Development of the Direct Injection Carbon Engine (DICE)

Louis J Wibberley

Leader, Advanced Carbon Power,

CSIRO Energy Technology, Mayfield West 2304, Australia

Email: louis.wibberley@csiro.au

Abstract

Firing coal directly into internal combustion engines was proposed by Rudolf Diesel in 1892, the

promise of which launched the development of the Diesel engine by MAN. Since then, the engine has

been the subject of a number of development programs, initially with dust firing, and then with

micronised refined coal slurries (MRC). The most comprehensive program was undertaken for the US

Department of Energy (USDOE) over 1978–92 for locomotives and small scale generation - and as an

alternative to fuel oil. Although the technical issues were overcome, the program was terminated due to

low oil prices and before a commercial engine was developed. Recent changes to economic and

industry drivers provide DICE with new advantages, as a considerably more efficient, nimble and

adaptable coal generation technology than is possible with current coal-fired steam plants or

gasification based technologies. It is also twice as efficient as stand-alone technologies which presently

utilise solid biomass fuels. This paper reviews developments and details a recent Australian program

on 3rd

generation DICE for base load, load following and distributed generation to compete with

conventional coal, fuel oil and natural gas technologies.

Key words: micronised refined carbon, MRC, diesel engine, DICE, high efficiency

INTRODUCTION

Renewed interest in DICE is because, size-for-size, DICE is the most efficient means of converting

carbon-based fuel energy to electricity, especially for low rank coals. Since the USDOE program, there

have been important changes to both economic and industry drivers; including carbon penalties, the

need to support a step increase in intermittent renewables, changes to the structure of the electricity

supply industry, energy security issues, the need to be capture ready and capture efficient, and the

shortage of cooling water. These changes provide DICE with new advantages, and overall it offers a

considerably more efficient, flexible and adaptable coal power generation technology than is possible

with current coal-fired steam plants or gasification based technologies. It is also approximately twice as

efficient as current stand-alone technologies using biomass fuels.

Advantages of DICE include:

A step reduction in CO2 intensity of around 20–30% for black coal, and 30–50% for brown

coals, and doubling of the CO2 benefit of biochars.

High efficiency at small unit size (smaller and easier investment steps).

Lower capital cost at $1200–2000/kW (about half that of supercritical pulverised fuel plants)

which, together with tolerance to load changes, makes stop-start operation for peak and backup

duty a practical and economic option for coal-based generation. Unlike natural gas turbines, this

flexibility can be provided without losing efficiency or increased maintenance.

Allowing ultra-efficient use of opportunity biofuels, particularly biochar, to further reduce the

net carbon footprint. For example, MRC could be co-fuelled with char to provide a sweetener

for char by improving its ignition and combustion.

Providing an enabling technology for CCS, by enabling bolt-on integration of CO2 capture, with

a substantially lower energy penalty, and without significant power output de-rating.

Presented at the 38th Clearwater Clean Coal Conference, 2-6 June 2013

Maintaining rating under hot arid and high altitude conditions, and with low overall water use

(only used for fuel production, at a rate which is similar to that for a dry cooled pf plant).

The paper gives a brief review of developments over the last 110 years, including more recent

development towards the 3rd generation fuel cycle which aims to compete with base load coal and

natural gas load following, and fuel oil for distributed generation.

HISTORY OF DICE

Development of the diesel engine was initiated by Rudolf Diesel’s proposal to use coal in a compression

ignition engine in 1892. However, shortly afterwards he abandoned coal as a fuel and concentrated his

work on oil fuels. Serious work on coal-fuelled diesel engines was renewed in 1911 by Rudolf

Pawlikowski, a former co-worker of Diesel.

