mfioretti: photovoltaic*

Bookmarks on this page are managed by an admin user.

42 bookmark(s) - Sort by: Date ↓ / Title / Voting / - Bookmarks from other users for this tag

  1. Replacements for oil need to be profitable and be able to pay taxes, at currently available price levels–low $40s per barrel, or less.

    We need to be careful in aiming for high-tech solutions, because of the complexity they add to the system. High-tech solutions look wonderful, but they are very difficult to evaluate. How much do they really add in costs, when everything is included? How much do they add in debt? How much do they add (or subtract) in tax revenue? What are their indirect effects, such as the need for more education for workers?

    We need to be alert to the possibility that solar PV and most wind energy may be energy sinks, rather than true energy sources. The two hallmarks of providing true net energy to society are (1) being able to provide energy cheaply, and (2) being able to provide tax revenue to support the government. When actually integrated into the electric grid, electricity generated by wind or by solar generally requires subsidies–the opposite of providing tax revenue. Total costs tend to be high because of many unforeseen issues, including improper siting, long-distance transport costs, and costs associated with mitigating intermittency.

    Unless EROI studies are specially tailored (such as this one and this one), they are likely to overstate the benefit of intermittent renewables to the system. This problem is related to the issues discussed in my recent post, Overly Simple Energy-Economy Models Give Misleading Answers. My experience is that researchers tend to overlook the special studies that point out problems. Instead, they rely on the results of meta-analyses of estimates using very narrow boundaries, thus perpetuating the myth that solar PV and wind can somehow save our current economy.
    https://ourfiniteworld.com/2016/08/08...updated-version-of-the-peak-oil-story
    Voting 0
  2. It is true that you can find a few studies (very few) that look serious (perhaps) and that maintain that PV has a low EROI. However, in a recent study, Bhandari et al. (1)⁠ surveyed 231 articles on photovoltaic technologies, finding that, under average Southern European irradiation, the mean EROI of the most common PV technology (polycrystalline Si) is about 11-12. Other technologies (e.g. CdTe) were found to have even better EROIs. Maybe these values are still lower than those of some fossil fuels, but surely not much lower (if they are lower) and a far cry from the legend of the "EROI smaller than one" that's making the rounds on the Web.

    Then, if you are worried about another common legend, the one that says that PV cells degrade rapidly, think that those of the plant described at the beginning of this article were found to be still working after 30 years of operation, having lost just about 10% of their initial efficiency! In addition, consider that the most common kind of cells use only common elements of the earth's crust: silicon and aluminum (and a little silver, but that's not essential). What more can you ask from a technology that's efficient, sustainable, and long lasting?


    All that doesn't mean that a world powered by renewable energy will come for free. On the contrary, it will take a very large financial effort if we want to create it before it is too late to avoid a climate disaster (quantitative calculations here). But a better world is possible if we really want it.
    http://cassandralegacy.blogspot.it/20.../but-whats-real-energy-return-of.html
    Voting 0
  3. my core prediction for 2016 is that all the things that got worse in 2015 will keep on getting worse over the year to come. The ongoing depletion of fossil fuels and other nonrenewable resources will keep squeezing the global economy, as the real (i.e., nonfinancial) costs of resource extraction eat up more and more of the world’s total economic output, and this will drive drastic swings in the price of energy and commodities—currently those are still headed down, but they’ll soar again in a few years as demand destruction completes its work. The empty words in Paris a few weeks ago will do nothing to slow the rate at which greenhouse gases are dumped into the atmosphere, raising the economic and human cost of climate-related disasters above 2015’s ghastly totals—and once again, the hard fact that leaving carbon in the ground means giving up the lifestyles that depend on digging it up and burning it is not something that more than a few people will be willing to face.


    Healthy companies in a normal economy usually have P/E ratios between 10 and 20; that is, their total stock value is between ten and twenty times their annual earnings. Care to guess what the P/E ratio is for Amazon as of last Friday’s close? A jawdropping 985.

    At that, Amazon is in better shape than some other big-name tech firms these days, as it actually has earnings. Twitter, for example, has never gotten around to making a profit at all, and so its P/E ratio is its current absurd stock value divided by zero. Valuations this detached from reality haven’t been seen since immediately before the “Tech Wreck” of 2000, and the reason is exactly the same: vast amounts of easy money have flooded into the tech sector, and that torrent of cash has propped up an assortment of schemes and scams that make no economic sense at all. Sooner or later, as a function of the same hard math that brings every bubble to an end, Tech Wreck II is going to hit, vast amounts of money are going to evaporate, and a lot of currently famous tech companies are going to go the way of Pets.com.

    my best guess at this point is that photovoltaic (PV) solar energy is going to be the next big energy bubble.

