Den globala energiproduktionen och dess konsekvenser för jordens klimat på längre sikt Lennart Bengtsson University Reading och Uppsala ISSI, Bern Medlem av KVA 1
Hur säkert kan vi bedöma framtiden? Låt oss försöka titta fram till år 2050 Vad visste vi om 2013 år 1976? Vissa förhållanden kan extrapoleras, andra är överraskningar som Internet, smarta mobiltelefoner, billiga superdatorer osv. För att inte tala om politiska ändringar som sovjetsystemets sammanbrott, Tysklands återförening, den kinesiska utvecklingen etc. Vad kan vi extrapolera idag och vad kommer att bli fullständiga överraskningar 2050? Rent allmänt är energiproduktionen konservativ mycket på grund av omfattande kostnader för investeringar och den långa tid de tar att genomföra. 2
Några grundläggande villkor Jordens befolkning kommer att öka till mellan 9 och 10 miljarder Bara att förse alla med näringsrik mat kräver omfattande mängder energi. (Idag har vi ca 5*x2500 Kcal/dag/person =5000 KWh/år. För 10 miljarder människor är detta lika med ca 50 000 TWh/år) Det stora flertalet vill få ett bättre liv vilket knappast kan klaras utan mer energi Tidigare framsteg på vår jord har berott pa att vi förnuftigt kunnat utnyttja resultaten av den vetenskapliga utvecklingen * 5 är en allmän multiplikationsfaktor som är en följd av energibehov för djuruppfödning mm 3
The likely scenario: ~ 9 Billions in 2040 2040 Credit: H Bruhns
Möjliga ändringar till 2050 Senaste framstegen inom fusionsforskningen är lovande och finns den politiska viljan kommer vi sannolikt att ha de första operativa fusionskraftverken Nya fissionsbaserade kraftverk kommer säkert att finnas i stor omfattning men sannolikt främst i Asien I Sverige och Europa är det svårt att föreställa sig radikala ändringar såvida inte detta kommer att drivas fram av omfattande sociala och politiska krafter 5
Jordens energibehov och möjligheter att lösa detta Förekommande energi och effekt-begrepp Vilka är behoven och vilka är möjligheterna? Hur mycket energi kan vi få från den förnybara energin? Vilka möjligheter har kärnkraften? Vad blir konsekvenserna av ett fortsatt användande av fossil energi? 6
Energienheter i enheter av 1000: Kilo, Mega, Giga, Tera, Peta, Exa 1 Kalori = 4.187 Joule (J) (värmer upp 1g vatten 1 C) (för att klara detta på 1 sekund krävs en effekt på ca 4 Watt (W). 1 W kan också lyfta 1 kg ca 1 dm på 1 sekund) och 1 GW lyfter 9 Gton 1 m på 1 dygn. 1 Kilokalori = 4.187 kj = 0.00116 KWh 1 Kilowattimme (KWh) = 3.6 MJ = 862 (kilo)kalorier 1 MWh = 1000 KWh; 1 GWh = 1000 MWh 1 TWh = 1000 GWh; 1 PWh = 1000 TWh = 3.6 XJ 7
Vilka är energikällorna? A. Residuals of solar radiation (fusion energy) Fossil fuels: peat, coal, oil, natural gas Non-fossil fuel: direct solar radiation, wind, hydro energy, biomass, ocean currents, waves B. Residuals of Earth energy (fission energy) Geothermal energy Radioactive material uranium, thorium etc. C. Tidal energy, using the energy of slowing down the Earth s rotation (planetary energy) 8
The following is required to produce 1 PWh 2010: (Sweden produced 0.60 PWh) (US 25.78 PWh and China 28.11 PWh) 90 Mton oil 140 Mton coal 95 Gm 3 natural gas 9000 km 2 solar panels ( rad. cond. typical of US) 150 000 wind generators ( 3MW capacity, 25% efficiency) 330 Mton biomass ( ca 40% water content) (0.5-1.5K/m 2, larger figure requires supply of reactive N) will require 800,000 km 2 land area. 6 Kton natural uranium (0.7% enrichment) 9
Energy production in 1973 (left) and 2010(right) Total 71 PWh Total 148 PWh Fossil 86.6% Nuclear 0.9% Hydro 1.8% Combustion, waste 10.6% Fossil 81.1% Nuclear 5.7% Hydro 2.3% Combustion, waste 10.1% Others, wind solar etc.) 0.1% Others 0.9% 10
Energitillförsel och Elproduktion i Sverige, EU-27 och Världen 2011 ( uppgifter: Eurostat och IEA) Område Energitillförsel % Fossil % El El-prod. % Fossil %Förny. % Kärn Sverige 600 TWh EU-27 20 000 TWh Världen 150 000 TWh 36 % 25 % 150 TWh 76 % 17 % 3 300 TWh 81 % 15 % 22 000 TWh 3 % 52 % 45 % 53 % 19 % 28 % 67 % 20 % 13 % Credit: Sven Kullander 11
