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Energy Researchat DLR

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Today, the widespread availability ofenergy enables many people to havea relatively high quality of life. How-ever, we are predominantly using non-renewable resources such as oil, coaland gas as energy sources, and load-ing the atmosphere with environmen-tally harmful carbon dioxide. In orderto supply the population and industrywith energy for the long term, weneed a sustainable energy system.

The German Federal Government hasset ambitious objectives in energy poli-cy in less than 40 years, greenhousegas emissions are set to be reducedby at least 80 percent and primary

energy consumption by 50 percent,compared to the levels in 1990. Atthe same time, the reliability andcost-effectiveness of the supply hasto be guaranteed. We are thereforestanding at the threshold of a histori-cally unique transformation process,in which we must make the supply ofheat and electrical and mechanicalpower sustainable for every applica-tion in industry, domestic use andtransport.

Energy research for our future

Research can and must make signifi-cant contributions to this, in both tech-nical advances and in the design andimplementation of the entire process.The current German energy researchprogramme is heading in the right di-rection; its intention is to continue de-veloping energy technologies intensive-ly and broadly. Furthermore, thecomplex energy supply system needsto be continually monitored and re-thought to develop robust solutionsfor the future.

Energy research at DLR is operatingsuccessfully in the technological sectorand in modelling the overall system.

The large proportion of funding fromindustry and public research pro-grammes bears witness to the high l ev-el and productivity of DLR energy re-search. This includes numeroussynergies with DLRs aviation, spaceand transport research.

I invite you to take a look at the re-search we conduct in the pages thatfollow. DLR the best energy researchfor our future!

Contents

Energy research at DLR

Overview _____________________________________ 4

Gas turbines __________________________________ 6

Solar energy __________________________________ 8

Wind energy _________________________________ 10

Materials research ____________________________ 11

Decentralised power plants ____________________ 12

Energy storage systems ________________________ 14

Energy systems analysis ________________________ 16

Energy research institutes at DLR ________________ 18

Ulrich Wagner, DLR Member of theExecutive Board for Energy and Transport

DLR solar research scientists check the qualityof mirrors and other components in solar ther-mal power plants and set standards.

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DLR has been working on energyresearch and making important con-tributions to a sustainable energysystem since the mid-1970s. Multi-disciplinary teams with access to theunique test facilities and extensivecomputing capabilities of a majorresearch institution are working onvarious key issues. DLR has adopteda nationally and sometimes inter-nationally leading role in many ofthese areas.

Key topics

Energy research at DLR is primarilyfocused on innovative techniques for

power generation, developing energystorage systems and modelling theenergy system. This brochure givesan overview of the diversity of theseresearch areas.

Combustion and gas turbine technol-ogy is aimed at improving gas turbinesin terms of their efficiency, reducingemission levels and increasing flex-ibility. In addition to conventional gasturbines for power plants in the severalhundred-megawatt output range, microgas turbines with outputs of just a fewkilowatts are being researched andoptimised.

Solar research is primarily concernedwith optimising solar thermal powerplants that use concentrated solar radia-tion to generate sustainable base loadpower using a steam-power process andthermal storage systems. DLR is continu-ing to develop well-known conceptsand is implementing new approaches.The aim is to improve the technology,reduce costs, and thus accelerate marketacceptance. Wind power research is nowalso part of the DLR research portfolio.

In this area, DLR can make use of itsextensive aviation-derived expertise toimplement more economical designs forwind turbines.

Materials research at DLR is a cross-disciplinary area that makes substantialcontributions to various energy issues.It plays an important role in the de-velopment of lighter rotor blades forwind power generators, heat-resistantcombustion chambers, lighter blades forgas turbines and more robust radiationreceivers for solar tower power plants.

Energy storage systems will play asubstantial role in the energy systemof the future. DLR energy researchersare working on thermal, chemical andelectrochemical storage systems. Withelectrochemical storage systems, DLR iscollaborating closely with other centres

in the Helmholtz Association to researchthe next but one generation of batteriesand new applications for fuel cells.

DLR energy systems analysis assesses thevarious energy technologies, and usesmultiple scenarios to investigate whatthe energy mix of the future might looklike. Systems analysis provides the basisfor decision making in both governmentand research.

