Roadmap for Australian Electricity Generation

8/11/2019 Roadmap for Australian Electricity Generation

1/18

ESSAYRoadmap for Australian

Electricity Generation


2/18

TABLE OF CONTENTS

Table of contents I

1. Introduction 1

1.1. Australias energy profile 1

2. Carbon capture and storage 3

2.1. CO2 capture techniques 3

2.1.1. Post combustion 3

2.1.2. Pre combustion 42.1.3. Oxyfuel combustion 4

2.2. CO2 storage 4

2.2.1. Structural storage 5

2.2.2. Residual storage 5

2.2.3. Dissolution storage 5

2.2.4. Mineral storage 5

2.3. Geological sites 5

2.3.1. Deep saline formations 5

2.3.2. Coal seam 6

2.3.3. Depleted oil and gas fields 6

2.4.Projects underway 7

3. Enhanced oil recovery (EOR) 7

4. Trigeneration Systems 9

4.1. Prime mover 9

4.1.1. Gas powered prime mover 11

4.2.Cooling technologies 13

5. Conclusion 14

6. References 15

I


3/18

1. INTRODUCTION

Australia as a nation relies heavily on coal to satisfy its energy needs. This

reliance has led heavy CO2 emissions which are becoming a serious concern.

There is a dire need for Australia to rethink its electricity generation plan for the

future.

This essay proposes a roadmap for the future of Australian electricity generation

taking into consideration various options like renewable energy, carbon captureand storage and government policies. My proposal focuses initially on the process

of carbon removal and then on trigeneration systems which have better

efficiencies and lower emissions compare to conventional power plants.

1.1.Australias energy profile

The desire for higher life standards and comfort levels along with

technological advancement and growing population in the last threedecades have led to a steep increase in the worldwide energy consumption.

The total primary energy consumption has increased from 4948.66 MTOE

in 1970 to 12476.63 MTOE in 2012. While Africa has the least share of 3.2%,

Asia Pacific leads the energy consumption with 40.01% in 2012. Europe &

Eurasia consumes 23.47% of the total primary energy closely followed by

North America at 21.84% [1].

Conventional fossil fuels are still the dominating source of fuel in 2012. Fig.

2 represents the primary energy world consumption by fuel type and the

reliance on fossil fuels is clear. Oil, natural gas and coal make up for 86.9%

of the worlds fuel usage while nuclear contributes 4.49%, hydroelectricity

6.6% and renewables make up just about 1.9% [2]. As per the Australian

energy update by BREE, the energy consumption by renewables has fallen

by 7.3% from 2010-11 to 2011-12 [3].

Page 1


4/18

This heavy reliance on fossil fuels has lead to an increase in CO2 emissions.

The global energy-related CO2 emissions increased by 1.9% to 34.47

gigatonnes in 2012 compared to 2011 [1].

Fig. 1. World Primary Energy Consumption by fuel types [4]

30% of the total energy consumption is accounted for by the buildingsector. Energy used in buildings is mainly for electric power, heating and

cooling/refrigeration needs [5]. It hence becomes important to reduce

energy usage or increase efficiency. Most of the power buildings receive are

from power plants employing fossil fuels; coal is predominantly used in

Australia. These power plants are known to have high rates of energy losses

mostly in the form of heat. Coal power plants convert 39% of the available

heat to electrical power [6]. Additional losses during transmission along

Page 2


5/18

with huge infrastructure costs mainly borne by the customers, emphasises

on the need for more efficient and cost effective technologies.

2. CARBON CAPTURE AND STORAGE

Carbon Sequestration (CS), also termed as Carbon Capture and Storage (CCS) is a

method of capturing carbon from industries such as energy or oil and gas

industries, compressing it and then storing it in the earths crust at sufficient

depth to make sure it remains there indefinitely.

It involves various stages, first one being capture, in which the carbon dioxide is

captured from flue gases and other sources using an appropriate process. Once

the carbon is captured it needs to be transported to the required site for storage.

For easier transport, the carbon dioxide is pressurised and liquefied. There

already exists mature technology that is needed for this transport. The final stage

involves injection of the captured carbon dioxide into the earths crust. There are

various mechanisms by which this can be injected. The injected carbon dioxide

can also be used to recover oil and gas that could not be reached during previous

exploration from already exploited gas and oil fields.

There are various natural ways as well to conduct carbon sequestration. Plants act

as a reservoir for carbon dioxide. Increasing plantation can also help in reducing

the carbon dioxide content from the atmosphere.

2.1.CO2 capture techniques

2.1.1. POST COMBUSTION

Separation of Carbon dioxide from other flue gases after combustion

is known as Post Combustion capture. This separation can be done

by solvent absorption or by using membrane or adsorption

technologies.