After solving many technological problems, four firms, including Pawlikowski’s firm Kosmos, reported

the successful operation of 19 engines from 6–400 kW and engine speeds from 160–1600 rpm. It is

noteworthy that these small engines obtained thermal efficiencies approximately 200% that of the much

larger steam power plants of the time. All of these 1st generation engines used dust firing – either by

aspiration/fumigation into the inlet air, or by air blast injection[1]

. Little development of fuel processing

is reported from this period, with the engines using commercially available coals, coke and charcoals

(biochar) – some with up to 12% ash, and with engine operation up to 8,000 hours.

Following World War II, abundant low-cost oil removed the economic incentive for further

development until the early 1970s, when coal-diesel mixtures were investigated as fuel extenders –

mostly in small high-speed engines. A short series of tests was also undertaken in Europe using large

slow-speed research engines at Sulzer Bros (now Wärtsilä) and at Burmeister and Wain (now MAN

B&W) using unmodified engines. Chronic wear of injector nozzles was experienced which resulted in

severe cylinder wear. It is now speculated that the coal-diesel mixtures used in these early tests would

have given very poor combustion due to agglomeration of the coal particles – leading to cylinder wall

contamination and piston ring jamming from unburnt coal.

A short test series with coal water slurries (ie MRC) was also reported by Sulzer in 1982[2]

, with better

results. These tests led to a larger development program by the USDOE over 1982–92, involving

AMAX (fuel production), Cooper-Bessemer/Arthur D Little, Sulzer, General Electric, Adiabatics,

General Motors ElectroMotive Division, Detroit Diesel Corporation, and Southwest Research Institute.

The program not only defined economic and technical conditions under which engines could be

commercialised, but also advanced the state of the art through pilot testing of both fuel production and

engines.

In comparison to the earlier developments, the USDOE program focussed entirely on pressure

atomisation of MRC with excellent results:

MRC was produced by a range of processes, including milling and flotation, selective

agglomeration, dense medium separation, solvent refining and chemical cleaning, with ash

levels of 1–3% being achieved.

Durable injection systems were developed for medium speed engines (400–1000 rpm) with

atomiser nozzles giving a life of several thousand hours, and cylinder/rings up to 8,000 hours.

A Cooper-Bessemer prototype engine was demonstrated with these technologies (a six-cylinder,

1.8 MW engine) with two hundred hours of continuous engine testing, and a cumulative

1050 hours of engine testing during component development[3]

.

Similar developments were achieved by General Electric using a heavy haul GE Dash 8

locomotive on the Morgantown test track[4,5]

.

Processes for producing low ash MRC were developed based on integration of a special cleaning

module with conventional mine mouth coal preparation plant. Conventional coal cleaning

technology was used (mostly by dense media cyclones), and a full-scale modular MRC storage

and handling system was also demonstrated.

Key technological issues

The use of coal in engines requires addressing a number of technological issues, many of which are

critical to producing a commercial engine with acceptable longevity and R&M requirements. While all

issues were considered in the comprehensive USDOE program over 1978-92, and should be easier for

the larger engines and lower speed engines being targeted in the current initiatives, all remain as areas of

consideration. This is because the measures required depend on trade-offs between fuel quality and

engine modifications, and the technology solutions need to be reassessed in the context of developments

in ultra-hard materials and manufacturing over the last 20 years.

The following gives a summary of key issues (in decreasing order of significance), effects and

measures:

MRC production cost In past programs, the cost of coal processing has significantly reduced the

cost advantage of DICE over the fuel oil engine, and was the main factor in

terminating the USDOE program with falling oil prices in the early 1990s.

For most MRC, micronising is likely to represent ~60% of fuel production

cost. Recent initiatives have the advantage of large and efficient

commercial scale bead mill technology (eg the Isamill) which has proved

highly effective for coals, and improvements in fine coal cleaning. Both

allow cost effective recovery of MRC from tailings, and provide a step

reduction in MRC processing cost over that in the early programs.

