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  • Researchers: “Upconversion” Creates “Super-efficient” Solar Cells

    The work, published in the journal Physical Chemistry Chemical Physics, aims to increase efficiency in crystalline and amorphous silicon solar cells through application of synthesized sensitizer and emitter molecules. Such “single-threshold” materials “produces voltage by promoting electrons above this threshold upon absorption of light,” explained paper co-author Tim Schmidt; photons with energy below that threshold can’t be harvested, and any energy above that threshold is lost through heat, he added.

    Maximum efficiency of single-threshold PV converters is about 30%, the group notes. One proposed way to improve that is to place an upconverting material behind the cell, to convert low subthreshold photons into usable light; such a cell would have an efficiency limit of >50%, though best-recorded efficiency has been ∼ 10 -6. Their work specifically focuses on using “triplet-triplet annihilation” in organic molecules. When two triplet emitter molecules encounter each other, the result is either a singlet, triplet, or quintet spin state; if a singlet (1:9 chance), it converts to a lower energy state and fluoresces, yielding “upconverted” light.

    Applying this “upconversion” method, the group says, results in striking improvements: efficiency limit “under the standard solar spectrum” of over 50%, and up to 63% under 100-fold solar concentration. From the paper abstract:

    Emitter triplet states are produced through triplet energy transfer from sensitizer molecules excited with low energy photons. The triplet emitter molecules undergo triplet-triplet annihilation to yield excited singlet states which emit upconverted fluorescence. Experiments comparing the 560nm prompt fluorescence when rubrene emitter molecules are excited directly, using 525nm laser pulses, to the delayed, upconverted fluorescence when the porphyrin sensitizer molecules are excited with 670nm laser pulses reveal annihilation efficiencies to produce excited singlet emitters in excess of 20%. Conservative measurements reveal a 25% annihilation efficiency, while a direct comparison between the prompt and delayed fluorescence yield suggests a value as high as 33%. Due to fluorescence quenching, the photon upconversion efficiencies are lower, at 16%.


    (Read more from Photovoltaics World at electroIQ.com)

  • The future of oil

     

    Superficially, the so-called “super majors” appear to be in good health. Fortune‘s Global 500 list places the “big six” – Shell, ExxonMobil, BP, Chevron, Total, and ConocoPhillips – among the seven largest corporations in the world, as measured by 2008 revenues. In third place, Wal-Mart stands alone as the only top seven company not dedicated to finding, extracting, processing, distributing and selling the liquid transportation fuels that drive the global economy, although few business models are as dependent on the ready availability of relatively cheap oil.

    Worryingly for such companies, 2008 may prove to have been the high water mark for the global oil industry, with geological, geopolitical and climate-related pressures now creating new market dynamics. The oil question is now, more than ever, a transport question. Cheap and reliable supplies of transportation fuel are the very lifeblood of our globalised economy. So it matters profoundly that we are entering an era in which oil supplies will be neither cheap nor reliable.

    For the likes of Shell, BP, and ExxonMobil, whose rates of liquid hydrocarbon production peaked in 2002, 2005, and 2006 respectively, the current economic paradigm requires them to replace reserves. Investors primarily value IOCs on this basis, as well as their ability to execute projects on time within budget. A key problem for the IOCs is that petroleum-rich countries feel increasingly confident in the ability of their own national oil companies to steward their domestic resources. So generous concessions once offered to IOCs in return for technical and managerial expertise are now deemed unnecessary.

    The imperative to satisfy investor expectations fuels an increasingly risky growth strategy, which drives IOCs towards energy-intensive (and potentially climate-destabilising) unconventional oil substitutes, such as tar sands (in Canada), gas-to-liquids (in Qatar), and coal-to-liquids (in China and elsewhere). These pathways are not chosen as ideals: they are more or less reflexive responses to external market pressures.

    Meanwhile, the uncomfortable fact is that our economies are addicted to liquid hydrocarbon transport fuels, the consumption of which creates a catalogue of negative side effects. And we cannot hope to address this addiction by way of our “dealers” developing even more damaging derivatives of the same drug.

