Sustainable Practices: Clean Technologies, Pollution Control, and Green Initiatives

Posted on Dec 16, 2024 in Geology

Clean Technologies vs. Cleaning Technologies

1. Differences Between Clean and Cleaning Technologies

  • Cleaning Technologies (Clean-Up Technologies): These technologies aim to reduce environmental impact by modifying or adding processes at the end of the production line (end-of-pipe). They are always implemented in an already established process or facility.
  • Clean Technologies: These involve conceptual or procedural changes in the manufacturing of products and human activities aimed at preventing environmental damage. They take into account all phases of a product’s life cycle or activity. These are inherently cleaner technologies.

Graphical Representation of Cleaning Technologies:

  • A: Developed Countries – Higher cost, lower environmental load.
  • B: Developing Countries – Lower cost, higher environmental load.

Graphical Representation of Clean Technologies:

  • D: Reduces environmental damage while maintaining cost.
  • F: Reduces costs and damages.
  • E: Reduces cost while maintaining environmental load.

Note: If the environmental burden is not reduced, we cannot classify it as a clean technology.

Excessive Pollution Control

2. Excessive Pollution Control

This is the economics of pollution, represented by two curves:

  • CMR (Decreasing Marginal Cost): Represents the reduction of pollution. The less that is emitted, the higher the economic cost will be.
  • DC (Increasing Damage Caused): Represents the damage caused by the release of waste, reflecting what we are willing to pay. As more contaminants are present, the damage increases.
  • CC (Critical Load): The rising curve at the bottom indicates when the environment is significantly impacted. This is the critical load, beyond which environmental damage is excessive.

The intersection of the CMR and DC curves represents the optimum point. This is the point where the cost of reducing pollution aligns with what we are willing to pay, using the best available technologies (BAT) and ensuring everything is at an optimal level. This point is often dictated by legislation and BATNEEC (Best Available Technology Not Entailing Excessive Cost).

Excessive pollution control occurs when the cost of reducing pollution to this level is much higher than what we are willing to pay.

Functional Unit vs. Physical Unit in LCA

3. Differences Between Functional and Physical Units and Their Uses in Life Cycle Assessment (LCA)

  • Physical Unit: Refers to a product.
  • Functional Unit: Refers to a function and is most commonly used. It is used to compare products, such as milk packaging. Calculations are similar to those based on material balances.

Normalization of Environmental Indicators

4. Normalization of Environmental Indicators of Impact Categories

This involves selecting the environmental indicator in question and dividing it by a real or predicted magnitude of the impact category corresponding to a geographic area and/or a reference time. This process is performed for all categories, resulting in an environmental profile where all impact categories can be compared. Many LCAs stop at this stage because there is no consensus on the relative severity of different impacts.

Slow-Release Fertilizers

5. Slow-Release Fertilizers (Gradual or Controlled Action)

There are two main types:

A) Coated Fertilizers: These are conventional fertilizers coated with a semipermeable membrane (low solubility). They are more expensive and have restricted use. Examples include urea-sulfur or fertilizers coated with polymeric material.

B) Low-Solubility Fertilizers: These require a large amount of water for complete dissolution. Examples include urea-formaldehyde and inorganic ammonium metal phosphates.

Header Molecules in Pesticides

6. Header Molecules (Pesticides)

In current combinatorial chemistry, sulfonylurea-type herbicides are commonly used. An improvement in this type of herbicide is the use of a CH group instead of an aldehyde group. Currently, there are 20 sulfonylurea-based herbicides with dosages of less than 100 g/ha.

Advantages of PET

7. Advantages of PET

  • Excellent barrier against external agents.
  • Protects from harmful gases, making it suitable for food packaging.
  • High transparency with the original material, without the need for many colors.
  • Containers with good consistency.
  • Excellent resistance to chemicals and temperature.
  • Provides quality care.
  • Recyclable.

Gasification Process and Products

8. Gasification: Process and Products

Gasification is the conversion of a material to gas by partial oxidation at high temperatures (1000-1500°C). It is a classic technique, often applied to coal to produce syngas (CO + H2). For plastics, it is used to produce fuel gas. The calorific value of the gas produced varies depending on the operating conditions (temperature, pressure), the gasifying agent (O2, H2O), and residual moisture. Reactors are usually moving bed (countercurrent) or fluidized bed.

