CSP - The Solar Alternative That Rivals Nuclear
Alternatives to nuclear energy, no doubt something on a lot of minds, provides interesting answers today. Creative applications in Concentrated Solar Power (CSP) specifically are providing energy solutions that accomplish what nuclear does - transfer heat, using the sun as fuel. Thermal heat created by nuclear fission (using plutonium or uranium as fuel) can't be directly converted to electricity, but is used in a heat transfer process to heat a liquid like water to steam, which in turn drives a turbine connected to a generator that creates the electricity that keeps your summer popsicles conveniently chilly in the local supermarket freezer.
[June 2011 - I've made a correction in reference to nuclear "fission" in the above section, which should not refer to nuclear "fusion". I had been receiving so many comments disputing this article that I had wrongly changed it to "fusion" (based on a commentors feedback) from the original "fission" which I had correctly indicated when first writing this article.
In the flurry of comments from those wanting to challenge my viewpoint on CSP, in retrospect I think I was a bit overwhelmed. Sorry to readers for the confusion however, as I am referring to "nuclear fission", which is what is used in nuclear energy plants around the world today. Nuclear reactors house the fission of heavy atomic nuclei, the most common of which is uranium-235, which produces intense heat. For those interested in understanding the full fission process, which my article doesn't capture, I would recommend reading a better description available here from the European Nuclear Society. Thanks.]
Aside from our many nuclear questions, Fukushima provides an opportunity to focus on how we create energy and the value solar and renewable technologies bring to the world as we look ahead. CSP stands apart from the crowd because it creates the world's cheapest per watt electricity, leveraging the sun's thermal radiation as part of a process in electricity generation, as opposed to harnessing light which is used in standard photovoltaics and thin film solar, used widely in utility scale solar parks.
A CSP system includes two primary parts. First it uses parabolic mirrors that track the sun's path through the sky, capturing and focusing concentrated solar radiation onto pipes carrying a liquid, or onto an energy efficient surface. Secondly the absorbed thermal heat is transferred through a pipe system, and the heat in turn is used to drive a steam turbine, that connects to a generator which creates electricity. No, it's not your imagination, the CSP system operates very much the same as a nuclear plant, creating the same results, only without the safety headaches, while doing so in more cost effective ways.
"In terms of demand characteristics, CSP offers the possibility of dispatching energy almost 24/7 thanks to thermal storage.....except from an interview with Dr. Christoff Wolff,Chairman of the Board and Chief Executive Officer at Solar Millenium, a leading CSP company based in Germany.
In 2011 installed CSP technologies contributed 679 MW's of electricity worldwide, while 2000 MW's are currently under construction. Spain and the U.S lead in this field, although Spain has 89% of current construction efforts. Parabolic trough systems like Nevada Solar One, described below, dominate the market at present accounting for 88% of installed capacity. For a closer look at how CSP is being used, we can reference a few examples at work around the world.
CSP Parabolic Trough System
ACCIONA’s Nevada Solar One CSP Plant, based in the US has been in operation since 2007. This 64 MW plant is the third largest CSP plant in the world, providing power to more than 14,000 homes each year. The facility is based on 400 acres in the Nevada desert, and uses 182,000 mirrors that concentrate the sun’s rays onto more than 18,240 receiver tubes containing fluid. Fluid heated at 390°C flows through the tubes and is used to create steam that drives a conventional turbine connected to a electricity generator. Acciona states that if the US would set aside a 100 square mile area in the southwest region of the U.S. for CSP it would have the potential to produce enough solar energy to power the entire nation indefinitely. Three new CSP plants are being built in Nevada in the next few years, which will add an estimated total 410 MW's to the state. The terrain and sun exposure in areas like the Nevada desert provide ideal conditions to maximize the electricity capacity of this technology.
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Desertec, a non-profit project started in 2009, means to create clean energy from deserts around the world, primarily using CSP. Their Europe-Africa grid connection plans seem a bit sci-fi, requiring that massive additional infrastructure be built, at equally sci-fi over the top costs. They're got some interesting concepts underway using CSP, bringing together dialogue, industry and finances to help carve out new CSP energy projects worldwide.
