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TRANS AFRICA PIPELINE: Sustainable Water for Sub Sahara Africa Rod Tennyson, PhD, PEng

Professor Emeritus, University of Toronto Institute for Aerospace Studies 614-99 Harbour Sq., Toronto, Ontario, Canada, M5J2H2

rctennyson@aol.com

ABSTRACT This paper provides an overview of the technical and economic feasibility for

constructing a Trans Africa Pipeline (TAP) across the sub-Saharan region of Africa for

the delivery of fresh clean water. To provide a sustainable supply of fresh water from

unlimited ocean resources, desalination technology can deliver the necessary quantity of

clean water and allow fertile farm oases to be created adjacent to TAP. As the

population’s health improves, and the number of farm oases increases, export of food

products will reduce poverty. Desalination is the only source of sustainable fresh water

available for the sub-Sahara countries if this water crisis is to be solved. Based on

population statistics for the countries in the sub-Sahara region, the number of people

who will directly benefit from TAP is estimated to be over 20 million.

Keywords: water supply and delivery, desalination, pipelines, storage tanks, Africa NOMENCLATURE B billion (109) d day gal US gallons h hours k kilo (103) kW kilowatts kWh/d kilowatt hours per day l liters l/p/d liters per person per day mg milligram M million (106) m meter MW megawatts SCADA supervisory control and data acquisition software tds total dissolved solids USD US dollars yr year

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INTRODUCTION Water is the single most important factor that will ensure the survival of millions

of Africans scattered across the many countries adjacent to the encroaching

desertification of Africa. The objective of this paper is to demonstrate the feasibility of

building a water pipeline across the sub-Sahara region of Africa to begin to alleviate

human dehydration, reduce diseases caused by infected water and poor sanitation,

eliminate agricultural drought, and begin the transformation of this region back to a self-

sustaining existence.

Recent United Nations’ studies state that over 2 billion people will suffer severe

water shortages by 2050. In the next 10 years, all of the countries predicted to be “water

scarce” are in Africa in the sub-Sahara region. The expected doubling of this area’s

population in the next 40 years will exacerbate this problem. Regional conflicts over

water supplies are also predicted to increase in this time frame, particularly in those

countries that have access to rivers flowing across their boundaries. However, the sub-

Saharan countries have no access to sustainable water supplies. It is well documented

that most of these countries, numbering about 14 in total, are the driest regions in Africa,

frequently suffering severe drought conditions year after year.

A sustainable supply of fresh water from unlimited ocean resources using current

desalination technology can alleviate annual drought and death tolls, and provide for the

creation of local farm oases along the TAP route. As the population’s health improves,

and the number of farm oases increases, export of food products will reduce poverty.

Desalination is the only source of sustainable fresh water available for the sub-Sahara

countries if this water crisis is to be solved.

THE TAP CONCEPT The TAP concept is envisaged as an east-west pipeline, approximately 6000 km

long, originating from coastal nuclear powered desalination plants. Desalination plants

will be built at each ocean terminus to provide security of supply, and redundancy when

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plant downtimes are required for repair and maintenance. Water will flow in both

directions simultaneously to fill massive water storage tank farms strategically located

along the path of TAP to service local populations. TAP consists of a primary Grand

Trunk Pipeline (GTP) connected to the desalination plants, with north-south distribution

pipelines branching off the GTP to supply distributed tank farms to service local

population centres.

Pumping stations will be located as required along the TAP route to maintain

water flow rates and supply the storage tank farms. Solar energy combined with wind

power are the energy sources of choice where no access to electrical power off a grid is

available. The nuclear powered desalination plants will be located in areas adjacent to

ocean harbours or bays. The pump stations will also serve as monitoring sites employing

pipeline sensor systems for detection of pipe leaks, third party intrusion and system

integrity. Using standard SCADA systems, the data will be relayed via satellite to central

monitoring stations located in each country that will be responsible for TAP security and

maintenance.

HUMAN WATER REQUIREMENTS The major purpose of TAP is to provide potable water for the populations of the

sub-Saharan countries. The basic human survival requirement for drinking water in a hot

climate is about 3 to 5 litres/day. Taking into account additional human needs for

sanitation, bathing and cooking, this figure grows to about 30 to 50 litres/person/day

(l/p/d). (Gleick,1996). Applying this criterion for a population of 20 M people yields a

minimum required production capacity of 600 million litres/day . This corresponds to

600,000 m3 per day production from desalination plants, which is equivalent to about

160M US gal/day (1m3 = 260 US gal; throughout the paper, all gallons are US).