    As if that were not enough, there is the hot topic of “peak oil“, defined as the point at which global oil production reaches a maximum rate, from where it steadily declines. The basic principle is uncontroversial: production of a finite non-renewable resource cannot expand endlessly, and this has been demonstrated in practice at national level all over the world. The heated debate centres on the point at which the peak in global oil production is likely to be reached.

    “Early toppers” argue that the peak has already been passed, and that the world will never produce more than 85 million barrels per day. By contrast, “late toppers” point to the huge scale of unconventional reserves – for example, Alberta’s tar sands resource is vast – that remain untapped, as well as the potential bounty locked away in frontier regions such as the Arctic Ocean, where global warming is opening up new areas for oil and gas exploration.

    Unfortunately, what matters is not the absolute size of these unconventional and frontier resources, but the rate at which they can be developed and brought to market. By definition, this is the “difficult” oil. Production rates are determined by a series of significant financial, social, and environmental constraints that raise grave concerns for the viability of a global economic system made possible by liquid transport fuels.

    At the same time, leaders of all the major economies finally acknowledge what scientists have long been warning: to avoid catastrophic climate-change impacts, the global average surface temperature increase must be limited to 2° Celsius compared with the pre-industrial era. To stand any reasonable chance of avoiding a 2° Celsius rise, our best understanding of the climate change science suggests that global greenhouse-gas emissions must peak within the next five to 10 years, and then decline by more than 80% on 1990 levels by 2050. Realistically, meeting this requirement will demand that we engineer a transition to a zero-carbon energy system by mid-century.

    So what might a zero-carbon energy system look like? As well as dramatic improvements in the energy efficiency of buildings and appliances, and massive deployment of sustainable renewable energy technologies, we will no longer be allowed to burn fossil fuels without capturing and sequestering the carbon dioxide emissions. This implies that we must restrict our use of fossil fuels to stationary facilities, such as power plants, where carbon capture and storage (CCS) is practical (see “Outlook and obstacles for CCS“). Strikingly, a zero-carbon energy system will also mean that no liquid hydrocarbon fuels, with the exception of biofuels, can be consumed in mobile applications such as transport.

    This does not make pleasant reading for international oil companies. Their core business today may be described as: digging geological carbon resources out of the ground, converting those resources into liquid fuels, then marketing those fuels to consumers who set them on fire in internal combustion engines to move around. By 2050, these activities will all be considered to be strikingly primitive.

    SustainAbility and of Volans. His personal website is http://www.johnelkington.com. Gary Kendall is director of SustainAbility’s Energy Sector and Climate Change Programme.

    John Elkington is co-founder of

     

  • UK carbon capture competition ‘dead on its feet ‘says expert

     

    Speaking to BusinessGreen.com, Professor Stuart Hazeldine, a geologist at the University of Edinburgh and leading expert in CCS technologies, said that the Department of Energy and Climate Change (DECC) should close the competition and award the funding to Scottish Power to develop CCS at its Longannet plant in Fife in order to prevent any more time being wasted.

    “Scottish Power are the only people who can deliver by 2014 now,” he said. ” The competition timescale has already slipped and to get it back on track the award needs to be made soon.”

    Back in 2007 the government said it would award the winner of its CCS competition around £1 billion to help fund a commercial scale carbon capture demonstration project.

    The government has said it plans to announce the winner some point next year with three proposals in the running: Longannet, RWE npower’s station at Tilbury in Essex, and E.ON’s plans for a new coal plant at Kingsnorth in Kent.

    “RWE npower are showing a manifest lack of movement on their CCS offerings and E.ON have delayed Kingsnorth plans,” said Hazeldine. “That leaves one obvious winner.”

    He added that the long-running competition had discouraged other firms from coming forward with project proposals. “The UK has such a slow track record on developing CCS that anyone who is able to has gone elsewhere,” he said. “We need to get on with it.”

