San Luis Obispo County Shooting for US Solar Energy Leader

San Luis Obispo County Shooting for U.S. Solar Energy Leader With its three planned solar energy projects, San Luis Obispo (SLO) County in California is clearly in the running to become the nation’s leading solar energy producer.Though the projects represent considerably less power output than three other projects planned for California’s Mojave Desert (BrightSource’s 400-megawatt concentrating solar thermal plant; ISEGS Ivanpah I,II, and III, 400 megawatts; Mojave Solar Park, 553 megawatts; and AV Solar Ranch One, 230 megawatts), the likelihood of their gaining all the needed approvals is (marginally) better than anything planned for the Mojave, where fragile ecosystems have found a champion in the likes of influential and outspoken Senator Dianne Feinstein (D-CA).SLO County projects include the Carrizo Energy Solar Farm, a solar thermal energy project that will deliver 177 megawatts via compact linear Fresnel lens; High Plains Ranch II LLC, a 210-megawatt monocrystalline solar photovoltaic system with single-axis tracking; and the Topaz Solar Farm, a 550-megawatt thin-film photovoltaic installation which changed hands (from OptiSolar to First Solar) in April.According to the Solar Energy Industry Association, once completed, High Plains and Topaz would become two of the largest photovoltaic systems in the world, while Carrizo would occupy that same prestigious position in the world of solar thermal plants. Currently, the largest is the Solar Energy Generating Systems, or SEGS, consortium of nine parabolic trough solar thermal/gas plants in the Mojave producing 354 megawatts. The largest proposed (and presumably photovoltaic) solar installation in the world is First Solar’s recently announced Chinese venture, at a mind-numbing 2 gigawatts.Once online, possibly as early as 2013, all three would produce enough electricity to power 240,000 homes, according to some solar experts, though these estimates vary widely – from as few as 90,000 to as many as 290,000 homes. This is because of a constraint known as the capacity factor.For example, coal-fired generation has a capacity factor of about 70 percent; that is, a coal-fired power plant generally produces 70 percent as much energy as it potentially could running 24/7 at maximum combustion – the other 30 percent given over to planned outages or unplanned shutdowns or slowdowns. So a coal-fired plant powers about 800 homes per megawatt generated.Since the sun doesn’t shine at night or on cloudy days, and solar irradiance varies from morning to evening, while most photovoltaic panels are fixed to capture only the high irradiance values of midday, solar photovoltaic energy systems “max out” at about 17 percent – part of this determined by the low efficiencies (rarely more than 14 percent) of the panels themselves. Solar tracking systems improve this figure by about 30 percent.The capacity factor is higher for solar thermal energy, up to 31.25 percent for solar dish/Stirling engine configurations. Thus, efficiencies achieved by the Carrizo Plains solar trio through tracking and solar thermal generation potentially allow each megawatt to power 300 homes, so the 977 megawatts produced could potentially electrify up to 293,100 homes on a very good day.The impetus behind such unprecedented solar energy production in California is Gov. Arnold Schwarzenegger’s determination to have 33 percent of the state’s power coming from renewable energy (preferably solar) by 2020. To further aid this drive, more than 130 state, local and utility incentives – in the form of cash rebates, tax rebates, “green” building fee waivers, leases, and solar loans – provide everyone from the lowliest homeowner to the largest installer with good reasons to go solar.For the Carrizo Plains solar trio, the biggest incentive is the fact that regional utility Pacific Gas & Electric has agreed to purchase all the electricity they produce, and these power purchase agreements, or PPAs, are like money in the bank or a sterling credit rating when it comes time to finance construction.The downside, of course, are the 11 square miles these three will occupy (10 for the photovoltaic installations, one for the concentrating solar thermal). This area contains some of California’s last remaining native prairies, and increasingly fragile ecosystems like the migratory pathways for tule elk and pronghorn antelope.The upside is the 300,000 pounds of carbon dioxide (and associated greenhouse gases) per month that won’t be emitted by burning fossil fuels – a benefit even the tule elk can appreciate.