Exam Prep Flashcards
1
Q
Club of Rome
A
The human ecological
footprint cannot continue to grow at the
current rate, otherwise the carrying
capacities of the system will be reached
and the system collapses
2
Q
Stockholm Conference
A
the UN’s first major conference on international environmental issues
turning point in the development of international environmental politics.
3
Q
physical conversion of fuel
A
mechanical pressing of crops with high oil content. The vegetable oil obtained, a mixture of methyl esters of fatty acids, can be used directly as fuel for diesel engines or chemically treat to make biodiesel
4
Q
Sustainable development
A
development that meets the needs of the present without compromising the ability of future generations to meet their own needs
5
Q
Brundtland Report 2 main concepts
A
- The concept of “needs”, in particular the essential needs of the world’s poor, to
which overriding priority should be given. - The idea of limitations imposed by the state of technology and social organization on the environment’s ability to meet present and future needs.
6
Q
The Triple Bottom Line
A
– People, the social equity bottom line
– Planet, the environmental bottom line
– Profit, the economic bottom line
7
Q
Cumulative Energy Demand (CED)
A
sum of the primary energy demand associated with the whole life
cycle of a product
▪ It covers extraction, production, usage
and disposal
▪ Unit: MJ per unit
8
Q
Analytic Tools to Evaluate Sustainability
A
(1) Cumulative Energy Demand (CED)
(2) Energy Return on Energy Invested (EROEI) / Harvesting Factor
(3) Grey Energy / Embodied Energy (EE)
(4) Life Cycle Assessment (LCA)
9
Q
functional unit
A
a quantified description of the function of a product. It serves as reference basis for all calculations regarding the impact assessment.
10
Q
Energy Return on Energy Invested (EROEI)
A
indicates how often a plant recovers the
cumulated energy demand (CED) during its lifetime
Output/Input
Energy delivered / Energy required to deliver the energy
11
Q
Grey Energy / Embodied Energy (EE)
A
excludes the operational energy, i.e.
the energy demand during usage, as
well as the disposal of materials.
▪ Unit: MJ or kWh per unit weight (kg or
tons) or per area (m²)
extraction + production
12
Q
Life Cycle Assessment (LCA) framework
A
- Goal and scope definition
- Inventory analysis
- Impact assessment
- Interpretation
models a product, service or system‘s life cycle.
13
Q
impact category
A
a “class representing environmental issues of concern to
which life cycle inventory analysis results may be assigned”.
14
Q
Waste management hierarchy according to the EU framework directive 2008/98/EG (5 steps)
A
- Prevention
- Preparing for reuse
- Recycling
- Other recovery, e.g. energy recovery through waste incineration
- Disposal
15
Q
What speaks for the incineration of waste in the context of sustainable thinking?
A
Generation of electricity and district heating by substitutes of fossil fuels.
Increasing resource productivity through metal recovery. This production of secondary raw materials is often less
energy-intensive and produces fewer emissions than the extraction of primary raw materials.
Recovery of non-recyclable waste with high pollution loads that would otherwise be dumped on landfills.
16
Q
What speaks against the incineration of waste in the context of sustainable thinking?
A
Generation of greenhouse gas emissions as a result of the incineration process.
Can be at the expense of material recovery (recycling) and undermine the idea of a circular economy → Conflict with
the waste management hierarchy.
(Example: In Germany, incineration capacities increasingly exceed the volume of waste, which lowers the price of waste
disposal. As a result, the attractiveness of material recycling is decreasing).
Orientation towards the idea of waste disposal. The aim should be to shape consumer behaviour in such a way that
less waste is produced.
17
Q
System
A
definable part of relevance
18
Q
system boundary
A
separates system from its environment
19
Q
mechanical energy transfer
A
energy in the form of work
20
Q
thermal energy transfer
A
energy in the form of heat
21
Q
material flow energy transfer
A
Different types of energy (e.g. kinetic) cross system boundary with material flow
22
Q
system types
A
isolated
closed
open
23
Q
isolated system
A
matter and energy impermeable
no energy transit possible
24
Q
closed system
A
matter impermeable
energy transfer in the form of work and heat
25
open system
matter permeable
energy transfer in the form of work, heat and material bound energy transport
26
law of conservation of energy
the sum of all forms of energy always remains the same, but
energy = exergy + anergy
27
exergy
the energy that can be convreted into any other form
the exergy share decreases in all conversion processes
28
anergy
the energ that cannot be converted
29
potential energy
force effects on the resting system
30
kinetic energy
force effects on the moving system
31
internal energy
force effects within a system
32
circular processes
stationary process where initial state is identical to the final state
33
thermal State variables
depend on the prevailing temperature
temperature
pressure
volume
34
caloric state variables
describe the energy content of a system
internal energy U
enthalpy H
Entropy S
35
Extensive properties
properties whose values result from the division of a system as the sum of the corresponding state variables of the parts (additive)
volume, internal energy, enthalpy, entropy
36
intensive properties
properties that are not additive when diving a system
temperature, pressure, specific internal energy, specific enthalpy, specific entropy
37
process variables
work and heat
38
isochore process
as heat is added, the volume stays constant (and pressure and temperature rise)
39
isobar process
the prssure stays constant when heat is added as volume and temperature rise
40
adiabatic process
energy is not transferred as heat to surroundings but as work
41
Energy carrier
physical manifestations and substances from which energy can be produced. A distinction is made between primary, secondary and final energy sources.
42
Primary energy sources
energy sources offered by
nature in their original form not yet treated. Their energy content is called primary energy. The primary energy sources are divided into regenerative and non-regenerative sources.
43
Secondary energy sources
originate from one or more processing or conversion processes (e.g. drying, desulfurization, power generation)
44
Final energy sources
all energy sources used by the end user to cover the energy demand
45
Useful energy
only the energy that is available to the consumer after the last
conversion to meet all needs is called useful energy.
46
Energy services
energy services are the needs satisfied or goods produced from the use of useful energy and other production factors (e.g. pleasantly tempered rooms,
information, transport, etc.)
47
Axial compressors in gas turbines
compress working fluid by first accelerating it (rotor) and then decelerating it (stator) in order to maintain the pressure increase. The centrifugal effect is eliminated within the blading.
48
Radial compressors
the air enters the compressor in an axial direction but is then conveyed outwards perpendicular to it. This exerts a strong centrifugal force.
49
Tube combustion chamber
in large industrial turbines. This type of combustion chamber is particularly suitable for engines with radial compressors.
Advantages:
simple design, easy maintenance and long
service life.
50
Annular combustion chamber
important in aerospace applications where cross- sectional area is important.
51
Tube ring combustion chamber
This type of combustion chamber combines the tube and ring combustion chamber and is particularly suitable for very large and powerful gas turbines because it is mechanically very stable.
