Desalination to supplement water supply

ENVIRONMENT

WATER is an essential component for life.
There is no life without water. Water is required in every form of life for survival. You can give up light but you cannot trade water for any other reason. Water means sustainability of life on earth. Trading water is like giving away your life or your life support system.
Take away water, that is fresh water from this planet earth and see what will happen. Yes, there will not be any life form on this planet except a large dry barren landmass. You know why there is so much poverty in the African continent? There is not enough water to enable farming or agriculture activities for food to feed the masses.
Look at the current ongoing water shortages in the urban centers of Papua New Guinea, especially Port Moresby. There are continuous shortages and rationing of water. What are the sources of water? Water is available from rainfall which is collected from rooftops and stored in holding tanks or reservoirs, from rivers, creeks and lakes, and underground aquifers extraction through wells.
Is that all to the supply of water? Of course not; you have a massive source available from seawater. How do you extract freshwater from seawater? It needs science and technological engineering to enable this source of alternate water to be made available to people.

Water crises
The chronic and persistent development issue in Papua New Guinea is controlled unavoidably by water availability and electricity supply. To find some solutions the Government is tapping into new infrastructure or projects to boost and enhance their supply.
However, regrettably, there seems to be no end to the crises. Look at the ongoing persistent shortage of water supply and continuous power blackouts in Port Moresby. The Sirinumu dam, the main supplier of water and electricity to Port Moresby is finding it much more difficult with increasing human population and industrial developments pressing for more and more of these commodities.
What about the recently commissioned Hedevu dam? Has it solved the problem? Of course not, it just continues. The Government needs to think outside of the box and consider new technologies to ease these essential development ingredients for a better tomorrow.
There is so much technology available and in used worldwide to address such issues. These technologies were developed, used and refined for efficiency over time. So we need to identify a relevant available technology to supplement water especially to the coastal development centers like Port Moresby, Lae and in fact most cities based around coastal zones.

Alternate water supply
The country needs to consider converting seawater (ocean saline water) into freshwater to ease water shortages. The conversion process is called desalinisation. The supply of seawater is enormous and we will never ever run out of the resource for conversion into fresh water.
Papua New Guinea is surrounded by a huge body of seawater called the Pacific Ocean, the largest and the deepest of the world’s oceans. This massive ocean body covers 63 million square miles and containing more than half of the free water on earth. All of the world’s continents could fit into the pacific basin.
Papua New Guinea will never ever run out of supply of the priceless commodity and more than of half its problem in shortages and rationing water would be solved. Most other countries are reverting to this technology to supplement their water supply so why can’t Papua New follow suit?
Countries like the United States, Europe, Australia, New Zealand and even the desert kingdoms like United Arab Emirates (UAE), Saudi Arabia and Israel are using this technology.
Papua New Guinea needs to invest into this technology at a substantial scale by installing desalination plants around the country and we will never again be faced with shortages of water for human consumption and industrial use. Once we master this technology with the abundance of seawater available 24/7 our water shortages will be a thing of the past.