CREATING FARMING OASES BY IRRIGATION Although there are irrigated regions located in many of these sub-Sahara

countries, they are insufficient to alleviate the massive droughts that plague most of

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these regions and devastate their populations. Modern irrigation technology can be

employed to ensure efficient use of water supplied from the TAP project. Turning desert

areas into arable land is now common. Irrigated agriculture is usually sustained by

tapping into underground reservoirs and rivers, which is not feasible in these areas.

Because of the costs involved, the use of water from desalination plants must be

carefully monitored if this system is to be viable economically. The following tables

illustrate the water requirements to sustain a variety of crops and livestock.

Table 1

Crop Inches of water/ton crop** Millet 2.4 acre inches*

Sorghum 2.4 Corn 3.2

Sugar beet 3.3 Sudan grass 3.4

Potatoes 4.6 Barley 4.6 Wheat 5.2 Oats 5.2

Soybeans 5.7 Flax 7.4

Alfalfa 7.6 Note: * 12 acre inches of water = 325,850 US gallons ** Ref: Crops and Water Use, North Dakota State University

www.ag.ndsu.nodak.edu/aginfo

Based on the data in Table 1, a plot of the nominal total water required over a year is

shown in Fig.1 as a function of the crop yield, assuming an average water supply of

125,000 gal/ton is available for irrigation. To achieve this capacity, water storage using

reservoirs or tank farms will be necessary.

Table 2

Livestock Water consumption (litres/day)*

Poultry 5 to 7 Dairy Cattle 26 to 75

Horses 40 to 55 Swine 4 to 11

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Note: * 1 litre = 0.26 US gallons Ref: Water Requirements for Livestock, Ontario Ministry of Agriculture and Rural Affairs,www.gov.on.ca/OMAFRA

Fig. 1 Cumulative water requirements (B gal/yr) for different crop yields (kilo tons/yr)

Fig. 2 Daily water requirements for poultry and dairy cattle Figure 2 presents the daily water requirements for poultry and dairy cattle as a function

of the number of livestock that can be serviced, based on the data in Table 2. For

example, it can be seen that for 4M gal/d, one can provide sufficient water for 2.5 M

poultry, and about 0.4 M dairy cattle. If 100 Mgal/d were available for crop irrigation, this

would provide an annual yield of about 300 kilo tons of food.

ANNUAL CROP YIELDS AS A FUNCTION OF WATER SUPPLY (based on average crop requirement of 125,000 USg/ton)

020406080

100120140

3.7 7.3 11 14.6

Water required (Bg/yr)

Annu

al c

rop

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d (k

tons

/yr)

WATER REQUIREMENTS FOR MIXED LIVESTOCK

0

0.5

1

1.5

2

2.5

3

1 2 3 4

Available water (Mg/d)

Num

ber

of li

vest

ock

(mill

ions

)

PoultryDairy cattle

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DESALINATION TECHNOLOGY Desalination is the only source of sustainable fresh water available for the sub-

Sahara countries if this water crisis is to be solved. The International Desalination

Association estimates that there are about 100 countries employing desalination

technology, with half of the fresh water output located in the Middle East and North

Africa. Desalination plants are growing at a rapid pace to meet the demands for clean

water throughout the world, with an estimated 15,000 plants in operation (or under

construction) at the present time. Although there are several methods used in

desalination plants, the most common method is reverse osmosis using specially

designed synthetic membranes. This method forces water to travel through the

membrane under the action of high pressure, rejecting about 99% of the salt. The major

problem associated with this technology is fouling of the membrane by contaminants,

which requires cleaning and regular maintenance.

Even though ocean salinity varies from 35,000 ~ 44,900 mg/l, desalination can

reduce this value to about 25 ~ 50 mg/l. The WHO standard for drinking water is 1000mg

of total dissolved solids (tds)/l. However, this process could present some environmental

issues, such as returning the sea brine back into the ocean and the disposal of solid

waste. The TAP project, as described later, directs the brine to salt ponds to create a

source of high quality salt that can be sold to offset the operational costs of the

desalination plants. The general efficiency of this process ranges from 15 ~ 50 gal pure

water for each 100 gal seawater.

Although the cost of constructing desalination plants depends on available

electrical power and on the pumping capacity required, it is known that the cost of fresh

water from desalination plants ranges from $2.75 ~ $3.25 USD per 1000 gallons. For

example, let us consider the Tampa Bay desalination plant that has been operational for

a few years, and is still ramping up production. Based on the data in Table 3, the cost for

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a single desalination plant having 80 M gal/day output is estimated at $300 M USD. This

represents about one quarter of the total capacity required for TAP to meet the projected

total demand for water for 20M people supported by farming oases for crops and

livestock.

