Reduce Evaporation losses from reservoirs and lakes
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Our process can reduce evaporation losses from lakes and reservoirs by chilling the surface of the lake using cold water from deeper in the lake. If the water doesn't evaporate it can be used without reducing the amount of water flowing downstream or the lake level. This can benefit nearly every country in the world and  can reduce water stress for billions of people world wide?

Government studies have demonstrated that a 1C (1.8F) reduction in surface temperature can reduce evaporation by approximately 2,900 gallons per acre per day.  On some lakes it may be feasible to reduce the surface temperature by more than 1C which multiplies the available water saving. 

Our approach uses solar power and can be deployed as easily as simple as dropping a set of self positioning buoys in the lake. No chemicals, no pipe network, no electric bills and precious little maintenance. Preliminary analysis indicates a cost between $100 and $700 per acre foot saved which is far cheaper than trying to replace the water with desalination.

Quick Market Analysis

Initial analysis indicates that 1% coverage will cost $2.2 million USD per 1 square kilometer of reservoir surface area. With a 1C reduction in  surface temperature the system will reduce evaporation losses by approximately 2.74 million liters per day when the surface water is above 60F. Savings could be higher in very dry or very windy conditions.

Further tests will be conducted to determine necessary adjustments to surface area coverage  and pump volumes to fit local climates. At the estimated cost levels the water saved will be less expensive than replacing the same volume of water using desalination or long distance pipelines such as the California Aqua-duct. The main cost driver is the surface water temperature and the temperature delta between surface water and deeper water in the same reservoir.

The USGS indicates 660,000 sq kilometers of reservoir surface area1 world wide which provides a maximum market of value of 1.36 trillion USD.   The USGS also indicates 1.5 million sq kilometers of freshwater lakes   Not all of these water bodies can use or benefit from the technology but a reasonable projection is over 5% of the available freshwater surface area.

Example of USA water bodies which are good candidates.

Deployment Options

Any water body that has a thermocouples layer (over 4 meters deep) are viable candidates. Water bodies with distinct summer versus summer seasons are the best candidates.      

Water bodies like Lake Powell, Lake Mead and Lake Lanier which suffer from significant summer stratification are the best candidates because they can deliver a high degree of chilling per unit of pumping invested.   

Areas where water shortages are current or looming within 10 years and where developing alternative water sources will cost more than $500 per acre foot are ideal.

Example Opportunity (Lake Lanier near Atlanta)

A interesting example opportunity is in Atlanta where a Federal court case has mandated that Atlanta reduce their water extraction from Lake Lanier to 1970 levels within 3 years. Once this technology proves out,  it could deliver about 80 million gallons a day to Atlanta for an investment of about $320 million USD.  

This opportunity would only be viable if the local and state government could negotiate permission to use the water they help retain in the reservoir. This kind of water trading is already being done so there is ample precedent to allow a upstream city to fund downstream projects as long as the water delivered to downstream users nets out the same.     

Lake Powell and Lake Mead on the Colorado River would also be good candidates. The Las Vegas area is currently spending multiple billion $ for a controversial project to pipe water from surrounding counties so a 300 million investment for infrastructure installed in lake Mead would be a easy decision with the right kind of publicity.    

Project financing is available which allows investors to install systems of this type in exchange for a commitment's from the local government to purchase the water at a given cost for a extended period of time. This allows the local government to deliver the benefits of the system without consuming their cash or credit to fund the installation.

Some History and Science

Core Science

The core science was done by government studies stretching back into the early 1900's. Our Analysis is based on their peer reviewed science. The core of the science is centered around the following areas. It has all been extensively peer reviewed and many modern studies have validated the work done in earlier.
Our approach is unique and I believe is more deployable, sustainable and maintainable than other approaches to the same problem. Full stratification's  has been a well researched area but little work has been done on partial stratification's when used purely as a mechanism to reduce surface evaporation. 

1 Magnitude and Significance of carbon burial in lakes, reservoirs and norther peatlands.

P.S. Please blog or publish articles about Reduced Evaporation Losses, it helps spread the word.

Thanks Joe Ellsworth
CTO and principal engineer
206-601-2985 USA

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