    The government has now committed to helping fund “up to four” CCS plants in the UK. The first – the competition winner – will be funded by the Treasury, but any further plants will be funded primarily from a levy on energy bills.

    As well as awarding the competition to Scottish power, the government should announce a “feed study” – a detailed engineering evaluation – for CCS at Kingsnorth so that E.ON can install the technology when it likely revives the plant in the second half of this decade, Hazeldine advised.

    Hazeldine first made his controversial recommendations at a Westminster energy forum last month, where Martin Deutz, director of the cleaner fossil fuels unit at DECC, defended the department’s position.

    “It is an active commercial negotiation and I’m not going to say anything about the commercial position of each of the companies,” he said. “But I would say that the negotiations that we have been having with the bidders have thrown up a number of extremely interesting and important issues… they are important issues which have to be dealt with financially, operationally and in regulatory terms.”

  • IEA calls for global push to end energy poverty

     

    Energy firms have no incentive to build power plants or connect remote areas to the grid if people are too poor to pay the bills. “It’s not likely to happen unless there’s a major international concerted effort by rich countries,” Birol said. “We will start to push it on to the main agenda at Copenhagen.”

    Birol will appeal for international support on the issue ahead of the Copenhagen summit when he delivers a speech at the UN in New York on 23 November.

    today, the IEA outlined its annual World Energy Outlook, which forecasts that global oil supplies could increase by more than a fifth from just under 85m barrels a day last year to 105m by 2030.

    The Guardian revealed on the eve of the report’s publication that senior figures within the organisation disagreed with its forecast, believing that it would be impossible for the world to maintain oil supplies even at 90m-95m barrels. They claim that the IEA, under pressure from the US and to prevent panic on global stock markets, is deliberately exaggerating the level of accessible new supplies of oil.

    The IEA responded today by publishing on its website a key chapter from last year’s outlook report detailing how it estimates the decline in the rate of production from the world’s largest oilfields. The information is normally only available to those who buy the entire report for €150 (£134). The agency, which dismissed the Guardian’s report as “groundless”, said it wanted to show the public that its research was independent. Birol said: “We are very proud of our analysis and independence. We have a lot of critics. It’s not possible to make everyone happy.”

    The IEA’s forecast of global oil supplies hitting 105m barrels in 2030 represents its “doomsday” scenario, which, it said, would result in catastrophic global warming and energy supplies becoming increasingly vulnerable to terrorists or accidents. This is based on Copenhagen failing to reach a deal that ensures a higher carbon price, which would make the consumption of fossil fuels such as oil and coal more expensive and encourage the use of low-carbon forms of energy such as renewables and nuclear instead.

    This business-as-usual scenario would leave the west even more dependent on oil from the Middle East, it said. Emissions would soar by more than a third from 2007 levels and global temperatures rise by up to 6C over the next two decades.

    Birol said: “The reason why we showed it is to say this is the way that we are going and we should not go there otherwise there will be an accident in terms of climate change and energy security. We do not want it to happen.”

    The IEA, set up to advise its 28 member countries, said that the alternative scenario would see oil consumption only increase slightly between now and 2030. This is based on countries agreeing at Copenhagen to stabilise the concentration of greenhouse gases in the atmosphere to 450 parts per million. This would give the world a 50% chance of limiting temperature increases to 2C, it said.

    Birol admitted that there was “lots of resistance” to such a “450 scenario”, particularly among Opec nations which stand to lose trillions of dollars in revenue from lower consumption of oil and gas. But he said the global economic downturn provided a “window of opportunity” for the world to take tough action. Many companies and countries had shelved investment in power plants because of the fall in energy demand. “But in the absence of a signal from Copenhagen, in 2010, or 2011, they will be built,” he warned. “If a coal plant is built, it will emit for 50 years.”

    He added that last summer’s record $147 a barrel oil price had “traumatised” many developing countries into looking for less volatile and costly forms of energy. Birol said oil prices, which had since fallen back to about $80, would continue to be volatile and would rise over the long term.

