Like a flash of light in the cosmic darkness, this planet's fossil fuels will have disappeared—gone forever—within a few hundred revolutions around the sun : a mere fleeting event in its history.

L a i d d o w n as m u c h as 250 mil l ion years ago, the discovery, exploitat ion, a n d exhaus t ion of this relic of pr imeval jungle swamps occupies a t ime span so m i n u t e tha t a g r a p h of its use looks like a spike on a t ime axis extending to infinity in e i ther direct ion. Fossil fuel will have gone in a puff of smoke , leaving a c loud of smog to sett le.

So what ? I t will b e too bad , really, if we find later t ha t we could have done be t t e r th ings wi th fossilized vegetat ion. A t t he m o m e n t our machines m u s t b e kept moving , our boilers fired, our homes hea ted a n d lit. Energy is wha t m o d e r n civilization craves, and oil, coal, a n d na tu ra l gas are its cu r ren t sources .

T h e awareness of t he c r u n c h tha t is coming w h e n fossil fuels r u n ou t is steadily filtering t h r o u g h to our collective consciousness. T h a t t hough t , at one t ime dismissed to t he farther reaches of t he m i n d , is n o w coming tangibly close. P res iden t Car te r has t r i eee red t h e b ra in

cells of m a n y into ' fu ture shock ' w i th his project ion of a wor ld energy shor tage .

T h e first rescue m o v e is directed towards l iquid fossil fuel—oil. Fo r a n u m b e r of reasons, most ly involving convenience, l iquid fuels are preferred for mo to r vehicle engines . M o r e t h a n 6 0 % of Austral ia 's oil consumpt ion is u sed in t r anspor t and , as it h a p p e n s , oil will b e the first fossil fuel to r u n o u t — a n event t ha t could b r ing m u c h of t he t r anspor t as w e know it to a hal t .

Already, local oil p roduc t ion has levelled off and will short ly begin to decline, self-sufficiency having reached a m a x i m u m of 7 0 % . W i t h i n about 10 years we' l l be impor t ing more t h a n we p roduce ,

We still can't be complacent about our coal resources, using them indiscriminately.

a n d well before t he year 2000 (unless large n e w deposits are quickly discovered) domes t ic c rude will provide only a small fraction of total needs . M e a n w h i l e con­s u m p t i o n cont inues to increase, wi th n o sign of a t u r n - a r o u n d , widening the gap be tween needs a n d resources .

T h e cost of impor t ing all t he pe t ro l eum for our forecast needs in t h e year 2000 is impossibly h igh . I n t e rms of present prices it would be abou t $10 000 mil l ion, a n d we have n o guaran tee tha t supplies would b e available even if we could afford i t !

Sooner or l a t e r—depend ing on h o w well we eke ou t available pe t ro l eum resources—the wor ld ' s oil wells will r u n d ry .

N a t u r a l gas will keep th ings going for a b i t longer. A n d t h e n , of course , there ' s coal : oil f rom coal ; gas from coal ; energy of all sorts f rom coal! I n d e e d , coal should keep machines h u m m i n g for at least ano ther h u n d r e d years .

Coal provides a b rea th ing space. I t gives us t i m e to develop renewable or inexhaust ib le energy suppl ies—solar a n d wind energy, biofuels, even nuclear fusion if we learn how to make this viable. Howeve r . we still can ' t b e complacent

3

Husbanding our coal resource

s

abou t our coal resources , us ing t h e m indiscr iminately. T h e po in t is t ha t coal i sn ' t s imply coal. I t comes i n m a n y different varieties, each sui ted to different uses . Power stat ions can b u r n just abou t any th ing , b u t i t ' s p la in b a d sense to b u r n p r i m e coking coal in a power s ta t ion boiler. O t h e r special coals are bes t for p rov id ing oil, and others of super ior quali t ies are of special value for expor t a n d the foreign exchange i t b r ings .