Data and facts

Around 500 employees in variousdisciplines work on energy researchat DLR sites in Cologne, Stuttgart,Braunschweig, Gttingen, Jlich andAlmera, in southern Spain. In 2011, DLRcommitted funds of around 21 millioneuros to energy research from its corefunding, provided by the GermanFederal Ministry for Economics andTechnology and the German states.Third party funds raised from publicresearch programmes and industryamounted to some 47 million euros in2011. High third party funding almost70 percent of the total has put DLR at

the forefront of energy researchinstitutions in the Helmholtz Associationfor some years.

From basic research to applications

A system of programmatic controls isused to manage and focus DLR energyresearch topics; this ensures that thenecessary capabilities are available forsuccessfully dealing with relevant issues.While some work is more focused on thefundamentals, other research is directedtowards the needs of industry. It is an es-tablished principle at DLR that the entirescope is covered, from the fundamentalmechanisms to industrial applications.For this reason, and in combination withexpertise in the areas of aviation, aero-space and transport, DLR is able to offera unique spectrum of capabilities that

can perform well in the face of competi-tion and secure competitive advantagesfor its industrial partners.

Collaboration

DLR energy research is involved in numer-ous national and international networks.It cooperates with various universities thatare active in this field and, by so doing,attracts competent young researchers.Generally, DLR institute and departmentheads also teach at universities. Intensiveand wide-ranging collaboration withindustry ensures both the linking of energyresearch to current issues and the fund-ing of associated research projects. DLRenergy research also cooperates with othernational research institutes and selectedinternational partners from science andindustry.

In addition to internal scientific assess-ments, DLR energy research is subject toevaluation every five years in the contextof the Helmholtz Association. This involvesreviewing the medium-term orientationand strategic coordination between themember centres of the Helmholtz Associa-

tion.

DLR energy research practical solutions

Battery research higherenergy density with lithium-sulphur and lithium-air bat-teries

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Thermal power plants are capableof generating power on demand,and so are able to compensate forseasonal and temporal fluctuationsin the availability of wind and solarenergy. Furthermore, the construc-tion of new power plants, or themodernisation of existing plantsoffers the option of replacing oldfacilities with modern, high-effi-ciency power plants worldwide.In recent years, major advances havebeen made in increasing power plantefficiency, and in reducing pollutantemissions. The efficiency of powergeneration using combined cycle gas

and steam turbine power plants hasincreased from less than 40 to over60 percent; at the same time, therehas been a significant reduction in theemission of nitrogen oxides (NO

X). Energy

researchers are working on furtherincreasing the level of efficiency, forexample by using improved combustiontechniques. Every percentage point bywhich the efficiency of power generationin Germany is increased corresponds tothe power produced by a conventionallarge power station, and meets theneeds of 500,000 people.

Less carbon dioxide efficient and flexible gas turbines

Better combustion with a steadyflame

Researchers at the DLR Institute ofCombustion Technology in Stuttgart aredeveloping new combustion systems,one of which is based on FLOX(FLame-less OXidation) technology. This technol-ogy provides a particularly homogeneousand stable flame, significantly reducingthe emission of pollutants while loweringthe thermal load on the materials of thecombustion chamber walls. In addition,this type of combustion chamber can beoperated using different fuels, so that,with this technique, future gas turbineswill have the capacity to make betteruse of gases with fluctuating quality and

biomass-based fuels. New combustionchambers for gas turbines can be testedunder real conditions in the high-pres-sure combustor rig in Stuttgart.

Alternative fuels

Alternative fuels and what are known asdesigner fuels are playing an increas-ingly important role in energy supplyand, particularly, environment-friendlyindividual mobility. DLR researchers areworking on generating such fuels fromrenewable energy sources. These fuelscan also be produced by the gasificationof biomass and coal. They are character-ised by a high content of hydrogen and

carbon monoxide, and have differentcombustion properties than natural gas.

Contactless measurement forlow-emission combustion

Making combustion processes more effi-cient and environment-friendly requiresan understanding of what is happeningin the flame and how to control it. DLRresearchers are using contactless lasermeasurement techniques to examine theproperties of and processes in a flame.In contrast to measurement probes, lasermeasurement methods do not disturbthe flow field or interfere with the chem-ical reactions. Data can be acquired withgreater temporal and spatial resolution;up to 10,000 measurements per secondare possible. The interaction betweenthe flow field and the chemical reactions

DLR researchers use laser measurementtechnology to determine the properties of aflame

DLR researchers are devel-oping more flexible andpowerful power plant gasturbines

Alternative fuels improved combustionproperties and lower emissions

A glass combustion chamber offers a view ofthe combustion process in a gas turbine

can be measured, as can the tempera-tures of the combustion chamber wallsand the flame. Also of importance is theability to measure the concentrations ofsubstances involved in the reaction.