52
Axial flow turbines
flows enter and exit in axial directions. Used in more than 80 % of all applications.
large machines
large mass flows
higher efficiencies
expensive
difficult production
53
Radial-flow turbine
like a radial compressor with reversed flow and counter-rotating. It is used for lower load
small machines
small mass flows
lower efficiencies
cheap
simple production
54
Clausius Rankine Cycle steps
1 -> 2 increase pressure through work
2 -> 3 heat feed water to evaporation temperature
3 -> 4 evaporation
4 -> 5 Superheating steam
5 -> 6 Relaxation of steam within turbine while work delivered
6->1 liquefaction of steam int he condenser while heat is released
55
Clausius Ranking assumptions
1-2 and 5-6 isentropic
2-5 and 6-1 isobaric
56
Firing Systems Function
release of chemical energy
from fuels
57
Firing methods
Fixed-bed or grate firing
Fluidized bed combustion:
Burner firing
58
Fixed-bed or grate firing
combustion of solid fuels on a
(moving) grate
59
Fluidized bed combustion
combustion of (mostly) solid fuels
in a fluidized bed of inert particles
through which air/oxygen flows
60
Burner firing
fuel is injected simultaneously with air/oxygen (finally ground solid, liquid or gaseous fuels)
61
Steam generator function
convert heat from firing into energy of steam
62
steam generator components
economizer, evaporator, superheater, reheater, air preheater and numerous auxiliary machines
63
steam turbine function
conversion of potential energy into kinetic energy and then into mechanical energy
64
Impulse turbines
Conversion of the
enthalpy gradient into
kinetic energy completely
in the guide wheel
– Inlet and outlet velocity
equal at impeller
65
Overpressure turbines
Conversion of the
enthalpy gradient in both
the guide wheel and the
runner
66
condenser function
Reversal of the evaporation
process (cooling/condensation)
and closing of the cycle
– Generation of a vacuum (steam
from turbine is expanded to lower
pressures than environment
→ higher efficiencies)
67
condenser working method
– Condensate and cooling medium
in two separate circuits
– Large quantities of heat to be
dissipated → as large as
possible mass flow of the cooling
medium
– Heat sink: environment
(atmosphere, waters)
68
ORC: Organic Rankine Cycle
Based on the Clausius-Rankine process
mainly used when the available temperature gradient between heat source and sink is too low to operate a turbine driven by steam. This is especially the case for electricity generation using geothermal energy, combined heat and power generation, solar power plants and ocean thermal power plants.
▪ thermodynamic cycle in which a low-boiling organic substance, such as hydrocarbons or silicone oils, circulates as a working medium instead of water.
69
Organic rankine cycle advantages
▪ Advantages:
– Smaller and cheaper turbines
– Operational advantages as the turbine is not exposed to
erosion or corrosion
– Use of lower temperatures
70
organic ranking cycle disadvantages
Disadvantages:
– Higher costs due to the heat exchanger
– Corrosion and fouling problems (deposits) on the heat
exchange
71
Gas turbine working fluid
flue gas
72
gas turbine components
compressor, combustor, turbine
73
gas turbine installation cost compared to steam turbine
lower
74
gas turbine efficiency compared to steam turbine
less efficient
75
gas turbine time and space requirements for installation compared to steam turbine
less
76
steam turbine working fluid
high pressure steam
77
steam turbine main components
steam boiler and accessories
78
Combined Cycle Power Plants
high inlet temperature of gas turbine with lower waste heat temperatures in water-steam process -> high efficiency
79
CCPP advantages
High efficiency
▪ Low specific investment, operating and
maintenance costs
▪ Short amortization period (10 to 12 years)
▪ Low start-up losses
▪ High partial load efficiency
▪ Short approval procedure
▪ Simple construction
▪ Step-by-step expansion possible
▪ Short delivery times (18 to 24 months)
▪ Low personnel requirements
▪ Locations close to consumers
▪ Short starting times
▪ High reliability (96 to 99 %)
▪ High availability (92 to 96 %)
Low requirement of cooling water
▪ Low pollutant emissions
▪ Low space requirement
▪ Further improvements in performance and
efficiency
80
Igneous rocks
formed from crystallization of molten rock from within the earth’s mantle.
high pressure -> high density
Granite and basalt.
81
Metamorphic rocks
formed from pre-existing rocks by
mineralogical, chemical and/or structural changes due to shifts in
temperature, pressure, shearing stress and chemical environment.
These changes generally take place deep within the earth’s crust.
Slate and marble.
82
Sedimentary rocks
formed as sediments, either from eroded fragments of older rocks or chemical precipitates
Sediments are lithified by compaction and cementation after burial under additional layers of sediment
Typically deposited in horizontal layers, or strata, at the bottom of rivers, oceans, & deltas.
Limestone, sandstone and clay.
83
prospection
Search and exploration of new
previously unknown deposits.
Using Geological maps and other available remote sensing information
The entire Prospection period of an exploration area is usually completed after several years of investigation with the start of the exploration phase
84
exploration
Follows a successful prospection phase
goal: detecting raw material deposits and extract them
usually completed after 5 to 10 years, followed by the actual exploitation of the deposit and thus extraction.
85
Drill Planning goals
maximize yield
minimize risks
reduce costs
comply with safety and environmental standards
86
rotary drilling method
The drive is located on the rig and drives the drill rod from above
To change the bit, the drill rod has to be removed and reinstalled
("round trip")
Method is used for vertical drilling
87
Advantage of Top-Drive in the rotary drilling method
installation of new drill rod is simplified
88
Downhole Mud Motor (Directional Drilling) aka turbine drilling
driving turbine located behind drill bit
turbine driven by hydraulic pressure
allows for change of direction at a certain depth
89
Horizontal drilling
carried out within the reservoir
can exploit hydrocarbon reservoir with small nr of vertical drilling holes
90
fermentation
biochemical transofmration where sugars converted into ethyl alcohol
91
Solid rock deposits
Primarily in magmatic deposits and as intrusions in hydrothermal deposits
Australia, Canada, Zimbabwe
usually found with other minerals, few of wich are economically usable
92
Brine deposits
salt lakes, continental deep waters, oilfield water
sometimes not economically feasible to extract from brines (only done in salt lakes currently)
in South America (Chile, Argentina, and Bolivia)
93
Lithium Demand in the Future
demand increase because of emobility
94
lithium extraction effects on environment
decrease of fresh water
large area requirements
high water demand
high energy consumption
recycling not yet established
95
CCS
capture of CO2 from energy intensive industries
ie. power plants, cement, iron and steel, chemicals and refining
96
CCS absorption method
Utilized for low or moderately concentrated CO2 in flue gas
streams.
97
CCS Chemical Absorption
Involves alkaline solvents (e.g., monoethanol amine - MEA) to
capture CO2.
98
CCS Regeneration
Heat-based release of absorbed CO2, followed by solvent recycling.
99
CCS Challenges
Energy-intensive due to breaking chemical bonds between solvent and CO2, contaminants in flue gas need removal
not all CO2 captured (around 90%)
100
IGCC Process (integrated gasification combined cycle)
converting solid or liquid carbonaceous fuels into a synthetic gas (syngas), which can then be used for power generation or the production of chemicals and fuels.
1. **Gasification**: The first stage of the IGCC process is gasification, where the solid or liquid feedstock, such as coal, petroleum coke, biomass, or waste materials, is converted into a syngas through a high-temperature chemical reaction in a gasifier. The gasifier operates at elevated temperatures and pressures in an oxygen-starved environment (partial oxidation or partial combustion), resulting in the breakdown of the feedstock into its constituent gases, primarily carbon monoxide (CO) and hydrogen (H2), along with other gases such as methane (CH4) and carbon dioxide (CO2).
2. **Syngas Cleanup**: The raw syngas produced from the gasification process contains impurities such as sulfur compounds, tar, particulates, and trace metals, which need to be removed to meet environmental and operational requirements. Syngas cleanup technologies, including scrubbers, filters, desulfurization units, and tar removal systems, are employed to purify the syngas and remove contaminants before it enters the power generation or chemical synthesis stage.