Atomiser nozzle wear Consistent and effective atomisation is the most critical issue for coal fired

diesel engines. Poor atomisation leads to a sequence of phenomena which

can destroy an engine within hours: it increases the droplet size, resulting in

slow ignition, late burning and incomplete combustion, and also increases

fuel jet penetration. All of these factors will result in raw or partially

combusted coal depositing on the cylinder walls, resulting in chronic ring

jamming and rapid cylinder wear. While MRC slurry can be effectively

atomised by using high injection velocity, this causes rapid atomiser nozzle

wear which ultimately reduces atomisation quality.

Solutions include diamond compact or sapphire nozzles, and the use of

lower speed engines with increased time for combustion and therefore a

higher tolerance to coarser atomisation.

Air blast atomisation is also being considered by CSIRO for next generation

paste fuelled engines.

Ring jamming Particles of ash and coal deposited on the cylinder walls are continually

scraped by the action of the piston rings. If the particle loading is

sufficiently high, these particles accumulate and pack behind the piston

rings causing chronic ring scuffing and rapid wear. Unburnt coal is

expected to be particularly difficult in this regard, due to the presence of

tars which exacerbate ring sticking.

To date, the most effective control measure has been to ensure effective

atomisation and correct injection profile to avoid exposure of the cylinder

walls to fuel spray. However, it is likely that other design factors (eg ring

contact profile) will also be important, and that solutions for 4-stroke

engines will be different to those for 2-stroke engines employing total loss

cylinder lubrication.

Abrasive wear Abrasive wear of the cylinder, rings and ring grooves has been shown to be

chronic for unhardened engines. A range of technological solutions were

demonstrated during the USDOE program using plasma spray coatings, in

particular tungsten carbide. Use of these coatings is now more wide spread

for larger engines, and, whilst increasing the cost of engine components, is

likely to be the key enabling technology for DICE. Other measures include

the use of larger bore engines which will reduce wear/wear effects due to

increased clearances and a proportional reduction in cylinder area for a

given engine capacity.

Ignition/ignition

delay

Rapid ignition after injection is critical to reliable and efficient diesel

operation. Fuels that exhibit a long ignition delay (say 20 ms for low speed

engines) can produce shocks from excessively rapid pressure rise early in

the combustion event, and a peak pressure that exceeds the mechanical

limits of the engine. Overheating and ring failure can also occur. This

requires engine derating, which increases engine cost per MW and reduces

thermal efficiency.

An extreme case of failure can occur if ignition does not occur, say due to

poor atomisation or failure of an atomiser nozzle. With coal, catastrophic

engine failure from hydraulic lock would occur within seconds from the

resulting deposits of fuel mud in the combustion chamber.

To avoid these issues, pilot injection with diesel fuel was used in many of

the USDOE pilot engines. Whilst acceptable for starting and warm-up, for

normal operation this reduces the cost advantage of DICE, and it is

expected that other measures will be developed to ensure consistent

ignition, and to guard against ignition failure.

Recent CSIRO work has shown that the ignition delay for MRCs is around

5 ms (and better than most heavy fuel oils), providing that good atomisation

is achieved. The CSIRO work has also shown the benefits of air blast

atomisation for achieving a very short ignition delay and a step

improvement of atomisation quality – even with highly viscous MRC.

Exhaust valve seat

wear

Chronic wear has been observed for conventional valve materials, however

it is expected that the ultra-hard materials will avoid this issue. These

valves are already available as an option for many large engines, but are

usually not justified.

Fuel system

blockages

Due to the high solids loading of MRC, it can block orifices and other parts

of the fuel system when the fuel is stagnant for more than a few seconds,

especially with hot atomiser nozzles.

Proven solutions include recirculation fuel delivery systems, flushing the

fuel system with a water-based fluid during engine shut down, and avoiding

rapid cross sectional area changes in the fuel lines (dead spots). It is

generally assumed that flushing with diesel fuel is not appropriate as it

results in immediate agglomeration of the coal.

Some fuel formulations with unusual gel-sol behaviour are more prone to

blocking, and this phenomenon requires more fundamental research to

develop better dispersants.