Page 3


6/18

Post Combustion CO2capture using special chemicals called amines

is the most commonly used process. The CO2 rich gas (power plant

exhaust) is passed through an amine solution. The CO2 bonds with

amines, while other gases pass through the solution. This solution

hence has CO2 captured and is pumped into a stripper where the

captured CO2 is extracted. The solution containing amines can be

recycled [7].

2.1.2. PRE COMBUSTION

As is the case in Post Combustion capture, Pre Combustion capture

also has various processes like solvent absorption, adsorption and

membrane separation.

Once coal is gasified, the produced syngas then enters an absorption

column. In the absorption column, the gas comes in contact with the

solvent, which absorbs the CO2. The CO2rich solvent is pumped into

another column known as the stripping column while the other gases

leave out of the absorption column. CO2 is released from the solvent

by heating it to 120C. The CO2that emerges is cooled at the top of the

tower so as to remove traces of water and solvent. The solvent is then

used again for the absorption process [8].

2.1.3. OXYFUEL COMBUSTION

Also known as oxyfiring, it is the combustion of coal in pure oxygen

instead of air, mostly used in conventional steam generator. The CO2

in the exhaust is highly concentrated due to the fact that no other

gases are introduced in the combustion chamber. This method is

relatively easy in capturing and compressing CO2, though it is still in

testing stages [9].

2.2.CO2 storage

Page 4


7/18

2.2.1. STRUCTURAL STORAGE

When CO2 is pumped underground, as it is more buoyant than water, it

will rise up through the porous rocks. As it rises, it will eventually reach

a layer of impermeable layer of cap-rock under which it gets trapped.

Plugs made of steel and cement can be used to seal the holes drilled to

pump in the CO2 [10].

2.2.2. RESIDUAL STORAGE

Residual rocks behave much like a tight, rigid sponge. As we know that a

sponge has to be squeezed several times before all the air in it can be

replaced with water. Similarly when liquid CO2 is pumped into these

rocks, they get stuck within the pore spaces of these rocks and do not

move [10].

2.2.3. DISSOLUTION STORAGE

CO2 dissolves in salty water, which makes it heavier. This water that has

CO2 dissolved in it and is heavier than the surrounding water, sinks to

the bottom of the rock formation [10].

2.2.4. MINERAL STORAGE

The salt water that has CO2 dissolved in it is weakly acidic and can react

with surrounding minerals forming new minerals. The new minerals

that are formed form a coating on the rocks around it. The process caneither be quick or very slow and it binds the CO2 to the rocks [10].

2.3.Geological sites

2.3.1. DEEP SALINE FORMATIONS

These are underground formations of permeable reservoir rock, such as

sandstone. The formations are covered with impermeable cap rock and

Page 5


8/18

contain very salty inside. Only at depths below 800m, CO2 formations in

deep saline formations are expected.

They are widely distributed and are frequently close to concentrated

sources of man-made CO2 emissions in cities and industrial zones. There

is a lot of potential capacity available in saline formations across the

world. However, a great amount of assessment work is needed to prove

their suitability for CO2 storage.

2.3.2. COAL SEAM

Coal steam storage involves another form of trapping in which the

injected CO2 accumulates on the surface of in situ coal, thereby

displacing other gases like methane.

Coal seam storage is considered to be feasible when undertaken with

enhanced coalbed methane recovery where in the production of the coal

seam methane is assisted by the injected CO2. Permeability of the coalseam also impacts the effectiveness of the technique.

2.3.3. DEPLETED OIL AND GAS FIELDS

Depleted oil and gas fields are geologically well defined and well

explored. These are known to have proven ability to store hydrocarbons

over extended periods of time (millions of years). This process is

discussed further in detail in the following sections.

Australia completed in 2011 all elements of its CO2 injection and

storage framework at the federal level for offshore storage. Three of its

states have state-level legislation in place to regulate onshore storage

(Victoria, South Australia and Queensland), and one state (Victoria) also

has a legislative framework for offshore CO2 storage in its jurisdiction.

In addition, The Barrow Island Act 2003 is project-specific legislation

that was enacted solely to regulate the CCS activities associated with the

Page 6


9/18

Gorgon project in Western Australia. The Western Australian

government is now in the process of developing broader CCS regulation

through amendments to the existing Petroleum and Geothermal Energy

Resources Act 1967, building on knowledge gained from the application

of the Barrow Island Act. [11]

2.4.Projects underway

List of projects underway in Australia [12]:

Callide Oxyfuel Project, Queensland;

CarbonNet Project, Victoria;

South West Hub Project, Western Australia;

The CO2CRC Otway Project, Victoria; and

Gorgon Project, Western Australia

3. ENHANCED OIL RECOVERY (EOR)

Shell has joined a research project exploring CO2-driven enhanced oil recovery

(CO2-EOR) in the North Sea.[13]

We anticipate significant growth in CO2 supplies available to the EOR industry.

