Saturday, November 7, 2009

Carbon Nanotube Membrane Elements for Energy Efficient and Low Cost Reverse Osmosis

NanOasis Technologies has received $2 million in DOE funding in the ARPA-E program to develop "Carbon nanotubes for reverse osmosis membranes that require less energy and have many times higher flux. Could dramatically reduce the cost and energy required for desalination to supply fresh water for our crops and communities." Water supplies in most of the world are threatened and finding supplies of fresh clean water is a critical worldwide need.

They are one of several companies pioneering the use of carbon nanotubes in reverse osmosis membranes. They claim their technology "substantially lowers energy use, size and capital requirements for desalination, and other water purification and fluid separations applications." The technology is based on work by Dr. Jason Holt, co-founder of NanOasis, following his work at Lawrence Livermore National Laboratory.

NanOasis membranes consist of a thin, dense polymer film having carbon nanotube pores (or holes) atop a highly porous support. The super smooth inside of the nanotubes allow liquids and gases to rapidly flow through, while the tiny pore size can block larger molecules. By filtering out larger molecules it automagically purifies water.

Membranes that have carbon nanotubes as pores could be used in desalination and demineralization. Salt removal from water, commonly performed through reverse osmosis, uses less permeable membranes, requires large amounts of pressure and is quite expensive. However, these more permeable nanotube membranes could reduce the energy costs of desalination by up to 75 percent compared to conventional membranes used in reverse osmosis.

One of the main problems with reverse osmosis desalination tech to date has been that the basic process of pumping water and forcing it through a membrane to separate out the salt is highly energy-intensive, making for a high cost. The energy (electricity primarily) is used to pump water at high pressure through membranes. That electricity accounts for perhaps 44 percent of the cost of reverse osmosis desalination. The LLNL announcement of Dr. Holt's earlier work claims "these more permeable nanotube membranes could reduce the energy costs of desalination by up to 75 percent compared to conventional membranes used in reverse osmosis."

NanOasis Technologies

Nanotube membranes offer possibility of cheaper desalination

Cheap Drinking Water from the Ocean

Beyond Salt: Desalination Startup NanOasis Eyes Wider World of Clean Water