CSP and Multi-Junction PV Cells
Zenith Solar, based in Israel, is combining the basic concept of CSP with PV cells and claim to have the most cost effective, energy and space efficient solar energy system on the market. They've created low cost optic units (mirrors) seen here, that focus the sun's radiation onto a very high efficiency semi-conductive solar PV cell, reducing overall cost while increasing energy output. The highly efficient multi-junction PV receivers are coupled to a Heat Exchanger that converts concentrated solar radiation into electrical power and uses thermal power for hot water. Their Z20 CSP product is FIT certified and can be assembled for community, commercial, hospitality or industrial use.
The company has been operating a utility scale CSP system in Israel which uses 16 Z20 units located in grape vineyards providing hot water for some 230 residents and creating electricity that is sold at profit to the Israeli grid. There's more to understanding Zenith Solar's CSP system, cost savings, and potential applications, captured nicely in this video:
The NREL has been working with multi-junction PV cells similar to Israel, with outstanding cost and energy efficiency output. The technology is so efficient that NREL stated that "the cells can make electricity at a cost competitive with natural gas".
CSP Solar Islands - The Future
In 2007 Nolaris SA was formed, an off-shoot of CSEM SA, a company dedicated solely to the development of solar technology and to carrying forward their Solar Islands concept. CSEM SA is a private Swiss non-profit company founded in 1984, created to connect micro-technology R&D with the economics of a rapidly evolving technological marketplace.
The Solar Islands Concept is a cost effective, precisely technical energy plant that floats on a cushion of air suspended in water, several kilometers in diameter. Using concentrating solar panels (CSP) with a solar thermal system model, a Solar Island can effortlessly track the sun to maximize solar radiation capture. Land mounted CSP solar arrays typically use a technically complex tracking system to track the sun throughout the day, whereas Solar Islands rotate as a singular platform without having to align each solar panel to the sun. Similar to other CSP plant concepts, a Solar Island uses panels that direct sunlight onto pipes that heat water to steam at a temperature of 250°C. The heated steam is directed to a Organic Rankine Cycle (ORC) turbine, which directly transforms steam into electricity without using heat exchangers. The circuit is a complete thermal pipe system that draws in fresh water as needed. Construction takes into account wave and wind variables that allow the island to buffer changes in weather. It’s closely estimated that one Solar Island can produce 1GW of electricity. The first prototype is being built and tested on land in the UAE.
The Solar Industry
A few factors can augment the rate and scope of solar deployment worldwide, for the better or worse. Primarily, government long-term solar energy plans and policies, as well as feed in tariffs, provide crucial frameworks that encourage private sector investment and business development, and that in turn facilitates ongoing renewables R&D. Feed in tariffs are short-term incentives usually put in place by governments for 20+ years, offered for the express purpose of helping a solar technology achieve market integration. The other somewhat nebulous issue less easily solved, is the status-quo free market energy suppliers that grew to corporate dominance within the now defunct era of "unlimited growth". Oil, coal etc. Indeed the only sector demonstrating opposition to global advancement of safe and eco-smart renewables, are old players in a changing free energy market who continue to conduct business as usual, somewhat in seclusion from global consensus on success factors demonstrated by many renewable energy technologies. An energy transition of this magnitude has historic proportions, and as history goes, undoubtedly there will be bumps in the road. It's certain however, that we are well on our way.
Interestingly 2011 is dedicated to celebrating nuclear science and marks 100 years since the discovery of the atomic nucleus - a timely spotlight to reflect on how we manage this technology and how we create electricity. It's helpful to note the size of the nuclear industry which has 442 civic nuclear fission plants in operation worldwide, not including 100's more used for research and military purposes. The industry hurdles forward on the premise that to operate nuclear plants by nature implies that we absorb the extreme safety risks a natural disaster could infer, whereas CSP easily out competes nuclear, providing some of the safest energy applications we have today - a technology that's more quickly deployed, comparatively very cost effective, creating jobs, while promoting a healthier future.
**image courtesy of Zenith Solar
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