Overall CO2 utilisation by CO2-EOR (including both industrial and natural CO2)

will nearly double by 2020to 6.5 bcfd by 2020 from 3.5 bcfd in 2014 [14]

Three phases of oil production exists: primary, secondary and tertiary. EOR is the

tertiary approach, which increases the production from a well up to 75%. Three

main categories of EOR have been found to be of successful application:

Page 7
http://www.globalccsinstitute.com/projects/12416http://www.globalccsinstitute.com/projects/12651http://www.globalccsinstitute.com/phttp://www.globalccsinstitute.com/projects/12646http://www.callideoxyfuel.com/What/CallideOxyfuelProject.aspx


10/18

Thermal Recovery To lower the viscosity and improve the ability to flow, heat

is introduced in to the well. The introduction of heat can be done through

injection of steam. Over 40% of US EOR production is done using this method.

Chemical Injection In order to increase the efficiency of water flooding or to

boost the effectiveness of surfactants, which are cleansers that help lower

surface tension that inhibits the flow of oil through the reservoir, long chained

polymers are introduced into the reservoir. This technique is not commonly

used as its effectiveness is unpredictable and high costs are involved.

Gas Injection gases such as carbon dioxide, nitrogen or natural gas, which

expand in the reservoir, are used. The compressed gas is pumped in and once it

expands, it either pushes the additional oil out of the wellbore or it dissolves in

the oil, subsequently decreasing its viscosity and increasing its flow rate. This

method is widely used as CO2 is readily available and it is cost effective. Nearly

60% of the US EOR production is done by this method.

Fig 3. Schematic diagram of CO2-Enhanced Oil Recovery (Source: http://www.worldcoal.org/

coal-the-environment/carbon-capture-use--storage/ccs-technologies/ccs-technologies-more/)

Page 8


11/18

The gas injection method discussed above is used for two benefits at the same

time. It helps in storing carbon dioxide while recovering the otherwise hard-to-

recover oil. Once all the oil is recovered and the well is filled up with carbon

dioxide, it can be sealed and it is sure to stay there for a significant period of time.

4. TRIGENERATION SYSTEMS

Trigeneration systems or CCHP (Combined Cooling, Heating and Power) systems

are those which produce electricity, heating and cooling from a single source of

fuel. These primarily consist of a prime mover running on a conventional fuel,

electric generator, a heat recovery system and an absorption chiller for cooling

needs.

4.1. Prime mover

Page 9

Power System Electricity

Heat Recovery

Thermally driven

refrigeration

Heating

Cooling/

refrigeration

Fuel


12/18

A prime mover is what drives a trigeneration system. It converts fuels

energy to useful mechanical work. Following is a comparison of various

prime mover technologies available which are primarily divided into two

categories, combustion based and electrochemical based. Some of the

technologies like reciprocating engines and gas turbines are in a mature

stage and widely available, while others are relatively new and in

development stage.

Table 1. Comparison of different trigeneration prime movers [15]

Page 10


13/18

4.1.1. GAS POWERED PRIME MOVER

Considering all the above criterions and feasibility, for our analysis

gas powered prime mover is chosen. Though fuel cells have better

part load efficiencies, higher lifetimes and low noise levels, gas

turbines are a better option as they have higher capacities along with

lower investment costs, lower footprints and comparable efficiency.

Page 11


14/18

Also, the lack of maturity of fuel cell technology makes gas turbine

an ideal choice.

Table 2. Key performance parameters and cost estimates [16]

A gas turbine CCHP consists usually of a generator, compressor and

turbine connected by a shaft, combustion chamber, recuperator and

an absorption chiller [17]. A heat recovery system is used to recover

heat from the hot exhaust gas. For different commercial and

industrial applications, various gas turbine systems ranging from

several hundred kilowatts to several hundred megawatts are

available. To serve small scale applications, recently, micro turbines

have also been developed which put out 30 - 400 kW [18]. Systems,

using regenerative Brayton cycle and high speed centrifugal turbo

machines are considered as potential alternatives to the conventional

ICE systems, especially for small scale applications [17]. Gas turbines

are more compact and require less maintenance compared to ICE

based systems. Hot gases released from gas turbines at 250C can

Page 12


15/18

easily drive thermally activated cooling technologies like absorption

chillers [19].