  • Key oil figures were distorted by US pressure, says whistleblower

     

    The allegations raise serious questions about the accuracy of the organisation’s latest World Energy Outlook on oil demand and supply to be published tomorrow – which is used by the British and many other governments to help guide their wider energy and climate change policies.

    ‘There’s suspicion the IEA has been influenced by the US’ Link to this audio

    In particular they question the prediction in the last World Economic Outlook, believed to be repeated again this year, that oil production can be raised from its current level of 83m barrels a day to 105m barrels. External critics have frequently argued that this cannot be substantiated by firm evidence and say the world has already passed its peak in oil production.

    Now the “peak oil” theory is gaining support at the heart of the global energy establishment. “The IEA in 2005 was predicting oil supplies could rise as high as 120m barrels a day by 2030 although it was forced to reduce this gradually to 116m and then 105m last year,” said the IEA source, who was unwilling to be identified for fear of reprisals inside the industry. “The 120m figure always was nonsense but even today’s number is much higher than can be justified and the IEA knows this.

    “Many inside the organisation believe that maintaining oil supplies at even 90m to 95m barrels a day would be impossible but there are fears that panic could spread on the financial markets if the figures were brought down further. And the Americans fear the end of oil supremacy because it would threaten their power over access to oil resources,” he added.

    A second senior IEA source, who has now left but was also unwilling to give his name, said a key rule at the organisation was that it was “imperative not to anger the Americans” but the fact was that there was not as much oil in the world as had been admitted. “We have [already] entered the ‘peak oil’ zone. I think that the situation is really bad,” he added.

    The IEA acknowledges the importance of its own figures, boasting on its website: “The IEA governments and industry from all across the globe have come to rely on the World Energy Outlook to provide a consistent basis on which they can formulate policies and design business plans.”

    The British government, among others, always uses the IEA statistics rather than any of its own to argue that there is little threat to long-term oil supplies.

    The IEA said tonight that peak oil critics had often wrongly questioned the accuracy of its figures. A spokesman said it was unable to comment ahead of the 2009 report being released tomorrow.

    John Hemming, the MP who chairs the all-party parliamentary group on peak oil and gas, said the revelations confirmed his suspicions that the IEA underplayed how quickly the world was running out and this had profound implications for British government energy policy.

    He said he had also been contacted by some IEA officials unhappy with its lack of independent scepticism over predictions. “Reliance on IEA reports has been used to justify claims that oil and gas supplies will not peak before 2030. It is clear now that this will not be the case and the IEA figures cannot be relied on,” said Hemming.

    “This all gives an importance to the Copenhagen [climate change] talks and an urgent need for the UK to move faster towards a more sustainable [lower carbon] economy if it is to avoid severe economic dislocation,” he added.

    The IEA was established in 1974 after the oil crisis in an attempt to try to safeguard energy supplies to the west. The World Energy Outlook is produced annually under the control of the IEA’s chief economist, Fatih Birol, who has defended the projections from earlier outside attack. Peak oil critics have often questioned the IEA figures.

    But now IEA sources who have contacted the Guardian say that Birol has increasingly been facing questions about the figures inside the organisation.

    Matt Simmons, a respected oil industry expert, has long questioned the decline rates and oil statistics provided by Saudi Arabia on its own fields. He has raised questions about whether peak oil is much closer than many have accepted.

    A report by the UK Energy Research Centre (UKERC) last month said worldwide production of conventionally extracted oil could “peak” and go into terminal decline before 2020 – but that the government was not facing up to the risk. Steve Sorrell, chief author of the report, said forecasts suggesting oil production will not peak before 2030 were “at best optimistic and at worst implausible”.

    But as far back as 2004 there have been people making similar warnings. Colin Campbell, a former executive with Total of France told a conference: “If the real [oil reserve] figures were to come out there would be panic on the stock markets … in the end that would suit no one.”

     

  • Space-Based Power System Needed to Solve Earth’s Energy Woes.