I n this article, we out l ine t he s tudies of D r Geoff Tay lo r of t he C S I R O Div is ion of Minera logy , wh ich highl ight t he diversi ty of ou r coal resources a n d gauge h o w these resources m a t c h u p to t h e d e m a n d s likely to be placed u p o n t h e m . His s tudies , unde r t aken wi th his colleague D r M i c h i Shibaoka, indicate w h a t t he m o s t appropr ia te uses of Austral ia 's coal deposi ts appear to be . T h e y show t h a t t h e k ind of coal r equ i red is impor t an t , no t jus t t he a m o u n t . Only by apprec ia t ing such considerat ions can we act as res ­pons ib le s tewards of our vast , b u t finite, coal inher i tance .

I n t h e b e g i n n i n g

W h a t t h e n is coal, if i t 's no t mere ly black (or b rown) lumps of carbonaceous ma t t e r d redged from the g r o u n d ?

Jus t as an essential difference be tween rocks such as sands tone a n d grani te resides in t he minerals they contain , coals differ in t he type of p lan t remains tha t fo rmed t h e m . T h e s e componen t s , called 'macera l s ' , occur in coal in grains a n d layers of varied size a n d shape .

T h e mos t str iking way of mak ing the macerals appa ren t is to cu t a t h i n slice of coal a n d to examine it u n d e r t he microscope. F r o m a seemingly amor ­phous black l u m p , s t ruc tures of amazing pa t t e rn and detail t h e n spr ing in to view, pa in ted in r ich w a r m colours ranging from br igh t yellows to deep reds and b rowns . T h e t rue mean ing of coal be ing a fossil fuel t h e n leaps in to t h e cent re f ront stage of our m i n d s : coal is indeed a mass of fossils, t he remains of ancient p lan t life p reserved in microscopic detail . H e r e cell walls become visible, the re pol len grains . Somet imes larger s t ruc ­tures such as fern leaves or a t ree t r u n k can b e seen.

J u s t as fresh vegetat ion varies in the way it behaves w h e n b u r n t , depend ing on whe the r it is leaves, t runk , or root , so too coal varies according to t he sort of fossil vegetat ion i t contains. T h r e e major g roups of coal macerals (or p lan t remains) can b e easily dis t inguished. T h e y are vi t r in i te , exinite, and iner t ini te .

D o w e n e e d l i q u i d f u e l s f o r o u r c a r s ? T h i s o n e r u n s o n m e t h a n e g a s .

T h e a b a n d o n e d u r a n i u m - m i n e a t M a r y K a t h l e e n , Q l d . U n l e s s b r e e d e r r e a c t o r s a r e p e r f e c t e d , A u s t r a l i a h a s m u c h m o r e e n e r g y t i e d u p i n c o a l t h a n i n u r a n i u m .

C o a l d i s a p p e a r s i n t o t h e P o r t A u g u s t a p o w e r s t a t i o n . C o u l d w e d o b e t t e r t h i n g s w i t h i t ?

Vitr ini te is most ly der ived from w o o d tissues of t rees and s h r u b s — t h e stems b ranches , a n d roots . I t s n a m e alludes to t h e observat ion tha t v i t r in i te-r ich coal i often b r igh t wi th a vi t reous lustre . U n d e the microscope the botanical s t ructure inc luding sometimes individual cell walls becomes evident .

Vitr ini te can only have formed if the original p lan t debris was pro tec ted from biological decay t h r o u g h some agency such as a fungus. Fol lowing deposit ion t h e p lan t tissues have changed chemical ly a n d been compressed to such a degree t h a t a former t ree t r u n k has become a layer several cent imetres thick and a former twig become a pape r - t h in film.

Macera ls of t he exinite g roup also have special proper t ies tha t cause coals to differ accord ing to h o w m u c h of then they contain. Exini te is der ived from the waxy par t s of p lants—cut ic le , spores , an< pol len gra ins . As readers t ra ined in biology would know, t he outer tough leathery coat of a pol len grain is called t h e 'exine ' . Des igned to p ro tec t t h e pollen from damage and decay, t h e exine layer is preserved, often wi th remarkab le pe r -fection of detail , even mill ions of years after i t formed in to coal a n d was compressed .

