produce
electricity in daytime only. However, the design must eventually accommodate
grid-scale energy storage and other power sources, to provide 24-hour service.
1.2. PV Power Station Site:
Recommended siting for the PV Power Station shall be determined. Two sites
shall be studied and compared: 1) Ubangi River site adjacent to pumps; 2)
remote site in the Sahel (more sunlight) requiring a transmission line. Considerations
will include insolation (amount of sunlight available), road access,
installation costs, transmission line route, operator personnel needed, and
maintenance requirements.
1.3. Grid-Scale Battery Storage:
Grid-scale battery technology is rapidly evolving. Current projections indicate
that large lithium-ion batteries may fall to $100/kWh by 2028. Large grid-scale
batteries can enable water pumping for 24 hours per day. New options for
grid-scale energy storage battery will be reviewed for cost, reliability,
lifetime, and maintenance requirements. The study will recommend selection and
staged implementation of grid-scale batteries.
1.4. Transmission Line:
Initially, electrical power transmission from the PV Power Station to the pumps
will be during daylight hours only. However provision shall be made for future
grid-scale energy storage technologies to extend power delivery into evening
hours. Eventually, the solar power system can be connected to other power
grids, proving continuous power. The optimal transmission line route shall be
determined. Voltage, pylons vs. ground level, and power conditioning technology
shall be specified. Provision for surplus electric power distribution to nearby
towns and villages shall be addressed.
1.5. Staged Construction:
A staged construction plan for the PV power station shall be considered. Early
startup of PV power may enable pumping sooner. If and when grid-scale energy
storage technology becomes available, allowing nighttime pumping, this may
affect the size of the PV Power Station. Staged development of solar power
should be matched with the staged development of water intakes, pumps and
pipelines.
2.
Pumping
Water from the Ubangi River
2.1. Water Usage from the Ubangi River
Monthly seasonal flow estimates, average and peak, shall be provided, along
with amounts of water available each month for daytime pumping to Lake Chad.
The goal is to pump surplus flow from the Ubangi River. Identify possible low
flow periods in the Ubangi River when pumping is not desirable. The amounts of
water taken from the Ubangi River shall have low impacts on potential future
developments of a hydroelectric dam at Palambo on the Ubangi River or of the Grand
Inga hydroelectric dams on Congo River.
2.2. Impact of Pumped Water on Lake Chad
Based on pumped volume estimates, the change in volume and level of Lake Chad
shall be calculated over time (including evaporation, diversions of water for
irrigation, and local water use). Three scenarios shall be analyzed for project
size, staged construction time, pumping time, and cost:
• Level 1: enough water for irrigation of agricultural crops in the Lake Chad
Basin;
• Level 2: enough water to restore Lake Chad fisheries and pastureland;
• Level 3: enough water to restore the natural ecosystem of Lake Chad.
2.3. Pumping Site Location
Previous engineering studies have identified the Palambo site on the Ubangi
River for a hydroelectric dam. The advantage of the site is the Ubangi River is
narrow, reducing the cost of dam construction. However, since the Solar Option
avoids the use of a dam, other sites may be better for water intakes and pumps.
The study shall specify the intake/pumping site location with the objective of
minimizing the length of pipes needed to transport water under pressure to the
inter-basin crest.
2.4. Submerged Water Intakes
In order to avoid flooding of the Ubangi River, submerged water intakes shall
be used. The study shall provide the specification and design of the submerged
water intakes. The intakes may be in the Ubangi River or in a constructed
diversion. The intake design shall consider means to minimize silting,
scouring, exposure during low water flows, and the impacts of flooding.
Riverbank infrastructure, connection to pumps, maintenance requirements and
procedures shall be specified. Fish screens and/or other technologies (e.g.
electric fish barriers) on the intakes shall be considered. Submerged intakes
shall not adversely impact navigation on the Ubangi River.
2.5. Pumping Requirements
Based on the volume amounts of Ubangi River water available for pumping, the
type, size, efficiency, and power of pumps shall be determined. The pumps may
be integrated with submerged water intakes or in a separate location. Multiple,
parallel pumping stations will allow variable amounts of water to be pumped,
according to amount of seasonal availability of solar power available.
2.6. Pipelines & Canals
The previous CIMA Feasibility Study specified a pipeline and canal route across
the CAR, eventually reaching the Chari River in Chad. The CIMA study specified three
parallel conduits of 6 meters in diameter for pumped water from Palambo site on
the Ubangi River; this specification shall be reviewed for practicality. More
pipelines, and/or smaller pipelines, may provide a better match to the staged
development of submerged intakes and pumps.