Fuel stability Coal water fuels are inherently unstable and given sufficient time will

settle. Stability and fuel handling equipment and procedures has received

extensive consideration in the commercialisation of coal water fuels for

boilers. While this is generally applicable to MRC for DICE, the lower

solids content of MRC makes stability a bigger challenge. Solutions

include correct formulation of dispersants (more is not necessarily better)

and the use of paste-type fuels, with minor dilution with water immediately

prior to use (viz using a fuel preconditioning module – as is employed for

most heavy fuel oils).

Fouling This has received scant attention, probably because ash fouling has not been

reported as an issue. A complete lack of fouling is unexpected, as coal

cleaning processes only remove the extraneous mineral components in coal,

leading to flyash with proportionally higher amounts of deleterious

Combustion of biochar MRC (10 MPa, 700°C)

elements (Na, K, S, Cl, Ca, Mg) from the original coal – a condition certain

to cause fouling in combustion devices. However, past engine tests

totalling several thousand hours, including continuous operation periods of

over 100 hours, have not observed cylinder or turbocharger fouling.

Compared to boilers (and gas turbines), the lack of fouling has generally

been attributed to the highly cyclic heat flux within reciprocating engines:

cylinder surfaces are only exposed to gases (say above 800°C) for ~10% of

the cycle, and the temperature of the metal surfaces is lower (mostly below

300°C). It is also noted that the lack of fouling from coal in diesel engines

was the main reason for terminating development of the coal fired gas

turbine in favour of the diesel engine in the late 1970s - which resulted in

the comprehensive USDOE coal engine program.

Fuel system

corrosion

Although corrosion rates from sometimes low pH MRC can be reduced by

pH control, it is expected that corrosion resistant fuel systems will be

essential (as required for some biofuels). This will avoid the need for

complete corrosion protection by fuel additives/pH control – both would

further complicate achieving the optimum fuel rheology.

RECENT R&D – AUSTRALIAN CONTEXT

Over the last four years there has been strong interest in DICE, and CSIRO has been involved in a

number of projects to assess MRC production and its use in a converted diesel engine. The basis for this

work is the potential for DICE to be the lowest cost and lowest CO2 coal generation technology, and to

provide flexible coal-based power to support a high penetration of renewables.

From a coal industry perspective, these benefits could create new markets for domestic and export

thermal coals, and give the option of recovering MRC economically from coal washery rejects and

higher ash bituminous coals. The cost and energy for MRC processing is more than offset by these

benefits. Similar opportunities are being pursued for both black and brown coals, including the potential

to export brown coals as MRC paste (brown coals are not exported, because unprocessed they contain

too much water, and dried they are pyrophoric and difficult to ship – even as briquettes).

Another potential new market (interest by Maersk, D/S Norden and SEACO) is fuelling the global

deepwater shipping fleet with coal (a market of around 250 Mtpa carbon equivalent), which, with a

small amount of biochar co-firing, can achieve a carbon footprint below that of fuel oil, but at

significantly reduced cost.

In contrast with previous work, the main R&D objective has been to produce low cost MRC with

sufficient quality to enable DICE to compete with new base load pf power plants, and with a target

thermal efficiency of 50% HHV basis. Much of the R&D has been into producing MRC with a

relatively high coal content compared to previous studies, and with an ultimate target of 65wt% solids

from black coals, and 60% from brown coals.

In general the R&D has provided excellent results (though more work is required to meet some of the

aspirational targets and to understand the fundamentals):

Suitable MRC has been produced from 17 carbon sources (black and brown coals, coal tailings

and biochar), with solids contents of up to

60 wt%.

Good atomization has been achieved for

fuels up to 700 mPa.s @ 100/s, and most

MRC were found to exhibit shear thinning

up to injection shear rates of 200,000/s.

Both black and brown coal MRCs have

given excellent ignition and combustion

characteristics under engine conditions,

with ignition delays ranging from 5–10 ms (comparable to fuel oils).

