The environmental impact of the world’s largest solar thermal plant
California would seem to be the ideal place for solar power. Most of the year the region is blasted with sunshine just begging to be converted into clean, renewable energy. Recently the world’s largest solar thermal plant went online in the Mojave Desert not far from Los Angeles that is expected to produce 377 megawatts power – easily enough for 140,000 homes.
Chairman of the California Energy Commission Robert Weisenmiller said, “When this project comes fully online, California will become home to the largest solar thermal electric project in the world, creating stable jobs in a rural community and helping us to meet our goal in curbing the effects of climate change with renewable electricity.”
Apart from the obvious virtue of solar power, the sheer scale of the utility poses some environmental challenges. California desert tortoises have to be relocated with diminishing suitable habit already an issue. There are fears also that local bird-life could suffers burns from the focused sunlight and collisions with the mirrors.
Unlike photovoltaic (PV) cells that directly convert sunlight into electricity, solar thermal plants work by concentrating the sun onto collection stations with a field of mirrors that then heat water to power steam turbines. The process requires a lot of water, a scarce commodity in the desert especially during a drought. Decreasing rainfall has turned the area into a dustbowl, with 2013 being the driest year since the records began 119 years ago.
Existing solar thermal plants are exploring options that reduce water consumption. The new Ivanpah plant utilises “dry cooling”, a technique that returns condensate to the cooling turbines and cuts water consumption by up to 90%. Dry cooling is more expensive and produces less electricity on very hot days than the traditional evaporative methods and could be difficult to retrofit to existing thermal plants.
With a cost of $2.2 billion and requiring six years of construction it’s vital that future energy plants are viable in the longterm. California has set a goal of generating 30% of its energy from renewable means so we haven’t seen the last of solar thermal plants like this.
