For this Masters Project, our team evaluated both the water and energy supply and
demand at the Mpala Wildlife Foundation and Conservancy (Mpala) in Laikipia, Kenya from a
systems perspective. Mpala operates and manages a 48,000 acre wildlife conservancy, working
ranch (“the Ranch”), research center (“the Centre” or “MRC”), and a variety of community
health and outreach programs in Laikipia, Kenya. Its objectives include preserving biodiversity
of the region, supporting the natural migration of native species, providing research and learning
opportunities for students, as well as sharing their findings regionally and internationally to
contribute to the fields of science and sustainability.
The purpose of this study for Mpala was to make recommendations to develop energy
and water systems that are economically and environmentally sound, and can be maintained and
functional for long into the future. We evaluated each system’s current state and examined
potential solutions to the inefficiencies and shortfalls. The energy group evaluated the potential
to reduce the Mpala’s dependence on fossil fuels, while the water group evaluated expanding
rainwater catchment as a way to insure adequate water supply and reduce the Centre’s and
Centre Village’s reliance on the non-replenishing aquifer and the intermittent river on site.
Water
The water portion of this study proposes a method of capturing and storing a safety
stock of water for human consumption during seasonal rains and wet years to provide water
during seasonal dry periods and drought years. The Mpala Ranch headquarters (“the Ranch”)
was recently equipped with a land weir to supply all of the drinking water to the people that
reside at the Ranch employee residences (“the Ranch Village”). Therefore, our team examined a
solution for all of those residing and visiting the Centre (“the Centre Village” and “the Centre”).
We demonstrate that the current rainwater catchment system at the Centre requires only
additions and improvements to provide the current population of the Centre and the Centre
Village essential water needs. We also make recommendations for expansion in the future. Our
group recommends improving the catchment and filtration systems on the building roofs
currently equipped to catch rain water, and expanding the current storage capacity with either
underground storage or above ground storage.
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We began our study by evaluating current water systems. First we examined the borehole
water system. We calculated that Mpala was drawing approximately 30-35 cubic meters of water
from the borehole well each day. However, the measured draw at both the Centre and the Ranch
added up, on average to a little over half that amount. Despite some expected measurement
error on the part of the meters installed, we determined that it was likely the transport system of
underground piping was experiencing leaks. The distance of transport (under miles of terrain)
was a contributing factor of this inefficiency. At the Centre and the Ranch, the water was used
for washrooms for the visitor’s quarters as well as for drinking. In order to drink the borehole
water, it first had to be put through an expensive filtering system called Reverse Osmosis.
Next we looked at their use of river water, which is drawn from the Ewaso Ngiro (river).
This river began to run dry in 2009, the first time in known history. It has since run dry for a
period of months each year. This could be due to the more severe droughts the region has been
experiencing, but likely, it is from increased abstraction from upstream agriculture. The presence
of this agriculture is also a concern for the quality of river water, as unsafe levels of nitrates may
be found as a product of run-off from the agricultural land. This water has not been tested.
The final source of water evaluated was the rainwater storage. The Centre has extensive
storage tanks at many of the buildings at the Centre, and a few small tanks at the Centre Village.
This is a great source of local water; however, the system is not being fully utilized. Our team
witnessed water being poorly covered and invested with insects and debris. We also witnessed
several birds on the rooftops, leaving dangerous waste that flowed into the tanks during a rain.
In addition to these system issues, we also witnessed water running off the roofs and not being
captured. This is unmet potential.
After evaluating the sources of water, we looked into ways in which the Centre and the
Ranch can reduce their water use levels. We recommended installing low flow fixtures in all of
the washroom and shower facilities. This provided a water savings of 14% of the total
consumption at the Centre. Since the visitors were the only people that used these facilities, and
they made up only 25% of the total population at the Centre and Centre Village, the reduction in
washroom consumption was reduced by half, but the overall impact was much smaller. The next
system we looked at improving for water use reduction was grey water. Grey water is water that
is recycled or reused from such uses as hand washing, bathing and cooking. Grey water can be
used to irrigate landscape plants, flush toilets, and, also in the case at Mpala, supply a biogas
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plant. This type of system, considering maximum capacity at the Centre, could provide these
uses with 888 liters of water per day.