3. **Power Generation**: The cleaned syngas is then combusted in a gas turbine to generate electricity. The high-temperature, high-pressure combustion of syngas in the gas turbine drives the turbine blades, producing mechanical energy that is used to turn an electrical generator and produce electricity. The exhaust gases from the gas turbine, which are still at high temperatures, are directed to a heat recovery steam generator (HRSG) or boiler.
4. **Steam Generation and Combined Cycle**: In the HRSG or boiler, the exhaust gases from the gas turbine are used to generate steam by transferring heat to water. The steam produced drives a steam turbine, which generates additional electricity. This combined cycle configuration (gas turbine + steam turbine) maximizes the overall efficiency of the power plant by utilizing both the high-temperature exhaust gases from the gas turbine and the steam generated in the HRSG.
5. **Emissions Control**: Emission control technologies, such as selective catalytic reduction (SCR) for nitrogen oxides (NOx) and flue gas desulfurization (FGD) for sulfur dioxide (SO2), are employed to reduce air pollutants and comply with environmental regulations. Additional measures may be implemented to capture and sequester carbon dioxide (CO2) emissions from the gasification process to mitigate greenhouse gas emissions.
The IGCC process offers several advantages, including high fuel flexibility (ability to use a wide range of feedstocks), potential for higher efficiency compared to conventional coal-fired power plants, and the ability to capture and utilize by-products such as hydrogen and carbon monoxide. However, IGCC plants require significant capital investment and operational expertise, and the technology is still relatively less mature compared to conventional power generation technologies.
absorption using solvents like selexol or rectisol.
101
CCS Pressure & Temperature
Solvent capacity increases with pressure and decreases
with temperature, and regeneration is less energy-intensive.
102
CCS methods
chemical and physical absorption
oxyfuel for pure oxygen combustion
103
oxyfuel for pure oxygen combustion in context of CCS
Combustion of fossil fuels in pure oxygen, removing nitrogen from flue gas streams.
104
Advantages CCS oxyfuel
Higher CO2 concentration, no need for costly CO2 capture; potential to
compress and store trace pollutants.
105
disadvantages CCS oxyfuel
Drawback: Production of oxygen in air separation is expensive.
106
carbon storage methods
geological formation - depleted oil and gas reservoirs
deep aquifers
ocean storage
107
carbon storage methods
Geologic Formation - Depleted Oil and Gas Reservoirs
▪ Environmental Safety
Lower risks and uncertainties compared to ocean storage.
108
carbon storage methods
Geologic Formation - Depleted Oil and Gas Reservoirs
Utilization
CO2 is stored in depleted oil and gas reservoirs, used by Enhanced Oil Recovery (EOR) companies for tertiary recovery.
109
carbon storage methods
Geologic Formation - Depleted Oil and Gas Reservoirs
Environmental Impact
Least potential environmental risk
110
carbon storage methods
Geologic Formation - Depleted Oil and Gas Reservoirs
Longevity
Demonstrated ability to store pressurized fluids for millions of years
111
carbon storage methods
Geologic Formation - Depleted Oil and Gas Reservoirs
Concerns
Possible CO2 leakage through fractures and groundwater contamination.
careful site selection and operation with regulatory oversight necessary
112
carbon storage methods - deep aquifers
advantage
lower transportation costs
113
carbon storage methods - deep aquifers
environmental concerns
uncertainty, mitigated by suitable storage site selection
114
carbon storage methods - deep aquifers
ideal aquifers
impermeable cap, high porosity, permeability
115
carbon storage methods - deep aquifers
storage process
formation of stable carbonates through chemical reactions for longer storage times
116
carbon storage methods - ocean storage
capacity
largest potential for CO2 storage
117
carbon storage methods - ocean storage
injection depth
varies, deeper depths minimize impact on marine life
118
carbon storage methods - ocean storage
methods
direct injection, towed pipeline, stable isolated lake formation, dry ice blocks
119
carbon storage methods - ocean storage
challenges
costly refrigeration and compression, impact on ocean acidity
120
Geological sequestration CCS method
CO2 injected at around 1 km or deeper
121
Geological sequestrration CCS primary trapping steps
beneath seals of low permeability rocks
1. capture
2. compression
3. pipeline transport
4. underground injection
122
Geological sequestrration CCS secondary trapping
dissolution, residual gas trapping, mineralization
123
United Nations Framework Classification for Resources three criteria
economic viability
feasibility
geological knowledge
124
oceanic crust
lies under oceans
thin (8-11 km)
heavy rock formed as molten rock (magma) cools
125
continental crust
thick (16-48 km)
lighter rock
continuously changing and moving due to orogeny and weathering/erosion
126
orogeny
mountain building
layers of crust folded and pushed upward by plate tectonics and volcanism
127
weathering and erosion
opposing forces where sediments broken down and transported
128
where does geothermal energy come from
areas of volcanic activity
129
UNFC tool
classification tool to reduce transaction costs and make risks visible
130
Try to make an UNFC characterization for a wind power project
UNFC Characterization for a Hypothetical Project: Sustainable Energy Development
1. Energy Resource Category:
Primary Energy Source: Wind Power
Location: Offshore Wind Farm in XYZ Region
2. Project Phases:
a. Exploration Phase:
- Preliminary Wind Resource Assessment
- Geological and Geophysical Studies
b. Appraisal Phase:
- Advanced Wind Resource Assessment
- Environmental Impact Assessment
- Technical Feasibility Studies
c. Development Phase:
- Construction of Offshore Wind Turbines
- Installation of Transmission Infrastructure
- Regulatory Approvals and Permits
d. Production Phase:
- Ongoing Operation and Maintenance
- Continuous Monitoring of Wind Farm Performance
- Energy Generation and Transmission
3. UNFC Classification:
a. Class 1: In-Place Energy Resources (Area):
- Wind Energy Potential in the XYZ Offshore Region
b. Class 2: Exploration Results:
- Confirmed Wind Resources
- Environmental Impact Assessment Data
c. Class 3: Recoverable Resources:
- Estimated Recoverable Wind Energy Reserves
d. Class 4: Production:
- Annual Energy Generation from the Wind Farm
4. Quantification and Units:
Energy resources measured in gigawatt-hours (GWh)
Physical attributes such as wind speed, depth, and distance from shore are quantified.
5. Environmental and Social Considerations:
Integration of sustainable practices in construction and operation phases.
Community engagement and benefits.
6. Economic Viability:
Cost-Benefit Analysis
Return on Investment (ROI) calculations
7. Risk and Uncertainty:
Identification of key project risks and uncertainties
Mitigation strategies
131
How is the UNFC interlinked with other resource declarations?
4. **Sustainable Development Goals (SDGs):**
goals related to affordable and clean energy (SDG 7),
responsible consumption and production (SDG 12), and
climate action (SDG 13)
3. 1. **UNFCCC (United Nations Framework Convention on Climate Change):**
assessment of greenhouse gas emissions and carbon sequestration potential
2. **UNSD (United Nations Statistics Division):**
standardization of resource-related statistics
3. **UNEP (United Nations Environment Programme):**
goals of sustainable development and environmental protection promoted by UNEP
6. **Mineral Resource and Reserve Classification Systems:**
compatible with existing mineral resource and reserve classification systems, such as the Committee for Mineral Reserves International Reporting Standards (CRIRSCO) and the Society for Mining, Metallurgy, and Exploration (SME) guidelines.