Simulations for better combustionchambers

The DLR Institute of CombustionTechnology has developed powerfulnumerical methods to test future burnerand combustion chamber concepts usinga computer, and without the need forexpensive trials. These methods are usedto simulate the formation of pollutants(particularly nitrogen oxides) in combus-

tion chambers, as well as the noise andoscillation of flames. Using computa-tions, the researchers can also makeimportant predictions about the thermalload on combustion chamber walls andthe spark ignition or compressionignition characteristics of fuel/airmixtures.

New requirements for large powerplant turbines

The power grid of the future will placenew demands on fossil-fuel powerplants they will have to generate powerefficiently and conserve resources, notonly during baseload operation but alsowhen operating at partial load. At theDLR Institute of Propulsion Technology inCologne, researchers are working closelywith partners in industry to improve

power plant gas turbines. They are inves-tigating the pressure and temperature incombustion chambers of various perfor-mance classes under realistic conditions.The plant manufacturers and researchersare aiming to make power plants moreproductive, environment-friendly andflexible.

To this end, the researchers are in-vestigating how both axial and radialcompressors can be optimally designedfor baseload and partial load use. Theyare also simulating the aerodynamic be-haviour of larger turbine blades to ensurethat there are no dangerous vibrations,which are referred to as blade flutter.

The aim of the research is also to makepower plants more efficient by reducingthe need for cooling air in the turbines astemperature of the gas increases. To dothis, the flow calculation tools designedat DLR for industrial applications arebeing continuously developed and testedusing extensive experiments.

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Higher temperatures for greaterefficiency

DLR scientists are also investigatingsolar power plants with higher processtemperatures. Such power plants haveincreased cycle efficiencies, and hencerequire fewer collectors per kilowatt-hour generated, which reduces powergeneration costs. One important, in-novative approach in parabolic troughpower plants is direct steam genera-tion. With this system, the steam thatdrives the turbine is generated directlyin the absorber tube. This removes the400-degree-Celsius limit that applies toconventional heat transfer fluids (thermal

oil). DLR is also investigating new heattransfer media such as molten salt, par-ticles and gases to achieve even higherprocess temperatures.

Concentrated solar radiation solar research at DLR

Solar power plants

Solar thermal power plants use mirrors to concentrate solar radia-tion and convert it into thermal energy. This process is called Con-centrating Solar Power, or CSP. The concentration enables tempera-tures of 400 to 1200 degrees Celsius to be reached. This thermalenergy can be used to generate power as in a conventional ther-mal power plant or with a Stirling engine.

Depending on the type of power plant, the solar radiation is con-centrated using four different mirror shapes. In parabolic troughpower plants, trough-shaped mirrors concentrate the radiationonto a tube mounted at the focus of the parabola. If the large,curved mirrors are divided into long flat strips, Fresnel collectorsare created; these also concentrate the radiation onto a tube. Withtower power plants, a number of flat mirrors direct the radiationonto a receiver at the top of a tower. Lastly, dish units involve astand-alone parabolic reflector that concentrates the solar radia-tion to a point.

The Sun provides an abundance ofenergy; it has the potential to meetthe needs of the entire populationof Earth 10,000 times over. Thechallenge is to exploit this climate-neutral energy source efficientlyand cost effectively. Solar thermalpower plants, which DLR has beenresearching for over 30 years, canmake a substantial contribution tothis exploitation and so to theenergy supply of the future.

Power around the clock

Solar thermal power plants concentratedirect sunlight to produce temperatures

high enough for technical use. Thus, theycan be used to provide large quantitiesof environment-friendly power fromrenewable sources in sunny regions.This technology has another importantadvantage; energy can be stored in theform of heat at a relatively low cost.Using a thermal storage system such aslarge salt storage tanks, for example,these power plants can also be reliedupon to provide power during the hoursof darkness.

The DLR Institute of Solar Research isone of the worlds leading organisa-tions in the field of solar power plants.The scope of research at the Instituteranges from laboratory and fundamentalresearch through to operational testingof complete solar power plants. The aimof the research work is to improve theprocesses and materials used in construc-tion, and to optimise the system designand operation of the facilities. To do this,DLR scientists are carrying out impor-tant research and development work toaccelerate innovation cycles and reducepower generation costs.