    Solar PV is a good deal less environmentally benign than its promoters like to claim—like so many so-called “green” technologies, the environmental damage it causes happens mostly in the trajectory from mining the raw materials to manufacture and deployment, not in day-to-day operation—and the economics of grid-tied solar power are so dubious that in practice, grid-tied PV is a subsidy dumpster rather than a serious energy source. Nonetheless, I expect to see such points brushed aside, airily or angrily as the case may be, as the solar lobby and its wholly-owned subsidiaries in the green movement make an all-out push to sell solar PV as the next big thing.
    http://thearchdruidreport.blogspot.it/2016/01/down-ratholes-of-future.html
    Voting 0
  4. Oxford Photovoltaics is one of many firms, both small and large, that see promise in perovskites. These are compounds that share a crystal structure and are named, collectively, after the mineral that was the first substance found to have this structure. Often, they are semiconductors. This means that, like the most famous semiconductor of all, silicon, they can be used in solar cells.
    In this section

    Crystal clear?
    The X-files
    To sleep, perchance
    The watcher in the water

    Reprints
    Related topics

    Technology
    Science and technology
    Energy technology
    Alternative energy
    Solar energy

    The first perovskite solar cells were made in 2009. They converted 3.8% of the light falling on them into electricity. Now, the best hoover up around 20%. This rate of conversion is similar to the performance of commercial silicon cells, and researchers are confident they can push it to 25% in the next few years.

    Moreover, unlike silicon, perovskites are cheap to turn into cells. To make a silicon cell, you have to slice a 200-micron-thick wafer from a solid block of the element. A perovskite cell can be made by mixing some chemical solutions and pouring the result onto a suitable backing, or by vaporising precursor molecules and letting them condense onto such a backing. If these processes can be commercialised, silicon solar cells will have a serious rival.

    the variations on the photovoltaic theme that most excite researchers at the moment are tandem cells, which have layers of both perovskite and silicon in them. These will permit more of the spectrum to be converted into electricity. Perovskites can be made to many different formulae, which means they can be tuned to absorb different parts of the spectrum. The top layer of a tandem cell is a perovskite that has been tweaked to absorb strongly at the blue end of the spectrum. Beneath it is a layer of silicon, which mops up the red.

    The first such tandem was unveiled in March by researchers from Stanford University and the Massachusetts Institute of Technology. It had an efficiency of 13.7%. This week, Oxford Photovoltaics showed off one that has an efficiency of 20%. It hopes to see its first commercial tandems roll off production lines in 2017. This marriage of convenience between the old and new ways of doing photovoltaics may not, however, last long. Henry Snaith, Oxford Photovoltaics’ founder, looks forward to all-perovskite tandems that have cells of different composition, each tuned to harvest a particular part of the solar spectrum.

    The main obstacle to the march of perovskites is water: they decompose in it. Perovskite solar panels must thus be totally watertight. But technology exists to make effective seals on solar cells. The standard tests for cells, including those for watertightness, are set by a body called the International Electrotechnical Commission. One of these tests requires that cells sustain their performance for more than 1,000 hours at 85°C and 85% humidity. Others put cells through drastic temperature swings, artificial hailstorms and so on. Dr Snaith says that Oxford Photovoltaics’ cells have passed the 1,000 hour test and are well on the way to making 2,000 hours.

    Another way around the problem of a potentially limited lifetime is to find applications where it does not matter. In these, perovskites should do well. Some firms, for example, hope to enter the mobile-device market—reasoning that such devices are usually replaced by their owners every few years and so do not require a long-life cell. Saule Technologies, in Poland, and VTT, in Finland, are experimenting with flexible perovskite cells intended to charge mobiles. Olga Malinkiewicz, Saule’s founder, says that her company has made prototype flexible cells which are 3% efficient, and she thinks its engineers can get to 10% in the next two years. When Saule’s cells are commercialised, she plans to make them using inkjet printers that spray perovskite precursors onto adhesive backings. This will permit the cells to be stuck onto any device
    http://www.economist.com/news/science...r-cells-run-their-money-crystal-clear
    Voting 0
  5. According to these numbers, electricity generated by photovoltaic systems is 15 times less carbon-intensive than electricity generated by a natural gas plant (450 gCO2e/kWh), and at least 30 times less carbon-intensive than electricity generated by a coal plant (+1,000 gCO2e/kWh). The most-cited energy payback times (EPBT) for solar PV systems are between one and two years. It seems that photovoltaic power, around since the 1970s, is finally ready to take over the role of fossil fuels.

    Manufacturing has Moved to China

    Unfortunately, a critical review of the PV solar industry paints a very different picture. Many commenters attribute the plummeting cost of solar PV to more efficient manufacturing processes and scale economies. However, if we look at the graph below, we see that the decline in costs accelerates sharply from 2009 onwards. This acceleration has nothing to do with more efficient manufacturing processes or a technological breakthrough. Instead, it's the consequence of moving almost the entire PV manufacturing industry from western countries to Asian countries, where labour and energy are cheaper and where environmental restrictions are more loose.