Biochar (eucalyptus) gave the longest delay of around 15 ms, and, although tolerable, these can

be shortened and combustion improved by sweetening with black or brown coals to improve

engine performance (both efficiency and output). The figure shows biochar MRC combusting

into a laboratory high pressure spray chamber.

Full-scale injector spray tests have been undertaken using tonne batches of MRC from black and

brown coals.

Solutions have been identified for adapting

fuel systems and managing engine wear.

Tests have shown that Victorian coals and

flyashes actually exhibit anti-scuffing

lubricity properties.

Preheating can be used without affecting

rheology, and therefore substantially

reduce the slurry water penalty on thermal

efficiency.

On an LCA or fuel cycle basis, MRC-

DICE should be more energy efficient than

for fuel oil (and have a similar CO2

intensity).

DICE (30–110% load) has a similar CO2

intensity to open cycle natural gas (at full

load). With biochar co-firing, even lower

carbon intensity could be achieved.

Short-duration engine operation has been achieved with a small laboratory engine, and the use of

electronically controlled injection will allow the engine to operate at all loads without auxiliary

ignition sources. Run duration was limited by the use of steel injector nozzles – ceramic nozzles

are required for longevity, but the complication of manufacturing these is not warranted as the

engine is too small to be a practical research tool for the large engines targeted.

A novel atomisation system has been

identified for brown coal pastes involving

ultra-efficient blast atomisation. This

system promises to reduce atomiser nozzle

wear by at least an order of magnitude, and

allow the use of higher solids (paste-like)

brown coal MRC; the figure shows a brown

coal paste fuel jet (at 10 MPa chamber

pressure).

Technology options have been identified for

bolt-on integration of highly energy

efficient CO2 capture. This could be

achieved without significant de-rating of

power output, and ultimately at a cost below

likely Australian carbon taxes[6]

.

Preliminary MRC fuel specifications have

been developed in conjunction with MAN

Diesel and Turbo, who are the lead engine

manufacturer assessing DICE.

A regenerative pumping arrangement has been identified to reduce the pumping energy for

hydrothermal processing.

Proposals have been developed for several fast-track pilot projects as the first step of a staged

development program which aims to see DICE a commercial reality by 2020. These have been

Large injector tesing (in air) with tonnage MRC

Mid shot (t=5 ms) air blast atomisation of brown

coal MRC paste

developed with a range of partners for the demonstration of a medium-speed four-stroke engine

at Delta Electricity’s Munmorah site[7]

, and of a low-speed two-stroke engine at a Latrobe

Valley power station site[8]

.

DEVELOPMENTS IN MRC PRODUCTION FROM COAL

DICE requires cost-effective production of ultra-low ash coals. Although the cleaner the better, detailed

coal specifications for large diesel engines remain unclear. The earlier USDOE work concluded that

coal with 2–3% ash was suitable for DICE. After collaborating with MAN, the ash target is currently 1–

2%, but will be a trade-off between processing cost, and engine and maintenance costs. Depending on

engine speed, MRC should have a top size of around 50 µm, a coal concentration of at least 55%, and

enable effective pressure atomisation. However, it is likely that as DICE develops, coarser and higher

solids MRC will be preferred – reducing processing and transportation costs, and improving engine

efficiency and output.

Bituminous coals

For black coal, the MRC process can use a variety of technologies all commercially available and well

known to the industry. All involve micronising to increase mineral liberation, followed by

flotation/selective agglomeration or dense medium separation.

These processes have been used in a number of past studies[9-12]

. While in the past there was no ready

market for ultra-fine wet coal (dewatering to product normal moisture specifications being uneconomic),

with DICE, ultrafine wet coal is now alright.

Note that micronising before de-ashing also avoids needing to micronise clean product MRC before the

engine, thereby avoiding fuel contamination by the grinding media. Overall, this approach gives an

improvement over the processes used for the USDOE program.

In practice, there will be many options for producing MRC, including starting with washed coals

through to scavenging MRC from tailings streams, and blending of biochars, for example as shown

below.