Better mirrors and absorber tubes

The QUARZ test laboratory in Cologne(Test and Qualification Center for Con-centrating Solar Power Technologies) ishighly application-oriented in its work.Here, DLR researchers are investigatingthe quality of industrially manufacturedmirrors and absorber tubes using testrigs developed at the centre. As one ofthe worlds leading research institutionsin this area, DLR is currently workingto establish international standards forquality control of components and theassociated measurement methods.

Scientists at the DLR Institute of Solar Re-

search use the solar furnace in Cologneto conduct fundamental research. Thisfurnace is equipped with a 60-square-metre mirror array to concentrate solarradiation. Initial tests for generatinghydrogen directly using solar energywere among the tests carried out here.The DLR solar power tower plant in Jlichserves as a large-scale research facilityfor experiments involving high-tempera-ture solar technology.

DLR researchers also have access tothe Plataforma Solar de Almera (PSA)research facility in southern Spain. Thefacilities in Germany can be used forfast technology development from thelaboratory scale to industrial proto-type, whereas in Almera, long-termexperiments can be carried out underreal-world conditions. DLR scientists inCologne and Stuttgart are conductingresearch into better heat transfer fluidsfor parabolic trough systems and intoreceiver technologies, and are evaluatingfuture solar tower systems.

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Tower power plant in Almera greater efficiency in solarthermal power generation byusing higher temperatures

DLR solar tower in Jlich research powerplant for further development of high-temperature process technology

Mirrors under test quality investigationsat the Plataforma Solar in Almera (southernSpain)

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Precise wind predictionsenable better control ofwind farms

Electrical power from heat thermoelectricgenerator module

More output, less noise

At almost eight percent, wind ener-gy is already making an appreciablecontribution to power generation inGermany. According to the FederalGovernments energy policy targets,it should be supplying 30 percent ofthe total power demand by 2030.

To achieve these targets, it is not onlynecessary to expand the area availa-ble for wind farms, but also to furtherreduce the cost of generating power.This might, for example, be achieved byincreasing the output of wind energyfacilities by increasing their reliabili-

ty, through alternative control optionsor by improving the efficiency of theproduction processes. In future, offshorewind turbines are expected to reach anoutput of up to 20 megawatts. To dothis, the turbines, their construction andthe materials used will have to undergosubstantial development. In addition,wind power units will have to rotatemore quietly than they do now, especial-ly onshore.

DLR can make important contributionsto wind energy exploitation using exper-tise and technology from aeronauticsand space research. To optimise windenergy facilities from an aerodynamic,

Almost all work in energy researchis related to issues concerning mate-rials whether it involves robust,durable power plant componentsor highly heat-resistant combus-tion chamber walls. In its activitiesdeveloping and investigating high-performance materials in variousfields, the DLR Institute of Materi-als Research contributes to enablinginnovative components and systemsfor energy technology.

Greater efficiency in conventionalpower generation

New materials with better high-temper-

ature stability, corrosion resistance andthe ability to withstand thermal shockare needed for a new generation ofefficient power plants that producesignificantly less pollutant emissions.WHIPOX, the all-oxide fibre-reinforcedceramic matrix composite developedby DLR, meets these requirements. Incooperation with industry and otherresearch partners, materials researchersare manufacturing components madeof WHIPOX, and creating numericalmodels of the materials behaviour.

Materials capable of withstanding1000 degrees Celsius or more

When hundreds of mirrors are direct-ing radiation from the Sun onto a sin-gle point the radiation receiver ina tower power plant, temperatures of

aeroelastic and structural perspec-tive, DLR researchers are working withboth numerical simulations and experi-ments in wind tunnels that are uniquein Europe. DLR has considerable experi-ence in modelling the entire system of awind power facility. In future, intelligentmaterials and structures from adaptivesystems research should make con-trollable rotor blades possible to achievehigher efficiency, especially in strongwinds. In addition, using lidar systems laser-based optical scanning systems wind flows and their interactions withinan entire wind farm can be recorded.Satellite images also help with wind fore-casts for the site of a wind farm, enable

optimum control of the individual unitsand allow prediction of the power inputinto the grid.

Lighter and bigger wind turbines ofthe future

If wind turbines using current designswere to be enlarged to have an outputof 20 megawatts, they would need rotorblades 125 metres long and weighingmore than 100 tons. The fibreglassmaterials used at present are too heavyfor blades of this size. With carbon-fibrereinforced composites, it is possible tomake rotor blades that are five timesstronger and stiffer. DLR researchersare working on the integration andautomated production of carbon-fibrereinforced rotor blades to make themsignificantly lighter and more stablewithout increasing costs.

over 1000 degrees Celsius are reached,and large temperature gradients occur.Researchers at the DLR Institute ofMaterials Research are therefore identi-fying when and how the materials canbe damaged, carrying out ageing testsover accelerated timescales, and so pre-dicting the operating life of a radiationreceiver.

