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| بدائل الطاقة الكهربائية وطرق أنتاجها وسائل أنتاج الطاقة النظيفة المتجدده والبحث عن الافكار المفيدة أقتصادياً و بيئياً - Alternative - Renewable Energy |
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مستقبل الطاقة على كوكب الأرض العرض و الطلب
سلام عليكم و رحمه الله و بركاته فى المرة السابقة التى حاولت ان اختصر على الكثيرين عشرات الايام من البحث فى مواضيع منتهية من وجهة نظر العلم و لكن يبدو ان هذا لم يعجب البعض لذلك سأتعمد ان انشر بعض محاضرات " علماء الطاقة " حول العالم و سأضع المزيد هنا او فى غير ذلك الى قسم اخر تجنبا للصدامات المملة محاضرة اليوم بعنوان مستقبل الطاقة على كوكب الأرض العرض و الطلب Future World Energy Supply and Demand كتبها سير بروفيسور كريس سميث Prof. Sir.Chris Llewellyn Smith استاذ الفيزياء النظرية بجامعة اوكسفورد رئيس المجلس الاعلى للعلوم بالجامعة نائب رئيس الجمعية الملكية البريطانية القيت المحاضرة المنشورة فى القاهرة 31 مايو 2010 قاعة ايورت الجامعة الامريكية بالقاهرة - الجمهورية المصرية و الأن مع المحاضرة و سأترجمها كلما توفر وقت و ارحب بمساهمة الاخرين فى الترجمة تسهيلا على اخوتنا العرب الان مع المحاضرة Future World Energy Supply and Demand Available energy is the main object at stake in the struggle for existence and the evolution of the world” Ludwig Boltzmann Energy Facts The world uses a lot of energy, very unevenly at a rate of 16 TW. Per person in kW: World – 2.4, USA -10.3, UK – 4.6, China - 2.0, Egypt – 1.2, Bangladesh - 0.21 Note: electricity production only accounts for ~ 1/3 of primary energy use, but this fraction can/will rise World energy use expected to increase ~ 40% by 2030 Increase needed to lift billions out of poverty in the developing world 80% of the world’s primary energy is generated by burning fossil fuels (oil, coal, gas) which is causing potentially catastrophic climate change, and horrendous pollution unsustainable as they won’t last forever Will elaborate on developing world and sources of energy, then ask: What are the time scales to prepare for the end of fossil fuels, and for actions to avoid climate change? What actions can/should we take? 1.6 billion people (~ 25% of the world’s population) lack electricity:  There will have to be a change of expectations in both the developing and the developed world For world energy use per person to become the same as in The USA - total world energy use would have to increase by a factor of 4.3 (5.9 when world population reaches 9 billion) The UK - total world energy use would have to increase by a factor of 1.9 (2.6 when world population reaches 9 billion) This is not possible Sources of Energy World’s primary energy supply: Approximate thermal equivalent: 81.4% - fossil fuels* 77.5% 9.8% - combustible renewables and waste 9.3% 5.9% - nuclear 5.6% 2.2% - hydro 6.3% 0.7% - geothermal, solar, wind, . 1.3% * 42% oil, 33% coal, 26% natural gas Note: energy mix very varied, e.g. In Egypt: Gas* – 46.4%, Oil – 48.3%, hydro – 1.9%, Combustible etc – 2.1% * this is 70% of production; 30% is exported In China: Coal → 64% of primary energy; gas – only 3% This is (part of) the explanation for the very large number of premature deaths caused by air pollution in China. Annual figures (WHO 2007):
Globally - 2 million deaths, China 650,000, India - 530,000, USA - 41,000 |
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Timescale for the end of fossil fuels Saudi saying: “My father rode a camel. I drive a car. My son flies a plane. His son will ride a camel”. Is this true? Maybe: Oil will be largely exhausted in 50 years UKERC review - peak in production of conventional oil is ‘likely to occur before 2030’; ‘significant risk’ that it will occur before 2020. Production will then fall ~ 3% (?) p.a. ‘Unconventional’ oil (heavy oil, oil shale, tar sands): Could add ~ 50% to conventional oil resources, but extraction → huge environmental damage, uses energy & produces CO2, needs a lot of water for oil shale & tar sands, and is slow Timescale for the end of fossil fuels (cont) Gas – conventional gas estimated to last ~ 130 years with current use (73 years with [IEA] 1.5% growth), but recent huge expansion in prospects for unconventional gas (shale gas, tight gas, coalbed methane) adds ~ 130 years (not including methyl hydrates) Coal – often said “enough for over 200 years” (true?) but that is with current use; with 1.9% p.a. growth [IEA] this becomes ~ 115 years Note: growth in gas and coal will increase as oil become scarce Need to start preparing for the post oil era now, and thinking about the post fossil fuel era  Fossil Fuel Use
- a brief episode in the world’s history |
