CPV-7: Concentrating Photovoltaics at the Water-Energy Nexus

[Las Vegas, Nevada USA]

CPV, PV (Photovoltaic), and water: a perfect mix.

CPV-7 Opening CPV-7 (7. International Conference on Concentrating Photovoltaic Systems), Southern Nevada Water Authority (SNWA) and the Las Vegas Valley Water District General Manager Pat Mulroy welcomed conference delegates to Las Vegas, “a city that loves it’s energy”, and launched into a discussion of the Water-Energy Nexus.

Forget the glitz and lights of the Las Vegas Strip. SNWA is the largest user of energy in Southern Nevada treating and delivering 900 million gallons (3407 million liters) of water per day. Water is pumped 2500 feet (762 meters) uphill from Lake Mead, the reservoir formed by Hoover Dam, and 600 million of those gallons are treated in the largest Ozonation facility in the United States consuming enormous amounts of energy in the process.

Explaining SNWA water resources, Pat Mulroy said:

Most of our water comes from the Colorado River, a system that has been under severe stress for the last eleven years.

In the Black Canyon of the Colorado River, Hoover Dam generates inexpensive hydropower electricity for over 20 million people in the Southwest with no carbon footprint. Lake Mead’s water level has dropped from a high of 1220 feet above sea level to an all time low of 1083 feet last year. Mulroy said: “At elevation 1050, Hoover Dam stops generating electricity.

Living in the driest desert of the United States, southern Nevada receives no more than four (4) inches (10.2 centimeters) of rain per year and doesn’t “allow water guzzling power plants anymore.” Only air-cooled and water efficient technologies can be used for power generation in Nevada. Contrasting PV and CSP (Concentrating Solar Power), Mulroy said:

PV is different from thermal solar as you well know.
And to be very frank with you, we’re not big fans of thermal solar.
There are several of those plants around, but given what our water strain is, I’m not sure that that’s the most efficient use of Nevada’s water supply.

SNWA has deployed photovoltaic systems at their treatment plants, for example the six (6) Amonix 7500 CPV systems at the River Mountain Water Treatment Facility, pump stations, and, as a sustainability education tool, on the 180 acre Springs Preserve.

From Amonix 308 kW CPV at River Mountain Water Treatment Facility

Making the climate change connection, Pat Mulroy said:

Quite frankly, as we’ve struggled to get a handle on the water challenges that we’ve faced over the last eleven years, and that with climate change will stay with us invariably, we know that PV is an integral part of our future.

When you look at the water situation around the world, you have to ask yourself where is the water for the next generation’s food supply going to come from? Are we going to use it all to create energy or are we going to leave some behind to grow food and actually provide drinking water to the billions of people that are going to be dependent on it.

We need energy of it’s water need; and we need water of it’s energy needs are probably the two most daunting challenges facing the next generation and facing this century.

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