Another focus of research is the produc-tion of hydrogen from water usingsolar energy. There has already beensome success using concentratedsolar radiation to produce hydrogenin a ceramic reactor coated with ironoxide. Currently, materials researchers

are working with solar researchers todevelop improved functional ceramicsfor a higher hydrogen yield and longeroperating life.

Power from waste heat

Thermoelectric materials can convertheat flow directly into electrical power.This means that some of the waste heatin vehicles and heat flows in heatingand industrial facilities can be exploited.DLR researchers are developing materialsand manufacturing processes for higheroperating temperatures, where newmaterials are used to offer new possibili-

Synergies for wind energy research

Expertise from aeronautics and spaceresearch for improved wind energy systems

New possibilitieswith new materials

ties for expanding the scope of applica-tion and increasing the efficiency of theenergy conversion. Scientists at the Insti-tute are producing both thermoelectricmaterials from the raw material, a high-purity powder, and complete thermo-generator modules.

Aerogels ultra-light superinsulators

Aerogels are ultra-light solids that haveexceptional insulation properties dueto their nanoporous structure. Makingsimple chemical changes can createsoft, flexible materials from the mostbrittle substances. DLR researchers have

developed lightweight concrete withoutstanding insulating properties byadding aerogels to a cement mixture.They are also combining different typesof aerogels with plastic or metal; in thisway, they are developing superinsulatingcomposites for thermal isolation in space-craft and satellites.

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New materials and concepts in fuel cellresearch

Flying with fuel cells the DLR Antares H2powered glider is the first aircraft capableof taking off using fuel cell power.

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Additional decentralised powerplants situated close to consumersare needed to reduce environmen-tally harmful emissions and makebetter use of fuels. Together with anumber of project partners, the DLRInstitute of Technical Thermodynam-ics and the DLR Institute of Combus-tion Technology are investigatingpioneering, sustainable technologiesfor energy supply using combinedheat and power generators basedon micro gas turbines and fuel cells.

Power and heat at the c onsumerslocation

Decentralised power plants enable theexploitation of the heat created duringpower generation. Using combinedpower and heat generation (CombinedHeat and Power; CHP), the fuel can beexploited in an efficient and, hence,environment friendly manner, increasingcost-effectiveness and sustainability. Thecarbon dioxide emissions from CHPsystems are up to 70 percent lower than

Decentralised power plants energy where it is needed

ature fuel cells that can use natural gasdirectly and low temperature fuel cells,called polymer electrolyte fuel cells, thatuse hydrogen or methanol as fuel. Theresearchers are investigating new mate-rials and cell designs and are working onindustrial manufacturing techniques thatwill result in a reliable and highly scal-able production. The challenge facedwhen developing fuel cells is slowing theageing process, and thus extending theoperating life. By measuring the currentdensity distribution, scientists can mon-itor the degradation processes and thusimprove fuel cells in the medium term.

One innovative application largely devel-

oped by DLR is the integration of fuelcell systems in passenger aircraft. Amulti-functional fuel cell system iscurrently being tested. The system isused as an auxiliary power unit to supplyelectrical loads on the plane, and alsoto produce water for use in the cabin.The fuel cell also powers an electricnose wheel, which can substantiallyreduce the emission of pollutants duringground operations. The Antares DLR-H2powered glider is the first mannedaircraft in the world capable of takingoff using only fuel cell propulsion. Thisresearch aircraft is used as a flying testplatform for fuel cells in aviation.

comparable systems, where the genera-tion of power and heat is separated.Mini decentralised power generators areideal for single and multiple occupancyhouseholds, supplying energy where it isneeded. Unlike the gas-fuelled systemsused to date, a micro gas turbine can beoperated using a variety of fuels, emit-ting fewer pollutants as it does so. Microgas turbines have another advantage:longer intervals between maintenancechecks and reduced maintenance costs.There is still a need for research anddevelopment on their electrical effi-ciency, which is lower than in those withgas-fuelled systems. DLR researchers areworking on optimising the components,

minimising pressure and heat losses, andusing ceramic materials.