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Timescale to avoid climate change CO2 stays in the atmosphere for hundreds of years We should have taken action yesterday! Likely that most of the remaining fossil fuels will be burned in ~ 100 years, in which case the only action that can help is Carbon Capture and Storage*  *capture and burial of CO2 from power stations and large industrial plants which should be developed as a matter of urgency and (if feasible) rolled out on the largest possible scale (easy to say, but harder to do as it will put up the cost) Necessary Actions in Preparation for the End of the Fossil Fuel Era Reduction of energy use/efficiency - can reduce the growth in world energy use, and save a lot of money, but unlikely to reduce total use, assuming continued rising in living standards in the developing world Develop and expand low carbon energy sources need everything we can sensibly get, but without major contributions from solar and/or nuclear (fission and/or fusion) it will not be possible to replace fossil fuels without a huge drop in energy use Devise economic tools and ensure the political will to make this happen The above steps also crucial for tackling climate change, for which carbon capture and storage is also vital Use of Energy End Use (rounded)
25% industry 25% transport 50% built environment 30% domestic in UK (private, industrial, commercial) Energy Efficiency Three slides on buildings and transport - substantial gains possible elsewhere, e.g. raise world average thermal power plant efficiency from ~ 30% to 45% (state of the art), smart/interactive grid Huge scope and some progress (energy intensity = energy/gdp fell 1.6% pa 1990-2004) but demand is rising faster Efficiency is a key component of the solution, but cannot meet the energy challenge on its own |
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The Built Environment Consumes ~ 50% of energy Improvements in design could have a big impact e.g. could cut energy used to heat homes by up to factor of three (but turn-over of housing stock ~ 100 years) Lighting ~ 19% of all electricity world-wide Better use of natural light; reduce ‘over-lighting’; more efficient bulbs: - traditional incandescent bulbs ~ 5% efficient compact fluorescent lights ~ 20% efficient in longer term : LEDs (up to 50% efficient) Detailed US study: upgrading residential incandescent bulbs and ballasts and lamps in commercial buildings could save = 3% of all electricity use Tools: better information, regulation  Source: Foster and Partners. Swiss Re Tower uses 50% less energy than a conventional office building (natural ventilation & lighting TRANSPORT ~ 25% of primary energy IEA thinks 900 million vehicles today (700 m light vehicles) will grow to ~ 2,100 million in 2031 → huge increase in energy use, and CO2, unless much greater efficiency, and/or other fuels Big increases (~ 50%) in efficiency of cars powered by Internal Combustion Engines possible, but can do better: electric fuel cells* > electric batteries*> (plug in) hybrids > ICE * will be needed ( + bio-fuels) when oil is not available/scarce, although expect oil age to be prolonged by using coal & gas → oil But pro petrol: energy/volume and energy/mass Hydrogen fuel cell vehicles ‘unlikely to be more than a niche product without breakthroughs’ – methanol would be better Hydrogen excites public and politicians - no CO2 at point of use, but only helpful if no CO2 at point of production Regulation has a key role to play:  Improvements: front wheel drive, engine, transmission, computer control….. Note: US gallons (1 imperial gallon = 1.2 US gallons)  1975 – 1985 mandatory Corporate Average Fuel Economy standards improved annually, but thereafter manufactures continued to improve efficiency but built heavier, more powerful cars:
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Low Carbon Energy Sources What can replace the 13TW (and growing) from fossil fuels? Maximum practical additional potentials (thermal equivalent): Wind 3TW*, geothermal 100GW, hydro 2TW, bio 1TW, marine 100GW which add up to less than 7 TW * Stanford claim can in principle get 72TWe We should expand them as much as we reasonably can (easy to say, but harder to do as it will put up the cost), but the world will need something else, which can only be: Solar and/or Nuclear (fission or fusion) Conclusions are very location dependent: geothermal is a major player in Iceland, Kenya,…; the UK has 40% of Europe’s wind potential and is well placed for tidal and waves; the US south west is much better than the UK for solar; there is big hydro potential in the Congo;… Solar Potential Average* flux of 170 Wm-2 on 0.5% of the world’s land surface (50% occupied) would, with 15% efficiency, provide 19 TW (equivalent to much more primary energy) *220 Wm-2 at equator, 110 Wm-2 at 50 degrees north Photovoltaics are readily