132
How is coal created?
remains of plants that lived in swampy environments during the Carboniferous period (about 360 to 300 million years ago). As these plants died, their remains accumulated in waterlogged conditions, preventing complete decomposition
-> peat, an early stage of coal
- **Coalification:** Over millions of years heat and pressure increase.
lignite, bituminous coal, and anthracite form
133
how is natural gas created?
remains of microscopic marine organisms, such as plankton and algae, that lived in ancient seas. When these organisms died, their remains settled on the ocean floor.
- **Organic Matter Accumulation:** Over time, the organic matter from these marine organisms gets buried under layers of sediment, and as the sediment thickens, heat and pressure increase.
- **Thermal Decomposition (Maturation):** The heat and pressure cause the organic matter to undergo thermal decomposition or maturation. This process results in the formation of hydrocarbons, including natural gas.
- **Migration:** Natural gas can migrate through porous rocks until it gets trapped beneath impermeable rock layers, forming reservoirs.
134
How is oil created from the beginning?
organisms, including plankton and algae die
-> settle on ocean floor
-> buried under sediment
-> heat and pressure
-> converted into hydrocarbons
-> migrates through permeable rocks
-> settles in trap or reservoir
135
How could geothermal energy usage replace conventional, using similar infrastructures?
1. **Electricity Generation:**
Geothermal power plants often use similar infrastructure for electricity transmission and distribution, making the transition relatively seamless.
2. **Heating and Cooling Systems:**
Existing ductwork and distribution systems can often be adapted for geothermal heat pump installations.
3. **District Heating Systems:**
Existing district heating infrastructure can be adapted for geothermal use.
136
Where can we store CO2?
**Deep Saline Aquifers:** Deep underground saline aquifers, which are porous rock formations saturated with saltwater
-typically found several kilometers below the Earth's surface.
2. oil reservoirs
enhanced oil recovery (EOR)
3. **Unmineable Coal Seams:**
CO2 adsorbs onto the coal matrix
4. **Deep Ocean Storage:** limited
137
electricity - what type of energy source?
secondary energy source generated by primary sources like fossil fuels, nuclear, wind, solar
138
what can convert primary sources of energy into electrical energy?
generator, battery, fuel cell, solar cell
139
efficiency
electrical output (+ heat extraction) / heat input (fuel power)
140
capacity factor
electrical output (+ heat extraction) / heat input (fuel energy)
141
what is the difference between efficiency and capacity factor?
efficiency is in a point of time while capacity factor is in a period of time
142
how is electricity made?
results from the interaction of electrically charged particles
electrons and protons
143
electric current
flow of electric charge
144
Electric charge Q in Coulomb (C)
basic property of building blocks of matter, distinction between electron and proton
a neutral atom becomes +/e ion by addition/elimination of an electron
ions and electrons are carriers of electric charge
145
Current (amperage) I in Ampere (A)
Directional movement of charge carriers
Quantity of electric charge flowing through a cross section per time unit
146
I = ?
Q/t
147
Unit of Ampere A
C/s
148
Voltage U in Volt V
Difference between electrical potentials
Maintains the movement of charge carriers
149
Power P in Watt
Measure for the amount of energy transferred or converted per time unit
150
How to calculate P
U*I
151
Electrical resistance R in Ohm
Charge carriers cannot pass unhindered through the conductor
some of their electrical energy is transformed into heat, which is due to the conductors resistance
152
Ohms law
Resistance R is constant and not dependent on voltage or current
Increasing voltage (U) results in a proportional change in
current (I).
R=V/A
153
How to calculate R
U/I
154
Units of Ohm
R= V/A
155
Direct Current
if direction of movement of the charge remains constant over time
used in batteries, can be generated with fuel cells and PV modules
increasingly important as low loss transmission is possible
156
Alternating current
if direction of movement changes at intervals (looks like sine curve)
known from household appliances and used in electrical power distribution
time dependent
frequency of changes in direction is expressed in Hertz
157
What does 50 Hz imply
direction of the current changes 100 times per second
158
Lorentz force
resulting force on moving charges in the magnetic field
interaction between two magnetic fields
159
How to determine Lorentz force
Right ahnd rule
middle finger is lorentz force
thumb is direction of current
pointer finger is magnetic field
160
three phase current
3 coils -> 3 overlapping phases add up to zero at any moment
generator rotates
rotating magnet induces voltages in coils
for industrial appliances
161
galvanic element
conversion of chemical into electrical energy
potential caused by electro surplus on anode and deficit on cathode
162
redox potential
measure of readiness of ions to accept electrons
163
fuel cell
generate electricity and. heat from hydrogen and oxygen
cold combustion
164
hydrogen electrolysis
chemical reaction
what type of energy?
efficiency level?
H2O + Energy -> H2 and O2 through electrolysis
energy can be chemical, heat, electrical, etc.
very efficient
165
Calculating resistance parallel connections
1/ Rtotal = 1/ R1 + 1/ R2...
166
Calculating resistance series connections
Rtotal= R1 + R2...
167
theoretical supply potential
physical supply without "practical" boundary conditions
e.g. incident radiation * area * max efficiency
168
technically usable potential
consideration of the technical state of the art (exergy share, efficiency, degree of utilization). available area, integration
eg. efficiency * load max * full load hours
169
average wind speed
A* k-th root of 0,287*k^(-1)+0,688*k^(-0,1)
A: measure of characteristic wind speed
k: form factors between 1 and 4
170
Energy yield of wind turbine
sum of (hi * Pi * T) = sum of (hi * density/2 * A* vi^3* cp,i*T)
h: how often % does wind speed i occur compared to others
P: power output of wind turbine at wind speed i
cp, i: optimum power coefficient (rotor speed)
T: hours in period
171
economic potential
inclusion of costs. economic comparison to alternatives
172
expectation potential
realistic estimation for a period of time, "forecast"
173
environmentally sustainable potential
part of the technical potential whose use does not lead to "unreasonable" interference with nature
174
challenges on hydropower development (reasons for declining)
future policies
electricity prices
project development lead times
high cost
short payback periods
175
undershot water wheels
blades immersed in water absorb kinetic energy and transfer it to the wheel and shaft
176
undershot water wheels advantages
little slope and water needed
little sensitivity to fluctuating water volumes
few hydraulic engineering works required
177
undershot water wheels disadvantages
low speed
needs gearbox
large space requirements
low efficiency
not suitable for large power plants
178
overshot water wheels and water turbines
use potential energy of water
179
overshot water wheels strengths
higher speed
no gearbox required
suitable for any height of fall
higher efficiency
180
overshot water wheel weaknesses
high slope required
sensitive to fluctuating water levels
extensive hydraulic engineering works required
181
pelton turbine
high pressure
high altitude differences
low mass flow
182
pelton turbine components
water flow
inlet nozzle
wheel
outlet
183
francis turbine
intermediate pressure
wide range of applications
potential and kinetic energy convrted
184
francis turbine components
water inflow
casing
guide blades
wheel
outlet
185
kaplan turbine
low pressure turbine
less pressure so more water flow needed to generate energy
186
kaplan turbine components
water inflow
guide blades
rotor hub
moving blades
turbine shaft
outlet
187
run of river power plant
use flow of river to generate electricity
need high flow velocity and large volume of water (kaplan and francis)
low hight of fall with large but seasonally fluctuating water volume
188
storage power plant
use water from reservoir to produce electricity using dams
energx depends on amount of water and height
large height of fall but relatively small volume of water
can be started and shut down quickly
189
pumped storage power plant
has upper and lower reservoir
can go into generator and pump mode
generator mode
upper reservoir water goes into turbine
electricity produced fed into grid
pump mode
operates as motor
suppled with energy from grid and drives the pump
takes water from lower reservoir and pumps it back into upper reservoir
190
power formula for hydropower plants
power = water density * gravitational acceleration * height difference * volume flow * efficiency
191
primary biomass
plants and animal matter, crops
192
secondary biomass
waste and byproducts of primary biomass
193
tertiary biomass
products derived from primary and secondary biomass through conversion steps
194
what kind of energy is stored in biomass
solar energy
195
is biomass considered a sustainable energy source? why?
yes but not the best because it releases the amount of CO2 that was removed from atmosphere during plant growth
196
problems with biomass
tank and plate controversy
land use issues
loss of biodiversity
is it CO2 neutral or CO2 absorbing sink?
