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MHD: High Promise, Unsolved ProblemsAuthor(s): Dietrick E. ThomsenSource: Science News, Vol. 102, No. 9 (Aug. 26, 1972), pp. 138-140Published by: Society for Science & the PublicStable URL: http://www.jstor.org/stable/3957354 .

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The MHD generator in the U-25 plant outside Moscow is designed to deliver 25 megawatts of electricity.

M H D : H i g h promise, unsolved problemsGeneratingelectricity directlyfrom hot conducting gases appears to offer a more efficientwayto use fuel reserves if problems of funding and technology can be solvedby DietrickE. Thomsen

"The power station of the future isworking," read a headline in Pravdaon Dec. 23, 1971. The reference wasto a 25-megawatt plant called U-25that generates electricity through themagnetohydrodynamic MHD) interac-tion of a very hot gas. MHD promisesto provide powerfrom fossil fuels withless pollution and greater efficiencythan conventional steam plants.Nothing comparable to U-25 existsin the United States, and yet, ironicallythe Russian program in MHD powergenerationwas heavilystimulatedby a1964 visit to the United States by V. A.Kirillin, now deputy chairman of theU.S.S.R. Council of Ministers andchairmanof the State Committee forScienceandTechnology.More recentlyEdward E. David Jr., science adviserto the Presidentof the United States,led a delegation to visit the SovietUnion in July as part of the imple-mentation of recent agreementson sci-entific and technological cooperation.Power is one of the main areas selectedfor cooperation,and one of the thingsthe David group was interested n see-ing was what the Russianshave donewith MHD in the eight years since Kiril-lin came to see what the Americanswere doing.

This is another in a continuing series ofarticles this year examining the potentialof new energy technologies. Previous arti-cles have consideredthermonuclear usion(SN: 1/8/72, p. 28), solar-energyconver-sion (4/8/72, p. 237), and hydrogen en-gines and fuel cells (7/15/72).In principle MHD power generationis simple. The idea is to replace themetal elements that conventionalgen-erators use to produce a currentwithhot electricallyconductinggases. In anordinary generator, metal armaturesare moved through a magnetic field by

rotation of the shaft on which they aremounted.The motion of the conductingmetal throughthe field causesthe elec-tric charges within it (its conductionelectrons) to begin flowing as a cur-rent. In an MHD generatorthe metalarmaturesare replaced by a very hotconductinggas. The motion of this gasacross a magnetic field causes itscharges to form a current, and thecurrent s collected by electrodesat thesides of the chamber n which the cur-rent is made.Arthur Kantrowitz,director of theAVCo Everett Research Laboratory inEverett, Mass., describes an MHD gen-

erator as "a rocketenginefiringinto amagnet."The MHD generatoromits twoenergy-losingparts of the conventionalcycle: making steam and turning aturbine. Conventional plants get effi-ciencies around 40 percent; 50 to 60percent is expected from MHD, espe-cially in an MHD-steam ombinationwhere the hot gas is used to makesteam for a conventionalturbineafterit leaves the MHD chamber.The rocket engine gives an impor-tant clue to the historyof MHD enera-tion. Although the principle has beenknown for a century,the gas tempera-turesrequired or anything ike efficientoperation of such a generatorhad towait for the developmentof the kindof technology that produced rocketengines.MHD ecamea laboratorypos-sibility in the early 1960's. By 1964AVCOwas working on some MHD gen-erators for the Departmentof Defense.The workwas classified.Westernscien-tists were organizing a Pugwash con-ference that year, and they wantedKirillinto come. Kirillin said he wouldif he could see the MHD work that wasgoing on. The work was obligingly de-classified,and Kirillin and a group ofRussians saw it. They were quite im-pressed, so much so, says Kantrowitz,