4.2.Cooling technologies

Of all the cooling technologies, absorption cooling is mature and well-

established. It has been in use for many years now in numerous cooling and

air conditioning applications. An absorber, generator, condenser and

evaporator are the four main components that make up an absorption

cycle. Absorption cycle uses the heat supplied to compress the refrigerant

vapour while conventional systems would use a rotating device or

compressor. Based on the number of times the heat is utilised within the

system, absorption cooling systems are classified in to single effect, double

effect and triple effect systems. Lithium bromide-water and water-

ammonia are the most commonly used working fluids.

Page 13


16/18

5. CONCLUSION

The future of our electricity generation does not depend only on the above

mentioned technologies. The technologies discussed above concentrate of

removal of existing carbon dioxide and reduction of emissions immediately.

Carbon capture and storage is of prime importance as we already have critical

amounts of carbon dioxide in our atmosphere which needs to be removed in order

to avert from the extreme consequences of global warming.

Carbon capture and storage alone is not enough as we do not have long supplies of

fossil fuels remaining. Focus also has to shift towards developing renewable

technologies which will be the future. Wind, geothermal and solar energy is most

abundant in Australia and it could hold the key to the future of our electricity

needs if economical electricity transportation methods are developed.

Nuclear energy is also a reliable option for a country like Australia. Australia

possesses vast amounts of barren flat land which are calamity free and ideal for

nuclear plants. The biggest advantage of nuclear energy is the fact that Australia

has substantial Uranium resources, all of which it currently exports.

In conclusion, the future lies in a balanced use of all the available technologies

and also government policies.

Page 14


17/18

6. REFERENCES

1. Statistical Review of World Energy 2013. Available from: http://www.bp.com/content/dam/bp/excel/Energy-Economics/statistical_review_of_world_energy_2013_workbook.xlsx.

2. Statistical Review of World Energy 2013. 2013; Available from: http://www.bp.com/content/dam/bp/pdf/statistical-review/statistical_review_of_world_energy_2013.pdf.

3. 2013 Australian Energy Update - July 2013, BREE, Editor. 2013.

4. Energy Charting Tool. [cited 2014; Available from: http://www.bp.com/en/global/corporate/about-bp/energy-economics/statistical-review-of-world-energy-2013/energy-charting-tool.html.

5. Stephan, A. and R.H. Crawford, A multi-scale life-cycle energy and greenhouse-gasemissions analysis model for residential buildings. Architectural Science Review, 2013.57(1): p. 39-48.

6. Power Generation from Coal - Measuring and Reporting Efficiency Performance and CO2Emissions. 2010; Available from: http://www.iea.org/publications/freepublications/publication/power_generation_from_coal.pdf.

7. POST-COMBUSTION CAPTURE OF CARBON DIOXIDE. Available from: http://www.co2crc.com.au/dls/factsheets/Post_comb_Solvent.pdf.

8. PRE-COMBUSTION CAPTURE OF CARBON DIOXIDE. Available from: http:// www.co2crc.com.au/dls/factsheets/Pre-comb_Solvent.pdf.

9. About CCS. Available from: http://www.co2crc.com.au/aboutccs/capture.

10. Carbon Capture & Storage Technologies. Available from: http://www.worldcoal.org/coal-the-environment/carbon-capture-use--storage/ccs-technologies/ccs-technologies-more/.

11. Technology Roadmap Carbon capture and storage. Available from: http://www.iea.org/publications/freepublications/publication/TechnologyRoadmapCarbonCaptureandStorage.pdf.

12. CCS in Australia. Available from: http://www.globalccsinstitute.com/location/australia.

13. Shell joins carbon capture project. 2014.

14. Oil and Gas journal. Available from: http://www.ogj.com/articles/print/volume-112/issue-5/drilling-production/co-sub-2-sub-eor-set-for-growth-as-new-co-sub-2-sub-supplies-emerge.html.

15. Jradi, M. and S. Riffat, Tri-generation systems: Energy policies, prime movers, coolingtechnologies, configurations and operation strategies. Renewable and Sustainable EnergyReviews, 2014. 32(0): p. 396-415.

16. Gas Market Report, October 2013. BREE.

Page 15


18/18

17. Arteconi, A., C. Brandoni, and F. Polonara, Distributed generation and trigeneration: Energy

saving opportunities in Italian supermarket sector. Applied Thermal Engineering, 2009.29(8-9): p. 1735-1743.

18. Gu, Q., et al., Integrated assessment of combined cooling heating and power systems underdifferent design and management options for residential buildings in Shanghai. Energyand Buildings, 2012. 51: p. 143-152.

19. Li, H., et al., Energy utilization evaluation of CCHP systems. Energy and Buildings, 2006.38(3): p. 253-257.

Page 16

Roadmap for Australian Electricity Generation

Documents

Transcript of Roadmap for Australian Electricity Generation