197
food vs fuel
using land for biomass enrgy production competes with food and feed production
-> food shortage
extensive land use and conversion of ecosystems, resulting in loss of biodiversity
198
iLUC - indirect Land Use Change
displacement effects triggered by additional demand (example for bioenergy sources)
additional demand for raw materials -> food production displaced to other land -> new cropland elsewhere -> conversion of natural ecosystems -> greenhosue gas emissions
199
liquid fuels first generation biomass
processes that are already technically mature today
only use fruit (sugar, starch, oil)
can be used in combustion engines or plants
200
examples of first generation fuels from biomass
vegetable oil fuel
biodiesel
bioethanol
201
gaseous fuels second generation from biomass
production processes currently under development
biomass difficult to use today (lignin)
can be turned into natural gas and fed into grid
202
examples of second generation fuels from biomass
biomethane
cellulose ethanol
203
pyrolysis
biomass into solid char, liquid bio oil and combustible gases by heating biomass in absence of air
400-800C
204
charring
fuel treated with oxygen through energy imput around 380C
products are hig carbon, solid fuels
205
coefficient of performance (COP)
quotient of the heat released into the heating circuit and the energy used
206
COP formula
COP=Q stream heat / W stream
207
maximum achievable coefficient of performance COPmax
limited by the reciprocal value of the Carnot efficiency
208
COPmax formula
1/carnot efficiency = Thot / Thot-Tcold
209
gasification
converts biomass into syngas by heating it with limited oxygen
500-1400C
products are gaseous fuels
210
biogas
through anaerobic
methane, carbon dioxide
lighter than air
direct electricity generation
211
anaerobic fermentation
conversion done by bacteria operating rich cellulose biomass
biogas about 65% methane
212
biomethane
processed biogas with natural gas quality of methane content above 96%
fed into gas grid and used for electricity, fuel and heating
213
steps of biogas generation
hydrolysis
acid formation
acetate formation
methane formation
214
pressure swing adsorptio
removal of H2S, H2O as pretreatmnt
physical absorption
under pressure using carbon molecular sieve
215
pressure washing
dissolve co2 in water by increasing pressure
216
tidal power plants
built in bays
uses gravitational pull of moon and water currents to generate electricity via generator
217
tidal power plants advantage
low operating costs
no odor or noise pollution
218
tidal power plants disadvantage
location dependency
tidal dependency
219
marine current power plants
rotating bodies similar to wind turbines
speed of rotation proportional to flow velocity of water
little explored, only prototypes exist
220
osmotic power plants
energy released when fresh water meets salt water
semi permeable membrane
pressure generated by transfer of water used to generate electricity
221
heat pump
uses electrical energy to raise heat from lower to higher temperature level
refrigerant circuit absorbs heat during evaporationa nd releases it agian during condensation
222
heat pump components
evaporator
comperssor
condenser
expansion valve
223
gas equation
pV=mRT
224
Weibull distribution wind formula
h= k/A (v/A)^(k-1) e°(-v/a)^k
where k >0 : shape factor, typical for europe =2 = Rayleigh
A > 0: measure for characteristic wind speed (m/s)
225
Rayleigh distribution for europe
Weibull distribution with k=2 and wind speed of v= 4 m/s
226
conversion chain of wind energy
mechanical energy in wind -> mechanical energy in rotor -> mechanical energy in shaft -> electrical energy
227
Mechanical energy in wind formula
Ewind= 0,5*m*v^2
228
Wind power formula
P = E stream wind =0,5*m!*v^2
229
rotor power formula
Protor= Pwind*power coefficient aka cp
230
electrical energy formula
Pel = Protor * Wirkungsgrad elec
231
Drag force
force that occurs when area A is perpendicular to wind flow
232
drag force formula
D= drag coefficient * air density/2 * Area * wind speed^2
233
drag coefficient
depends on object
eg. circle plate 1,11
open hemisphere left
234
Bernoulli's Law
applies to flowing liquids and gases
for frictionless flows and states
the sum of static pressure, gravitational pressure and dynamic pressure is constant
235
static pressure
pressure measured perpendicular to flow direction
236
gravitational pressure
pressure resulting from the weight of the liquid. changes only when a flow is not horizontald
237
dynamic pressure
acts in the direction of flow due to the moving fluid/gas
238
Bernoulli's law formula
static pressure + density of flowing fluid * gravitational pull * height + 1/2 density * flow velocity ^2 = constant
239
Basic components of typical horizontal axis wind turbine
Rotor blade
Rotor hub and blade pitch mechanism
Rotor shaft and bearings
Gearbox
Rotor brake
Generator
Electrical switch boxes and control systems
Bedplate
Yaw system
Power cables
Tower
Grid connection (transformation)
Foundation
240
Difference between leeward and windward rotor?
Leeward: rotor runs in wind direction behind the tower
Windward: rotor runs in wind direction in front of the tower
241
Windward rotor advantage
tower does not obstruct wind
242
Windward rotor disadvantage
Rotor must be quite rigid and needs a certain distance to the tower
Mechanism for wind direction tracking necessary
243
Leeward rotor advantages
passive wind direction tracking
lighter built than windward rotors
244
Leeward rotor disadvantage
greater noise emissions, power fluctuations and higher stress on rotor blades because tower doesnt block any wind
lower fatigue strength
245
tip speed ratio lambda
peripheral speed / wind speed
246
Power curve of a wind turbine
shows how much electrical power is generated as a function of wind speed
247
Power curve of wind turbine formula
P= 0,5 A * air density * cp * v^3
A is rotor area
cp is power coefficient
248
What are the parameters of the power curve of a wind power plant?
cut in and out speed
rated power output
rated speed
249
cut in speed and cut out speed
wind speeds defining the operating limits of the wind power plant
250
rated power output
always specified by generator and design and corresponds to its maximum permanent electrical output
251
rated speed
the wind speed at which the wind turbine just reaches its rated power output
252
Phases of power curve of wind power plant
I: partial load range: speed of turbine flexibly adjusted to optimum ratio between peripheral speed of rotor and wind speed (tip speed ratio) -> maximum efficiency
II: transition range: goal: keep rotor torque and noise low
III: full load range: protect generator from overspeed, pitch angles of rotor blades adjusted as soon as nominal wind speed reached. cp (power coefficient / aerodynamic efficiency) of blades is reduced
253
Difference of offshore wind turbines to onshore?
higher speeds -> higher electricity yield
more difficult maintenance and repair
longer distance of grid connection to coast
254
Solar constant G
energy from the sun per unit of time received on a unit area of surface perpendicular to the direction of propagation of the adiation at mean ear sun distance outside the atmosphere
255
problem with wind turbine
logistical challenges:
transport of large turbines (rotors)
256
air mass
length of path sunlight travels through earths atmosphere to reach the ground
257
global radiation = ?
