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Sustainable energy > Hydrogen and CCUS > Flashcards

Hydrogen and CCUS Flashcards

1
Q

When and who agreed upon the 2DS? What is 2DS?

A

In December 2015, 161 states officially adopted the target of max temperature increase of 2 degrees by 2100 during the CoP21 in Paris.

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2
Q

What does IPCC stands for?

A

Intergovernmental Panel on Climate Change

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3
Q

What does NET’s stands for?

A

Negative emission technologies

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4
Q

What is anaerobic digestion?

A

Anaerobic digestion is a process through which bacteria break down organic matter—such as animal manure, wastewater biosolids, and food wastes—in the absence of oxygen. Through this process biogas is produced.

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5
Q

What does CHP stands for?

A

Combined heat and power: CHP is a technology that produces electricity and thermal energy at high efficiencies using a range of technologies and fuels.

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6
Q

What does RGGO stands for?

A

Renewable Gas Guarantees of Origin (RGGOs) are unique identifiers issued by the GGCS for each kWh (rounded to the nearest whole number) of biomethane injected into the grid and registered with the Scheme (see below for details of RGGOs related to other types of green gas).

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7
Q

What are the 3 pathways towards carbon neutrality?

A
  1. Increase energy efficiency and circularity
  2. Electrify as much as possible
  3. The need for more molecules
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8
Q

Making sure all our electricity generation is green is crucial but is not sufficient, why?

A

It will only reduce our overall emissions by 38 %. Industry, transport and building account for half of emissions today! Emerging technologies mainly required for industry, mobility and buildings.

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9
Q

What is an important matter concerning existing plants and their emissions?

A

We must not only build new clean aluminum, cement, iron and steel, chemical, … plants BUT must address emissions from EXISTING infrastructure since many assets are still young! CCUS and H2 will be required.

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10
Q

What is in important for the electrification scenario (electrify as much as possible) for the industry?

A

Molecules and import of renewable energy will be important and need new emerging technologies (P2X = power to molecule).

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11
Q

In what different ways can H2 be formed?

A
  1. Green H2 produced from electrolytic process using renawable energy sources like wind and solar.
  2. H2 can be a by product from other industrial processes
  3. SMR-CCS = Steam Methane reforming - carbon capture storage = reforming of natural gas to produce H2 associated with the capture and storage of CO2
  4. Pyrolysis H2 = cracking of methane under the effect of heat seprating H2 from solid carbon
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12
Q

How is green hydrogen produced?

A

Electrolysis using wind/solar/hydro/tidal/geothermal with a minimal GHG footprint

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13
Q

How is purple/pink hydrogen produced?

A

Electrolysis using nuclear power with a minimal GHG footprint

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14
Q

How is yellow hydrogen produced?

A

Electrolysis using mixed-origin grid power with a medium GHG footprint

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15
Q

How is blue hydrogen produced?

A

Reforming of natural gas + CCUS using natural gas or
Gasification + CCUS using coal
This has a low GHG footprint.

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16
Q

What is gasification?

A

Gasification is a process that converts biomass- or fossil fuel-based carbonaceous materials into gases.

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17
Q

How is turquoise hydrogen produced?

A

Pyrolysis using natural gas that gives solid carbon as by-product.

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18
Q

What is pyrolysis?

A

Pyrolysis is the heating of an organic material, such as biomass, in the absence of oxygen. The pyrolysis (or devolatilization) process is the thermal decomposition of materials at elevated temperatures.

One of the most common application of pyrolysis is the conversion of biomass, such as wood or agricultural waste, into biofuels. In this process, the biomass is heated to high temperatures in the absence of oxygen, causing it to break down into volatile gases and liquids, such as methanol and acetic acid. These can then be further processed to create biofuels like bio-oil, biochar, and syngas.

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19
Q

How is grey hydrogen produced?

A

Like blue hydrogen using natural gas reforming but without CCUS. The GHG footprint is a bit higher (medium).

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20
Q

How is brown/black hydrogen produced?

A

Trough gasification of brown/black coal without CCUS. This has a high GHG footprint.

