L2 Flashcards
What does the energy system consist of?
Primary energy sources
eg. ff, renewables and nuclear
energy transformation processes (secondary/final energy)
eg. electricity, heating fuels and transport fuels
Useful energy and energy services
eg. lighting, information processing, thermal comfort and mobility
What is primary energy?
energy that is embodies in resources as they exist in nature
eg. chemical energy in ff like coal, oil, natural gas and biomass
e.g. kinetic energy of water from a reservoir
e.g. electromagnetic energy of solar radiation
e.g. energy released in nuclear reactions
What is secondary energy?
converted and transformed primary energy
e.g. electricity and fuels like gasoline, jet fuel, or heating oil which serve as energy carriers for subsequent energy conversion or market transactions
What is final energy?
delivered energy
energy transported and distributed to the point of retail for delivery to final users eg. firms, individuals or institutions
e.g gasoline at a service station
e.g. electricity out a socket
e.g. fuel wood in the barn
final energy is generally exchanged in formal monetary market transactions, where also typically energy taxes are levied
What is useful energy?
final energy converted in end-use devices like appliances, machines and vehicles into energy forms that can be used
eg. kinetic energy or heat
e.g. useful energy is measured at the crankshaft of an automobile engine,
e.g. the mechanical energy delivered by an industrial motor
e.g. by the heat of a household radiator or an industrial boiler
e.g. the luminosity of a lightbulb
What are energy services?
application of useful energy serving a purpose
e.g. movement of a vehicle (mobility)
e.g. a warm room (thermal comfort)
e.g. process heat (for materials manufacturing )
e.g. light (illumination)
what is the heat loss associated with a power station?
40% of the energy you put into the power station comes out as electricity the rest is heat loss
inefficiencies however depedne on the age of the power plants
laws of thermodynamics you can’t convert one source of energy perfectly into another
What is the climate change causal chain starting with fossil energy systems?
fossil energy systems -> release of Co2 emissions –> CLIMATE SYSTEM heat trapping ghg gases and earth system reflectivity –> impact of cliamte on human and natural systems
What are the response options to the climate change causal link?
decarbonise and reduce energy demand –> inudstrial CO2 management (CCS) –> CO2 remorval
MITIGATION ^ ADDRESS CAUSES
solar radiation modification–> prevention and minimise climate damages
ADAPATION^ ADDRESS IMAPCTS
What is a carbon sink?
any process, activity or mechanism which removes a GHG, an aerosol or a precursor of a GHG or aerosol from the atmosphere
What is mitigation?
a human intervention to reduce the sources of enhance the sinks of GHG
What is carbon dioxide removal?
carbon dioxide removal methods refer to a set of techniques that aim to remove Co2 directly from the atmosphere
What is adaptation?
The process of adjustment to actual or expected climate and its effects
What is the difference between CCS and CO2 removal?
CCS avoids emissions into the atmosphere it doesn’t remove Co2 from the atmosphere
What is the supply side approach to reducing GHG
renewable energy sources
nucelar power
reducing carbon intensity of ff
producing power and reducing emissions
reducing the carbon intensity of ff by using CCS -doesnt completely go to 0 but avoids some share of the emissions from ff
What is the demand side approach to reducing GHG
reduce overall demand - behavioural change
energy efficiency
change to technologies that don’t use ff
How much of total primary energy is produced from FF?
84.3% ff
33.1% oil
27% coal
24.2% gas
4.3% nuclear
How much of total primary energy is low carbon?
~15%
What is the subsitution method for comparing primary energy sources?
= estimates primary energy from non-combustible sources as being equivalent to heat of combustible fuels that would have been required in conventional thermal power plants to substitute the generate electricity or some other form of secondary electricity
includes power plant production and losses
What is the direct equivalent method for comparing primary energy from various sources?
= counts one unit of secondary energy such as generated electricity from non-combustible sources as one unit of primary energy with 100% efficiency
power plant without losses
What is the physical energy content method for comparing primary energy from various sources?
hybrid approach
= using direct equivalent approach for all energy sources other than those where primary energy is heat, such as nuclear, solar thermal and geothermal energy sources
for the latter - their primary heat content is taken including losses for geographtermal a 10% efficiency is assumed
mix and match - direct equiv for all renewables except those renewables that have heat as part of the energy production process
What is electricity?
electricity is the flow of electrons driven by a potential difference - voltage
How is electricity different to a gas?
must be used as it is created - can only be stored in specifically designed devices
What are the two different types of current?