T h e characteris t ic o rnamenta t ion or scu lp tu red surface Of pol len—designed to enhance t h e likelihood of t r anspor t by wind or insect—is often so well preserved in coal tha t fossilized exines can b e used to de te rmine t he geological age of the s t r a t u m in which they occur . U n d e r the microscope , exines show u p as b r igh t yellow b y t r ansmi t t ed light. P lan t cuticle — t h e waxy shiny layer on leaf s u r f a c e s -behaves similarly w h e n fossilized, and coal m i n e d today still shows the projec­t ions t h a t keyed in to the fleshy cellular s t ruc tures of t he leaf.

A few Austra l ian coals have an exinite con ten t of 1 0 % or m o r e and these are ideal for gas-making, since exinite car yield a relatively h igh p ropor t ion o: volati les, especially in low-ranking coals (discussed below). W h e n heated , exinite becomes very plastic (even fluid) and decomposes to gas, leaving comparatively litt le res idue. T h e gas t ends to b e r ich in h y d r o g e n a n d so has qui te h igh calorific value. W i t h some coals, especially those low in vi t r in i te , t he plast ici ty of t h e exinite p romotes t he format ion of coke f rom coal

T h e remain ing major const i tuents of coal are macerals of t he ' iner t in i te ' g roup r e m n a n t s of p lan t t issue t h a t were degraded chemically — such as by fungus—at t h e t ime the p lan t mater ia l

4

T h e m o n u m e n t t o o u r o i l d e p e n d e n c e — t h e r e f i n e r y .

en te red t h e coal s w a m p . Iner t in i te appears as microscopic fragments a n d larger charcoal-l ike layers, wh ich are essentially iner t du r ing coke formation. However , it b u r n s well and has a reasonably h igh calorific value.

R a n k a n d t y p e

Accompany ing the chemical a n d physical change , t h e macerals have unde rgone geological m a t u r i n g , in wh ich pea t first changes in to b r o w n coal, wh ich in t u r n m a y become b i tuminous coal and t h e n anthrac i te .

T h e dis tance t he coal has travelled along this p a t h is referred to as t he ' r ank ' of t he coal, a n d is usually descr ibed b y specifying the percentage of carbon in t he vi t r ini te macerals .

T h e ' t ype ' of coal is de t e rmined b y the na tu re and p ropor t ion of macerals present . A useful simplification is to specify t ype by measur ing t h e a m o u n t of vi t r ini te in t he coal fas a percentage of the volume) .

T o g e t h e r , t he type a n d rank of a coal give a fairly good indicat ion of its p r o ­per t ies . F o r example , since vi t r ini te in coal of b i tuminous rank becomes plastic w h e n hea ted , t he type ( amoun t of v i t r i ­nite) a n d rank (matur i ty of t he par t icular b i t uminous coal) will give a good ind i ­cat ion of h o w well a coal will form coke sui table for metal lurgical use . O t h e r proper t ies , such as yield of volatiles w h e n hea ted ( impor tan t for gas-making) or yield of tar (for some oil-from-coal processes) can b e descr ibed and , wi th in l imits , p red ic ted once type and rank are known.

W h a t h a v e w e g o t ?

Given this idea of some of t he ways in wh ich coals differ, let 's take a look at h o w Aust ra l ian coals fit in to t he pa t t e rn .

T h e m a p shows the location of coal­fields in this coun t ry a n d their p roved reserves. A l though Austral ia is reckoned to have only about 2 % of t he wor ld ' s coal resources , on a popula t ion basis we are

A b l a s t f u r n a c e a t W h y a l l a , S .A . C o k e d e r i v e d f r o m s p e c i a l c o a l s i s n e c e s s a r y f o r i t s o p e r a t i o n .

5

M a k i n g c o k e a t W h y a l l a .

r ichly endowed . O u r well-establ ished reserves are calculated at 480 X 1 0 1 8 J . T h a t ' s a lot of energy : even in t h e year 2000 (when the D e p a r t m e n t of Minera l s and Energy est imates we will b e us ing 4 X 1 0 1 8 J a year, or four t imes our cu r r en t usage) only 2 % of our available black coal a n d 1 6 % of available b r o w n coal will have been exhaus ted . Of course , this ignores t he possibil i ty of us ing coal for oil p roduc t ion .

T h e char t shows wha t massive reserves of coal we have in compar i son wi th those of o the r fuels, inc luding the u r a n i u m used in n o n - b r e e d e r reactors .