Options for black coal-MRC production

MRC is somewhat similar to the coal water fuel produced for boilers and gasifiers in China, where

conversion of combustion equipment to use cleaner and more efficient coal water fuel receives a range

of subsidies, leading to rapid growth of the industry over the last few years to over 100 Mtpa. Although

similar, MRC has a finer grind, lower ash specification, and slightly lower solids content. The Chinese

boiler fuel is significantly more viscous than that specified for DICE – at least with conventional

pressure atomisation; see images below.

Low rank coals

Low rank coals have received far less attention for DICE. It is generally assumed that processing will

need to reduce the porosity of the coal (eg by hydrothermal processing, roller/press compaction, or

both). As it is unlikely that surface selective separation techniques (eg flotation or selective

agglomeration) will be suitable for low rank coals, especially Victorian brown coals, size/density

separation would be used for a de-sanding step.

These processes have been successfully tested by Exergen, JGC Corporation and in the current Brown

Coal Innovation Australia (BCIA)-CSIRO R&D project. It is noted that most of the ash formed from

Victorian coals is from organically bound elements in the coal, and not mineral ash (this can be as low

as 0.3%), and that the de-sanding step is mostly to remove relatively coarse sand entrained during

mining operations.

After de-ashing/de-sanding and hydrothermal treatment, it is necessary for partial dewatering of the fuel

to achieve the required solids concentration, followed by micronisation.

For all coals, formulation may then be required with small amounts of dispersant/stabiliser to obtain the

required rheological properties (low viscosity, high stability). The stability specification will depend on

the transportation and storage requirements, and end application (for example, for captive MRC-DICE

plants, fuel stability is unlikely to be an issue). The amount of dispersant required varies greatly with

the coal and dispersant used, and is typically 0.05-0.5wt%.

ENGINES FOR DICE

Although a wide range of engines have been

used to fire MRC, including up to 1900 rpm, it

is generally accepted that the lower speed

engines are most suitable: the low-speed two-

stroke marine type engines (10–100 MW at 90–

120 rpm) and largest four-stroke medium-speed

engines (20 MW at 400-500 rpm). This is due

to their longevity and tolerance to lower quality

fuels (such as residual fuel oils which contain

up to 0.15% of highly abrasive corundum-like

catalyst fines), to allow easier MRC fuel

specifications – higher mineral ash content,

coarser coal top size, higher viscosity. The

choice of engine will be site and application

dependent: while the low-speed engine has

slightly higher efficiency and lower

Left, coal water fuel for a boiler by JGC[13]

; right, MRC for DICE

50 MW engine and generator (MAN)

maintenance costs, the cost of these engines is higher at around $1.8 M/MW compared to $1.2 M/MW

for medium-speed engines.

Despite being a mature technology, these engines continue to undergo development that will further

improve their suitability for MRC firing (eg higher firing pressure, electronic control, more efficient

turbochargers, new materials and adaptations to enable the use of alternative fuels such as biofuels and

bitumen water fuels). The new electronically controlled (ME) variants are being implemented as

“intelligent engines” with auto-tune ability – perfect for maximising efficiency with MRC.

The use of bitumen water emulsions and slurries in diesel engines provides a good analogue for MRC.

Over the last 20 years there have been a number of initiatives to produce bitumen water fuels to replace

HFO in boilers, and these fuels have also been used in diesel engines. Such fuels include Orimulsion

produced from natural bitumen, and MSAR[13]

(multiphase superfine atomised residue) produced from

refinery residue (an extremely heavy tar).

Wärtsilä has extensive experience with firing Orimulsion into medium-speed engines (including a

40 MW demonstration power plant at Vaasa and a 150 MW power plant in Guatemala). Wärtsilä expect

that MRC will need similar adaptations[14]

.

