|By Chris Nelder | December 12, 2012, 3:00 AM PST
For complete article: http://www.smartplanet.com/blog/take/coming-soon-100-renewable-power/296?tag=content;siu-container
Photo: BrightSource’s 377 MW Ivanpah solar project, the world’s largest solar thermal plant, now under construction in California’s Mojave Desert. Image from Brightsource.
One day in the not-too-distant future — probably sooner than many expect — some parts of the world will have power grids that are completely powered by renewables. Eventually, the entire world could be powered by renewables.
These are not green pie-in-the-sky fantasies, but the conclusions of recent research.
There is no doubt that renewable resources are positively vast. Solar alone could power the world: The solar energy that falls on the Earth every minute is more than the amount of fossil fuel the world uses every year. Wind alone could provide about 15 times the world’s energy demand. The recoverable geothermal heat under the U.S. is about 140,000 times its annual energy consumption. Wave power alone could supply twice as much electricity as the world consumes.
Capturing that energy, and being able to use it to power everything, is the hard part.
Probably the most ambitious attempt to quantify that challenge to date has been done by Mark Jacobson and Mark Delucchi of Stanford University, who have published a series of papers over the past several years outlining how it could be done. In 2010, they published two papers (Part Iand Part II) estimating how the world’s energy demand for all purposes — including electric power, transportation, heating and cooling — could be met with renewables by 2030, and replace the existing energy generation mix by 2050:
(A quick word on units: A kilowatt, or kW, is 1000 watts. A megawatt, or MW, is 1000 kW. A gigawatt, or GW, is 1000 MW.)
A real-world model
A new paper from researchers at the University of Delaware attempts to answer these questions. They developed a model of how the PJM Interconnection (the RTO that coordinates the movement of wholesale electricity in all or parts of Delaware, Illinois, Indiana, Kentucky, Maryland, Michigan, New Jersey, North Carolina, Ohio, Pennsylvania, Tennessee, Virginia, West Virginia and the District of Columbia), constituting one-fifth of U.S. electric power demand, could be met using only wind, solar, and storage.
Some of these numbers may seem impractically large at first blush, but they’re useful for imagining what the system might look like, and they’re feasible. A real-world generation mix would involve fewer and larger generators, including offshore wind turbines twice as large, larger onshore turbines, and commercial rooftop solar systems up to 500 kW in size, like those installed on Ikea and Walmart buildings over the past two years.
Several remarkable conclusions emerged from the Delaware study.
Briefly, let’s review.
Extract from : www.theconversation.edu.au
As a consultant, Colin Hunt prepared the assessments of fisheries for the Australian Marine Conservation Society’s Australia’s Sustainable Seafood Guide. The Conversation provides independent analysis and commentary from academics and researchers.
We are funded by CSIRO, Melbourne, Monash, RMIT, UTS, UWA, Canberra, CDU, Deakin, Flinders, Griffith, La Trobe, Murdoch, QUT, Swinburne, UniSA, UTAS, UWS and VU.
Photo: Courtesy of Sea Bounty, Portarlington
The report, Status of Key Australian Fish Stocks 2012 is the first official report combining assessments of major Commonwealth and state-managed fisheries into one document. The report paints a rosy picture. Of the 150 fish stocks assessed only two are found to be overfished.
How should consumers respond to this finding?
In the case of southern bluefin, the fattened fish are sent to Japan, so the Australian consumer is not faced with a decision. The inference is that only school shark, whose stock is fished to a very low level, is of concern. When we go to the market, they’re suggesting, we really don’t need to worry – all the other Aussie fresh fish on offer is sustainable.
Analysis reveals anomalies
A deeper reading of the report throws up some concerns. There are underlying issues with 52 of the 150 stocks assessed. The descriptions of stock status have become very sophisticated in the report. For example “transitional depleting stock” is code for a stock subject to overfishing, and this affects three stocks.
“Transitional recovery stocks” is actually an overfished stock, affecting eight stocks. There are also 25 stocks “undefined”, on which the report fails to express an informed opinion that would help the buyer.
Pink snapper (Pagrus auratus) is a rather worrying classification in point. This is a very popular fish with consumers and with recreational fishers, who take the bulk of the catch. Heavily fished virtually everywhere it occurs and vulnerable to over-exploitation, snapper stocks are generally recognised as precarious. In fact, in state assessments in Queensland, NSW and WA (Shark Bay and West Coast) the stock of pink snapper has been officially classified as overfished. In Victoria, stocks are officially in decline and in SA uncertain.
However, the report asserts that snapper in Queensland, New South Wales and Victoria is “undefined”, while in WA it is in “transitional recovery”.
The treatment of the popular southern crayfish (SA, Victoria and Tasmania) is also debatable. The report’s assessment is “sustainable”. But catch rates in the fishery have been in steep decline and stocks have been depleted to a quarter of the previous levels, as acknowledged by the report itself.
The report says the cuts in catch quotas appear to have been successful in generating greater abundance of stock (author’s emphasis). However, lobster egg production as a percentage of virgin egg production suggests extreme caution (see chart).
An objective assessment should surely conclude that the fishery will need a long recovery period before it can be confidently classified as sustainable.
Consumers’ needs for information
While the report assesses Australian fish stocks with the greatest value and volume there are some notable absences. For example, not included are popular east coast fish jackass morwong, officially overfished; gemfish, subject to overfishing, and blue warehou, officially overfished and subject to overfishing in ABARES’ Fishery Status Reports of 2011. The same applies to the popular garfish in SA and Victoria: both were overfished in state assessments.
The consumer is helped to a limited extent by the classification of major Australian wild fisheries. At a local level, retail outlets carry many fish not covered in the report. Some of these would be locally caught and some raised in ponds or pens. But most of the fish on offer is imported – we now consume more cheap imports than we do domestic fish. Moreover, sales of canned fish are high – take a look at the overwhelming choice in the supermarket. But again the report is no help.
Apart from the sustainability of fish per se, consumers are becoming more aware of the bycatch and environmental problems associated with fishing. The recent banning of the super trawler Abel Tasman, largely because of seal mortality, is an example of the importance the public attaches to bycatch issues once it is informed.
The South East Trawl Fishery, responsible for much of the nation’s “sustainable” fish – blue grenadier, flathead and silver warehou – is notorious for its bycatch. Many more seals die in the nets of the 35 small trawlers than would have been killed by the Abel Tasman.
Again, prawns are listed as “sustainable”, but the level of bycatch is an issue. In Australian prawn fisheries between 300 and 500 other species are commonly trawled along with the prawns; and most bycatch is returned to the ocean dead.
On visiting the fish and chip shop this Friday, differentiating between the overfished school shark and other “sustainable” shark sold as flake will be a challenge. I am sure consumers would be interested to know that in the Great Barrier Reef World Heritage Area many thousands of 40 species of these top predators, which are in serious decline globally, are caught in nets every year.
The sanctioned shark catch includes some 2000 scalloped hammerhead, which is listed as endangered world-wide by the International Union for the Conservation of Nature.
Many consumers would also have qualms about buying Atlantic salmon if appraised of its problems. Fish pens are taking up a large proportion of some formerly pristine Tasmanian estuaries. Furthermore, there are ethical considerations – that some take seriously – over confining such predators at high concentrations.
An ecological assessment of key fisheries by the report’s authors is said to be two years away. Meanwhile, consumers would do well to consult the guides available from non-government organisations before they go shopping or, while they are shopping, using the apps available for smart phones. These cover the sustainability of imports, aquaculture and canned fish, while providing information on bycatch and the environmental effects of fishing.