The final suggestion made for reducing water use is to educate. By communicating the
value of water conservancy with a campaign of signage and training, as well as regular education
of the employees, their families and the visitors, water use can be reduced through behavior
change.
After recommending ways to reduce demand, our team looked at the best method of
increasing supply. We identified rooftop rainwater collection as our focus for this study. We
began by looking at historical rain data from 1999-2009. We identified levels of rain during the
driest years, as well as levels of rain during those years with high rainfall. We also became
familiar with the distinct seasonality of the rains at Mpala and the region.
The next step was to look at total cumulative demand, and potential cumulative supply
based on different levels of rainfall and varying percentages of available rooftop. There is
4255m3 of roof area when considering all of the built structures at both the Centre and the
Centre Village. We assumed current population at the Centre Village, maximum occupancy at
the Centre, and unlimited storage (we calculated cumulative run-off with the assumption we had
no storage constraints and could capture all of the runoff). What we found was that in a wet
year, there was enough water to provide essential water needs (eight liters/person/day) for all of
the people at the Centre and Centre Village, and much to spare for a dry year. However, in a dry
year, even when the maximum rooftops were used, there was not enough supply to meet
demand or provide for a dry year. In addition, we were asked by Mpala management to consider
future population growth. When modeling that variable, there simply would simply not be
enough water to supply this area of Mpala.
Once we completed that evaluation, we determined that we would design a rainwater
catchment system that could provide the current population and make recommended additions
for the future expected growth. We looked at their current rainwater catchment system.
Currently, they have 1973m2 of rooftop area equipped with metal roofs, gutters systems and
some form of water storage, sizes varying by building. We calculated, that in a wet year,
characterized by heavy and above average rainfall, using only the rooftop area equipped to
capture rain, the Centre was missing or not catching a volume as high as 444m3 or 444,000 liters
in a year. This takes into consideration daily draw of the essential water needs of the current
population, just over 1000 liters per day. This volume missed was a function of insufficient
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storage for the current catchment systems. Therefore, we identified which buildings were
missing the greatest amount of rainfall, sized the supplemental storage and determined where
and how much additional storage needed to be built.
Once that was complete, we turned our attention to their current catchment systems. A
rainwater harvesting (RWH) system is comprised of six general components: a catchment area or
surface, such as a roof; gutters or pipes as a conveyance system from the catchment area to the
storage tank; a roof washer, to filter major contaminants; a storage container; a method for
distributing the water from the tank; and a process of purification, if the water is intended for
human consumption (Kinkade-Levario, 2007). We described each component of this RWH
system and recommended specific products, providing costs as well.
Once the RWH system was recommended, we evaluated two types of storage – the
above ground system of tanks, an expansion of what currently exists at Mpala, and an
underground storage tank. Increasing storage capacity from the current 187,000 liters to over
600,000 liters will have a much larger footprint. The underground, centralized tanks will require
less space, less capital investment (~$20,000US) and more than adequate water for the Centre
and Village; however, it is less secure, as contamination can destroy the entire supply. The
belowground option also leaves potential above ground space for future additional above
ground storage, as well as tie-in of new buildings. The above ground option can be phased in,
making less of an upfront financial impact (which is estimated at a total of more than
$50,000US), and spreading the risk of contamination out, so that if one tank loses its supply
from contamination, the remainder is still secure. We leave it to the Mpala management to make
a choice that best suits their immediate priorities.
Energy-Water Nexus
Our team briefly looked at two areas where renewable energy can be used to supply
water for Mpala. We looked at a solar pump located at the borehole well and a solar thermal
water heating system to provide hot showers for the visitors to the Centre. The solar pump
needs to have specifications that allow it to pump 2.5 cubic meters per hour and at a great
vertical height because the aquifer head is currently 70 meters below ground and declining. The
reduced borehole water use, a result of a grey water system and low flow fixtures at the Centre,
comes to about 25-28 m3 per day. Therefore a pump with the above specifications is required.