However , t he reserves are only est i ­ma ted . T h e figures d e p e n d very m u c h on t h e progress of explorat ion, so we can p robab ly expect large increases in p roved reserves in a n u m b e r of bas ins , such as Oaklands a n d in t he Sydney Basin, par t icular ly a r o u n d Singleton.

T h e thickness of coal deposi ts na tura l ly affects t he reserve est imates also. A r o u n d Singleton, coal seams m a y aggregate 38 m in thickness ; in o ther areas of t he Sydney Basin t he total thickness of coal is less than 4 m. Coal from th in seams is difficult to recover economical ly, a n d env i ronmenta l p rob lems associated wi th m i n i n g increase rapidly , since these p r o b ­lems a n d t h e m i n i n g area increase at similar ra tes .

T h e available tonnage of recoverable coal can also fall w h e n min ing competes wi th other uses of land, such as u r b a n deve lopment . T h a t ' s no t an over- r id ing factor, since t he t o w n can be shifted—as Yal lourn will b e — b u t t he cost is great . A l though coal occurs benea th Sydney , we are no t likely to see it m o v e d !

Such schemes as remote minings perhaps by hydraulic methods, need to be studied.

Some seams contain coal of inferior qual i ty , possessing too m u c h minera l ma t t e r ei ther as di r t bands or in finely divided form. T h i s m a y make the coal uneconomic to mine and use , or may rule out its in tended use al together . S o m e Austral ian coals contain p h o s p h o r u s , which makes t he coke m a d e from t h e m unsui table for blast furnaces because t h e i ron reacts wi th t he phosphorus .

G e t t i n g d o w n t o i t

Some deposits lie at so great a d e p t h t h a t they m u s t b e ru led out in calculating recoverable reserves. F o r example , a massive b i tuminous coal deposi t of 3 . 6 mill ion mill ion tonnes occurs in t he Cooper Basin, b u t at dep ths far too great to mine at p resen t—1000 m a n d deeper . However , its very magn i tude and qual i ty should s t imulate effort towards new ways of recovering it.

Such schemes as r emote min ing , pe rhaps by hydraul ic m e t h o d s , need to be s tudied. I n t h e hydraul ic scheme , a p ipe is dr iven down to t he coal a n d water ejected from it at h igh pressure breaks u p the coal, wh ich is b r o u g h t to t h e surface t h r o u g h another p ipe . Ano the r idea tha t has long been discussed is u n d e r g r o u n d gasification; par t ia l combus t ion of coal at d e p t h creates t empera tu res tha t d e ­compose t he coal to form gas, wh ich is p iped to t he surface. T h e Americans are p lanning to apply the i r P loughshare program—involv ing the peaceful use of a tomic explosions—to achieve a similar resul t . A n u n d e r g r o u n d nuclear explosion

in a coal seam would vaporize t he coal a n d leave a huge cavity filled wi th gas t h a t could be later p iped to t h e surface.

However , our immedia te concern shou ld be to improve me thods of extract­ing coal at depths less t h a n 500 m. M a n y older u n d e r g r o u n d mines are now reaching near this d e p t h and striking p rob lems . T h e s e mines usually began operat ion at t he r i m of a basin whe re t he coal seam angles u p towards t he surface, mak ing coal recovery easy. T h o s e near Newcas t le , at t he edge of t he Sydney Basin, are an example . However , having exhausted all the coal nea r t he surface, t h e mines m u s t follow t h e angle of t he coal seam d o w n to greater dep ths in t he di rect ion of t he bas in cent re .

At these greater dep th s , keeping the roof of the mine from falling becomes more difficult. Such roof p rob lems can resul t from certain geological s t ruc tures tha t weaken the strata above the coal seams. Prob lems of ' bad r o o f have m e a n t tha t typical min ing rates of 10 m per shift s l ump to only a m e t r e or so at dep ths of 400 m. I f t he roof becomes especially difficult to suppo r t in one par t icular area, min ing from the re m a y have to b e abandoned . As a resul t , all t he coal in t he seam d ipp ing d o w n beyond tha t area becomes inaccessible and lost to recovery or, in min ing jargon, 's teri l ized' .

