SOLAR POWERED DESALINATION OF SEA WATER

Transcription

1 SOLAR POWERED DESALINATION OF SEA WATER Okwisia Musumba, Snr. Station Chemist-Kipevu, Edward Mbaya, Snr Supritendant Mechanical Kipevu, ABSTRACT This concept explores the use of a solar powered sea water desalination plant as a solution to the perpetual water shortage at the 2- diesel power plants at Kipevu. Despite having constructed a new water line from Mombasa water and sewage company depot in Birikani changamwe to Kipevu at cost of 7million Kes, piped water flow to the station has remained elusive as a result of a the county global demand outstripping the supply from the area water supplier. Generally Mombasa County is water -scarce county despite being an island. Man shall not leave on the banks of the river and wash his hands with spittle Chinua Achebe (legendary West African Writer). This document also proposes solar water desalination on commercial bases to alleviate a water shortage in the county. The current shortage stands at approx. 300,000 metre cubes per day at a current municipal rate of kes 150/m3. The concept has also been motivated by the existence sea water intake infrastructure inside the ocean left behind by the retired steam plant at Kipevu. The facility is currently abandoned but serviceable if repaired. The concept will leverage on existence of the infrastructure to cut down on initial costs. This plant will use the latest technology to supply highly purified water to the power plants, the surplus can be sold to ships that dock at Kenya Ports authority and other prospective customers around Mombasa county. This business plan also provides a cost analysis of the viability of the desalination plant. From the cost analysis, it s evident that this business has the potential to generate an annual profit of 970.8million shillings.

2 INTRODUCTION Mombasa County has been hit by water shortage which usually comes from Baricho in Kilifi county, Mzima springs in Taita Taveta, Marere and Tiwi bore holes in Kwale county. Water from these areas is not enough compared to the consumers and the growing number of industries coming up. With water scarcity problem growing worse as the world population grows, water supplies need to be increased at house hold levels. Lack of clean drinking water to households has already a significant effect on international development. In Mombasa 50% of diseases reported are attributed to lack of access to clean water solving water crisis in its many aspect is one of the greatest challenges facing mankind, it is no wonder may are encouraged to look at the sea where the majority of the world water belong. Seawater desalination has been seen as a long term freshwater source. Desalination is the process of removing dissolved salts from water, thus producing freshwater from seawater or brackish water. One of the most sensitive and critical aspect of any water project is cost. For membrane desalination, decreasing cost and producing superior water quality are among a number of significant reasons why this technology continues to be the water treatment technology of the choice around the world. This paper serves to provide an overview of cost drivers and components to the desalination process; present cost associated with desalination compared to other water supply alternatives. It highlights the need for water and seeks financial support in order to set up a desalination plant which will help cope up with the menace of water shortage. Although membrane desalination was first commercialized in the United States in the 1960 s, reverse osmosis membrane technology was not widely implemented until the 1980 s; largely due to relatively high cost compared to other portable water treatment alternatives. Why have those cost decreased or appeared more reasonable and competitive over time? Although there are a number of reasons the reduction in cost are primarily related to improvements in manufacturing methods, increased market demand and competition for membranes. Hotels in Mombasa County are suffering as it is difficult to offer services to tourists. Power generating plants; Kipevu 1 & 3 and Tsavo power are sometimes forced to buy water from vendors at very high costs.

3 This project intends to set up a water desalination plant which will have the mandate of providing cost effective and affordable quality water suitable to serve residents of Mombasa, Hotels and Power plants. It will also ensure that standard and licensing requirements are compiled with as stipulated by the service provision Agreement (SPA) which will be signed with Coast Water Service Board. PROJECT DESCRIPTION The argument was made at one time that desalinating seawater is generally more expensive than the production of reclaimed water and implementation of water conservation measures. However, with the exception of portable reuse, water conservation and recycling do not create new sources of drinking water. Also, under conditions of prolonged drought when the available water resources cannot be replenished at the rate of their use, aggressive reuse and conservation can help but may not completely alleviate the need for new water resources and water rationing. Simply put, if your back yard well is dry, you cannot solve your household water supply challenges by reusing or conserving more of the well water which you do not have. LOCATION Identified location of the plant will be at the Kipevu 1 Diesel plant premises. This power plant is located at the coastal area where land of approximately one hundred square meters is available after decommissioning of the old Steam plant. The power plants are the most affected and the management has offered the land to solve the problem of high cost of producing power due to increased operation cost attributed to water situation.

4 MARKET The power plants consume more than 70 cubic meters per day and this is definitely a ready market. Nearness to the port of Mombasa makes it cheaper to supply water to Docked ships whose consumption is high. Supplements can be sold to the Mombasa water and sewerage company, it has a storage facility at Changamwe for distribution to the residents of Mombasa. COST A typical large scale desalination plant produces 100,000 cubic meter of water per day. Assuming a per capita consumption of 300liters per day, this equals to 300,000 people. The installed cost of desalination plant serving 300,000 people typically cost in the region of 100 million. The cost of infrastructure to distribute water must be added to this. But looking at the location, the percentage will be minimal as compared to the buying price. The cost of desalinated water, the majority of which is accounted for by plant capital costs and energy is typically in the range of cubic meters (20-50 shillings per liter of water). The lower end of the scale corresponds to regions where electricity costs are low and the higher ends to the regions where electricity cost are high. For this project we intend to use Solar energy during the day and negotiate with KPLC for better rates at night when the power demand is low, or supply directly from the generating plant. The cost of water desalination has many variable including the chemistry of the water, the point to deliver and the treatment being used. The lower the TDS (Total dissolved solids) the lower the cost. Experiments have been done at Kipevu and the area has the advantage of the cost being low.

5 Cost Benefit Analysis Desalination plant Maximum water output= 300m 3 per day Optimal operating water output= 280m 3 per day Maximum water demand= 1400m 3 per week Plant operating schedule= 5 days in a week Consumer Water Demand by various consumers per day Consumption in M 3 per day Tsavo power, Kipevu 1 and Kipevu 2 70 Ships 50 Hotels, water vendors, Education institutions 70 NB: 490M 3 to serve as weekly reserve capacity in case of shutdown or fluctuation in demand. Cost Analysis Cost of 1litre of treated water= 20/- ( current wholesale price) Quantity sold in a week= 1.33 million litres Total weekly sales=26.6 million Total monthly sales= weely sales x 4= 26.6 million x4=106.4million

6 Item 1. Employees 2. Routine Maintenance 3. License and taxes 4. Plant Depreciation 5. Loan 6. Miscellaneous TOTAL Monthly Expenditure 500,000/- 15 million 2 million 4million 2million 2million 25.5 million Monthly Profit =Total Monthly sales- Total Monthly Expenditure = = 80.9 Million Annual Net Profit= 80.9 x 12= million From the above analysis, it s evident that this is a viable business that is able to bring back the amount invested within a period of 1 year.

7 CONLUDING REMARKS One of the most sensitive and critical aspect of water project is cost. Membrane desalination has experienced an overall downward trend in overall costs and technological advances will continue to bring costs down even further. For membrane desalination, decreasing technological costs, drought-proof nature of the process and producing superior water quality are among a number of significant reasons why this application is the water treatment technology to choice around the world. RECCOMMENDATION The financier should look more into the underutilized available water resource; seawater because surface fresh water is almost being depleted. This is an opportunity to stabilize the Mombasa water system by providing good quality water at reasonable cost and at the same time improving on the economy. Return on investment is reasonable. References 1. Moch,Querns and Steward D. Desalination and water purification Research and Development Program Report No. 130, February GWI/DesalData cost estimator: