PERGAMON Renewable Energy 16 (1999) 899-903

Means to Reduce CO2 - Emissions in the Chinese Electricity System,

with Special Consideration to Wind Energy

Author: Thomas Ackermann. e-mail: t.acketmann@rl.cri.nz or 101547.2060~compusenr.com

Wind Energy Group. Technical University Berlin. German! Now: Royal Institute of Technology; Dept. of Engineeting -Electric Power Systems

Teknikringen 33, 10014 Stockholm. Sweden

Abstract: This paper analyses the technicol possibilities which exist to ovoid (I large increase 01 carbon dioxide emissions produced by electricity generation in China.

The paper evaluates tifferettt technical means such 0s wind energy solar energy (thermal and PT7.

hydra energy , tidal energy geothennol energy and biomass /or electric@ production in Chino. The

potenttol o/each power source is estimated In o jinal scenario. the influence of these technical means

on the CO2 reduction in the yew 2020 will be prelcted.

0 1998 Published by Elsevier Science Ltd. All rights reserved.

1. Introduction It is believed that the “pcnhoux effect” till lead to a worldwide climate chaage with tmptrdictable but probably dangetuus climate chaages for human beings in most parts of the world. l’be “gme&mse effect” is a result of a rising atmospheric omcenttatioa of carbon dioxide emissions and other “greeahoose gases”.

Most scientists around the world nxottmxnd that these emissions should be reduced significantly if mattkind intends to stop the climatic changes. However, China argues that coontries with high per kad C@&oos such as the USA, the EU and the former USSR sboold mduce their emissions first. Fur&rmom, &se wmUries have an obligation to mduce their CO+missions because tluy have been responsible for a high prwpottion of the emissloos ovnthelan4oyears.OnthcothahpndChinais~~~~~for11,2perantot~C~cmi~~, which places China in third place bebind tbe USA atul the former USSR. .

.The growing economy in China till lead to a rapid increase in CO+missions in the future, which will have important implications for any intemational effon to cut CO+missions to reduce the risk of global warming.

As electricity production is responsible for aboot 23 % (or 575 million tons in 1992) of Chinese coremissioas, this sector is of particular interest &i er al. (1994) [2]/. This paper analyses the technical possibilities which exist to avoid a large increase in C02-emissions produced by electricity generation in China.

2. Existing Galcntioll SyStem

Tbcadstingelectricity~~eminChinairpndominaelybaPcdoncoalwhicbproducesabout74pcrcentofthe electricity, followed by bydro with 17 % In addition, some nuclear (total 2.1 GW), biomass (6 MW), tidal (8.3 MW), wind(3lMw)and~rmal(4oMw)power~ti~hsvcbeeninstalledinChina.

Chiaesecoalpowerplantsareosuallysmalliasizeandoperatewith anaverageefflciettcyof29.2percent. In mmpariso!t:Galnaq%coalpowcraati ens have an ~erage efliciency of 35.7 pctunt NDE (1994). [3]/. A similar obrcIvation~bemadtabouthydrostations:Onlythr&hydrosWionsarrlarBerlhanlOW,ktt~63,000hydro station5 are smaller than 400 kW. The small qnits am mainly located in remote areas. Amend 800 of 2,133 electricity supply~dcpndtaallyonsmallhydrostatioas.HowMr,iti9cstimatedthataround2oomllliwpeoptcinChina have no access to electricity. In particular in the aorth and north~ region of China them is a lack of eloztricity production..

Another important aspect of the Chinese elecwicity system is the high transmission line losses. The average trans- mission line losses in China were 8.2 percent campamd to Getmany with only 4.5 percent NDE (1994). p. 40, 19; IEA(1994)p.l91,[4]/.OncbeotherhendChinsharpltcohtidaabk &ortintothedevelopmentofnewgenemtion csprdty,whichgmufrom65GWin198otol82GWin1993.Hamva,intotalthis~ gmwihhasnotbeen enough to keep up with the growing electricity demaud combined with the growing economy / Li et pf. (1994) p, 720,

[2~.ItisgtimcltcdthatNmntlyabout17percentofthelcaricitydrmandcaanotk~. Therefore, the chioese govemmen tdevelcrpalaplanfoextendth~~cspecityto8U)GWbytbcyear2020.

Tofblfllthisplan,a5OOMWpowergetterationuaitmustbe wmmissionedevexy~fromnavonmuiltheyear 202O.However,enagyanalysussythatcnnthisgrowthwillnotksufficient~Jupplythehmureledrici~~needs China.

3. Fwail Energy Raourees As demand site rm0aBeMllt will not reduce the total demand for electricity, but will only reduce the lack of electricity, it is important to look at the di&eat mmurceswltichChinacaauseforitsfuhurpowa~ Figure 1, shows the geographical distribution of coal and oil as well as the gross national paodua for di&rrnt mgim. It can be seen that the east and sooth-middle (S&f) regions produce more thao 58 pram of the grws national

0960-1WWS--see front Fatter 0 1998 Published by Elsevier Science Ltd. All rights reserved. PII: SO960-i481(98)00302-4

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pmduct,_but tbey have access to ooly 11.6 percent of the total nationwide energy resouxs. This dunoasurtc the major D&&III for the fuhue of China’s electricity system: The imporlant resotuces, partkokly coal and water, are

Total coal resources in China are estimated at 115 billion tones, or 11 percent of the world coal resources. If the demand for coal stays constant, the coal resootces will be sufficient for aboot 90 years /World Resources Institute (1994). p. 66 + 169. 1111.

The coal most be transported over large distances from the runes to the coal power stations. Moa coal is waosported @ train. In 1990 around 609 millioo toes of coal were transported by railway, each ton over an average distaoce of 2,000 km iTodd er al. (1994), p. 613, [a]/

In addition to large coal resoorm, China has the largest hydm potential in the world. This is estimated to be 380 GW. Corrently only about 10 % of this pncntial is utilized &nil, (1988), p. 24, [6]/. Most of the hydm potential is located along the Himalayas. which are aboot 2,000 km from where the power is needed. Gil resoorces BR estimated at 3.2 million tons (2.4 % of world oil resource+, and naturaI gas resomxs at 42.7 PJ (0.8 % of world rerwcer). china already imports oil for its gnnving transport needs IDorian, (1994). p. 97, 1711.

Therearetwopos&ilititaforted&ngCC+ emissions in an electricity system: Improving e&Ancy on the use* side andtbcrrbynducingpowapmduaion~~rcducingco2-emissioaJdaringpowcrpodtlctiaa.~~,evmwith asi@fxantinaxase inc&cicncyontbeuscrsideinChinathmwiUalwnysbc~&mandtoL#pthc~r generators nmnhtg at full capacity. The&ore. an e&iency imxeaseontheurersidewillnotlead-atle.astnotfortbe next 20 to 25 yeam- to a reduction of C& emissions. Nevertheless, efkiency increax on the oser side is an imponantstmtegyforreduciqtheovetalldemattd.

Inthefokwingaactions,di&entpossibUtiesforreducingC~-etnis&u on the produion side will be dkossed.Gnlyakadyexistinganddnnoartntal k&Mk+swiIlkptBellted.

4.1 Exi&g Fossil FueI Fawcr Plants neuseoffossilhclforpowcr gemxatkpmduasC~-emisaions.Toreducetheemikom, two pos&ilities exist: Swhchtoothufossil fttelswithlowaspecific~emissioas,aadk iqwememofthecfficiencyoftheclectricity I

s+uaica* - pmdu&n.Nahualgas,hastheloweatspecificC&cmksions,

followed by oil. (see Figure 2). However, as pmviottsly showa,

~ Hunle 82.8 China has only veq limited lxaucesofoilatuigasavailable. Theretbre,onlyaswltchfmmbrowncoaltobatd~seems 1 ; 83.4

/ lu~_lDl.7

possible.CurfendyChineaepower~nseccalwlthanaverage net calotilic value (ncv) of 19.5 M&kg. Accord@ to Li cl al. (1994),[2]ratSrimtcoalwi~mncvd20.9MULg*aMilrblcto

Lmo!-j 111.1 4 beusulinthepowe-rstatbms.Inaddition,coalwasbingcouId

i owwmm’m~ lilnherin?pnwzthencvto22.5MIlkg.

Asbsbeaahdy~th~egickocyofchilusc F&lllt 2: Speckic C0+lissiotts hl kg co, aml power plaats is onIy 29.2 peroe~. However, aewnIiq to

per GJ /source: Beisiq (1994), p. 77, [9y. exputawhowc4kedon&ciatcy impmwnrntprogslns~~- Genna@spouerplants,itisvcry~~ther&tevery eqlensivetoimprovetkeakieaqof~ootdradpower

Jtationr.only~lsrgepowaunitr(~z(MMw)basitnxm~mrlrc~toworlrartheimpromnent.Tbc fblbAngta&dcalnteansarepessible:

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The best option for smaller coal power stations (total around 81 GW) is to substitute them with highly efficiem micro co-generation plants or small. modem coal power plants. However, keeping the power shortage in mind, the shutdown of any power station seems unrealistic.

4.2 New Fossil Fuel Power Plants State-of-the-art coal power plants can reach an efficiency of I5 percent for hard coal and 40 percent for brown coal For large combined gas-steam power plants the efftctency IS up to 54 percent Further improvements in efficiency are expected. By the year 2010 the following efficiency levels are predicted (Betsmg (199-t) p 77, 191):

0 hard coal power plants 50 percent: 0 brown coal 42 percent; ?? combined gas-steam turbines 54 percent.

As natural gas resources ate limited in China, another technology, which is currently being tested worldwide. offers vety promising opportunities: Gas-steam power systems utilizing gas obtained from coal gasification units Currently these systems reach an efftciency of 43 %. but an efficiency of 50 % is predicted /Beising (1994). p. 78 1911

4.3 Hydra Potential The use of hydm energy for power production dces not lead to any direct CO:- emissions. However, during the construction of the hydm dam. CO:- emissions will be reteased. These indirect emissions are estimated to be 0.002 to 0.005 kg Ct&/ kWh produced over a time of 30 years / Ftitsch ef ol. (1989) p. 279, [IO]/.

Chinese investigatiotts have determined a hydro potential of 379 GW with a yearly production capacity of 1,923TWh. However, a more detailed analysis of the Chinese data shows that some umeaiistic places have been included in the study For exampk, the river Yarhmg Zattgbo Jiig, better known as Brahmaputra, is located in Tibet close to the border to Nepal and India. Even if it is possible to develop the hydra potential of the Bmhmaputra, it would not make any sense to transmit the electricity over 5,000 km across the Tibetan high plateau to the main industrial areas. Instead it would be more appropriate to sell the electricity to India or Nepal, which are only a few hundred miles away. Therefore, if only the realistic utilizable hydro potential is con&erect, a total hydm potential of 192 GW, or 960 TWh exists, These figures include the already existing 40 GW installed hydro capacity.

4.4 Wind Energy Potential The use of wind energy for power pmduction does not lead to any direct COs- emissions. The indirect emissions during construction are estimated to be 0.011 kg C&l kWh pmducod over a timeapan of 20 years and a 6 m/s average wind speed I Fritrh er 01. (1989) p. 278, [lo]/.

Asthcpowcroutputofwindturbinerisafunnionofthewindspeditiscssentialtohavead*ail#lknowledgcof the wind distribution in China to estimate the wind energy potential. The currently available wind data have been analysed based on the wind data from 900 Chinese weather stations and d&rent wind energy projects.

As each station covers a large average sine, for example each weather station in Imter Mongolia covers a size of 11,2450km2,thesedatscenonlybcsctnasanapproxiraationwhichmustkusedbacarurformon~ofChinano other data exist. Besides this, most weather stations are installed close to buildings, for example airports, which have an influence on data quality. Reliable wind data have been measured within wind energy projects which show a high wind speed, particularly along the east coast, in Inner Mongolia and in Xinjang Pmvince. It can be aanmted that other Provinces have also areas with high wind speed but because of the lack of detailed maps (most amas am still military areas and therefore no public maps for these areas ate available) and limited access, no wind data exists.

The most interesting aspect of the available wind data is that a high wind potential exists along the east coast between Hongkong and Shanghai and further on to Tianjin. These ate the areas with the highest demand for electricity, and wind energy is the only natural resource which is available within this area. Fmthermore, between Shanghai and Tiijin a huge oEhore wind farm potential exists, because the water is less than 10 meters deep in an area up to 100 km offshote. Another pmmising area for wind energy mihzation is ltmer Mongols with an average windspeedof8m/s.Windfarmsinthisateacanbewtmectedtoexiating tmnsmimionlinesmmtingfromcoalpower plants, which am installed close to thecoal mtnes in Inner Mongolia, to Beijing.

In total, it is estimated that China has a wind energy potential of 180 GW (558 TWh) which can be developed over the next 25 years. The Chinese Academy of Meteorological Science esumams the wind potential at 2,300 GW (or 7,060 TWh), which is ditXcult to mntinn with the data cmrently extsting I Grubb er ul. (1993), p, 195, [ 1 I]/.

4.5 Geothermal Potentfat The CC+ emissions of geothetmtd power plants depend on the chemical compounds in the natural steam. According to DiPippo (1991) p. 803, [12] the CC&emissions are between 0.05 and 0.07 kg CG&wh. China’s geolhumal potartttat is estimated to be 2,613 GW, which is one of the highest in the world. The potential is wncentrated in two areas, the “Yumtan-Tibet high temperature gcothermat zone” in western China and the “Eastern Taiwan high temperature geothermat zone”, which leads to geothermat activity along the east ccast up to the Beijing area &nil (1988), p. 15. ]6]/. Unfortunately, most of the east coast potential cannot be used for dectricity pmductton because of too low temperature ditfmnccr. Furthermore, only parts of the taotentiat in Tibet am suitable for electricity production, and these areas are too far away from the major demand. Altogether, it is estimated that a realistic potential for electricity production utilizing geothermal energy is about 2 GW.

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1.6 Tidal Energy Potential Tidal Energy does not produce any direct CO:- emissions. The indirect emissions are similar to hydra energy. A

detailed Chinex Study estimates the potential for tidal energy to be 20 GW (58 TWb per year). 8 GW of the potential was located in the Fujian and Zhejiang provinces Ningrong (1991). p. 893, [ 1311. Together. both provinces currently have an installed capacity of 10 GW. but both provinces are part of the growing business areas along the coastal region. Therefore the use of tidal energy would be a realistic option.

4.7 Solar Energy Potential The we of solar energy does not lead to any direct CQ- emission. The indirect emissions depend on the solar system installed There are two different basic ideas for utilizing solar energy: photovoltaic and solar themul systems

Solar thermal systems cnnccntrate the solar light. using different technical approaches. to produce high temperahues to evaporate water, which is utilized in steam power twbines. Photovohaic 0, on the other hand, uses semiconductors to produce electricity by using the son light. The indirect CO:- emissions of PV are estimated at 0.228 kgCO:l kWh./ Lewin (1993), p. 173, [14]/. For the coastal region and central China it is estimated that solar energy can produce electricity of around 75 TWh per year.

4.8 Biomass The use of biomass for electrici? production is usually seen as CO: neutral, because the CO:, which is set free by the burning or fermentation of the biomass, was once absorbed by the biomass using photosynthesis.

China has already installed about 5 million biomass-gasitication systems, however, almost ail off them are used for cooking and not for electricity power systems. This use will also be the tithue of biomass utilization in China and therefore, there will be only a limited amount of biomass available for power genemtion. The estimation that China has a biomass potential of 100 GW (or 495 TWh) for electricity pmduction is the&ore far too high I Wii (1992), p. 27, (1511. A more realistic approach shows a potential of 25 GW (or 162 TWh) using basically sewage sludge in the main city areas.

4.9 Nuelerr Power A nuclear power station does not produce any direct C&- emissions. The hdirect Cf&- emissions are eatimated to be between 0.054 and 0.028 kg C@/ kWh. /Fritsch et al. (1989) p. 173, [IO] and Lewin (1993), p. 173, [14]/.

Nuclear power seems to be a possibility for limiting C@- emissions, however, the nuclear waste problem and secority concents will probably limit the foture development of nuclear power. According to the International Energy Agency, China could have an installed nuclear capacity of 21 GW by the year 2020. /IEA, p. 168, [4]/. This low estimation is based on the ondcrstanding that China has wy little knowledge and em in boilding, maintaining and oPr.rating nuclear powet stations. However, this situation applies to almost all the gonemtion Mmologies discwed in this paper, parhlarly wind energy. However, it is nwcb mom complicated and time consuming to start anuclcarpowcrinduNylhanitistogdawindindurayoffthcgmund.Inaddition,midrLcsinthedmlopmmtof windpowerduringthelearningproccganle9bumfultotbeenvironmcntthanthcyarrinthcnuclearpower industry. Therefore, even the Imemational Energy Agency reamuw& a slow dwelopment of nuclear power in ChiIU.

5. Scenario Toanalysesthei~ucnccofthcmtanstoreduccC~-anirrionr,twosansrioshaveb&ndcveloped.Botbsanarios are based on the assotnption that by the year 2020 an electricity prhction of 3,580 TWlt will be achieved. Both scenarios consider only direct COz- emissions.

5.1 Business-as-Uual Seen&o ThisscwariouseJcumnttnndsinthcdevclopmntofthcChineseelecvicitysyaantop~~thestnrturrofthe poww system by the year 2020. Table 1 (nexl page) givea an ov&ew of the scenario. The scenario is based am the following wons: ??Theexistingthcrmalpowerplantswillopnncwithanefficicncyof29.2Y*andusccoalwithancvof20.9MI/Lg; 0 123 GW of additional hydm power will be built; 0 atotalof21GWnoclearpowrwillkinstaU~, 0 PV.windandtidalencrgywillhaveatotal~~caprityofl6GW; ?? the remaining elect&city will be produced by new, to lx installed, umventionalthemlalpowerplants.onellalfof

thiscapacitywillkfinanccdbyintanationalcompaniaandwilluseamorrmodcm~,withanavuage eBiciency of 44Yr The other half will be built by using Chinese tuhology. This technology will achieve an average efliciency of 37 %.

AccordiqtotheB osiness-as-Usual Scenario, the C@- emissions in the electricity sector will be 2,040 million tons, or 350 % higher than io 1992.

5.2 sav4le-Climate Sscenario Thz Save-the-CIimatc Scenario tries to utilize renewable enere arid mcdem thermal techoology in a realistic and responsible manner, tomdocetheiaaerw of CQ- emiSions.

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I smn I MD I ,040 I Tabel 1: CO?- emissions based on Business-as-Usual Scenario/Source: Author/

cd and substituted by micro co-generation units based on diesel engines;

ThClSUItSOfthCSCOWlOWtlbC sceninTable2.Thcassun@ons tn& by the Save-the-Climate scenario are described next. ??The effkiency of large

currently existing thermal stations will be improved b, 6.3% and all thermal power stations will use coal with a ncv of 22.5 MJlkg;

0 The small thermal power plants will be dccommision-

0 Biomass, hydro, wind energy, geothermal, nuclear pmver and PV will utilize their potential as described above; 0 Nahtral gas/ coal co-generation will have a total installed capacity of 70.8 GW and coal gasification co-

generation will have a total installed capacity of 150 GW, 0 The remaining electricity will be supplied by conventional thermal stations with an average elikiency of 44 %.

In total, the power stmcture used in the Save-the-Climate scenario would lead to yearly C@- emissions, produced by electricity production, of 851 million tons. These emissions are about 58 % lower than in the buks-as-usual sanmio, but still 48 % (or 276 million tons) higher than the CQ- emissions of the electricity sector in 1991. In comparison: The 276 million tons am equal to 28.5Yo of the total (not only electricity) C&-emissions of united Germany in 1991.

Tabel2: CO,- emissions based on Save-Climate Scenario I Author/

9. conehnIon Iftheworldwantstoavoidachangeof climate, countries like China must stabilize thcirCol-emi%ionsattheircurmltlevel.

To achieve this goal, China’s power gaormustutilizercnewableenergy~sufharwind,hydro,solnr,gcothamPlaadtkhltornewpowa genemtion. The potential of such rr~ourcaisri~Ia~~windmrgycaaplayamppr~leinthefuhlcc of Chinas’s electricity sator. This is because of the high wind potential along the east- Chin& major industrial area.

The optimistic (50 % of the ekbicity is pe by renewable sour@ but nalistic (only prwcn resotmzes are used)scenarIofortheyear2020showstlut evcothis~misticcnagymixisnolenoughtoavoidalargeincrrasof C@- emissions in Chinese electricity sector: This demomtmtes the huge alTorts which are rapdred to stabilize coz- emissions at their current level. 10. References