T h e quant i ty of sterilized coal has t e n d e d to increase wi th increased m e c h a ­nizat ion, a n d so in t h e H u n t e r Valley, for example , some mines have been a b a n ­doned wi th mos t of the coal still in t he g round .

A n y loss of large resources of h igh -quali ty coal is a nat ional loss, no t just a company mat te r , s ince it makes nonsense of our reserve figures.

T w o csiRO Divisions have been look­ing a t this p rob lem. T h e Divis ion of

Y a l l o u r n t o w n s h i p ; i t w i l l b e s h i f t e d t o g e t at t h e c o a l u n d e r n e a t h .

6

Mine ra l Physics has been a t t empt ing to correlate t h e appearance of surface pa t t e rns revealed in satellite photos wi th geological faults and m i n i n g difficulties encoun te red u n d e r g r o u n d . T h e y h o p e tha t cer ta in surface features m a y allow geologists to make a good predic t ion of be low-ground stabili ty. T h e Divis ion of Appl ied Geomechanics is s tudy ing the bes t way of tackling b a d roof p rob lems once they are encounte red .

All in all, t hen , our s ta ted reserves should b e t rea ted wi th caut ion. M o r e ­over, once we take a figure, it is impor t an t to look-at h o w this total a m o u n t is d iv ided be tween t h e different sorts of coals. T h e bes t way of doing this is to categorize our coal resources according to rank a n d type . I f we d r aw a g r a p h tha t shows rank in

one direct ion and type in t he other , we e n d u p wi th someth ing like t h e d iagram on this page , wi th t he a m o u n t of coal of each sort be ing shown b y the he ight of t he peak. Deposi t s of less t h a n 300 mil l ion tonnes have been omi t ted .

M a k i n g t h e m o s t o f i t

N o w tha t we can see wha t we 've got , wha t can we do wi th these coals ? D u r i n g t h e rest of this cen tu ry our coal will p robab ly have th ree ma in uses : for coke-making , for electricity generat ion, and for convers ion to l iquid a n d gaseous fuels.

Each of these processes requires pa r ­t icular , and often different, sorts of coal.

Firs t ly , to make coke, t he coal m u s t b e of a certain rank a n d m u s t also have a fairly h igh content of vi tr ini te ( the maceral

tha t becomes plastic on heat ing) . T h i s narrows the available Austra l ian coals to those located in t he s t r iped area on our r a n k - t y p e diagram. I n addi t ion , t hey m u s t b e low in phosphorus and su lphur , and have as little minera l ma t t e r as possible.

T h e Austra l ian steel indus t ry will have a steadily increasing d e m a n d for coking coal, a l though there ' s p robab ly enough a r o u n d to mee t our own requ i rements . Bu t J apan a n d other countr ies are likely to wan t more too , a n d we m a y r u n in to local supply prob lems long before any nat ional shortage. Fo r example , reserves of t he vi t r ini te-r ich Wongawil l i seam in t he Sydney Basin are insufficient for future demands . Alternat ives m a y be to resor t to t he coal f rom t h e Bowen Basin in Queens land or to separate ou t t h e vi t r ini te fraction from coal used for power generat ion. (Vitr ini te is m o r e br i t t le t h a n the o ther coal macerals , so t h e finer f ragments of c rushed coal are r icher in it.)

Turning to coal for electricity generation, we can be thankful that just about any sort of coal will do.

A n o t h e r al ternat ive is t o make formed coke, a coke subs t i tu te m a d e f rom low-vitr ini te coal. However , ne i ther this a l ternat ive 'nor the use of char , gas , or t he direct reduc t ion of i ron ore appears likely to displace conventional coke before t h e e n d of this century .

T u r n i n g to coal for electricity gen ­era t ion, we can b e thankful t ha t jus t abou t any sort of coal will d o , since power stations are easily t he biggest coal con­sumers at present . T h e p r i m e r equ i r e ­m e n t is for an assured supply to last t h e life of t he stat ion. Preferably it shou ldn ' t leave too m u c h ash, a n d the fly-ash should b e efficiently cap tu red b y electrostatic prec ip i ta tors . Such coals m a y b e located a t any pos i t ion on our t y p e - r a n k diagram, b u t clearly w e shou ldn ' t b u r n t he type of coal in power stations tha t is needed for o ther purposes . T h i s means that we should no t use the mater ial represen ted b y the s t r iped area on our d iagram.

