Floating

May 13, 2023

The lead article in yesterday’s Business section of my local newspaper ran with an idea that is becoming more popular in the US, after already experiencing rapid growth in China.  A study in the journal Nature Sustainability in March found more than 6,000 floating solar fields in 124 countries.  Not only do these solar fields produce electricity, but they also save water by reducing evaporation from the ponds they cover.  Floating solar farm company Ciel & Terre has built 270 projects in 30 countries.  Director Chris Bartle says workers like to install the panels because they get to go out on the water rather than rooftops.  They joke about having to bring life jackets for work rather than ladders, and they get to work in the cool shade over water rather than a hot rooftop.

When I looked online, I found floating photovoltaics (FPV), or floating solar (floatovoltaics), are solar panels mounted on a structure that floats on a body of water.  They are typically found on reservoirs or lakes, such as city water reservoirs, quarry lakes, irrigation canals, or remediation and tailing ponds.  A small number of systems exist in China, France, India, Japan, South Korea, the UK, Singapore, and the US.  Floating systems have advantages over photovoltaics (PV) on land.  Water surfaces often cost less than the surrounding land, and there are fewer rules and regulations for structures built on bodies of water.  Life cycle analysis indicates that foam based FPV have some of the lowest energy payback times (1.3 years) and the lowest greenhouse gas emissions to energy ratio (11 kg CO2 eq/MWh) in crystalline silicon solar photovoltaic technologies reported.  Unlike most land-based solar plants, floating arrays can be unobtrusive because they are hidden from public view.  They can achieve higher efficiencies than PV panels on land because water cools the panels. The panels can have a special coating to prevent rust or corrosion and are sealed which acts as a lid that brings evaporation down to nearly zero.

In May 2008, the Far Niente Winery in Oakville, California, pioneered the world’s first floatovoltaic system by installing 994 solar PV modules with a total capacity of 477 kW onto 130 pontoons and floating them on the winery’s irrigation pond.  Kyocera developed what was the world’s largest floating farm, a 13.4 MW farm on the reservoir above Yamakura Dam in Chiba Prefecture with 50,000 solar panels.  Salt-water resistant floating farms are being constructed for ocean use, but mastering the tides and rough seas is problematic.  The largest announced floatovoltaic project as of 2015 is a 350 MW power station in the Amazon region of Brazil.  The market for this renewable energy technology has grown rapidly since 2016. The first 20 plants with capacities of a few dozen kWp were built between 2007 and 2013.  Installed power reached 3 GW in 2020, with 10 GW predicted by 2025.  The costs for a floating system are about 10-20% higher than for ground-mounted systems.

Thoughts:  Floating solar panels save land for production of agriculture or habitation as the reservoirs already existed and no new land was used in construction of the floating fields.  The panels save water by reducing evaporation which shields the water resource from draught.  The only drawback seems to be the cost of higher installation.  In the US, the federal government may pay around half the cost through a HUD grant, and other grants are available.  It comes down to the environmental awareness of the entity paying for installation.  For Cohoes, NY (the city in the article), it was a matter of pride to be known as a city championing environmental justice.  This is an example more should emulate.  Act for all.  Change is coming and it starts with you.