The CIMA pumped pipeline route followed the bed of the Tomi River up to the
inter-basin crest, where a trench would make it possible to reach the Lake Chad
basin. Canals and works on the Tomi, Fala, Ouham and Chari rivers would convey
the water by gravity to Lake Chad. The new feasibility study of the Solar
Option will re-examine the CIMA pipeline and canal routes, with a view to
minimizing distance and costs. Impediments shall be identified, including
physical, geographical and infrastructure conflicts (e.g. roads, railways,
etc.). The study will identify measures to overcome difficult terrain.
2.7. Kotto River
The CIMA Feasibility Study also specified a second water source for Lake Chad
from the Bria Dam on the Kotto River (in the Eastern CAR near South Sudan).
Since the Solar Option obviates the need for dams, the Bria Dam will not be
considered. However, the feasibility study will examine the Kotto River as a
seasonal water source for Lake Chad. Gravity flow from the Kotto River may, or
may not, be practical.
2.8. Maintenance, Lifetime & Security
Since the solar powered pumps, pipelines and canals to replenish Lake Chad will
be installed in remote regions of the CAR, low maintenance is an important
issue. Estimates of numbers and types of skilled workers needed to keep IBWT
working shall be provided. Possible trade-offs between technology upgrades,
project cost, maintenance costs, and project lifetime shall be considered.
Finally, since the pipeline, canal and transmission line routes go through
regions of political instability and civil unrest, sabotage, water theft and
security monitoring shall be considered.
2.9. Environmental Impact Assessment
• Cross-contamination of Species
Water transfer from the Ubangi River
creates the risk of Congo Basin river species being introduced to Lake Chad.
Other water transfer schemes have addressed this problem, such as fish screens
(as used for hydroelectric power plants) or the electric fish barrier in the
Chicago Sanitary and Ship Canal. The new study will assess risks and recommend
specific counter-measures.
• Migration and Animal Crossings
Construction of pipelines, canals and
transmission lines that across hundreds of kilometers will interfere with local
animal movements. Animal crossings (bridges, tunnels) and other mitigation
technologies shall be considered.
• Construction Impacts
Construction of pipelines, canals and roads
my adversely affect sensitive environmental sites, such as riverbanks. These
shall be identified along with recommended mitigation measures. Pipelines
should be buried where they cross roads.
• Environmental Benefits
Use of solar electricity for cooking can
reduce fuel-wood consumption, promoting reforestation (Great Green Wall).
2.10.
Social
and Economic Benefits
The engineering study shall include a summary of the project’s direct and
indirect social and economic benefits. Estimates of economic benefits shall be
divided into three categories: infusion of financial support, employment during
construction, and long term infrastructure upgrades (including roads, water for
villages and rural electrification). [NB: Additional long term social and
economic benefits—including agriculture and food security, increased employment
opportunities and wealth generation—will arise from an expanded sustainable
agriculture industry for the peoples of the Lake Chad Basin.]
2.11.
National
and Cross-Border Issues
International cooperation is needed for IBWT from the Ubangi River to Lake
Chad. Since the Ubangi River forms the border between DRC and CAR, removal of
water may impact both countries. However, no infrastructure is required in the
territory of the DRC. Water from the Ubangi River will cross the CAR and enter the
Lake Chad Basin on one or more tributaries of the Chari River; the location(s)
for this border crossing shall be determined and any engineering and
environmental issues identified. After crossing from the CAR into Chad, water
will enlarge the upper flows of the Chari River, with potential environmental
impacts; any water works needed on tributaries to the Chari River, and on the
Chari River itself, such as bank stabilization and dredging, shall be
identified.
3.
Budget
& Schedule for Construction of the IBWT Solar Option
The new IBWT Engineering Feasibility Study shall produce a comprehensive budget
and schedule for construction of the project. The following items should be
included (but not limited to):
• Cost of two Solar Option variations: solar panels, grid-storage batteries,
switchgear, etc.
• Cost of intakes, pumps, and pipelines, including installation and
maintenance.
• Cost of canals and improvement of waterways, including the Chari River.
• Cost of administration, management and accounting of IWBT, including role of
the LCBC.
• Cost of infrastructures needed, including roads, power, worker
accommodations, etc.
• Cost of labour for construction of each stage and component of the IBWT
system.
• Cost of ongoing maintenance for each component of the IBWT system.
• Cost of necessary security measures during construction and beyond.
• A detailed schedule for Staged Construction, including milestones.
• Staged cost schedule, allowing gradual infusion of financial support.