    Less than 10 years ago, almost all solar panels were produced in Europe, Japan, and the USA. In 2013, Asia accounted for 87% of global production (up from 85% in 2012), with China producing 67% of the world total (62% in 2012). Europe's share continued to fall, to 9% in 2013 (11% in 2012), while Japan's share remained at 5% and the US share was only 2.6%. 5 »

    Price of silicon solar cells wikipedia

    Compared to Europe, Japan and the USA, the electric grid in China is about twice as carbon-intensive

    At least as important as the place of manufacturing is the place of installation. Almost all LCAs -- including the one that deals with manufacturing in China -- assume a solar insolation of 1,700 kilowatt-hour per square meter per year (kWh/m2/yr), typical of Southern Europe and the southwestern USA. If solar modules manufactured in China are installed in Germany, then the carbon footprint increases to about 120 gCO2e/kWh for both mono- and multi-si -- which makes solar PV only 3.75 times less carbon-intensive than natural gas, not 15 times.
    http://www.lowtechmagazine.com/2015/0...ow-sustainable-is-pv-solar-power.html
    Voting 0
  6. Several new types of battery, each capable of cost-effectively storing the energy output from a wind or solar farm, are finally being hooked up to power grids. The so-called grid batteries could lower the cost of renewable energy by eliminating the intermittency problem that arises when the sun isn’t shining or the wind isn’t blowing.

    On Wednesday, Aquion Energy, a Pittsburgh-based startup that makes one such battery, announced that the technology will allow a small electricity grid in Hawaii to run around the clock on solar power.

    Conventional batteries would be too expensive or unreliable to use for grid-scale storage. The new batteries coming online use materials and manufacturing processes that not only lower costs but should also allow them to last for decades
    http://www.technologyreview.com/news/...s-for-wind-solar-find-first-customers
    Voting 0
  7. The publicized goal of Tesla's "gigafactory" is to make electric cars more affordable. However, that benefit may soon be eclipsed by the gigafactory's impact on roof-top solar power storage costs, putting the business model of utilities in peril. "The mortal threat that ever cheaper on-site renewables pose" comes from systems that include storage, said physicist Amory Lovins. "That is an unregulated product you can buy at Home Depot that leaves the old business model with no place to hide."
    http://www.bloomberg.com/news/2014-12...-utilities-with-fear-and-promise.html
    Voting 0
  8. Renewable energy, by definition, is inexhaustible or, at least, it can tap the sun's energy for times that can be considered infinite from our viewpoint. However, renewable energy doesn't live of sun alone. It needs metals, semiconductors, ceramics and more. A criticism often leveled against renewable energy is that it is not really "renewable" because it uses elements which exist in limited amounts and cannot be recycled.

    The question is complex and it depends on the kind of energy we are considering. For instance, in the case of solar cells, some use exotic and rare materials such as gallium or tellurium. However, the standard version on the market uses almost exclusively silicon and aluminum for the cell. The only rare element in it is silver for the back contact, but it can be eliminated with minimal or no loss. In several other cases of renewable technologies, rare metals are not used or can be efficiently recycled.

    A recent (2014) study on this subject has been performed by the Wuppertal Institute. The conclusion is that the problem of mineral availability for renewable energy technologies is not critical if we choose the right technologies and we are careful to recycle the materials used as much as possible.
    http://cassandralegacy.blogspot.it/20...11/renewable-energy-does-it-need.html
    Tags: , by M. Fioretti (2014-11-23)
    Voting 0
  9. solar energy is already going gangbusters. In the past decade, the amount of solar power produced in the United States has leaped 139,000 percent. A number of factors are behind the boom: Cheaper panels and a raft of local and state incentives, plus a federal tax credit that shaves 30 percent off the cost of upgrading.

    Still, solar is a bit player, providing less than half of 1 percent of the energy produced in the United States. But its potential is massive — it could power the entire country 100 times over.

    So what’s the holdup? A few obstacles: pushback from old-energy diehards, competition with other efficient energy sources, and the challenges of power storage and transmission. But with solar in the Southwest already at “grid parity” — meaning it costs the same or less as electricity from conventional sources — Wall Street is starting to see solar as a sound bet. As a recent Citigroup investment report put it, “Our viewpoint is that solar is here to stay.”
    http://grist.org/climate-energy/ameri...tion&utm_medium=rss&utm_campaign=feed
    Tags: , , , by M. Fioretti (2014-11-09)
    Voting 0
  10. The reason solar-power generation will increasingly dominate: it’s a technology, not a fuel
    http://www.bloomberg.com/news/2014-10...ource=twitter.com&utm_campaign=buffer
    Voting 0

Top of the page

First / Previous / Next / Last / Page 1 of 5 Online Bookmarks of M. Fioretti: Tags: photovoltaic

About - Propulsed by SemanticScuttle