The Global energy dilemma Why is so? The primary objective in developing countries is to improve living conditions. This requires more energy in suitable form, mainly in the form of electricity. Present available energy is insufficient. The inertia/complexity of energy producing systems favors the use of fossil fuel. Most renewable energies have inherent limitations. The public (and media) are generally against nuclear energy. The continued and increasing use of fossil fuel effects climate and have other negative environmental effects. 12
US Energy production per capita for some selected countries in 2010. Unit: MWh/year (Global average 20 MWh/year) Global total 148 PWh (Canada) China (Chinese Taipei) 83 (86) 21 (55) Sweden 64 Norway (Iceland) 75 Singapore 75 (196) Eritrea 1.6 13
Renewable energy sources Solar energy Direct solar energy ( electricity generation using photovoltaic solar cells) have generally conversion efficiency 10-20% (Weisz, 2004). ( present record, 2011 is ca 43%) Considering energy losses in transformers, power-equalization over time and efficiency losses for conversion or transmission would require and area of 9000 km 2 to generate 1 PWh/year using radiation conditions typical of US. 14
Renewable energy sources Wind energy The atmosphere is a very inefficient engine and only some 1% is converted to work (wind). Average energy density is 3 W/m 2. Modern wind turbines can produce about 800 KWh/m 2 /year in good locations (Hill, 2002). Scaling this up means that we need 150 000 wind generators of 3 MW capacity to generate 1 PWh/year electric energy Transition of energy into hydrogen gas or transmission losses might well double this figure. Special problems are related to the large variability in production due to the weather. Present projections indicate a contribution of some 6-10 PWh by 2030. Main limitations are the low energy density and high time variability. 15
Svensk vindkraftproduktion i timvärden för 2009 års 8760 timmar 16
Renewable energy sources Biomass-energy 60 Gton carbon is produced annually of which some 25% may be in a form suitable for energy production. Modern agriculture can generate 1-1.5 Kton/km 2 but will require supply of reactive nitrogen. More realistic figure is 0.5 Kton/km 2. 1 PWh will thus require 7-800 000 km 2 Assuming that 25-40 % of the vegetated land area of 80 Mkm 2 can be used then a primary production of 25-40 PWh/year could be achieved Present global use together with waste (fossil fuel derivatives) amounts to some 14 PWh 17
Renewable energy sources Hydro energy Hydro-electricity provides presently 2.7 PWh/year or some 2% of the total energy ( but some 16% of the electricity). Hydro electricity is totally limited and even the use of every drop of rain falling on land is actually less that the present TPES! ( first calculated by H Hertz in 1885) Feasible extraction is probably at most 5-7 PWh/year 18
Renewable energy sources Additional sources Tidal energy It is estimate that 3000 GW is available but only some 2% ( 60 GW or 0.125 PWh/year) can potentially be recovered from the tides. Total contribution is likely to be less than 1 PWh/year Geothermal energy Here there are huge potential possibilities but large practical problems as very high investments are needed to explore the heat at great depth. Present projections until 2030 will hardly come above 1 PWh/year 19
Maximum physically possible renewable energies,wm -2 Present use and future potential increase Energies global mean Wm -2 Maximum possible Present use In Wm -2 Potential increase in 2050 Solar 160 0.00005 0.0100 (200) Wind 3 0.00012 0.0050 (40) Bio 0.04 (0.25) 0.00314 0.0090 (3) Hydro 0.03 0.00061 0.0018 (3) Tidal 0.01 0.00001 0.0002 (20) Geo 0.09 0.00002 0.0002 (10) Global prod. 0.00395 0.0336(now) 0.0262 (7) 20
Maximum physically possible energies,wm -2 Present use and future potential increase Energies global mean Wm -2 Present use(pwh)/a Solar 160 0.2 40 Wind 3 0.5 20 Bio 0.04 14 40 Hydro 0.03 3 9 Tidal 0.01 0.02 0.5 Geo 0.09 0.05 0.5 Global prod. 0.034 (now) 17.8 150 PWh/a Estimated increase to (PWh)/a 110 21
What are the consequences? Renewable energies are insufficient with the exception of a massive use of solar energy in regions like Sahara etc. Nuclear energy can in principle do it but requires a very long lead time due to both political and technical problems The consequence is that fossil energy will continue to be used at least well beyond 2050. 22
Annual CO 2 emission in Mton (Global emission: 30326 Mton in 2010) Country 2002 2010 Increase Decrease Est 2012 China 3271 7270 +122% 8000-8400 US 5652 5369-5.1 % 5200-5400 Sweden 50.12 47.57-5.1 % ca 45 Denmark 51.17 47.02-8.1 % ca 45 Norway 33.06 39.17 +18.5 % ca 40 23
May 2013: 400.1 ppm 1960-70: + 10 ppm 2000-10: + 20 ppm 24
Radiation effect from human greenhouse gas emission 1979-2009 Watt/m 2 2011: 2.81 Watt/m 2 Kyoto agreement CO2 CH4 25
HadCrut3 temperature and NOAA/RCP forcing 26
Global surface temperature response Credit: M Lockwood ENSO events Volcanic effects Solar radiation Greenhouse gases 27
How will the climate system responds to a further increase of greenhouse gases? A continued increase of the temperature at the surface A cooling of the lower stratosphere More water vapor in the atmosphere (+ 6-7% för + 1 C) Gradual change in the precipitation zones Increased precipitation contrasts (more precipitation in rainy areas and less in the dry). ( north of 60 N + 20-30% more precipitation towards the end of this century). More extrem precipitation. Slowly raising sea level ( now + 3 mm/år) mainly from melting glaciers. Is expected to gradually increase. 28
IPCC projections of the surface temperature changes for two decades of the 21st century ( compared to the end of the last century) 29
Changes in the hydrological cycle 30
Changed hydro production in Sweden in a warmer climate. Credit: SMHI (S. Bergström) Increased precipitation. More generation during winter due to more rain Estimated increase by 5-20 TWh/year at the end of 21 st century More energy available when the need is largest 31
The facts and the questions To provide decent living conditions for all similar to in the industrial world, we would require at least 40 MWh/year/person. Most societies are expected to give priority to this. In 2050 with some 9 billion people this will require an annual energy production of 360 PWh or more than twice the present. How can this be produced? What are the consequences if we fail to deliver? What are the environmental consequences? 32
What will happen if we fail? Fossil fuel could be insufficient or prohibitively expensive around 2050. This might well generate severe political and military tensions Lack of energy will probably be considered as more severe than the environmental consequences (affluent societies might here have a different view). The inherent global limitation of renewable energies is a serious problem. The low density and its variability in time is a severely underestimated problem. Here the devil lies in the details. To believe that renewable energies should satisfy the energy needs of the future is, I am afraid, wishful thinking. 33
What needs to be done I believe serious efforts must be invested to explore new more efficient and safer ways to use fission energy for energy production. This must include a major effort to inform and educate the public and to increase scientific knowledge on all levels in society. To enhance research on fusion energy. Here we need a Manhattan type project. 34
SLUT Tack för uppmärksamheten! 35