A story I wrote last week for MIT Technology Review takes a look at a new energy-efficient approach to desalination developed by a Vancouver-based startup called Saltworks Technologies. Conventional desalination relies on reverse-osmosis and costly membrane technologies. Pumping the water at high pressure through these desalting membranes takes a lot of energy, which drives up the cost of this form of desalination. Another approach is to evaporate and then condense the water, another energy-intensive approach.

Saltworks has a completely different, and quite novel approach. It starts by using the sun or industrial waste heat to evaporate one pool of seawater until it becomes concentrated with 18 per cent salt (compared to 3.5 per cent for regular seawater). This concentrated stream is pumped into a desalting unit along with three other regular seawater streams. The concentrated stream is connected by specially designed “bridges” to two regular streams, and because it has a higher concentration it is compelled to diffuse its salt content — sodium and chloride — into the weaker streams. But the bridge connecting to the one weaker stream only allows sodium ions, which are positive, to flow through; the bridge connected to the second weaker stream only allows chloride ions, which are negative, to flow through. The end result at this stage is that one of the two weaker streams now has surplus positive ions, mostly sodium, and the other has surplus negative ions, mostly chloride. The two streams, now out of balance and eager to pick up ions of opposite charge, are separately “bridged” to the third regular seawater stream. The one stream with surplus positive ions strips the third stream of all its negative ions, and the second stream with surplus negative ions strips the third stream of all its positive ions. This leaves the third stream completely stripped of all ions — i.e. it’s de-ionized, or pure drinking water.

It’s a brilliant process because most of the energy that’s required comes at the front end through evaporation, which is accomplished in a low-tech way with abundant solar energy, or waste heat from a neighbouring industrial facility. The rest is accomplished through electrochemical reactions requiring no outside energy source. If Saltworks can scale this approach up, it could bring cheap desalination to the many parts of the world that need it.

It’s that time again. Sustainable Development Technology Canada has awarded grants to another round of companies eager to demonstrate their respective clean technologies. This time around 18 projects are being funded to the tune of $54 million. To date SDTC has invested $425 million in 171 clean technology projects. Of the 18, here are a few that caught my attention:

* Duropar Technologies Inc. of Brampton, Ontario, has partnered with Canadian Pacific Railway on a project that seeks to replace the use of creosote-covered railway ties with ones that are made of 100 per cent waste-based composite material. By waste, I mean plastic that is difficult to recycle through municipal programs and old asphalt, which is a pain in the butt to dispose of. Now, no secret that the old creosote ties have toxic chemicals in them that leech into the soil and ground-water along train tracks. Here’s a fact I didn’t know: the railway industry goes through more than 20 million ties a year in North America alone. “Each tie leaches up to 15 kilograms of creosote over its lifetime,” according to SDTC. Duropar has no apparent Web site, but I did find this link to one of their patents. Its composite ties don’t leech, so are considered a much “greener” alternative.

* Saltworks Technologies Inc. of Vancouver, B.C., has developed a desalination system “that reduces electrical energy requirements by up to 80 per cent, thereby improving the affordability and accessibility of clean water,” according to SDTC. The key to this is an inexpensive, low-temperature thermal energy conversion system that uses solar energy or industrial waste heat (process heat) to reduce electricity consumption. For the SDTC project, Saltworks will build a commercial-scale 5,000-litre/day “transportable” pilot plant that can be used for ocean water. The process doesn’t rely on chemicals. The company, as you can see by its Web site, is still pretty much in stealth mode. If its process and technology are as efficient as promised, this could be huge for the Middle East, Australia, and shoreline areas of the U.S. southwest that have scarce fresh-water resources. The Middle East alone, certainly an area with terrific solar exposure, wants to build several massive oil-fired generating stations that will be used to power desalination plants. The potential market is massive.

* And then there’s StormFisher Biogas of Toronto, a company I’ve written about several times before. Seems StormFisher is moving ahead with plans to produce biogas in anaerobic digesters that can be injected into Ontario’s natural gas pipeline — specifically, the pipeline owned and operated by Union Gas. It will be a Canadian-first if they can do it, though “Canadian first” means little when we know it’s being done all the time in Europe. Still, nice to see us getting into the game. StormFisher’s system will take methane produced from manure and food processing by-products (i.e grape skins from wine-making, waste from cheese and milk production, etc.) and will convert it into pipeline-grade natural gas. At the same time, StormFisher’s own process by-product — i.e. the digestate — will be turned into a quality organic fertilizer that can be sold back to farmers to displace the use of chemical fertilizers. “The project aims to validate next generation biogas technologies which, although commercially available in Europe, are not in use in North America,” according to SDTC.