In the area of combined heat and powergenerators based on micro gas turbines,the Institute of Combustion Technologyis also investigating new componentsand concepts for gaseous and liquidfuels. In doing so, the researchers aredetermining the combustion propertiesof conventional and alternative fuels.New, low-pollutant, fuel-flexible combus-tion systems for micro gas turbines arealso being developed. The Institute oper-ates a micro gas turbine test rig with an

Highest efficiency in hybrid powerplants

Combining a gas turbine with a hightemperature fuel cell system to create ahybrid power plant promises very highlevels of efficiency in energy conver-sion. The primary advantage of doingthis is that, as well as producing power,the waste heat from the power gener-ation process can be used. With unitsof more than 10 kilowatts output, elec-trical efficiencies of over 60 percentcan be achieved and over 90 percentof the energy can be used. This ispossible because the gas turbine feedspreheated, compressed air into fuel

cells, where power is produced by elec-trochemical processes. Controlling thecomplete system is a particular chal-lenge, as the dynamic behaviours of thetwo components are very different. DLRresearchers are using computer modelsto develop control strategies for this.

optically accessible combustion chamberto characterise and optimise the compo-nents under development and the sys-tem design concepts.

Efficient and reliable, even foraviation fuel cells

Fuel cells can be used for static powersupply (mostly in combined heat andpower systems) or for vehicle propulsion.The electrical efficiency of fuel cells isup to 60 percent higher than with othertechnologies. The DLR Institute of Tech-nical Thermodynamics is working on fur-ther development of both high temper-

Researchers can use lasers to look inside

a fuel cell

Highly efficient hybrid power plant achievedby coupling a gas turbine to a high tempera-ture fuel cell system

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In the event of an excess of power, theenergy can be stored in the form of hydro-gen for the long term

Heat storage unit

Caverns (compressed air)

Engine Air turbinesCompressors

Air input Air output

Generator

Operating principle of an adiabatic compressed air storage system

Concept of a pressure-tightheat storage unit for adiaba-tic compressed air storagesystem power plants

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With the increasing exploitation ofvariable renewable energy sources,it is becoming ever more impor-tant for energy to be available tothe consumer on demand. Energystorage systems will be a keycomponent for achieving this in asustainable energy economy.

Whether in the form of heat in rock orelectrical energy in a battery, energy canbe stored in a wide variety of ways. DLRresearchers at the Institute of TechnicalThermodynamics are developing thermal,chemical and thermochemical energystorage, adiabatic compressed air storagesystems and batteries.

How thermal energy can best bestored

Energy is most cheaply and efficientlystored in the form of heat. Largemolten salt storage systems are alreadybeing used in solar power plants. Inthe quest for more cost-effective, flex-ible, high-temperature thermal storagesystems, DLR researchers are devel-oping and using solid materials such asceramics, concrete and rock. In Stutt-gart, researchers at the Hotreg hightemperature thermal storage test facilityare able to test the storage propertiesof various materials with and withoutpressure at temperatures of up to 850degrees Celsius.

Latent heat storage systems energystored in the smallest space

Latent heat is hidden energy that a sub-stance absorbs during a phase changefrom solid to liquid or from liquid to gas without changing temperature as it doesso. Latent heat storage systems have theadvantage of being able to store a greatdeal of energy in a small space with mini-mal temperature change. DLR researchersare cooperating with partners in indus-try to develop latent heat storage sys-tems filled with mixtures of salts. The saltschange from a solid to a liquid state at anunchanged temperature. The energy inthe system can be very efficiently trans-

ferred and absorbed through a phasechange at constant temperature. An initialpilot plant, the largest high-temperaturelatent heat storage facility in the world,was successfully tested at Carboneras, insouthern Spain, in 2010/2011.Thermochemical storage using heatof reaction

Inexpensive substances such as calciumhydroxide can be separated into calciumoxide and steam by adding heat. Usingthis separation, heat can be storedindefinitely without loss before it isreleased again in the reverse reaction.Thermochemical heat storage systemsemploy this principle. Fundamental ques-tions concerning the reaction and the

process engineering implementation arebeing solved at DLR, in cooperation withindustrial partners for applications inprocess technology and solar powergeneration.

Chemical storage hydrogen storespower from renewable sources

What should be done with surpluspower when the wind is blowing anddemand is low? It can be used toproduce hydrogen through electrol-ysis. The stored gas can subsequently bere-used in a gas turbine or fuel cell togenerate power, or for other purposes.Researchers at DLR are working on

methods to generate hydrogen moreefficiently and cost effectively. Theyhave developed a coating for elec-trodes employed in alkaline electrolysis,which significantly reduces the electricitydemand for the production of hydrogen.With polymer electrolysis technology,DLR researchers are improving the dura-bility of the components that enablethe benefits of high hydrogen yieldand great flexibility of output to beexploited. High temperature electrolysis,which DLR is also working on, is still inthe early stages of development.