Table 3 Tampa Bay Florida (2007) Desalination Plant Capital Cost Capacity Annual Cost * of Water USD M gal/ day USD ~$245M 66 ~ 71 $72 ~ $78 M/yr

TAP PROJECT: Phase 1- one plant on each coast ~$300M 80 $88 M/yr ~$300M 80 $88 M/yr

* assuming a median cost of $3 USD/1000 gallons

ELECTRICAL POWER STATIONS

Since global warming has emerged as a worldwide critical issue that needs to be

addressed in this decade, it makes sense to consider nuclear powered desalination

plants. The option of using wind power for example, is too cost prohibitive due to a low

capacity factor of about 0.35, compared to nuclear plants that run around 0.90. Solar

energy farms are not yet large enough (~ 75MW) or cost effective to provide sufficient

power to run the desalination plants. They also suffer from a low capacity factor (~0.3).

However, they can be very effective for powering pumping stations along the TAP route.

Table 4 presents some cost comparisons for several nuclear reactors built in France, the

US and China. It is known that France has taken a dominant position in producing about

75% of its electricity from nuclear power. It should be noted that many of these countries

in Africa have large uranium deposits, much of which is currently being developed by

France. Preparation for the eventual installation of nuclear power plants in Africa is also

under discussion with several of these countries. To support these efforts, France has

initiated plans to train personnel for the operation and maintenance of their nuclear

reactors.

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Table 4 Comparison of nuclear power costs Source Nuclear Coal ($/kW) ($/kW) France Civaux $1350 US current $3150 $1500 ~ $2400 projected $1400~$2000 CHINA $1300~$1500 The costs for the French Civaux pressurized nuclear reactor will be used to estimate the

cost for the TAP system. In general, a desalination plant’s power requirements range

from 20 ~ 34 W h/gal. Assuming an eventual TAP requirement of 160 M gal/day

desalination capacity on each coast, a 200MW French Civaux Nuclear Power Station

plant would be required on each coast. Based on Table 4, the estimated cost of

construction is ~$270M USD for each plant, with a construction time ranging from 3 to 5

years.

PIPELINE CONSTRUCTION Ideally, the east-west corridor should be constructed to provide fresh water to

address the requirements of the most desperate African countries; Somalia, Eritrea,

Djibouti, Kenya, Ethiopia, Sudan, Chad, Niger, Mali, Mauritania, Senegal, Guinea,

Bissau, Gambia. However, it seems apparent that the GTP cannot run through all of the

countries mentioned above. Thus a network of Distribution Pipelines running in a

southerly direction will also be required.

The Grand Trunk Pipeline will be constructed adjacent to existing roads and

railway lines to reduce construction costs, and to provide the necessary access for

security, repair, maintenance and supply of materials. Clearly there will be regions where

new access roads will be required. In areas of animal migration routes, the pipeline will

be buried; otherwise an above ground pipeline is deemed most viable and cost-effective,

although susceptible to third party intrusion and damage.

It is estimated that the nominal length of the pipeline to traverse the sub-Sahara

region of Africa is about 6000km. In general, depending on the terrain, the cost of

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constructing pipelines ranges between 0.7 ~1.8 million USD per km. Thus a cost

estimate for the GTP varies from ~$4.2B to 10.8B USD.

The Grand Trunk Pipeline will have its terminus at the desalination plants, the

location of which will depend on the available infrastructure required to power and

operate them and the political stability in those countries. For illustration purposes,

Figure 3 shows a schematic of the TAP running across many of the countries noted.

One of the major problems that will need to be addressed is the legal issue of trans-

border pipelines (Ngurare,2001).

Fig. 3 Illustration of a TAP route using existing roads and railway lines

An analysis of pipe diameter as a function of water volume flow rate is shown in Fig.4. It

is evident that a 6ft diameter pipe can more than meet the requirements for the output of

the desalination plants used in this case study. For comparison purposes, the pipe

diameter used to build the ‘great man made river’ project in Libya is also shown, where

the volume flow is a factor of four larger. The Libyan pipeline connects to massive

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underground aquifers and pumps the water back to the coastal cities. Unlike ocean

desalination, there is a finite time before these aquifers are emptied.

Fig.4 Flow rate as a function of pipe diameter WATER STORAGE TANKS It is recommended that closed tanks (with floating roofs such as those used in

Saudi Aramco to store massive quantities of oil) be utilized to store the water to minimize

evaporation of this expensive commodity. Large tanks capable of storing up to ~ 5M gal

(20,000 m3) can be assembled with solar arrays mounted on their roofs. They are

capable of supplying sufficient electrical power to pump the water into the tanks, for

irrigation, and to maintain pump pressure in the main pipeline. The area of each roof is

about 450 m2. TAP requirements call for 160M gal/day plant outputs on each coast.