MSAR was developed as an Orimulsion replacement, and is an MRC of solid bitumen particles in

water. While it is a very difficult fuel, giving both poor atomisation and ignition, and contains highly

abrasive catalyst fines, it is being used in adapted engines. It is of note that recent CSIRO work shows

that, given reasonable atomisation, MRC from coal has superior combustion characteristics to MSAR

(and also compared to many heavy fuel oils).

Another interesting possibility is the potential to adapt dual fuel low- and medium-speed gas

reciprocating engines to future DICE operation, an adaptation that is not possible with gas turbines: the

choice of appropriate reciprocating engines to burn gas now, may provide the future option to convert to

MRC if higher gas prices eventuate.

A number of engine manufacturers are currently interested in DICE for applications ranging from new

base load capacity, down to 5 MW backup capacity. MAN Diesel and Turbo have engaged with a

number of MRC proponents and are the industry leaders. MAN have also established a staged program

to assess DICE, complete with a specially adapted low-speed 1 MW single cylinder test engine[15]

.

While all manufacturers have some previous negative experiences with coal fuelling of engines, all

acknowledge that the previous work was undertaken without a high level of commitment, and none of

the programs were completed because the expected scenario of oil shortages did not materialise or

funding ceased. Future developments will clearly benefit from recent experience with Orimulsion and

MSAR, the extensive experience from the USDOE program for black coals, and more recently by

CSIRO’s R&D for both black and brown coals and chars.

Suitable adaptations have been considered by two large engine manufacturers, and examples are shown

below, noting that several of these have already been developed for bio-oils. A fuel testing program is

underway with an engine manufacturer to develop fuel specifications, and to identify a suitable engine

for a demonstration plant.

INTERESTED GROUPS

A number of organisations are presently investigating MRC-DICE in Australia, Europe, Japan and

South Africa; examples are given below:

BCIA-CSIRO with

industry stakeholders

High efficiency power from Victorian brown coals; a consortium is

being established to undertake a staged development program leading to

a Victorian demonstration of DICE and export of brown coal MRC

ESKOM, various South

African mining

companies

A range of interests, including the use of DICE for remote generation.

Exergen Development plans to produce MRC and other products from CHTD

for both Victorian generation and export

Ignite Energy Development plans for efficient production of liquid transport fuels

from brown coals, and using DICE to utilise the CatHTR char (the

residue from coal-to-liquids processing).

InterTech Ultra-low ash coal produced by chemical processing of black coal for

all applications, including marine.

JGC Use of DICE as a new application for JCF boiler fuel from JGC

hydrothermal dewatering technology. 24t/day pilot plant operating in

Indonesia for lignites[17]

.

MAN Diesel & Turbo Established a staged program to assess DICE in association with fuel

production projects by Exergen, Newcrest, Xstrata and others[16]

.

Monolith Group Several DICE proposals in the Southern Africa region through various

partnerships.

Newcrest Assessing DICE to replace diesel generation for large gold mines.

RWE Assessing DICE for providing load following and backup capacity with

a high penetration of renewables.

Wärtsilä Assessing commercial merit and development of DICE in the context of

extensive experience with Orimulsion type bitumen-water slurries[15]

Xstrata-CSIRO Development of black coal MRC for DICE. Xstrata have a 1 t/day

MRC pilot plant at Bulga NSW[18]

Yancoal/UCC Use of chemically cleaned coals in DICE. Pilot engine tests at

Cessnock.

CURRENT APPROACH TO DEVELOPMENT

DICE needs considerable development and demonstration to match the technical development of current

technologies, but has strong technical merit because of the ability to carry out a near-commercial scale

demonstration at a relatively small size (around 10 MW), both quickly and at relatively low cost. Even

so, a staged development program has been devised with MAN for both black and brown coals to de-

risk the demonstration projects proposed for 2015. The nominal program is envisaged as follows:

2015-16 Pilot tests and initial development using a 1 MW single cylinder test engine,

firing MRC from pilot plants in the Hunter Valley and Victoria/Indonesia.