available with 15% efficiency or more, and concentrated solar power can be significantly more efficient Photosynthesis: Natural: even sugar cane is only 1% efficient at producing energy: wood ~ 1/6th efficiency of sugar cane Bio-fuels (2005) used 1% of agricultural land → 1% of road transport Artificial: exciting possibility of mimicking photosynthesis in an artificial catalytic system to produce hydrogen (to power fuel cells), with efficiency of possibly 10% (and no: wasted water, fertiliser, harvesting) – should be developed Solar (non-bio) Photovoltaics (hydrogen storage?) - cost needs to come down Concentration (parabolic troughs, heliostats, towers) → turbines (storage: molten salts,….) High T→ improved electrolysis (or even ‘thermal cracking’ of water to hydrogen? Challenges: new materials, fatigue…) Problem – cooling water   
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Nuclear Should be expanded dramatically now New generation of reactors Fewer components, passive safety, less waste, more proliferation resistant, lower down time and lower costs Several options - AP1000, EPR, CANDU, ESBWR,… Looking to the future, need to consider Problems and limitations (snails pace of planning permission in some countries, safety, waste, proliferation, uranium resources) Options (Different fuel cycles, Uranium/plutonium fast breeders, Thorium reactors, Fusion) Problems and limitations Safety – biggest problem is perception Modern 1 GW coal power station with W European population density causes ~ 300 premature deaths (~ 10 years loss of life) per year → 9,000 in 30 years: more than Chernobyl Waste – problem is volume for long term disposal US figures: Existing fleet will → 100,000 tonnes (c/f legislated capacity of Yucca mountain = 70,000 tonnes) If fleet expanded by 1.8% p.a. → 1,400,000 tonnes at end of century Proliferation – need to limit availability of enrichment technology, and burn or contaminate fissile products Uranium resources, including uranium in phosphates (said to be economically recoverable as a by-product of producing phosphoric acid): 38 Mt  (NEA, “Red Book” 2005 and 2007) 38 Mt in (current) conventional reactors at present rate of use would last 475 years (without phosphates: 16Mt → 200 years) If nuclear increased six fold, to ~100% of current world electricity production, 38 Mt would be enough for 80 years ( but 16Mt only enough for 33 years) Conclusion: if there is a big expansion of fission, will have to develop fast breeder reactors* seriously relatively soon (it takes ~ 12 years for 1 FBR to make enough fuel for a second) * which produce ~ 60 times more energy/kg, making much more U economic (even U in sea water?) or turn to thorium (doubling time ~30 years) but it’s not yet urgent Different Fuel Cycles Goals Reduce waste needing long-term disposal (destroy: [99.5+%?] of transuranics, and heat producing fission products [caesium, strontium]) Destroy or ‘contaminate’ weapons-usable material Get more energy/(kg of uranium) Options (some gains possible from improved burn-up in once through reactors; as in all thermal power plants, higher temperature → more energy/kg of fuel) Recycle in conventional reactors – can get ~2 times energy/kg + reduce waste volume by factor 2 or 3 (note: increase proliferation risk + short-term risk from waste streams) Fast Breeder Reactors Thorium Mixed economy: conventional reactors + burn waste by having some Fast Breeder or Thorium reactors, or Accelerator Driven waste burners Plutonium Fast Breeders In natural uranium, only 235U (0.7%) is fissile, but fast neutrons can turn the other 99.3% into fissile Plutonium: 238U + n → 239Np → 239Pu fertile fissile order 60 times more energy/kg of U far less waste, and can burn waste from conventional reactors Potential problems more expensive not quite so safe large plutonium inventory/potential for proliferation slow ramp up (1 reactor→ 2 takes ~ 12 years) Thorium Can burn 100% of thorium, which is much more abundant than 235Uranium*, and generates much less waste, using 232Th + n → 233Th → 232Pa → 233U fertile fissile * Accessible 232Th resource seems (??) to be over 4 Mt, vs. 0.1 Mt for 235U (if total accessible U resource is 16 Mt) To get started, need Pu or highly enriched U core (→ large number of neutrons) or neutrons from accelerator driven spallation source** Relatively rapid ramp up but doubling time ~ 30 years ** avoids having a near critical system, but economics suggest AD system’s best potential is for actinide burning FUSION powers the sun and stars and a controlled ‘magnetic confinement’ fusion experiment at the Joint European Torus (JET) (in the UK) has produced 16 MW of fusion power so it works   JET The big question is - when will it work reliably and