Storage facilities key components of a sustainable energy system

Underground adiabatic compressedair energy storage systems

Working together with partners inindustry, DLR researchers are investi-gating compressed air storage systemsthat will be capable of stabilising thepower grid. If there is an excess ofpower, air is compressed and fed intosubterranean salt caverns. When poweris needed, the compressed air is releasedto drive a turbine. With adiabaticcompressed air storage systems, the heatcreated during compression is storedtemporarily. The thermal energy is thenused to heat the compressed air to ahigh temperature prior to it being fed to

the turbine. This process can be used forshort-term power storage with up to 70percent efficiency. In cooperation withRWE and other companies, the construc-tion of a demonstration unit is plannedfor 2014.

Electric storage systems batterytechnology

Environment-friendly, inexpensivebatteries are a key challenge for electricmobility. A major objective of the workat DLR is the development of radicallynew battery technologies, mainly lithium-sulphur and lithium-air batteries, whichpromise significantly higher energy densi-ties using low-cost, environment-friendlymaterials.

For these next-generation batteries, DLRresearchers are, for example, working onbetter electrode structures to keep themstable over as many charge/dischargecycles as possible. Other improvementsare expected from a cathode construc-tion whereby the cathode undergoesless structural change during the charge/discharge cycles. In addition, there is

an innovative approach to electrodecontacts, which can be used to achieveexceptional properties. In parallel, theresearchers are working on thermoelec-trochemical modelling of batteries. Thesemodels can be used to predict chemicalprocesses related to operating life andsafety at the sub-micrometre or nano-metre scale.

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DESERTEC increased energy security witha power link between Europe and NorthAfrica

Researchers in DLR energy systems analysisare examining options for the energysystem of the future

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The complete energy system is com-posed of various components; eachof these is being researched and fur-ther developed. The aim of systemsanalysis in DLR energy research is tocreate a coherent overall system forthe future.

Scenarios and strategies for the en-ergy transition

The systems analysts use variousscenarios, in which specific targets orprerequisites are set, to consider possibledevelopments in energy supply. These

The full picture energy systems analysis

settings, which are being developed forGermany, for other countries and evenfor the whole world, represent a funda-mental basis for decision-making ingovernment, industry and research.Using systems analysis, decision makerscan make better assessments of thetechnical and economic possibilities andlong-term development prospects forthe energy system.

The results of systems analysis can onlybe effective if they are taken up andimplemented by government andindustry. In the context of guidance forvarious federal ministries, DLR makes asubstantial contribution to the develop-

ment of funding programmes and lawsfor efficiently implementing nationalobjectives in the renewable energysector.

National scenarios and labourmarket studies

Since 2004, and under contract to theGerman Federal Environment Ministry(BMU), DLR has been developing long-term scenarios and strategies forexpanding the use of renewable ener-gies. These pilot studies carefullyexamine the potential transformationpaths for the German energy system asit moves towards using high proportionsof renewable energy sources. Anotherimportant aspect of the pilot studies iscalculating the necessary investments fortransforming the energy system and theeconomic benefits that can be expected,

for example, from the avoidance of fuelcosts in the long term. Again undercontract to the BMU, DLR is carrying outstudies to investigate the short and longterm effects of the expansion of renew-able energy sources on the labourmarket and the economy. The focus hereis on the number of employees in thevarious renewable energy sectors.

Dynamic simulation of the powersupply system

At any time of year, power plants mustbe capable of meeting the needs ofenergy consumers, even in the event offluctuations in the amount of renewableenergy being fed into the grid. Using theREMix simulation model developed byDLR, systems analysts can simulate thishighly complex system. Data with hightemporal and spatial resolution onrenewable electricity generation poten-tial and the power consumption in Ger-many and Europe are included in thismodel. Other elements in the model arepower storage systems, variable power

plant capacities and the possibility oftrans-European power transmission asbalancing options. This allows the modelto provide answers on the developmentmeasures that are necessary and bestsuited for delivering the energy transi-tion from both technical infrastructureand economic perspectives.