direct radiation + diffuse radiaton
258
types of pv cells
silicium (cristalline, thin layer)
tandem (gallium arsenide, CIG, CdTe)
259
Photovoltaics
direct conversion of solar radiation into electricity
converts light into electricity using semi conductor materials
260
silicon as semi conductor material
most important
n type doping
diamond cubic cristialline structure
261
energy band model
bands are successively filled with electrons
1. valence band: outermost shell
2. conduction band: next higher band can be partially filled or empty
3. forbidden zone:space inbetween, which receives non allowed energy states
262
why are semiconductors important for PV
conduction band is unoccupied like in insulators but have smaller band gap
-> electrons can be lifted into conduction band by influence of radiation
-> inner photoelectric effect
263
how are electric fields created through pv
n layer: negative doped silicon
p layer: positive doped silicon
p silicon, which was neutral before, becomes negative, while n silicon becomes positive -> internal voltage
p doped and n doped semiconductors come together -> pn junction is formed
264
diode
component of electrical engineering which allows electrical current to pass almost unhindered in one direction, but blocks other (electrical one way street)
265
short circuit current
current flow through solar cell when voltage across solar cell is zero
short circuit current is largest current whch may be drawn from solar cell
266
open circuit voltage
maximum voltage available from solar cell and occurs at zero current
corresponds to the amount of forward bias on the solar cell due to the bias of the solar cell junction with the light generated current
267
rank types of solar cells in terms of efficiency
concentrated pv cell
monocrystalline silicon cells
polycrystalline solar panels
thin film
268
monocrystalline solar panel advantage
hgih efficiency rate (20%)
optimized for commercial use
high life time value
269
monocrystalline solar panel disadvantage
expensive
270
polycrystalline solar panel advantage
lower price
271
polycrystalline solar panel disadvantage
sensitive to high temperatures
lower lifespan
less space efficient
272
thin film PV advantages
relatively low cost
easy to produce
flexible
273
thin film PV disadvantages
shorter warrenties and lifespan
274
concentraved pv cell advantages
very high performance and efficiency
275
concentraved pv cell disadvantages
solar tracker and cooling system needed
276
steam reforming for hydrogen formation
heat + steam + carbon containig fuel (eg methane) -> hydrogen, carbon dioide, carbon monoxide
277
gasification for hydrogen formation
organic or fossil based material (coal, biomass) + heat + oxygen / steam -> carbon monoxide, hydrogen, carbon dioxide
without combustion
high level of maturity
278
pyrolyse for hydrogen formation
methane containing feedstock + heat -> hydrogen + solid carbon
technology readiness level of 4-5
279
water electrolysis for hydrogen formation
electricty + water -> hydrogen and oxygen
no significant byproducts or waste
280
green hydrogen
requires extraction from renewable sources
only sustainable option
uses electrolyzers
281
green hydrogen cost trend
cost of electrolyzers and renewable energy decreased significantly and further cost reductions needed
282
turquoise hydrogen
produced through methane pyrolysis process
solid carbon is produced instead of co2
283
orange hydrogen
hydrogen produced from bioenergy like biomass, biofuels, biogas, biomethane
after use, carbon in organic materials released back into the environment (lower carbon footprint from black hydrogen)
284
red hydrogen
produced using nuclear energy
through electricity through electrolysis or thermochemical splitting of high temperature wastewater
not considered sustainable due to challenges with uranium mining, decommissioning, and nuclear waste management
285
blue hydrogen
grey hydrogen with ccs
transitional solution but not carbon neutral due to potential greenhouse gas releases during ccs
286
white hydrogen
occurs naturally, esp in africa through fracking
287
grey hydrogen
originates from natural gas, through steam methane reforming
288
power to hydrogen
renewable electricity converted into hydrogen by electrolysis
then into methane or liquid fuels
289
brown hydrogen
derived from brown coal
290
black hydrogen
produced using coal, typically through gasification
291
electrolyzer cells
very small (less than 5kW) since the surface area o0f elevtrodes is limited by mechanical vonstrains
292
electrolyzer stacks
groups of hundred cells in series or parallel
293
electrolyte - alkaline, proton exchange membrane, solid oxide electrolyzer cells
KOH liquid
polymer membrane
ceramic membrane
294
technical maturity - alkaline, proton exchange membrane, solid oxide electrolyzer cells
commercial
initial commercial
research and development
295
what does hydrogen based electricity storage require?
a flexible electrolzer that is able to withstand variable loads
296
proton exchange membrane advantage over alkaline as electrolyzer
highly flexible
easier to operate
simple design -> potential for cost reduction
297
electrolyzer hydrogen production challenges
1. limited economies of svale
2. usually operated continuously - unable to compete with steam methane reforming in terms of flexibility
298
hydrogen storage
mainly in gaseous form (prssurized tanks, underground reservoirs)
liquid form (cryogenic tanks)
299
hydrogen main challenge
hydrogen volatile, expensive to handle
300
hydrogen storage - pressurized tanks
preffered for systems subject to high cycling rates because capital cost per unit of energy capacity is high and needs to be amortized by frequent utilization
economically scale uppable as long as cycling rate is high
negligible hydrogen leakage
301
underground storage for hydrogen advantages
most competitive and energy efficient option for large scale storage
fixed construction costs
302
underground storage for hydrogen disadvantages
limited geological availability (man made salt caverns)
303
underground storage for hydrogen - what kind of recycling rates and why`?
allows for lower cycling rates because capital cost per unit of energy capacity is much lower
304
metal hydrides as hydrogen storage
cycling rates between a day to week but still must demonstrate techno economic feasibility
minimal energy penalty and great handling safety
305
liquid storage for hydrogen
mainly suitable for large scale centralized storage with long distance transport
306
hydrogen blending into the natural gas grid
hydrogen enriched natural gas can be injected into gas grid
307
avantages of hydrogen blending over methanation
minimal investment
no dedicated hydrogen storage required
minimal additional energy losses
existing storage and transport capacity
308
disadvantages of hydrogen blending over methanation
H2 to natural gas ratio is technically limited to 17.25%
uncertain and very system specific, limited by grid integrity, safety, energy transport capaciy, specification sof end use application
costly adaptation of the real time hydrogen injection rate
309
CCS post combustion application area
biomass and biogas power plants
310
CCS post combustion advantages
highest market maturity
easy combination with existing technology
311
CCS post combustion disadvantages
low co2 concentration impairs efficiency of separation process
312
CCS pre combustion application area
biomass and biogas power pßlans
313
CCS pre combustion advantages
high co2 concentration improves sorption effiviency
fully developed tech
commercially used to an appropriate extend
easy combination with existing technology
314
CCS pre combustion disadvantages
temperature ependent heat transfer problem and efficiency losses associated with hydrogen fuel in gas turbines
high parasitic power requirements for rotary dehumidifiers
insuffiicent experience due to lack of gasification power plants on the market
high capital and operating costs for current sorption systems
315
oxyfuel combustion ccs advantages
very high co2 concentration improves absorption efficiency
mature air separation processes available
lower gas volume, therefore smaller boiler and other equipment
316
oxyfuel combustion ccs disadvantage
high loss of efficiency and eenergy
refrigeration co2 production costly
rust
317
methanation hydrogen
greater energy losses and high investment required than blending but full access to gas grid and benefits from higher volumetric density of methane compared with hydrogen
318
alkaline electrolyzer advantages
commericla
cheapest
ultra pure hydrogen output
319
alkaline electrolyzer disadvantages
limited cost reduction potential
limited efficiency gains
complex cell design
corrosive
operates at high pressure
low response time
320
PEM advantages
design simplicity and reliability
high efficiency, higher current densities than alkaline
very fast response time
higher cost reduction potential
321
PEM disadvantages
high investment costs
difficult to manufacture
lifetime of membranes
requires much greater water purity
322
solid oxide electrolyzer cell advantages
highest energy efficiency
low capital costs: high density and no noble metals
possibility of coelectrolysis of co2 or h2o for syngas production
reversible use as a fuel cell with possibility of heat recycling synergies
323
solid oxide electrolyzer cell disadvantages
immature technology
poor lifetime
limited flexibility
324
Which are the countries/regions with the highest hydrogen production potential? Is it probable/desirable from an ecological point of view that parts of the industry concentrate there?