I n pract ice , however , some coking coal m a y have to b e b u r n t in t h e Sydney Bas in : the N e w c a s t l e - S y d n e y - W o l l o n -gong conurba t ion here requi res so m u c h electricity, yet non-cok ing coal forms less t h a n half of t he resource (a l though fu ture explorat ion could change the p r o -

7

M e c h a n i z a t i o n h a s t e n d e d t o i n c r e a s e t h e a m o u n t o f c o a l t h a t h a s b e c o m e ' s t e r i l i z e d ' — i n a c c e s s i b l e t o f u r t h e r m i n i n g .

por t ion) . T h e answer m a y b e deeper , h igher- recovery open-cu t mines or p e r ­h a p s , again, we shou ld separate t h e vi t r ini te and b u r n t he remainder .

A n o t h e r suggest ion is to use t h e washery rejects p r o d u c e d f rom t h e wash­ing of coking coal as fuel for electricity generat ion. T h e C S I R O Divis ion of P r o ­cess Techno logy is invest igat ing this possibili ty. A pilot-scale f luidized-bed combus to r designed b y the Divis ion is present ly demons t ra t ing tha t t h e rejects of low-calorific value can b e b u r n t effi­ciently and tha t t he res idue is a p romis ing road- a n d br ick-making mater ia l .

A l though it would b e qui te uneconomic to t r anspor t sui table coal f rom dis tant fields to supply t he power s ta t ion boilers on which mos t Aust ra l ian cities d e p e n d , t r anspor t of coal to J a p a n for its boilers is expected to begin soon. T h i s u n d e r ­taking could expand rapidly , pu t t i ng a s t ra in on our own r equ i r emen t s . E x ­po r t ed s teaming coals are likely to b e low-vitr ini te coals of b i tuminous rank,

N o t e n o u g h i s k n o w n a b o u t t h e s t a b i l i t y o f u n d e r g r o u n d c o a l - m i n e s f o r m i n i n g t o p r o c e e d a t p e a k e f f i c i e n c y . R e s e a r c h o n t h i s p r o b l e m h a s b e g u n .

since these have a h igher calorific value t h a n lower-rank coals.

C o n v e r t i n g i t ?

T h e subject of us ing coal to make oil is s t r ewn wi th doub t s . Never the less , D r Tay lor finds it h a r d to see h o w Austral ia can cont inue to the e n d of the cen tu ry wi thou t a large conversion p r o g r a m , r equ i r ing enormous quanti t ies of coal. Even so , if we were t o t u r n all t he black coal current ly mined in Austral ia in to oil, we would only make enough for one -fifth of our p resen t oil consumpt ion . T h e social, envi ronmenta l , a n d economic impacts of such an under t ak ing are daun t ing .

T h e real p rob lem, t h o u g h , is t ha t we d o n ' t yet know the best way of t u r n i n g coal into oil. On ly one oil-from-coal p lan t is opera t ing in t he wor ld—the S A S O L works in S o u t h Africa. Yet one th ing is clear so far, and tha t is tha t various sorts of coals need different t r ea tmen t s t o opt imize conversion efficiency. A lot of

research is going on to find ou t m o r e ab o u t t he conversion process .

I t is especially impor t an t t h a t Austral ia under take research to ascertain h o w ou r o w n coal resources are bes t conver ted.

Broadly , t he re are t h r ee m a i n conver­sion processes : gasification a n d synthesis , in which coal is gasified by react ion wi th s t eam and oxygen and t h e n synthesized to l iquids ; pyrolysis , i n wh ich coal is hea ted in t he absence of gases to p r o d u c e tar a n d a res idual c h a r ; a n d hydrogen-at ion, in wh ich c rushed coal is mixed wi th solvent (and somet imes a catalyst) a n d hea ted to make a c rude oil and solid res idue. T h e s e processes are descr ibed in m o r e detail in Ecos 5.