However, the upfront cost (anywhere from $2,000 to $6,000) (Alibaba.com, 2011) is likely to
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have a payback period of less than two years up to six years due to costs savings accomplished
by eliminating the need for the diesel-powered pump, as $1,200 per year is saved from diesel use
reductions.
The solar thermal water heating system has an upfront capital investment of
approximately $15,000US. These systems, 220 liter tanks with 2.3m2 solar arrays would be placed
on the rooftops of the buildings that provide hot showers to both the visitors and the Centre
Director’s home. There is not money saved on diesel use reduction in this case, as the current
system contains solar flat plate collectors (many in disrepair) and wood-burning stoves. What is
saved is the health and environmental hazard of burning wood from the surrounding land to
fuel the current heaters.
Energy
The energy portion of this report evaluated several options for Mpala’s electricity system
now and in the future in an attempt to find sensible solutions that will provide inexpensive and
long lasting power to Mpala. The Research Centre management hopes to provide the current
visitor capacity with reliable and adequate energy service, as well as scale the system up to
provide a larger number of guests in the future. Thus Mpala, with its new system should be able
to support the entire additional load. For this reason, in all our analyses, we considered double
the current power load at Mpala. The following is an outline of the approach we took to solve
the issues at Mpala, and the steps we took to complete our analysis.
The existing system at Mpala is an off-grid power system that is powered primarily by diesel
generators and includes a small portion of solar PV and hydro-power. The Mpala Research
Centre (MRC) itself meets its load with solar PV, two diesel generators and batteries, whereas
the Ranch uses hydro power from a turbine, back-up generators and very little solar PV.
There are many issues with the current system. In general, the power supply is intermittent
and not sufficient to meet the entire load. The population at the Centre and the Ranch is
expected to increase in the next few years due to the growing popularity of the Research Centre
and Conservancy, The system is not well monitored and thus there are large amount of
inefficiencies.
At MRC, the generators consume diesel to power the entire area. This is especially
problematic due to the growing prices of diesel. The batteries are also not managed to the
optimal efficiency, and therefore have to be replaced from time to time.
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At the Ranch, the turbine is not consistently in working condition and will have to be
replaced. Also, in recent years the Ewaso Ngiro river to which the turbine is fixed has been
running dry for almost half the year.
Our initial approach was to track down all the inefficiencies in the current system and as a
first step we performed a thorough energy audit of the Ranch and Centre during our stay in
Mpala. The results of the energy audit showed us the most energy consuming buildings and the
most problematic areas in the system. Once the problem areas were spotted, we took a two
pronged approach to solve the issues at Mpala, namely
o Reduce power load - make the current system more efficient.
o Renewable sources – use more renewable sources to meet the new, more
efficient system with less power load.
Our first approach was to analyze the consumption of energy by the existing lighting
throughout the Centre. We evaluated different products available and found that LED light
bulbs provided the most economic and energy efficient solution over time.
For our second approach, we analyzed all of the renewable sources available at Mpala and
picked only the ones that are most useful for Mpala’s electricity system. Among wind, hydro,
solar and biogas, we concluded that everything except wind has great potential for the system at
Mpala.
The next step was to use these sources to meet the newly reduced load. To do this, we used
a simulation software program namely HOMER to compare the various systems that could be
made for Mpala with the renewable sources available at Mpala.
HOMER stands for Hybrid Optimization of Electric Renewables and is a tool provided by
National Renewable Energy Labs, Department of Energy of the United States. It is an excellent
tool that can be used to analyze, simulate and optimize various combinations of off-grid hybrid
renewable energy systems and is used all over the world.
