Interview: How can we harvest freshwater from brine?

This blog is part of a series of interviews on our Emerging Technologies 2014.

Why is desalination important as a way of obtaining fresh water?

The growth in desalination, at least in the United States, is largely going to be driven by the need to deal with water produced from fracking. When you recover fracked natural gas, a huge amount of salty water comes out of the ground. Right now we’re rejecting it, but regulation is pushing us towards desalinating it and using it for other things in agriculture. The growth is not motivated by the need for drinkable water but by what we do with this water that comes out of the ground during fracking.

Outside the United States, is this technology going to help parts of the world where there is a need for more fresh water?

Let me give you some stats about demand for water. The projection is that there is going to be a shortfall of 40% by 2025 in terms of demand for fresh water. So in a little over 10 years, we’re going to have a 40% shortfall in supply of useful water versus what’s actually required to drive agriculture, industry and domestic use.

To what extent is desalination currently used?

In the United States alone, the amount being spent on desalination is projected to be around $10 billion to $11 billion by 2016; Saudi Arabia will be spending $13 billion by 2016 and China will be spending about $6 billion.

Turning to emerging technologies, what’s the new thing that we are highlighting?

Typically, when technology has an impact, there are a couple of trends that converge. In this case there are three. One is demand for fresh water and that’s kind of obvious. The second one is the emergence and acceleration of technologies that can extract drinkable, or at least usable, water from brackish or salt water – and that’s one of the things that was highlighted in last year’s list of emerging technologies.

The new thing is some very specific ways of extracting some of the highest value elements out of those reject brines, specifically magnesium and lithium. That’s now getting significant investment from places like the Department of Energy in the United States, which is why it’s made it onto this year’s list of emerging technologies. The thing to highlight is that each different element that you try to extract has a different chemistry associated with it, so it’s not like there’s one way of solving the problem. There’s a focus now on using chemistry rather than brute force thermodynamics.

We know that lithium is commonly used in batteries but what makes magnesium so valuable?

Magnesium is extremely valuable in lightweight alloys, so if you want to replace steel with something that’s very strong but much lighter in weight, magnesium is probably the lightest material that still maintains those mechanical properties. The main limitation to making more lightweight magnesium available has been the source of the metal itself. It’s got the properties but it’s difficult and expensive to access.

So this technology is offsetting some of the cost of desalination in the first place. Is it cheaper than mining those specific elements in traditional ways?

It has the potential to be cheaper on a larger scale, but it hasn’t reached that point yet.

Once it’s scaled, will we be talking about something that not only addresses the shortage of fresh water but is actually a better way of getting at these valuable minerals that are so expensive to mine?

Correct. And the interesting thing is that if you said “let’s just go mine seawater”, it’s too dilute, which makes buying it very expensive. When you desalinate seawater you concentrate everything in the water that you don’t want, including valuable materials. So these reject brines have everything, both good and bad, highly concentrated, and right now they’re a cost for desalination.

If you try to extract lithium and magnesium from bulk seawater, you’re never going to compete with traditional mining technologies, whereas these reject waters that have been concentrated actually represent a viable, economically attractive resource that offsets the cost of desalination.

Is the new technology operational anywhere at the moment or is it still something that’s experimental?

Pacific Northwest National Labs, a recipient of a Department of Energy grant, has partnered with a company called Global Seawater Extraction Technologies to actually scale this. They’re working on a very specific chemistry for magnesium. Japan has made several announcements about having some success in scaling this for lithium extraction.

What is the value created by these new technologies for extraction?

The current cost of magnesium production is somewhere between €1,400 and €1,900 per ton and we’re talking about a threefold reduction in cost, making it similar to the cost of steel production, which is something like €450 per ton. That would have an impact on things like lightweight vehicles.

How plentiful is magnesium in seawater?

Obviously the most common elements in seawater are sodium and chloride but magnesium is the third most common element.

Would you say that this technology’s primary importance is that it would make it cheaper to get access to these minerals or that it’s making desalination financially viable?

It’s been driven by the former but the opportunity is to connect the two together. Then, when we design a desalination plant, when we think about the economics of fracking and the disposal of produced water, we can add in the potential value of extraction to offset the view that those wastes are a cost centre. That’s the change in thinking that will be transformational.

That’s often where we get hung up with these technologies. People say desalination is great but the cost of the water makes it economically unviable. What we’re saying is, there are other things that you can add to the economic equation that could tip the balance.

Is there a specific development that we’re expecting in 2014?

It’s the interest in funding and the actual identification of technologies by the Department of Energy that is renewing this interest. Millions of dollars are being invested into recovery of magnesium, which hasn’t happened before. There’s an element within the Department of Energy that’s very progressive and has recognized the issues that we’re talking about – that there is a way of solving some of these economic issues around desalination and dealing with other brackish or salty waters that are really energy driven. Everybody recognizes that desalination is an energy-intensive process so it’s driven by the cost of energy. And that’s why the Department of Energy is involved. They say OK, rather than just reducing the cost of energy, let’s look at offsets based on value created. That’s only just gaining relevance now.

Find out more on how emerging technologies are reshaping society, business and government in the Global Technology Leadership course of the Forum Academy.

Author: Jeffrey Carbeck, chief technology officer at MC10, talks about the impact of new developments in desalination, one of the Forum’s top 10 emerging technologies for 2014. Interview conducted by Shane Richmond.