Technology
Desalination is a process by which salt and other impurities from seawater or brackish water are removed making it suitable for human consumption and industrial use. It is a conversion process technology whereby saltwater or saline water is converted into fresh useable water.
It is an essential technology in regions with water scarcity. There are several methods for desalination. Saltwater, especially sea water is desalinated to produce water suitable for human consumption or irrigation and for use in the industrial processes. The by-product of the desalination process is brine.
Desalination has been developed in the past centuries and is currently being used on many ocean or seagoing ships and submarines. Most of the modern interest in desalination is focused on cost-effective provision of fresh water for human use. Along with recycled wastewater, it is one of the few rainfall-independent water resources. Desalination has been known to history for millennia as both a concept, and later practiced, though in a limited form. Desalination technologies have been trailed again and again throughout antiquity and the Middle Ages, but desalination was never feasible on a large scale until the modern era. During the Middle Ages elsewhere in Central Europe, work continued on refinements in distillation, although not necessarily directed towards desalination.
Before the Industrial Revolution, desalination was primarily centered on ocean going ships due to the need to keep supplies of fresh water on board. The supply of fresh water was made available by means of shipboard distillation process.
Desalination was already in trial far back as the 1600s with delay relating to desalination apparatus. More trials were being undertaken due to technical issues. There were no significant improvements to the basic seawater distillation process for a period of 150 years from the mid-1600s until 1800.
By the 1800s things started changing very rapidly resulting from the invention of steam engines and the so-called age of steam. The development and improvement of steam engine quickly demonstrated their potential in the field of desalination.
Remember desalination was being applied on ships only until the latter half of the nineteenth century.
Significant research into improved desalination methods occurred over time where there were delays in improvement and progress in refining this technology until 1961 when the first industrial desalination plant opened up in the United States.
Since then improvements have taken place over time and there are now about 21,000 desalination plants in operation around the globe. Recorded information shows that the biggest ones are in the United Arab Emirates, Saudi Arabia, and Israel. The world’s largest desalination plant is located in Saudi Arabia (Ras Al-Khair Power and Desalination Plant) with a capacity of 1,401,000 cubic meters per day.
Methodologies
The most common desalination processes where saltwater is converted into fresh water is through distillation and reverse osmosis. There are a number of methods available, each with their disadvantages and advantages but they are all useful.
The methods are membrane-based such as reverse osmosis and thermal-based such as multistage flash distillation. The traditional process of desalination is distillation which involves boiling and re-condensation of seawater to remove salt and impurities. The widely used technologies worldwide today are multi-stage flash distillation and reverse osmosis.

Reverse osmosis
In this conversion method, desalination plants use liquid nitrogen freeze thaw in conjunction with reverse osmosis to improve efficiency. Reverse osmosis desalination process is more acceptable in terms of installed capacity and yearly growth.
This membrane processes use semipermeable membranes and applies pressure preferentially and induce water permeation through the membrane while rejecting salts. Reverse osmosis plant membrane systems typically use less energy than thermal desalination processes.
Reverse osmosis uses a thin-film composite membrane, which comprises an ultra-thin, aromatic polyamide thin film. This film gives the membrane its transport properties, whereas the remainder of the thin film composite membrane provides mechanical support.

Solar distillation
This process works the same as the natural water cycle, in which the sun heats up sea water enough for evaporation to occur. After evaporation, the water vapor is condensed onto a cool surface. There are two types of solar desalination. The first type uses photovoltaic cells to convert solar energy to electrical energy to power desalination. The second type converts solar energy to heat, and is known as solar thermal powered desalination.

Cost
Due to its energy consumption, desalinating sea water is generally more costly than fresh water from surface water or groundwater, water recycling and water conservation. However, these alternatives are not always available and depletion of reserves is a critical problem worldwide. Desalination processes are using either thermal methods (in the case of distillation) or membrane-based methods (e.g. in the case of reverse osmosis) energy types.
Data shows that in 2018 some “18,426 desalination plants were in operation in over 150 countries. These desalination plants collectively producing 87 million cubic meters of clean water each day providing for the needs of over 300 million people.
The energy intensity has improved since then. Nevertheless, desalination represented about 25 per cent of the energy consumed by the water sector in 2016.
Desalination is currently expensive compared to most alternative sources of water, and only a very small fraction of total human use is satisfied by desalination.
It is usually only economically practical for high-valued uses (such as household and industrial uses) in arid areas. However, there is growth in desalination for agricultural use and highly populated areas such as Singapore or California. The most extensive use is in the Persian Gulf.

Government intervention
The PNG Government should consider investing in this technology to provide alternate source of water supply for the mass of ordinary people and industry. Currently water is extracted and supplied from rainfall, dams and underground aquifers.
These sources are restricted by weather systems where there is rainfall there is more water available. When there is long dry spell water supply diminishes; if there is a drastic shift in the rainfall pattern the result will be a very long dry spell.
Politicians are continuously embarking on trade talks with the world’ wealthy and powerful. Ministers and delegates travel overseas for bilateral talks on development projects covering technological developments in extractive industries in mining, fisheries and marine resources, mining, oil and gas, agriculture, hydropower development and other infrastructure.
When they discuss hydropower and water supply, they should also tap into other technologies such as desalination that are available which need to be investigated and developed.
They need to think outside of the box and not restricting themselves with the same old traditional development issues.