1. **Middle East**: abundant natural gas reserves and solar energy resources.
2. **Europe**: renewable energy capacity, especially wind and solar, to produce hydrogen through electrolysis.
3. **Australia**: With vast land areas and significant renewable energy potential,
4. **North America**:
5. **Asia-Pacific**: Japan and South Korea have been investing in hydrogen as part of their energy transition strategies. Japan, in particular, aims to import hydrogen due to limited domestic resources.
325
value chain natural gas
upstream: exploration, production , processing
midstream: transport, storage, distribution
downstream: sale
326
worldwide distribution of natural gas
russia
middle east
north america
austrialia
327
associated gas
1. **Associated Gas:**
- Associated gas is found in conjunction with crude oil deposits within
underground reservoirs.
- When oil is extracted, associated gas is also brought to the surface along
with the oil.
- The gas is dissolved in the oil under high pressure in the reservoir, and as
the pressure decreases during extraction, the gas comes out of the solution and is released.
- The composition of associated gas can vary, but it often contains a mix of hydrocarbons, including methane, ethane, propane, and other gases.
328
non associated gas
2. **Non-associated Gas:**
- Non-associated gas, on the other hand, is found in reservoirs that do not
contain significant amounts of crude oil.
- These gas reservoirs are separate from oil reservoirs, and the gas is not
associated with the production of crude oil.
- Non-associated gas is usually found in geological formations where the
conditions favor the accumulation of natural gas without the presence of significant amounts of liquid hydrocarbons.
- The composition of non-associated gas is typically higher in methane compared to associated gas.
329
central components of natural gas infrastructure
pipelines
compressor station
LNG terminals
unterground sstorage
330
radial network for gas distribution
tree structure
known flow direction
volume of volume flow among strands of network always clear
each point of the network can only be supplied by one route
331
meshed network
no clear flow direction
the distribution of volume flow among the strands of the network is unclear
each point of the network can be supplied by several routes
332
advantages of steel pipes for gas
no pressure limitation
better elasticity
good ductility
big sizes of single length possible
333
disadvantages steel pipes for gas
corrosion
334
plastic tubes for gas advantages
corrosion resistance
high flexibility and less weight than steel
easy to lay
pipe lengths variable for amount of needed junctions
if smaller than dn 300, usually more cost efficient than steel pipes
335
plastic tubes for gas disadvantages
pressure limitation at 4 bar
maximum outer diameter
lwo mechanical resistance
no aging resistance
336
pressure in gas pipes
pressure inside pipes drops continually with its length due ot friction -> speed rises
337
gas compressor station parts
drive unit: powers compressor using natural gas a fuel
compressor: increases pressure
cooler: cools gas when it heats up during compression
338
LNG advanatage
transport (road, rail, water) and storage possible without need for pipelines or natural gas storages
volume is 1/600 of natural gas
339
lng disadvantages
still significantly less important than pipelines
high energy inut needed to liquify the natural gas before it is transported
continual evaporation of lng requires cooling and or liquiefaction
340
process chain lng
natural gas -> liquification LNG
-> storage tanks
-> gas transport pipeline
.> jetty -> lng vessel -> jetty
-> storage tank -> high pressure pump
-> vaporizer -> gas transport pipeline
341
where can natural gas be stored
dep0leted fiels (porous rock)
salt formations (daily, weekly storage in cavern)
depleted aquifers (porous rock)
342
district heating - how does it work
heated water in central location -> hot water or steam via thermally insultaed piping system -> consumer
343
heating plants
provide only heat using coal natural gas and oil through water
boiler systems or heat exvhangers using geothermal energy or waste heat used for heating the water
efficiency only 60%
344
modern cogeneration plants
produces heat and electricity using energy of exhaust gas multiple times
highest efficiency - 89%
345
two pipe system distring heating networks
supply and return line
can be operated at constant temperature
temperature control of flow temperature tale3s place only below a crtain outside temperature
346
three pipe system district heating networks
two supply lines, one of which oprating at constant temperature and other at outside temperature
347
heat exchanger
transfer heat from one medium to antoher
348
high end temperature district heating
high temperature level of flow
eg berlin 130 c
high losses
349
medium temperature district heating
medium temperature of flo ca 60 c / 35 c
in comparison to low temperature sources such as solar thermal energy and heat pumps, better integration of renewable heat supply
350
low energy district heat lowex
renewable heat sources can be integrated more easily
only useful for supplying low temperature heat to energy renovated buildings
351
why is a wobbe index needed
value consideres both the calorific value of fuel gas and density
because a lighter a gas is, the faster it can be moved but it doesnt necessarily mean the calorific value is changed
352
wobbe index formula (upper)
upper calorific value of the fuel gas / square root relative density, so density fuel gas/density air
353
wobbe index formula (lwoer)
lower calorific value / square root relative density, so density fuel gas/density air
354
what doe the same wobbe index for two gases indicate
same heat load on burner at the same burner pressure and when identical burner nozzles used
output of burner is constant despite different calorific values of gases
355
wobbe index
characteristic value for the interchangeability of gases with regard to heat load
356
where to L gases come from
german and dutch deposits
357
what do declining l gas production indicate
in the l gas network areas, the networks must be converted
358
where do H gases come from
russia and north sea
359
Value chain of electricity
extraction primary energy
generation
grids, transmission and distribution
trading
sale
360
power grid
connection of spatially separated generators and consumers via lines and cables
361
fundamental challenges in network operation of electricity grid
electricity must be generated at same time as it is consumed
fluctuating demand and generation
ensuring security of supply and frequency stability
362
island grid electricity system disadvantages (stand alonoe)
grid frequency determined exclusively by speed of generator
if load increases
-> additional resistance in magnetic field of generator
-> braking
-> drop in frequency
363
electricity grids - radial networks
for small/medium networks
+shortest route length
-security of supply
364
electricity grids - ring networks
integration of several generators possible
+higher security
+easily expanded
-expensive because of longer track length and nominal diameter of the loops
365
electricity grids - mesh networks
for large distribution
+optimal supply security
+better expansion options
-very high investment costs
366
n-1 criterion - electricity grids
safety standard that must be met when planning and operating networks
when network component (eg transformer) can fail without causing unacceptable supply interruptions, interference propagation, without voltage exceeding or falling below permissible limits or components being overloaded
367
design requirements of pwoer grid in germany
transport electricity
balance between generatio and consumption
voltage maintenance: control of reactive power for transport
operational management: monitoring and control of switching status, network load and resources
market management: auctions, timetable maangement, market platform
bottleneck management: network rebuilding
368
Ohm's Law
the greater the resistance, the less current flows at the same voltage
369
what is the relationship between transmission losses and transmission voltage?
transmission losses decrease quadratically with increasing transmission voltage!