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that one of them took a penknife to asteel beam to make sure that the thingwas real and that they weren't beingshown a Potemkin village.In 1965, encouraged by their suc-cess so far, AVCO and other interestedfirms got together with the Governmentand suggested that if they could raise$13 million in private funds for furtherMHD research, the Government wouldmatch the amount. But when the pri-vate pledges had been received, theGovernment had lost interest. It was,says an AVCO pokesman, the "deathknell." Only a little work was done inthe United States during the next fiveyears.The reasons for the lack of interestseem to be that fission reactors, espe-cially breeders, were generally regardedas the power plant of the future inthe United States during those years.But gradually it became clear that fis-sion reactors were not doing as well asexpected. Public opposition to theirconstruction and public fear of breed-ers increased. Meanwhile there remainlarge supplies of fossil fuels, whichcould be used to help ease the fuelcrisis if more efficient and less pollut-ing means of employing them thanconventional boilers were available.For all these reasons and possibly moreanother look was taken at MHD in1969.That year the White House Office ofScience and Technology impaneled acommittee under the chairmanship ofLouis H. Roddis, chairman of theboard of Consolidated Edison of NewYork, to survey the whole energy situ-

ation. Considering MHD, the committeedetermined that its greater efficiencycould effect a saving of $1 1 billion infuel costs over a 15-year period. Thecommittee recommended spending $2million a year on MHD research.Kantrowitz refers to the $2 millionrecommendation as "a colossal nonsequitur." He estimates that in the yearssince 1964 the Russians have spent 10times as much as the United States onMHD. An AVCO scientist who visitedtheSoviet establishments last December,William D. Jackson, estimates thatmatching the current Soviet effortwould cost $50 million to $60 millionper year in the United States. The dol-lar equivalent of the U-25 installationincluding ancillary equipment is prob-

ably between $100 million and $150million, he figures.Neverthelessthere has been furthermotion in the United States. TheRoddis report led to a study by theMHD Power Generation Study Groupof Massachusetts nstitute of Technol-ogy, which recommendsa decade-longprogram of research and developmentaimed at showing whether a 1,500-megawatt MHD power plant burningcoal with an efficiency of 50 percentand a lifetime comparableto that ofa conventionalpower plant is feasible.(To demonstrate feasibility the pro-gramenvisionsactuallybuildinga 300-megawattplant which would be oper-ated under conditions of time and loadthat would simulate a 1,500-megawattplant.) Total cost of the program isestimated at $107 million, with $18million spent in the firstthree years.So far the plan remainsa plan, butthe budget for MHD research of theDepartmentof Interior'sOffice of CoalResearchis rising. It was $600,000 infiscal 1971 and $1 million in fiscal1972. For fiscal 1973 Congress hasmade it $3.5 million.How important s MHD regardedbythe physicscommunity?The new reportof the Physics Survey Committee ofthe National Academy of ScienceslistsMHD 11th of 69 programelements ina rating system it developedto assessthe extrinsicmerit of areas of physics.MHD was rated especially high in thecategories "ripeness for exploration,""potential contributionto technology"and "potentialcontributions o societalgoals."Controlledfusion was the onlyenergytechnologyratedhigher.Even if money for MHD comes inabundantly, here are still many majorproblems o be surmountedon the wayto the 1,500-megawatt plant. Eventhough the Russians have the U-25,they have by no means solved all theproblems,in the opinion of Americanswho have observed their operations.

TURBO MHDGENERATOR GENERATOR

GAs Low

Traditional generator with metal armatures is compared to MHD system.

AVCO Everett Research LaboratoryAVCO Everett's half-megawatt Mark VI is designed for long-duration tests.august 26, 1972 139

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The OST visitors in July came away withthe impression that U-25's operation todate is at power levels below the designlevel. Some of the problems come fromthe high operating temperature; somefrom the nature of the fuel, some froma combination of both factors.The temperature of operation needsto be above 2,600 degrees K. If com-bustion gases (from coal as envisionedin the United States or from naturalgas as done in the Soviet Union) areused, combustors that will supply themat these temperatures steadily over thelong term must be designed and built.Combustors are a large priority itemin the first three years of the MIT studygroup's program. (The only thing be-sides combustion gases that might beused would be exhaust from a thermo-nuclear fusion reactor, and they don'texist yet. Gases from fission reactorsare not hot enough.)The heat provides a very severe en-vironment for the solid materials usedin the generators. Getting rid of themoving parts helps some: Gas turbines,for instance, could not work at thesetemperatures because thermal effectswould foul up the clearances betweenmoving and stationary parts. But therestill remain difficult problems of com-patibility at the interfaces of differentmaterials.