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21
Q

What is a disadvantage of H2?

A

Very low energy density and is thus extremely hard and expensive to store and move around.

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22
Q

What are key factors for decreasing the cost of green H2?

A
  1. Affordable renewable power
  2. affordable efficient electrolyzers
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22
Q

What are key factors for decreasing the cost of green H2?

A
  1. Affordable renewable power
  2. affordable efficient electrolyzers
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23
Q

Why should we use hydrogen?

A
  1. It is an energy vector that is intrinsically 100%
    decarbonized.
  2. It can be ‘easily’ produced from renewable energies.
  3. It can be stored and transported (challenging though!)
  4. It can be turned back to electricity (through fuel cells) or
    methane (through methanation process)
  5. It can be used directly : green mobility, CHP for
    buildings, industry, intermittent renewable energies
    storage or peak shaving in smartgrids
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24
Q

What are the 3 types of electrolysis?

A
  1. Alkaline electrolysis (diaphragm) => most mature, robust and less expensive
  2. PEM electrolysis (polymeric electrolyte membrane) => high dynamical response (good for coupling with intermittent power sources and providing grid services)
  3. Solid electrolysis (ceramic oxide between anode and cathode) => still under development
25
Q

What is a fuel cell?

A

Like a electrolyser working in the opposite way. It is an electromechanical reactor that directly converts the chemical energy of a fuel into electricity and heat without any combustion and moving parts.

26
Q

What does LOHC stands for?

A

Liquid organic hydrogen carriers (LOHC) are organic compounds that can absorb and release hydrogen through chemical reactions.

27
Q

What role can fuel cell EV’s play in decarbonizing transport?

A

Usage for larger vehicles with a high mileage per day (+100). But for personal transport, BEV’s is winning the race.

28
Q

What technology is most efficient for personal heating?

A

Heat pumps (300% eff unlike 90% for hydrogen boilers). For personal heating using hydrogen boilers the following steps are needed:
1. Renewable energy production
2. AC/DC conversion (losses)
3. Electrolysis (losses)
4. Compression (losses)
5. Transmission (losses)
6. Boiler itself (losses)

Heat pumps only has losses on the transmission of the power from the renewable sources to the heat pump itself.

29
Q

What does PEC stands for?

A

Photo electrochemical cell: electricity generated directly from sunlight at the photo-Anode

30
Q

How can you produce hydrogen using solar?

A
  1. Electrolyser and multiple PV cells to have hight enough voltage for the electrolysis, main challenge is getting enough water out of the ambient air.
  2. PEC: Photo electrochemical cell, artificial photosynthesis
  3. Using living organisms (biotechnology)
31
Q

What does RTS stands for?

A

Reference Technology Scenario

32
Q

Where can CO2 be stored?

A
  1. Depleted oil or gas reservoirs
  2. Unmined coal seams
  3. Deep saline aquifers (is a geological formation of porous sedimentary rocks containing salt water)
33
Q

What are the three main categories to capture CO2?

A
  1. Pre-combustion
  2. Post-combustion
  3. Oxyfuel capture
34
Q

What is post-combustion capture of CO2?

A

Post-combustion means the capture of CO2 out
of flue gases after the combustion process. Post-combustion technologies using amine solvents are
the most developed, and some are commercially mature. The main advantage of post-combustion capture is that
it can be retrofitted to existing plants. TRL9 (used for steam turbines)

35
Q

What is oxyfuel capture of CO2?

A

Oxyfuel means combusting fuel in an oxygen enriched
environment to produce a CO2 rich flue gas. The technology is based on combustion in an oxygen enriched environment and in the absence of nitrogen, leading to flue gases containing mainly CO2 and H2O (vapor). Water is afterwards removed by condensation. The oxygen is diluted (verdund) with flue gas, which is cooled, recirculated, and injected into the combustion chamber to control the temperature. TRL7: demonstration phase (used for steam turbines)

36
Q

What is pre-combustion capture of CO2?