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Power link with North Africa the basic principle of DESERTEC

By connecting countries with high windlevels (around the North Sea, for exam-ple) and countries with high solar radia-tion levels (the Mediterranean region, forexample), a large part of the fluctuatingpower input from individual wind andphotovoltaic farms can be balanced over-all. With special regard to North Africancountries, DLR researchers have beeninvestigating how great the potential forsolar energy power plants is, the bestlocations for them, and the routes alongwhich the power can be fed to Europeanconsumption centres most cost effective-

ly. The concept being pursued by theDESERTEC Foundation and the DesertecIndustrial Initiative (Dii) is based on DLRstudies. In other studies, the researchershave also calculated the extent to whichsolar energy systems can be used forwater desalination, to counter the short-age of drinking water in southernregions.

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Energy research institutes at DLR

Knowing what happens in a flame DLRenergy researchers are optimising fuelsand the combustion process

Gas turbinesInstitute of Combustion Technology (Stuttgart), www.DLR.de/vt/en

Institute of Propulsion Technology (Cologne), www.DLR.de/at/en

Solar researchInstitute of Solar Research (Cologne, Stuttgart, Jlich, Almera), www.DLR.de/sf/en

Wind energyInstitute of Aeroelasticity (Gttingen), www.DLR.de/ae/en

Institute of Aerodynamics and Flow Technology (Gttingen, Braunschweig), www.DLR.de/as/en

Institute of Propulsion Technology (Gttingen), www.DLR.de/at/en

Institute of Structures and Design (Stuttgart), www.DLR.de/bk/en

Institute of Composite Structures and Adaptive Systems (Braunschweig), www.DLR.de/fa/en

Institute of Flight Systems (Braunschweig),www.DLR.de/ft/en

Institute of Atmospheric Physics (Oberpfaffenhofen), www.DLR.de/pa/en/

Materials researchInstitute of Materials Research (Cologne),www.DLR.de/wf/en/

Decentralised power plantsInstitute of Technical Thermodynamics (Stuttgart), www.DLR.de/tt/en

Institute of Combustion Technology (Stuttgart), www.DLR.de/vt/en

Energy storageInstitute of Technical Thermodynamics (Stuttgart), www.DLR.de/tt/en

Institute of Combustion Technology (Stuttgart), www.DLR.de/vt/en

Energy systems analysisInstitute of Technical Thermodynamics (Stuttgart), www.DLR.de/tt/en

DLR Project Management Agencywww.DLR.de/pt/en

Publisher

German Aerospace

Center (Deutsches

Zentrum fr Luft- und

Raumfahrt e.V.)

Address

Corporate Communications

Linder Hhe

51147 Cologne

Imprint EditingDorothee Brkle

(DLR Corporate

Communications)

Peter Clissold, Karin

Ranero Celius (English

language editors,

EJR-Quartz B.V.)

Design

CD Werbeagentur GmbH

Troisdorf

Printing

Druckerei Thierbach KG

Mlheim/Ruhr

Print date

July 2013

Reprinting (also in part) or otheruse is only permitted after priorarrangement with DLR.

www.DLR.de/en

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Corporate CommunicationsLinder Hhe51147 Cologne

www.DLR.de/en

DLR at a glance

DLR is the national aeronautics and space research centre of theFederal Republic of Germany. Its extensive research and devel-opment work in aeronautics, space, energy, transport and secu-rity is integrated into national and international cooperative ven-tures. In addition to its own research, as Germanys space agen-cy, DLR has been given responsibility by the federal governmentfor the planning and implementation of the German space pro-gramme. DLR is also the umbrella organisation for the nationslargest project management organisation.

DLR has approximately 7400 employees at 16 locations inGermany: Cologne (headquarters), Augsburg, Berlin, Bonn,Braunschweig, Bremen, Gttingen, Hamburg, Jlich,Lampoldshausen, Neustrelitz, Oberpfaffenhofen, Stade,

Stuttgart, Trauen, and Weilheim. DLR also has offices inBrussels, Paris, Tokyo and Washington D.C.

DLRs mission comprises the exploration of Earth and the SolarSystem and research for protecting the environment. Thisincludes the development of environment-friendly technologiesfor energy supply and future mobility, as well as for communi-cations and security. DLRs research portfolio ranges from fun-damental research to the development of products for tomor-row. In this way, DLR contributes the scientific and technicalexpertise that it has acquired to the enhancement of Germanyas a location for industry and technology. DLR operates majorresearch facilities for its own projects and as a service for clientsand partners. It also fosters the development of the next gener-ation of researchers, provides expert advisory services to gov-

ernment and is a driving force in the regions where its facilitiesare located.

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