Direct current - electrons
Alternating current - electricity on the national grid is AC
conversion between the two requires an inverter
What are the three energy generation systems?
Centralised systems - everything is connected to one source- more a philosophy - where power is generated and created into one grid
decentralised systems - several different sources not all connected
distributed system - pro-consumer = generating electricity for your own use and other users - distributors industries install pp for their own use and give the surplus to the grid
What is capacity?
The maximum output of electricity that a technology can generate under ideal conditions
typical unit is MW
What is generation or output?
The amount of electricity that is generated over a specific period of time
typical unit: MWh or kWh
What is the timing for nuclear construction?
v high compared to the low timescale requires for solar and wind construction time
due to buercracy and administrative approval of land planning etc.
different governance styles
How does carbon capture and storage work?
Co2 is captured at power plant
CO2 injected into geological formations like salt caverns, coal beds and depleted oil reservoirs
CO2 can be from an existing source through retrofitting or replacing existing power plants with CCS
What are the downsides of CCS?
costly
have to ensure there is no leakage otherwise it will escape again into the atmosphere
mineral reaction to the Co2 could cause an ecological crisis as a result of this
have to install the technology - 80/90% of costs is at the capture level at industry or power plants
adding CCS to existing plants result in efficiency losses and more chemicals like ammonia and limestone to control Nox and So2 emissions
What are the three potential points for CCS in power plants and can you tell me one thing about them?
Post-combustion
- easy implementation
pre-combustion
- requires new installation
oxyfuel
- low efficiency due to the costs of the air separation unit and oxygen purification
On the non-electricity supply side can you give some examples of directly supplied by fuels?
Coal burned in industry
solar water heater in buildings
gas cookers in buildings
From the non-electricity supply side can you give some examples of transformation?
Oil refineries - diesel or petrol consumed in transport
bioenergy refining - biodiseal consumed in transport
hydrogen production - hydrogen for shipping or aviation
Can you give some examples of what hydrogen might be used for?
Electricity and heat - to replace natural gas for heating and cooking in buildings
storage - hydrogen based energy storage
manufacturing - low-carbon production of steel in industry, ammonia or fertiliser
road - fuel cell electric vehicles
martime - transport
Can you compare and contrast the process of getting coal to an application compared with renewable electricity?
Coal requires casification and ccs which is then distributed on a hydrogen or gas grid to the application
renewable electricity requires electrolysis but no transformation before application to a pipeline
What two factors are important in comparisons of fuel?
capacity and cost per MWhr
What is the capacity difference from solar to coal?
Solar is around 12-23 depending on temporal and spatial factors
coal is around 80
What is a capacity factor?
share of %
the ratio of the actual electrical output over a given period of time to the maximum possible electrical energy output over the same period
What is a levelised cost?
$/kWh
LCOE is a metric quantifying cost of generation of a technology over its lifetime
represents the net present value cost of a generating asset per unit of electricity generated over its lifetime
useful metric for comparing costs of technologies with very different characteristics
What is emission intensity?
gCo2/kWh
represents the total quantitiy of ghg emitted by a technology over its entire lifetime - including construction, installation, fuel and operation - divided by the total energy produced over the lifetime of that technology
What is land area?
km2/TWh/yr
the amount of land required to generate a certain amount of electricity
particularly important in renewable electricity
Can you give some examples of dispatachable and non-dispatchable technologies?
Dispatch
- coal
- nuclear
- geothermal
-biomass
Non-dispatch
- wind
-solar
-hydroelectric
ie. cannot just be turned on and off to suit demand or controlled by an operator
What is the difference in LCOE for non-dispatch vs dispatch tech?
Non-dispatch has higher costs compared with dispatchable.
This does not take into account the risks costs - limitation to this method
Can you speak to the cost competitiveness of renewables?
Solar costs have declined by 85% - 2020 solar and wind is becoming cost competitive to ff
hardly any emissions vs emissions
no externalities vs externalities
What are some of the issues with LCOE?
ignores the effects of intermittency and non-dispatchability
does not account for the cost of risks
How do you work out the system LCOE of an intermittent source
sum of the marginal generation costs (LCOE) and the marginal integration costs