Assuming an 8ft diameter pipeline, then 12 tanks are required on each coast to store

backup water supply, with a minimum of 60 tanks needed along the TAP route for

storage and distribution purposes.

Since the Sahel region of Africa lies in a high solar radiation environment, then it

is reasonable to assume sufficient electrical energy is available using solar arrays

mounted on the storage tank roofs, or if needed, adjacent ‘solar farms’. Based on solar

map data, we can assume about 2500 ~ 3000 hours of sun per year. Commercial solar

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panels (area ~1.3m2) exist that can provide about 165W at peak sun hours. A square

array on the water tank roof can accommodate about 110 solar panels. Thus, for 6 sun

hours/day, the power available = 109 kWh/d. To calculate the total power budget for a

site containing N tanks, then Total Power = 109N kWh/d. The cost of each array is ~

$82,000 USD/ tank.

ESTIMATED CAPITAL & ANNUAL COSTS OF TAP PROJECT The estimated capital costs for constructing TAP are presented in Table 5. These

costs have been calculated for a total water output production of 320 Mgal/day using an

average value for the pipeline construction cost.

The recurring annual costs for operations and management shown in Table 6 do

not include those costs incurred by each country (through which the pipeline runs) for

security and maintenance, nor for the distributed pipelines branching off the GTP.

Table 5 Estimated Capital Costs

ITEM COST ($M USD)

Pipeline (6000km) 8,000 (avg) Desalination Plants (4) 1,200

(two on each coast: 320M USgal/d total capacity)

Nuclear Power Plants (2) 540 (one on each coast; 200Mw each)

Solar Power 7 (for 84 storage tanks)

Water Storage Tanks 126 & Pumps (84)

Pipeline Monitoring System 40

TOTAL ESTIMATED COST: $ 9,913M USD

Table 6 Annual Operations and Maintenance Costs CATEGORY $M USD/Year

Pipeline (6000km)* 18.6 ~ 37.2 Desalination Plants (4) 352

Nuclear Plants (2)** 10 TOTAL $380.6 ~ 399.2 USD/Year

* based on estimates ranging from $3100 ~ 6200 per kilometer ** based on French Civaux reactor costs ~ 2.54 US cents/kWh; from OECD/IEA NEA 2005 report

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These estimated costs are associated with a total production capacity of 320 million US

gallons of water per day. Based on these numbers, the O&M costs work out to be about

0.34 cents US per gallon using the high-end total shown above.

THE BRINE ISSUE The major by-product from a desalination plant is brine. The seawater used in the

desalination process contains about 3.5% (by weight) of dissolved minerals, with sodium

chloride (NaCl) constituting about 86% of that amount, or about 3.0% of seawater. As

fresh water is extracted from the seawater, the salt concentration in the effluent is greatly

increased, making it heavier than the original seawater by about 2%. If the brine is

recycled into the local water, it then becomes hyper saline, with heavy salt layers

forming near the bottom. They then mix with the currents, increasing the salinity, which

could well affect the fish life and local fishing industry.

The solution lies in directing the brine effluent from the desalination plants into

solar salt ponds. The sub-Sahara region of Africa is an ideal location for the mass

production of salt from solar energy, combined with the low rainfall, which would

enhance the salt production process by reducing evaporation times. As the brine

evaporates due to sun and wind actions, this increases the concentration of salt.

Commercial salt plants generally extract about 2% of the weight of the effluent brine.

Salt crystals begin to form when the brine concentration reaches about 26% sodium

chloride. Layers of salt then develop at the floor of the pond (about 10~25 cm thick),

which can be harvested by commercial equipment designed for this purpose. Typical

modern salt plants produce salt that is about 99.7% NaCl. The commercial applications

for salt have been estimated to number about 14,000, with solar generated salt usually

commanding a higher price because of the superior quality of the crystals. In the US for

example, solar salt sales were about 6 million tons in 2006 with revenues exceeding

$325 MUSD.

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Each desalination plant described in the TAP project was designed to produce 80

M gal/day of fresh water. Assuming an efficiency of 38% (based on a current plant

design), the amount of seawater processed each day would be about 210 M gal/day,

resulting in 130 M gal/day of brine. Over the course of a year, the brine totals about 47.5

Bgal (or about 207 million tons, assuming 1 gal salt water weighs about 8.55lbs, with

brine about 2% heavier). Assuming a salt extraction rate at 2%, then one obtains over

the course of a year about 4.1 million tons of salt for each desalination plant. With 4

plants operating at maximum capacity, this yields about 16.6 million tons of salt per year.