2017 Development and design of relevant components and systems for a prototype

engine.

2019 Demonstration-scale operation of MRC production with a prototype engine.

Consortia are being established for two possible demonstration projects: a

medium speed four-stroke engine demonstration at Delta Electricity’s Vales

Point Power Station, and a low-speed two-stroke engine demonstration in the

Latrobe Valley. Both demonstrations will provide near full-scale experience to

enable the next step of a commercial engine.

2019-20 Establishment of first commercial engine at site(s) and ongoing refinements.

The program aims to implement step improvements in technologies across the DICE fuel cycle that will

result in commercialisation of DICE in its 3rd

generation. These include technologies to give a step

reduction in the cost of MRC production, up to a 10 fold increase in cylinder size, and optimisation of

combustion using the latest electronic engine controls, but with an otherwise standard engine layout; see

figure below. In addition to the development of the 3rd

generation cycle, parallel R&D has also

commenced for the next generation DICE fuel cycle, one that is fully optimised for solid carbon-based

fuels, and with integrated CO2 capture.

Generations of DICE development: 1892-2013 and beyond

FUTURE DEVELOPMENT - HOLISTIC APPROACH NEEDED

To date, R&D has focused on the two key technically difficult areas – coal cleaning and combating

engine injector tip and cylinder wear. As the MRC-DICE fuel cycle is new, broad engagement of

stakeholders along the entire fuel chain is needed to ensure that all areas of technical risk are identified

and addressed:

Stakeholders are required both to support the proposed pilot and demonstration projects, and to

ensure long-term development of the technology and the new fuel cycle – internationally for

maximum global benefit.

Development requires full engagement of the coal and generation industries to provide both the

fuel and demonstration projects necessary for commercial deployment. Also a close relationship

is required with the engine manufacturers to integrate RD&D to optimise the needs of the engine

with the MRC quality that the industry can economically produce for different applications,

including understanding the value-in-use of MRC and the trade-off between engine R&M,

performance and cost with fuel production cost –for current and future engine designs.

Optimisation of the fuel processing chain for different applications and other benefits; eg

increased grade recovery of coal, support for renewables, ability for small-step staged

implementation, integration benefits with CO2 capture, water and CDM-type benefits.

Although MRC is higher quality than coal water fuels for boilers, the growth in China and

interest in Indonesia and India provides a ready market for higher ash MRC to help establish

logistics, and to break the chicken-and-egg nexus between MRC and DICE.

A key advantage of DICE is its potential to be an enabling technology for CCS (using post-

combustion capture or oxy-firing approaches), and much more work is required to investigate

this important adaptation.

As a first step towards addressing these requirements, an international

DICE development network www.dice-net.org has been established.

This organisation aims to support the development of the DICE fuel cycle

at both national and international levels, including the MRC supply chain

for a range of carbon sources.

20

40

60

1900 2000

Generation 1<0.1 MW/cyl

dust firing

Generation 20.3 MW/cyl

slurry firing

high cost MRC

Generation 31-5 MW/cyl

minimal adaption

slurry firing

low cost MRC

Generation 41-20 MW/cyl

optimised/intelligent

paste/slurry firing

optimised MRC

CO2 capture

biofuel co-firing

Distributed power Distributed generation

large land transport

Base, peak, distributed gen

large marine transport

Eff

icie

ncy (

en

gin

e o

nly

, L

HV

)

CONCLUDING COMMENTS

The diesel engine offers a range of important advantages for low emissions electricity generation from

coal and other carbon-based fuels. While excellent results have been achieved using a range of

coals/biochars and processing conditions, this new fuel cycle requires a more holistic approach to

establish the value-chain logistics necessary for commercial development. It is ironic that Diesel’s

promise of utilising coal in an engine provided a game changer for the development of the diesel engine

… finishing what Rudolf Diesel started now provides a game changer for coal and other carbons for

power generation, underpinning a high penetration of renewables, and it also provides a new market in

fuelling the global shipping fleet.

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