Ringtrough – The Next Generation of Solar Parabolic Trough

First goal is to build a prototype 12m³ per hour desalination plant powered by 100% renewables


JennSolar is taking on one of the world’s most important issues; providing clean water to millions of people who have inadequate natural resources. The startup’s first goal is to build a prototype 12m³ (3000 gal) per hour desalination plant powered by 100% renewable energy using the next generation of concentrated solar power called the Ringtrough. Current desalination is very costly primarily due to the amount of energy needed to operate the plants.

JennSolar’s Solar Thermal Desalination Technology Team

JennSolar’s Ringtrough was invented, patented and designed by founder and CIO, Kevin Jennings. He has been developing this innovation for the last 10 years and is now bringing it to market. The Ringtrough has several advantages over existing troughs, including being structurally capable of having a mirror aperture of 12m (40’), which is twice the size of current troughs. This allows twice the sunlight to be reflected onto the same amount of collector tube.

The even greater advantage is the Ringtrough’s collector tube is not attached to the trough, it is supported independently. This allows the collector tube to be piped solid to the manifolds at each end of the long line of mirrors. Current troughs rotate about an axis under the trough causing the collector tube located 2m (6’) away to rotate through a 4m (12’) diameter semicircle each day. Where the collector tube attaches to the manifold, rotating joints or flexible piping is required, limiting the type of thermal fluid to a synthetic oil. There is a company currently using parabolic troughs with synthetic oil for desalination, however the mirrors are smaller, and the heated oil then transfers the heat to the raw water in a heat exchanger. The Ringtrough will preheat the raw water directly in the collector tube with larger mirrors.

The desalination method JennSolar will use is standard Multi-Stage Flash Distillation (MSFD) and not Reverse Osmosis (RO). RO has increasingly been chosen for desalination over the past 30 years, primarily due to MSFD requiring much more energy to desalinate the same amount of water. RO uses high pressure pumps at up to 84 bars (1200 psi) to force water at room temperature through membranes which reject the solved salt molecules and allow just the pure water to pass. RO costs increase significantly where the raw water salinity is high, the intake temperature cold or the raw water contains excessive suspended solids.

MSFD is a low-tech desalination method where seawater is pre-heated to 110°C (230°F) and sprayed into a series of flash chambers with increasing vacuum pressures. The pure water flashes into steam and rises for collection, while the salty water falls to the bottom and is sent to the next stage for re-flashing. MSFD is less expensive than RO where adjacent power plants can furnish waste heat or where the salinity of the water is high. MSFD produces a better quality of drinking water and requires significantly less pretreatment filtering and chemicals and post treatment chemicals.

JennSolar’s Ringtrough – The Next Generation of Solar Parabolic Trough

The Ringtrough will be used as the heating source in a standard MSFD plant. Other Ringtroughs will provide supercritical plant utility steam to power pumps, reheating and plant heat. PV panels will provide the remaining plant electrical requirements. A Ringtrough plant will provide drinking water for less than RO or current MSFD processes and it will not be tied to available fossil fuel-based energy supplies.

This invention came to light based on the inventor’s concern for the future of his three children and grandchildren to come. Today, only 3% of the world’s energy is generated by solar, wind, geothermal and biomass. In 50 years, the world runs out of oil and natural gas. It has taken 50 years to achieve just 3% renewables and in 50 years we run out of oil and gas. This is not politics, it is arithmetic and common sense. The shift to renewable energy is not moving fast enough but JennSolar’s Ringtrough will help accelerate the transition.

Today we are faced with problems such as global warming and water scarcity worldwide. It is how we act today to change tomorrow! JennSolar is kicking off a Kickstarter Campaign on Sept 6th to help fund the design and construction of the first 100% renewable energy desalination plant. comment


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