A

Pre-combustion uses a gasification process followed by CO2
separation to yield a hydrogen fuel gas. An advantage of the pre-combustion process could be that the produced hydrogen can be used for other
applications (vehicles, fuel cells), or stored
(intermittent production → high flexibility). TRL 9 (used for gas turbines IGCC: Integrated gasification Combined Cycle)

37
Q

What is supercritical CO2 power cycle?

A

Process with CO2 as working fluid (instead of air).
Oxygen is injected in the mix for the combustion of
the fuel. This combustion results in CO2 and H2O
which then expand in a turbine generator.
When operating this cycle on high pressure, and
expanding the combustion gases from 300 bar to 30
bar, the global efficiency is 58%, comparable with a
CCGT, and CO2 is captured without additional energy
penalty.
Advantages compared to a CCGT or coal fired power
plant with CCS
— Higher efficiency
— Lower footprint
— Lower CAPEX
— Higher flexibility

38
Q

Whats the main issue concerning conventional CO2 capture technologies?

A

It reduces the efficiency of power plants with 7-12% points. This energy penalty explains why, in retrofit, capture should not be applied to old existing plants. But Energy penalty expected for the capture to fall below 4% point for carbonate looping and even below 1 % for chemical looping. Supercritical CO2 power cycle allows a global efficiency of 58%, comparable with a CCGT, and CO2 is captured
without additional energy penalty

39
Q

What is carbonate looping?

A

Use of CaO as a regenerable absorbent in post combustion capture of CO2.

40
Q

What is chemical looping?

A

The separation of combustion deploying oxygen carriers in oxyfuel capture of CO2.

41
Q

What is DAC and why is it useful?

A

DAC stands for direct air capture. Carbon dioxide can be removed from ambient air through chemical processes based on acid-base reactions. Direct Air Capture (DAC) is comparable to the respiratory system or the photosynthesis.

  1. DAC can capture the CO2 emitted by decentralized
    sources (e.g. transport)
  2. It can be decentralized towards sites that offer a
    cheap source of renewable electricity and heat.
  3. Deployed close to CO2 storage sites, DAC becomes a
    Negative Emission Technology (NET)
  4. Its modular construction means many of them can be
    built which can drive down cost
42
Q

What are challenges and difficulties concerning DAC?

A
  1. CO2 in the atmosphere is highly diluted (verdund) (~400 ppm):
  2. Large energy footprint
  3. Cost
  4. Large land footprint
43
Q

What two commercially available technologies are there for transporting CO2?

A

Ships and pipelines. Ship can transport 1400 tonnes CO2, a 800MW coal power plant emits 5 Mtonnes CO2 per year or 15000 tonnes per day!

44
Q

What is a major risk concerning pipelines for CO2?

A

The main risk associated with CO2 pipeline transport is a pipeline failure resulting in CO2 release. A pipeline failure, which can be either a (pin) hole or rupture, can be caused by external events (accidental rupture by external shock, corrosion, construction defects and ground movement). The accident record for CO2 pipelines in the USA shows accidents from 1968 to 2000 without any injuries
or fatalities corresponding to a frequency of approximately 3.10-4 incidents per km per year (remote and/or sparsely populated locations).
CO2 is heavier than air so in contrast to methane, does not move upwards..

45
Q

What are the two main options to store CO2 geological?

A
  1. Saline aquifers (TRL 9) biggest theoretical capacity
  2. Depleted oil and gas fields (TRL 9)
46
Q

What is CO2 valorisation?

A

CO2 can be used as building blocks for high added-value fuels, chemicals and materials.

47
Q

What are the two biological valorisation processes for CO2?

A
  1. Photosynthesis using sunlight
    Photosynthesis produces sugars from sunlight, CO2 and water. The
    sugars can be converted directly in ethanol or used to build-up
    biomass that is then converted into different fuels
  2. Fermentation without sunlight and oxygen
    Some bacteria get their energy and carbon sources for growth from
    CO2/CO (more than 100 species). In the absence of oxygen and light
    (eg in closed fermenter), they produce Acetate, Ethanol, Butanol or
    Hydrogen. They tolerate temperatures about 30 – 80°C. When
    combined with electrodes, some also produce electricity (Microbial Fuel
    Cells).
48
Q

What technolgies are used for biological valorisation of CO2?