Indica t ions to da te , however , are tha t only a few Austra l ian coals are ideally su i ted to convers ion to l iquid fuel. T w o s t and p u t : t he Gre ta coals in t he H u n t e r Valley of N e w Sou th Wales a n d coals like those at M i l l m e r r a n in sou the rn Q u e e n s ­land. Both have a h igh con ten t of exini te ( the waxy por t ion) and a low con ten t of t he ' iner t ' c o m p o n e n t of inert ini te . T h e y are of b i t uminous rank , have a compara ­tively h igh con ten t of h y d r o g e n , and give a h igh yield of volatiles.

Any oil-from-coal plant should be set up close to a power station that can use the residue.

Unfor tuna te ly , t h e recoverable r e ­serves of t h e G r e t a coal are p robab ly no t large e n o u g h for t h e very large-scale opera t ions convers ion typical ly requi res .

O the r coals, generally poorer in exinite, can b e used , albeit somewhat less easily. T h e y occupy t h e shaded area of our t y p e - r a n k diagram. Some of these coals show two desirable characterist ics.

Fi rs t ly , they have a low conten t of iner t in i te , wh ich is, in general , less reac­t ive t h a n the o ther macera ls , and a h igh con ten t of vi t r in i te , wh ich is reactive. Secondly , they have progressed i n rank to t h e stage where the i r mois tu re con ten t is reasonably low ( sub-b i tuminous coals), b u t have no t advanced to t h e stage whe re the i r yield of volatiles is too low (b i tumin­ous coals of relatively low rank) . O n e of ou r few resources of this sort of coal occurs nea r S ing le ton ; this deposi t has very large reserves as yet vir tually u n ­t o u c h e d .

T h e s implest way of get t ing oil f rom coal is b y pyrolysis , s ince this doesn ' t

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O p e n - c u t m i n e s a t M o u r a , Q l d ( l e f t ) , a n d

r equ i re any pressure vessels (while o ther m e t h o d s requ i re con ta inment of t he gases involved).

T h e p r o b l e m is tha t it yields relatively litt le l iquid. F lash pyrolysis , whe reby the coal is rapidly hea ted , enhances t he yield considerably. Eve n so, a substant ia l res idue of solid char will r emain . T h i s res idue could b e b u r n t in power s ta t ion bo i l e r s ; al ternatively, it could b e h y d r o -genated or gasified and l iquids synthesized f rom the gases.

T h e s e last two processes are m o r e complex , b u t they do allow convers ion of coal t ha t contains a large p ropor t ion of iner t ini te , or has a low rank. C o n ­sequent ly , t he S A S O L oil-from-coal p lan t in Sou th Africa follows a gasifi­ca t ion-synthes is rou te because it uses a coal h igh in iner t ini te as a raw mater ia l .

Hydrogena t ion proceeds fairly readi ly on the vi t r ini te a n d exinite fractions of low- to modera te - rank coal, b u t to get t he iner t ini te to react will p robab ly r equ i re m o r e ex t reme condit ions a n d the use of a catalyst.

Wha teve r process is used , and at t he m o m e n t we have insufficient informat ion on which to base a choice, it leaves some sort of solid res idue. Apparen t ly , t h e r e ­fore, any oil-from-coal p lan t should be set u p close to a power stat ion tha t can use t he res idue . Separat ion of t h e exinite a n d vi t r ini te macerals f rom the coal will he lp to ease t he restr ict ions on the sorts of coal sui table for a par t icular process a n d increase efficiency. Again , m o r e research is needed here .

W h a t ' s b e s t ?

W h a t does al l this add u p t o ? Perhaps t he clearest conclus ion—apar t from h igh ­l ighting our lack of knowledge of coal proper t ies—is tha t d e m a n d will b e s t rongest for coals near t he t o p central pa r t of our t y p e - r a n k diagram. T h e s e are t he h igh-vi t r in i te coals of b i t uminous

C o l l i e , W . A . ( r i g h t ) .

rank. So it seems sensible to avoid us ing these for electricity generat ion. A t t h e p resen t t ime some of these coals are being so used , notably in t he Sydney Basin.

