AVCD 

Advanced Vapor Compression Desalination

History

Water is easy to store, but difficult to move. Because costs are sensitive to transport distance, freshwater supplies are least expensive when sourced from local surface and groundwater close to usage sites.

 

In regions where surface and groundwater resources are contaminated with salt, potable water can be obtained via desalination. In past decades, desalination has been practiced almost exclusively in the Middle East where freshwater was limited, but energy was plentiful. Their demand for water drove the development of desalination technologies that extracted salt-free water from seawater and brackish water, regardless of efficiency or cost.

Problem

An enduring ambition is to desalinate brackish and seawater at costs comparable to fresh surface and groundwater. Traditionally, desalination has been an expensive technology suitable only for the wealthiest economies, rather than widespread adoption. Typically, these conventional desalination technologies have been large fixed-in-place facilities, often costing many billions of dollars.

 

Cost-efficient desalination has been elusive for the following reasons:

 

  • Energy efficiency is achieved only at larger scales

  • Pretreatment of the feed water is expensive and environmentally damaging

  • Robust operations are incompatible with energy efficiency

  • Brine disposal is expensive

  • Negative environmental impacts of brine discharge result in public opposition

  • Capital is underutilized when equipment is operated only during droughts

 

Solution

 

To address the above challenges, Cascade’s desalination technology can scale down to mobile units that exceed the cost efficiencies of conventional mega-scale reverse osmosis units. During a drought, the mobile units can be leased and then redeployed elsewhere when the drought ends. Our “zero discharge” technology eliminates environmental and economic issues associated with brine disposal, and introduces another profit center by recovering minerals from the brine.

 

The enabling technologies that achieve these benefits are the StarRotor™ compressor and supporting heat exchangers, both of which are exclusively licensed to Cascade.

Our Advanced Vapor Compression Desalination (AVCD) system exhibits efficiencies that equal or exceed reverse osmosis, the leading conventional technology.  AVCD produces salt-free water and saturated brine, which can be separated into pure salts used in fertilizer, metals manufacture, building materials, and chemical products.

 

AVCD solves each of the historical limitations as described below:

 

  • Energy efficiency of 85% or greater is achievable at small scale

  • Pretreatment of the feed water is not required

  • Robust operations are achieved combined with high energy efficiency

  • Brine disposal cost is eliminated

  • Negative environmental impacts are eliminated

  • Capital is fully utilized when equipment is redeployed when the drought ends

 

Why Now?

The 21st century will experience numerous regional water shortages for the following reasons:

 

  • Increasing demand as population grows and wealth increases

  • Decreasing supply as climate change increases droughts

 

Cascade addresses these challenges by lowering desalination costs and improving the mobility of water supplies.

 

Typical RO unit production cost vs. plant capacity

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