Reactions:

C + O2 → CO2

C + H2O → CO + H2

C + 2H2 → CH4

CO + H2O → CO2 + H2

CO + 3H2 → CH4 + H2O

Recovery, Recycling, and Utilization Rates

9. Rates of Recovery, Recycling, and Utilization

  • Recovery: Waste paper is recovered for recycling through various channels. Collection can be industrial (businesses, printers, etc., with a rate of 90%) or selective (municipal, through blue containers and door-to-door collection from small shops, with a rate of 40%).
  • Recycling: This is the consumption of recovered paper as a percentage of total paper consumed. It represents the use of recovered paper as raw material in making new paper.
  • Utilization: This is the ratio of recycled paper to the total new paper used.

TCF (Total Chlorine Free)

10. Which Processes are Suitable for TCF (Total Chlorine Free)?

DPDP → QPZP (No)

QDPZP → QPZP (Yes)

The former are ECF (Elemental Chlorine Free) but not TCF.

Solar Energy, Cogeneration, and Combined Cycle

11. Can We Speak of Solar Energy Production and Cogeneration in a Combined Cycle?

  • Combined Cycle: This involves the combined use of a gas turbine and a steam turbine, achieving up to 50% efficiency. It requires fuel for the gas turbine (typically natural gas).
  • Cogeneration: This is the use of thermal energy, typically for home heating, with yields of up to 90%. It is principally applied to other industries. For this, the installation should be small and close to the place of use.

Cooling Circuit Influence on Power Plant Performance

12. Does the Cooling Circuit (Open or Closed) Significantly Influence Power Plant Performance?

Yes.

  • Open Circuit: Cooling water is taken from a source like the sea or a river, passed through the condenser, and returned downstream.
  • Closed Circuit: Hot water is reused. It passes through a cooling tower where hot water is dropped from the top, and openings at the bottom allow for convection between air and the falling water, cooling it. The cooled water is collected at the bottom. Some water evaporates, contributing to the cooling process.

Closed circuits can have lower efficiency due to losses in the condenser. Therefore, plants are becoming smaller and more efficient.

Biomass Energy Utilization

13. Scheme for Energy Utilization of Biomass

a) Biomass:

Forest residue, agricultural residue, agricultural industry waste, forestry residue, and energy crops can be used to produce energy through refining processes, pyrolysis, gasification, densification, or without treatment.

b) Biogas:

Livestock waste, biodegradable industrial waste, sewage sludge, landfill degasification, and the organic fraction of municipal solid waste (MSW) can be used to produce electricity through anaerobic metabolism.

c) Biofuels:

Energy crops and agricultural surpluses can be used to produce biodiesel and bioethanol through alcoholic fermentation, extraction, and esterification. These are used in transportation.

Bioethanol as a Biofuel

14. Bioethanol as a Biofuel: Use Options

Barley is subjected to a metabolic process that creates alcohol (ethanol). Fermentation by yeast then occurs in tanks. This process produces a breeding ground for many substances, including CO2, which is transferred to other industries. Dehydration is then performed. The residue is dried with hot air to produce tablets.

Uses:

  • Transformation: Combined with refinery butenes, it becomes ethyl tert-butyl ether (ETBE), a common component in gasoline. ETBE replaced MTBE as an additive. The CH3 group is changed to CH3-CH2.
  • Direct Blending with Gasoline: Bioethanol can be blended with gasoline at a percentage of up to 10%. However, there are distribution challenges because ethanol is miscible with water. Therefore, the mixture is typically made at the gasoline supply center.

Comparison of Three-Way Catalyst (TWC)

15. What Would Happen if a Three-Way Catalyst (TWC) Were Used in the Context of Point 12.2?

The three-way catalyst aims to remove hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOx). HC and CO are oxidized with O2, while NOx is reduced with a catalyst. For the catalyst to work effectively, the O2 content must be low, and a sensor is needed to monitor the O2 levels. In the context of point 12.2, there would be much more oxygen, causing the engine to malfunction and potentially even burn, leading to damage to the car.

Types of Solar Collectors and Their Applications

16. Describe the Known Types of Solar Collectors and Their Applications

Solar collectors determine the possible temperatures that can be achieved.

  • Flat Plate Collectors: These can achieve temperatures up to 90°C (low) and are suitable for hot water in hotels. They are placed on rooftops, and the inclined surface is black. They are also used for air conditioning, cooling pools, etc.
  • Concentrators: These focus energy to produce heat. Parabolic shapes are ideal because they can project all impacting radiation onto a smaller area. Cylindrical-parabolic types are more commonly used. Air can be used instead of water. They may be coated with a reflective material. Central tower systems use a central tower to reflect radiation onto smaller plates. These are used to produce electricity in a steam turbine, with solar energy assisting in generating thermal energy.