The scenarios explored and analyzed using HOMER could be broadly divided into those
that use transmission lines, and those that are independent of transmission lines. With
transmission lines, the scenarios explored include different hybrid systems which utilize several
forms of renewable energy sources, as well as some diesel, that provide security and options for
Mpala.
While at first glance, the use of transmission lines appears to provide more stability and
security to the system, we will show how this might not be the case for Mpala. Due to the
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extensive existence of wildlife at Mpala, which presents a risk to both the equipment and the
animals, using underground transmission is the only viable option. However, using an
underground transmission system can prove to be 5-10 times more expensive and more difficult
to lay and maintain.
According the Kenya Electricity Transmission Board, underground transmission lines also
last only for half as long as compared to regular transmission lines. For Mpala, we estimate that
these lines will have to be replaced at least eight times if laid underground over a period of 100
years. For our analysis however, we assumed that these lines will not be replaced and will last for
all 100 years. Despite this assumption, the upfront costs and operational costs are high for a
transmission system.
The cost for transmission was calculated using a $20,000 cost/km and the actual distance
was found using UTM coordinates. We analyzed a total of six scenarios for both overhead and
underground transmission. They are
o All in one – uses all renewable sources and some diesel
o Only Solar PV
o Solar PV and backup generators
o Only Hydropower
o Hydropower and backup generators
o Only Biogas
Each of these scenarios was then compared to the existing system at Mpala. The results for each
of these scenarios are indicated with error bars to account for the above stated assumption that
transmission lines will not last for all 100 years without replacement.
We next moved on to analyzing systems that do not use transmission. The most obvious
sources for these being solar and biogas energy. The HOMER results for Solar and Biogas
showed that Biogas is the cheaper option due to which a more detailed study of the Biogas
system was performed.
The biogas scenario was designed such that it will use a separate system for MRC and a
separate system for the Ranch. Each of these systems will contain a biogas digester to process
the dung to biogas and a generator to produce electricity from biogas. The dung is obtained
from the ‘bomas’ at Mpala, the place where cattle are housed at night. This system will require
the use of trucks to carry the dung from the boma to the MRC and Ranch generator sites.
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Due to Mpala’s more than 2,000 heads of cattle and six bomas, there is a large potential for
biogas. From our analysis, we found that using just one boma could power the entire MRC and
Ranch. A complete ‘use phase analysis’ was performed to estimate the total carbon dioxide
emissions reduced in the process of using biogas as fuel. The major savings were from the
elimination of diesel at MRC and from the diversion of dung from undergoing anaerobic
digestion. Anaerobic digestion of dung will produce methane which according to the IPCC
fourth assessment report, has a Global Warming Potential that is 25 times that of carbon dioxide
when evaluated over a period of 100 years (Forster et al., 2007).
Using biogas without transmission could provide very cheap electricity and the upfront costs
(which are also low) could be recovered within 1.5 years due to cheap operating costs. In the
process, it will also have a total emissions savings that are as high as 15,400 kg/year.
If Mpala decides to power the villages also with biogas, these emission savings will greatly
increase and thus Mpala could look into potential funding using the Clean Development
Mechanism, but Mpala would need to create a development mechanism similar to what we
discuss in our Behavior and Education section. However, CDM was outside the scope of our
analysis and only briefly mentioned here.
Our team will also discuss the costs and benefits of each of these systems and show how
using scenarios that do not use transmission or considering other ways of energy storage can
prove to be cheaper and more reliable for Mpala.
The system, the existing or the new one, cannot function to its best ability if it is not
understood by the people operating the system and by those who are benefiting from it.
Education is thus a very important component of the new system to come. Education could be
in the form of training local personnel to work the systems and teaching the people using the
system to run their own. We have touched upon these options briefly and taken examples of
some previous good work that we thought would be suitable for Mpala.
This masters project group hopes this work can be used to improve the systems at Mpala,
but also be considered as potential energy and water systems in surrounding communities in the
region. Our goal was to propose the most feasible and affordable methods to provide selfsustaining,
long-lasting resource systems in Kenya.