A

Open ponds and photobioreactors can be used to produce fuel from sunlight
and CO2. Closed systems, as photobioreactors or fermenters show higher CO2
fixation rate. Photosynthetic systems require more space than fermentation
techniques. Fermentation requires hydrogen. Only the open ponds are fully commercial available, the other two technologies are in R&D.

49
Q

What is the mineralisation of CO2?

A

Mineralisation is a chemical valorisation process of CO2 into materials and is a slow, exothermic reaction between CO2 and an industrial waste or natural silicates such as olivine or serpentine; the reaction needs acceleration. Mineral carbonation refers to the conversion of magnesium or calcium oxides (typically contained in mineral silicates and industrial wastes) to solid carbonates, mimicking the natural process by which CO2 is removed from the atmosphere. >99% world’s carbon reservoir is locked up as limestone & dolomite rock – CaCO3 & MgCO. The reaction is thermodynamically favorable ie. energy is released, but it is kinetically very slow (ie. years/decades under natural circumstances). The resulting material are carbonates which can be used as construction or filling materials. In some cases, valuable by-products such as silica, metals and/or the inertisation of waste feedstocks are being targeted. TRL2-9

50
Q

What is a problem for upscaling mineralisation of CO2 for industry?

A

Operation requires the handling of enormous amounts of feedstock
material and the acceleration of the carbonation process; R&D needed on
the recovery of the energy that becomes available (exotherm process) Need for LCA!

51
Q

How can CO2 be converted into (non-fuel) chemicals?

A

Use the C in CO2 as a building block for these non fuel chemicals. Chemical reaction using catalysts to facilitate the reaction. The choice of the catalyst or micro-organism determines the nature of the end-product. This is polymerisation.

52
Q

Give two examples of P2G?

A
  1. Power for using electrolysis and converting H20 into H2
  2. Power for methanation process and converting C02 into CH4
53
Q

Give a G2P example?

A

Gas used for gas turbine

54
Q

Why should we convert power to gas?

A
  1. If extra electricity is available, it’s easier to store it in the gas grid
  2. Once transformed into gas, it’s not always necessary to come back to
    electricity ; the energy converted can be directly used as a gaseous
    energy
  3. Full usage and optimization of both infrastructures G & E
  4. H2 injection in the gas grid must remain below 20%, but H2 can be
    transformed into SNG (synthetic natural gas) if some CO2 is available (H2 methanation process)
55
Q

What is the most efficient P2G for CO2 using H2?

A

CO2 to methane = methanation instead of CO2 to methanol or liquid fuels

56
Q

What is P2L?

A

Power to liquids can be used as jet fuel (hydrocarbon fuel). Too expensive today
but highly dependant on electricity price and CAPEX for electrolysis. Will become competitive with fossil jet fuel and biofuel

57
Q

Why is aviation full on H2 difficult?

A

Energy Density remains crucial for aviation -> not likely to get (fully) out
of hydrocarbon fuels any time soon. Factor 4 larger tanks needed in case of LH2 and high weight for tank.

58
Q

What is photoelectrolysis?

A

It is a process that directly use photon’s energy to break the water molecule
and produce dihydrogen and oxygen. Production of green hydrogen

59
Q

What is Artificial photosynthesis (AP)?

A

Through the use of photo-
electrocatalysis, AP seeks to
replicate the photosynthesis process.
It widely uses semiconductors as
photocatalyst and often splits the
process in two steps :
1) Production of hydrogen by water
splitting using photocatalysis
2) CO2 reduction and subsequent
reaction with hydrogen to form
light weight hydrocarbons
through different approaches

60
Q

What is an energy vector?

A

Examples of this are electricity and hydrogen. We call these two man-made forms of energy “energy vectors”, because both of them enable energy to be carried and can then be converted back into any other form of energy.

Sustainable energy (17 decks)

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