The major problem that must besolved to ensure an economic lifetimefor an MHD generator s corrosion anderosion of the walls of the chamberand the electrodes. Most people in thefield seem to think specialcoatingswilldo it. Lately AVco has developed aprocesswhereby liquid zirconia is con-tinuouslysprayedinto the MHD cham-ber to coat the walls and electrodes.Company engineers have an experi-mentalmachine called Mark VI whichthey intend for a long-durationest: 20hoursat half a megawatt.The previouslong-durationest, an AVCOspokesmansays, was at only 10 kilowatts.Avco'sMarkV was able to produce 30 mega-watts, but for only a few seconds.Use of coal gases for fuel requiresdevelopmentof ways to removesludgefrom the MHD chamber.Natural gas iscleaner, but the United Staiteshas ashortageof naturalgas and an abund-ance of coal. Whatever the fuel, anumber of things must be processedout of the gas after it leaves the MHDchamber.First and foremost is the seedmaterial that has to be added to in-crease the electrical conductivity ofthe fuel gas. This materialwill mostlikely be potassium dioxide. It is soexpensive hat it mustbe recoveredandrecycledfor economicoperationof thegenerator.Getting back the seed will

provide an antipollutionbonus: It willrequirethe installationof very efficientelectrostaticprecipitators.Precipitatorsare not necessary to the operationofconventional plants, and there aremany complaints that power com-panies are sluggish about puttingthemon.As in all cases where coal is burnt,nitrogen oxides and sulfur oxides willbe produced and must be dealt with.Proponentsof MHD believethat, in partdue to the higher operatingtempera-tures, methodsfor removingthese pol-lutants can be developed that will bemore effectivethan those used on con-ventionalplants.The high temperaturealso means less thermalpollution:Thehigher the operating temperaturetheless heat the system rejects into theatmosphere.All in all the proponentsof MHD arepoised and ready. (The MIT studygroup found 26 institutions, private,nonprofit and public and 200 profes-sionalsplus supportingstaff that couldbe brought in at the beginning of anational program.) They are hopingthat current interest and the informa-tion exchanges with the Soviets maylead to a takeoff for the Americanprogram.But, says an AVCO spokesman,"We'restill waiting;it hasn'thappenedyet." 0

McGovern's science p i e : A n y n e w plums?McGovern nd Nixonboth want more relevant research but differ on what to sacrifice

by LouiseA. PurrettEvery four years the tribal councilsof the United States undergo a majorupheaval, and those who are not ac-tively promoting one potential chiefover another are wondering just howa change in government will affectthem, if at all. Though scientists as agroup are historically aloof from suchworldly matters,they have recentlybe-come a much more vocal group andoften take definite stands on political

issues. And indeed, since a large pro-portion of the money for research inthis country does come from the Fed-eral Government hey have a very realinterest n the outcome of the elections.The problem is to sift through themasses of verbiageand isolate just whateach candidate advocates on a givenissue, let alone what he'll do when hegets in office.President Nixon's science policieshave been before the public for fouryears.It is easier to figureout his poli-cies simply because they have takenthe form of concrete actions or non-

"Science is slowly dyingin this country."

Palevsky

actions. He has, for example, createda new agency to oversee research inoceans and atmospheresand has in-creased funding for several areas ofapplied research. Ft. Detrick, formerlydevoted to biological warfare is nowin the hands of cancerresearchers,andan intensifiedanticancerefforthas beenlaunched. Defense research is as biga giant as ever. In March Nixon sentthe first message by a President to theCongress on R&D. Its emphasis wason applying research o society's needs.

McGovern s another matter. He hashad less chance to influence sciencefunding and operations, so observersmust rely more on whathe says. As yetno coherent, official "McGovern Sci-ence Policy"has been released. A high-poweredgroup called Scientists or Mc-Govern is in the process of preparingposition papers on nine subjects thatMcGovern'sstaffthinks are most likelyto arise in the course of the campaign:space, energy, environmental controland protection, strategicweapons, con-version to a peacetime economy, em-ployment, transportation,housing andtechnological institutions (a study ofhow we fund science and technology).Scientistsfor McGovernwas formedabout six months ago and is headedby Harry Palevsky, a physicist atBrookhaven National Laboratory andHerbertYork of the University of Cali-fornia at San Diego. The organization'slist of sponsors includes six Nobellaureatesand, claims Palevsky, "all thepeople in physicsthat count."Palevsky

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