Based on US solar salt sales and revenues, the selling price is about $54 USD/ton. Thus

the potential sales from the solar salt ponds from the TAP project would amount to

$ 896M USD per year.

In addition to the reduction in long term foreign aid as a large segment of the

population’s health and food production improves, there is in fact a real economic return

on the sale of salt. These funds can offset the annual O&M costs, and thus reduce the

operating fees charged to the participating countries.

CONCLUSIONS

The TAP project appears to be technically and economically feasible. Poverty

and disease can be substantially mitigated once the people have access to clean water

and the opportunity to farm crops and raise livestock, not only for their own survival, but

for export as well. Returning the sub-Sahara region to self-sufficiency and reducing the

onslaught of desertification will be the greatest humanitarian project of the 21st century. It

is recommended that the UN undertake a feasibility study involving the AU to ascertain

more accurate cost estimates and the willingness for the African member states to

participate. It is proposed that the G8 countries undertake the cost of this project, based

on their financial aid commitments to Africa.

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The major issues facing such an undertaking, not withstanding the cost, can be

summarized as:

1. political instability

2. AU support for a feasibility study

3. security of the pipeline and nuclear plants

4. commitments by the AU and its member states to assume responsibility for the

project, its security and the distribution of water, along with member state fees to

meet operational and maintenance costs.

REFERENCES

Gleick,P.H. 1996 Basic water requirements for human activities: meeting basic needs,

J. Water International,21.

Ngurare, T.E. 2001 Legal and institutional implications of cross-border water pipelines in

international law: the Congo cross-border water pipeline project (CWPP) case study,

PMLP Annual Review 2001, Article 10.

APPENDIX : SUMMARY OF ISSUES

Political

• Which country will take the lead in promoting this project among the G8 ?

• Which country or NGO will finance and conduct the feasibility study?

• Will the United Nations endorse this project and seek the support and

participation of the African nations?

• Who will constitute the TAP Management Consortium?

• What G8 countries will undertake what tasks?

• Will each G8 country pay for the costs of these tasks undertaken by

companies within their country as part of their African Aid package?

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Feasibility

• Is there a feasible pipeline route that can service the relevant areas of the

African countries in need of a continuous supply of clean water?

(Feasibility addresses costs involved, barriers to construction, political

climate, availability of labour, source of suppliers)

• How many African countries will be involved in the Grand Trunk Pipeline

construction and how many people will be serviced by this route?

• Will the G8 countries be willing to accept project assignments and provide

the financial backing for their projects?

• Location of two desalination plants—are they practical sites and is there a

local infrastructure available to build and maintain these plants?

Legal

• What agreements and treaties must be drawn up to allow the

construction, security and maintenance of TAP within each country?

• What contracts and agreements must exist between the G8 countries to

ensure the financial and infrastructure commitments are met in a timely

way?

• What dispute resolution mechanisms must be in place?

• What will be the role of the United Nations?

• Who will assume the long-term security, repair and maintenance of these

pipelines and storage tanks?

• How much of the technology can be transferred to the African countries to

allow them to take over the operation of the desalination plants and

pipelines?

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Environment

• Disposal of brine from desalination plants in an environmentally

acceptable way.

• What long-term micro-climate changes could be expected as the number

of farming oases increase, and their effect on the growing impact of

desertification?

• Can water storage be done using underground aquifers to reduce water

loss through evaporation?

• Impact of irrigation and fertilization to create farming oases.

Technology

• Design, build and operate desalination plants with sufficient capacity to

maintain storage tank water levels to meet the demands of the African

countries involved, and the creation of farming oases.

• Construction of large diameter pipelines (~1.9m diameter?) to handle

water flow rates to meet domestic demand requirements.

• Installation of pumping stations in remote regions requiring power derived

from solar and/or wind energy. If not possible, then can that location be

serviced by thermal-electric generators using on-site fuel storage tanks,

assuming the site is close to a road or rail line?

• Installation of monitoring system for pipelines, with SCADA technology.

• Develop technology for handling the brine disposal problem that will

address the environmental concerns and issues.

• Provide the technology for irrigating and fertilizing desert-type land to

create farming areas suitable for crop growth.

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Education

• Train engineers and technologists for operating and maintaining

desalination plants and pipeline systems.

• Train local populations on irrigation and modern farming methods

• Develop potential export markets for their products