Desalination to the Rescue
2018年1月15日 Dr Peter Harrop
The world has very little fresh water and it is running out. At tens of billions of tonnes yearly, the fresh water of the ice caps is falling into the salty sea which is already 97% of the world's water. Rising sea levels will cause mayhem with the supplies of most of the world's cities because they sit low down near the sea. Much of India's water table drops around 0.3 meters a year. Why? Growing population. The barren farms of Syria show what happens when you extract all the ground water. Recycling of water is practiced only by a tiny percentage of the world's countries.
All this means that desalination gets more competitive even if its cost stays still: the competition such as cleaning river water or lakes or sucking up dying aquifers is either disappearing or getting more expensive. Desalination can work on salt lakes: the Caspian Sea has 70% of global inland salt water yet it is almost surrounded by water stressed regions. Actually, inland brackish water is 100 times as abundant as salt lakes and desalination can tackle it using much less energy than is needed for seawater.
So what is not to like? Well in the past desalination has been so expensive that it has been last resort, with Dubai, Saudi Arabia, Israel and Kuwait getting all or most of their water that way because they have no alternative. Desalination plants have got bigger and bigger with costs rising past the $1 billion level and they have often damaged oceanic wildlife by sucking in fish eggs and so on and spewing out concentrated brine in a poorly controlled way that kills wild life.
In most countries, the most competitive desalination technology remains reverse osmosis using electric pumps where electricity cost can be dominant. Desalination plants have almost always satisfied their huge appetite for electricity by fossil fuel plants on site or behind their grid connection warming the globe with carbon dioxide, some emitting localised poisonous gases as well.
However, the good news is that all this is being tackled very successfully. Saudi Arabia has the world's largest operating desalination plant and it burns a lot of gas as does the 140MW one in Israel. However, Saudi Arabia is going entirely solar. The cooler country, China, is starting to need a lot of desalination so it is deploying a lot of wind + solar and solar alone desalination plants with zero emission. In fact, as with grid supply, the zero emission options are rapidly becoming lower cost than burning fossil fuels. Yes, there are other options such as biosaline agriculture giving kelp to samphire and quinoa but all are needed because we have to drink too.
Desalination is practised in about 150 countries, with many more joining the fray. Demand is now so varied that plants of all sizes are now needed and in numbers and later volume of water, the medium and small ones may show greatest growth in future despite several monsters being planned. Economy of scale can be more than a matter of making ever larger plants. Indeed these are already into diminishing returns. Economy of scale can also mean mass production of standard medium and small sized plants and that work has scarcely begun.
With cyberattacks and weather shutting down grids in and their electricity prices typically rising, the dropping costs of off grid zero emission electricity are increasingly preferred, with the user enjoying both predictability and rapid adjustment.
It is time for a report on the heart of future desalination. This is the new IDTechEx report, "Desalination: Off Grid Zero Emission 2018-2028". It predicts that, coming from very little in 2018, off grid zero emission desalination will be a rapidly growing $35 billion market in 2028. The report looks closely at its roadmap of exciting new desalination and electricity technologies that will boost performance and reduce cost, in particular the two reducing what is usually the largest cost element - electricity. That embraces photovoltaics that is three times as efficient, Aerial Wind Energy AWE such as tethered kites more affordable and versatile than ground wind turbines and many new forms of water power that viably downsize and are sufficiently rugged and free of marine growth. It looks closely at combinations of harvesting technologies for security of supply and minimising storage. There is a lot of benchmarking best practice in other industries ahead in these aspects for all sizes.
This 160 page report covering 79 organisations is replete with new infograms and forecasts. They clarify such things as the increasing interaction and integration in this emerging industry. Desalination plants will refill the Dead Sea while providing drinking water and many will provide spare electricity for communities. Some will be part of village, island and ship microgrids. How many islands? Which countries? What is best practice? It is here including future desalination options and why certain ones are dying out.
The increasingly popular mobile desalinators will sometimes double as transport, provide electricity for farm robots not just water and some will replace increasingly unaffordable diesel gensets expensively modified to meet new emissions laws and involving yesterday's crippling fuel supply systems. There are many strategies for avoiding those expensive, dangerous, short lived batteries in desalination and actual examples are given.
For "Desalination: Off Grid Zero Emission 2018-2028", multi-lingual PhD level analysts from IDTechEx have carried out interviews worldwide, mined restricted databases and thought creatively on your behalf, presenting many new ideas. The research was carried out in 2017/8 and it is constantly updated. There are drill down reports for those wanting even more. They cover AWE, off grid overview, electricity from urban infrastructure and much more.
For information on further IDTechEx reports, please visit www.IDTechEx.com/research.