T h e huge a m o u n t of coal needed for convers ion to l iquid fuels points to t h e conclusion tha t we shou ld min imize ou r consumpt ion of oil. Conservat ion is cheaper t h a n conversion.

W e can conserve fuel in m a n y ways. One way is to no t bo the r abou t conver t ing coal to oil at all. D r Geoff Gar t s ide of t he C S I R O Divis ion of Chemical Techno logy regards l iquid fuel as a convenience we could do wi thout . Accord ing to h i m , there ' s n o reason w h y stat ionary engines need l iquid fuel, and gas converters can be a t tached to vehicles as they were in war ­t ime . W e can t h e n make coal last longer by no t wast ing abou t half its energy in conver t ing it to l iquids . Electr ici ty f rom coal-fired power stations could be used for electric cars and for comfort heat ing.

Ano the r al ternative for saving energy is to gasify coal on t he coal-fields at a r o u n d 8 0 % efficiency and to p ipe it to its po in t of use (pipelines are cheaper

. . . there's no reason why stationary engines need liquid fuel.

t h a n high-vol tage t ransmiss ion lines). Was te heat p r o d u c e d at electr ici ty-gener­at ing sub-stat ions could t h e n be dis tr i ­b u t e d to nea rby homes and factories. Yet ano ther idea is to a d d powdered coal to fuel oil to eke out suppl ies . Charcoal has also been suggested.

All these considerat ions mer i t serious evaluation, b u t w h o finally makes t he decisions about wha t coals should b e used for wha t purpose ?

A n impor t an t init iative in energy p l ann ing tha t has recent ly been taken is t h e es tabl i shment of a Na t iona l Ene rgy Advisory Counci l to advise t he Min i s t e r for Nat iona l Resources on Austral ia ' s energy requ i rements and resources .

At t h e t i m e of wri t ing, C S I R O is abou t to receive t he findings of its own Energy Review Commi t t ee . T h i s body , c o m ­pr is ing exper ts from outs ide C S I R O , was set u p to advise t h e Organizat ion 's Execut ive abou t where research on energy is mos t needed .

I f we don ' t begin to conserve a n d h u s b a n d our fossil-fuel resources , t h e prospects for living in t h e m a n n e r to which we have become accus tomed—in energy terms—looks as black as coal.

M o r e a b o u t t h e t o p i c

T h e rat ional use of Austral ia ' s coal resources . G. H . Tay lo r a n d M . Shibaoka. Proceedings of the Institute of Fuel, Biennial Conference, Sydney, November 1976, 1977.

M a k i n g oil f rom coal. Ecos N o . 5, 1975, 3 -9 .

Coal convers ion research in Aust ra l ia . R. A . D u r i e . Proceedings of the Third International Conference on Coal Re­search, Sydney, October 1976, 1977.

Coal research in Austral ia 1976. Pro­ceedings of the Third International Conference on Coal Research, Sydney, October 1976, 1977'..

Coal Research in CSIRO, N o s . 8, 9, 10, 16, a n d 45 . ( C S I R O Minera l s Resea rch Labora to r i e s : Sydney 1959-71.)

T o t a l gasification of solid fuels to i m ­p r o v e energy ut i l izat ion. K . M c G . Bowling a n d P . L . Wate r s . Proceedings of the Institute of Fuel, Biennial Conference, Sydney, November 1976, 1977, 7 .1-7 .14.

Deminera l i zed b r o w n coal as an al terna­tive to cu r ren t hydroca rbon resources . K . M c G . Bowling and H . Rottendorf . Technical Conference of the Institution of Engineers, Australia, M R B 102, 8 6 - 9 1 .

T h e energy cost of prospect ive fuels. G . Gar t s ide . Search, 1977, 8, 105-10.

T h e t he rma l efficiency of selected coal-convers ion processes. J . H . E d w a r d s . Proceedings of the Institute of Fuel, Biennial Conference, Sydney, November 1976, 1977, 11.1-11.15.

P roduc t ion of gaseous a n d l iquid fuels f rom coal. R. A. D u r i e and I . W . Smi th . Proceedings of the Australian Institute of Mining and Metallurgy Symposium on Australian Black Coal, Wollongong, February 1975, 161-72.

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