economically, on the scale of a power station? FUSION D + T → He + n + 17.6 MeV Tritium from n + Li → He + T - raw fuels lithium, very abundant, and water (→ D) The lithium in one laptop battery + half a bath of water would produce 200,000 kW-hours of electricity = EU per-capita electricity production for 30 years → essentially unlimited fuel, no CO2 or air pollution, intrinsic safety, no radioactive ash or long-lived nuclear waste (walls become activated but with right choice of materials can recycle in ~ 100 years), cost will be reasonable if we can get it to work reliably sufficient reasons to develop fusion as a matter of urgency Problem: it is not (yet?) available Now focus on magnetic confinement (inertial fusion should also be pursued, but is a generation behind, and faces additional challenges) A Fusion Power plant would be like a conventional one, but with a different fuel and furnace:  Challenges:
i) Heat ~2000 m3 D-T plasma to over 100 M 0C, while keeping it from touching the walls ii) Make a robust container able to withstand huge neutron bombardment iii) Ensure reliability of very complex systems The ‘blanket’ captures energetic neutrons produced in the fusion process, which: - react with lithium in the blanket to produce Tritium ( fuel the reactor) deposit their energy heat which is extracted through a cooling circuit and used to boil water and produce steam to drive a generator Cannot demonstrate on a small scale: (power out)/(power to operate) grows faster than (size of fusion device)2 - one reason why development so slow |
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Progress in Fusion has been enormous, but even JET (currently the world’s leading fusion research facility) is not large enough to be a (net) source of power  JET: Volume ~100 m3 Temperature ~ 150 M 0C World record (16 MW) for fusion power (1997  T3: Volume ~1 m3 Temperature ~ 3 M 0C Established tokamak as best configuration (1969) ITER  Aim - demonstrate integrated physics and engineering on the scale of a power station Key ITER technologies fabricated and tested by industry Construction beginning at Cadarache in southern France. Over 5 Billion Euros construction cost Partners house over half the world’s population  FUSION ‘FAST TRACK’ Time table for building first Demonstrator/Prototype Power Plant (‘DEMO’), assuming adequate funding, and no major adverse surprises: Build ITER ~ 10 years Operate and gain sufficient experience from ITER ~ 10 years In parallel: intensified materials work (approve and build IFMIF as soon as possible) and development of fusion technologies (magnets, remote handling, heating systems, fuel cycle, safety,…), and design work on DEMO Start building DEMO in ~ 20 years Power from DEMO to the grid in ~ 30 years ‘Commercial’ fusion power ~ middle of the century Could what is available add up to a ‘solution’? Known technologies could in principle meet demand with constrained CO2 (but > 500 ppm inevitable?) until the middle of the century but it will be very difficult (much harder than implied by the IEA’s 2010 World Energy Outlook) and will only be possible with - technology development, e.g. for carbon capture and storage - essential - increased efficiency: most obvious steps save money (see next slide) why’s it not happening? - all known low carbon sources pushed to the limit (including much more nuclear) - public willingness to pay more before the lights to out in order to reduce CO2 and prevent lights going out, and/or political will globally to force the public to do so → cost up through Carbon tax (best) or credits (more likely) + strong regulations  Final Conclusions Huge increase in energy use expected; large increase needed to lift world out of poverty Challenge of meeting demand in an environmentally responsible manner is enormous No silver bullet - need a portfolio approach Need all sensible measures: more wind, hydro, biofuels, marine, and particularly: CCS (essential to reduce climate change) and increased efficiency, and in longer term: more solar and nuclear fission, and fusion [we hope] Huge R&D agenda - needs more resources (to be judged on the ~ $5 trillion p.a. scale of the world energy market) Need fiscal incentives - carbon price, regulation Political will (globally) - targets no use on their own The time for action is now Malthusian “solution” if we fail? الى هنا نقلت كما اوتيت الى لقاء اخر فى ترجمة هذا المقال للأخوة العرب و سأضع مواضيع و محاضرات جديدة اذا تغير الاسلوب كما ذكرت سابقا و اكررها للمرة المليون انا لا احارب احد و لكنى اتحدث من منطلق من عمل بهذا المجال و يرفض انتشار الخرافة تحت اى مسمى كان |
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بسم الله
التعديل الأخير تم بواسطة : s.sultan بتاريخ 20-08-2012 الساعة 08:43 AM |