370
system components of power grids
generators: conversion
transofrmers: connect networks of different voltages
lines: ac /dc (connection of networks with different frequencies)
engines: consumer
equipment: change of transmission characteristics
371
transformers function
connect ac networks of different voltage levels
372
electrical substations
between generating station and consumer
includes transofmrers and grounding system
with switchgear: connect, interrupt, disconnect electrical paths
373
alternating current generation
by generators in power plants, cogenerations plants
374
ac advantages
simple transformation
easy operation
375
ac disadvantages
for some applications conversion to dc necessary
reactive power losses during transport through lines, esp with those with high electical capacity
376
dc generation
by PV, chemical processes (batteries, fuel cells)
377
dc advantages
directoperation of microelectronics possible
directly usable to charge batteries
significantly lwoer transport losses and no reactive pwoer losses
378
dc disadvantages
operation needs upstream electronics or special designs
generation not possible by generators in power plants
379
resistivity
termpature dependent material constant that characterizes electrical resistance of wire or resistor
reciprocal is electrical conductivity
380
dielectric strength
critical electric field strength at which voltage breakdown can occur
381
why do frequency deviations occur
momentary imbalances between generation and consumption
382
power frequency control
control method for maintaining electrical parameters agreen between TSO at the limits of their control zones during normal operation and in particular int he event of a failure
383
primary control - power frequency control
automatically acting, stabilizing control of entire interconnected grid in seconds (all power plants jointly regulated)
active reserve of power plants additional for self regulation of loads
384
redispatch
adjustment of active power feed in from power plants to avoid or resolve occuring congestion
by lowering active power feed in of one or more power plants while at the same time increasig active power feed in of one or more other power plants, total active power feed in remains virtually unchanged
385
what are possible causes for congestion in electricity grid
line interruptions for maintenance purposes
unanticipated incidents
weather
RE
386
main parts of power transformers
core, windings, casing
connected to transformer bank
387
advantage and disadvantage of single phase unit power transformers
+necessary placements
-cost of material
388
parts of overhead line system
poles made of steel, concrete or wood
insulators of porcelain, glass, plastic
lines (alu, steel)
389
what is the role of air in overhea lines
permanent renewing of insulation -> no aging
air dischanrges heat losses well -> short term overloads possible
lower costs of material
higher distances between lines required
390
cable systems for electric grid
very complex (high potential differences on small distances)
use oils and resins, plastics, synethetics
thermal overloading critical for durability of cables
391
cables disadvantage compared to overhead
fault locations not directly visible, complex detection/measuring necessary
392
what does the decision overhead lines vs cables depend on
grid reliability
renewable/replacement costs
oüperaional costs
393
what is better, overhead or cable systems?
cable for quality but more expensive
cable "state of the art"
394
cables vs overhead lines - status detection
no, yes
395
cables vs overhead lines - frequency of faults
low, medium to high
396
cables vs overhead lines - consequences of faults
repair costs, wide range from no effect to personal damage
397
cables vs overhead lines - operational costs
low, medium to high
398
cables vs overhead lines - date of renewal
proactive and not based on status detection, status detection
399
cables vs overhead lines - risk of renewal
primarily monetary, monetary and personal damage
400
temperature
intesive property: describes systems state and not its changes
Whether a temperature is “high“ or “low“ depends on the reference system with arbitrary classification (e.g. distances on thermometers).
401
Heat
quantity of energy that is transferred between systems of different temperature levels in form of a heat flow ሶ 𝑄 (when in contact via a diathermal* wall).
402
Low-temperature range
▪ All processes for temperatures below 100°C, mainly hot water production for washing
and food production.
403
Medium temperature range
This includes all processes in a temperature range from 100 to 500°C.
▪ The heat is usually supplied by steam through locally installed heating systems.
404
High temperature range
▪ Temperatures above 500°C are required, for example, for manufacturing processes in
the ceramics and metal industry.
▪ The provision of those high temperatures places special demands on the heating
systems.
▪ Often, electrical power is used for this purpose.
405
Power-oriented plant operation
– Selection, design and operation of the CHP system are based on the values for the electricity demand.
– The design must be such that excess heat is avoided, because excess heat has to be discharged from the
system in recooling plants.
– Insufficient infeed into the heat distribution network is provided separately by means of additional boilers.
406
Heat-oriented system operation
– Selection, design and operation of the CHP system are based on the values for the thermal energy demand.
– Usually, they are not designed for peak load, which is also covered by a boiler system.
407
district heating
is based on heating water in a central location and then supply domestic and
commercial consumers in form of hot water or steam via a thermally insulated piping system. The piping from
the heat generators to the load is referred to as flow and the piping from the consumer back to the heat
generators as return.
408
Difference between district and local heating:
The differentiation between district heating and local heating is
in particular a linguistic differentiation. The term local heating covers smaller decentralized heat networks, while
district heating refers to larger networks, which usually contain large transport lines. Technically, however, this
differentiation has no great importance. For both heating approaches the basic operation is the same. Also, there
exists no general definition like the length of a network to differ between local and district heating.
409
Heating plants:
provide only heat. Thus, the main part of exhaust gas remains unused by this plants.
410
Modern cogeneration plants:
based on the principle of
producing heat and electricity
by using the energy of the
exhaust gas multiple times.
There are different technical
systems. Combined units are
the most advanced, they have
the highest efficiency.
411
rate district heating in terms of nachhaltigkeit
Compared to a separate generation of electricity and heat the energy savings are between 30 and
50 percent. Therefore, the use of conventional energy carriers (hard coal, lignite, gas, oil) in those
power plants is economically reasonable. Nevertheless, the technology is mainly applied in urban areas mainly due to the limited possible transport distance for heat.
412
Solar district heating systems
heat supply systems that supply residential and industrial areas
with solar heat via large collector fields and heat networks.
413
geothermal district heating
three closed circuits are required.
1.000 to 10.000 households can
be supplied with heat.
▪ It is considered as 3rd generation district heating system.
▪ such systems are mainly used in the area around Munich.
414
what can be done in terms of power to heat? what is possible
space heating
process heating
415
why can not all processes be switched to electric heating
temperature levels (eg porcelain production require high levels of heat)
need of carbon (steel)
416
heat pump
heat pump is a machine that generates heating energy from a low-temperature heat
source using a (electrically driven) compressor.
417
parts of a heat pump
1. Condenser coil (hot side heat exchanger)
2. Expansion valve (gas expands, cools and liquefies)
3. Evaporator coil (cold side heat exchanger)
4. Compressor
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how does a heat pump work
cold liquid refrigerant pushed through with air from outside which warms it up
cold liquid refrigerant evaporates as temperature inreases. cold air is released outside
the liquid goes through compressor. pressure increases with temperature
hot air gets released inside
air condenses as it cools into liquid
liquid gets pushed through expansion valve, pressure drops, temperature drops
repeat
419
what are the components of a geothermal heat collector
horizontal geothermal energy collector
heat pumps
storage hot water
storage heating circuit
420
electrode boiler
water directly heated up without resistance elements. operated in ac mode to prevent electrolytic decomposition of water
421
HVAC - componentns and abkürzung
heating ventilation air conditioning and cooling
ventilation
filtration
heat recuperation systems
other (humidifier, cooling, sound absorber)
