A foot valve is a special type of non-return valve, with a strainer affixed to the open end. For suction lift applications, foot valves are widely used in the pump suction or at the bottom of pipelines. The use of foot valves, keeps the pump primed, the fluid flows in but does not flow back out, and hence they are ideal for wells, ponds, and pools. As the flow area of the foot valves is larger than the pipe size, there is very less head loss.
Working of a Foot Valve
Foot valves being unidirectional allow the flow only in one direction and the valve closes for reverse flow. The inlet strainer of the foot valve filters out the unnecessary solid particles from the fluid and thus prevents valve damage.
When pumps are used to move fluids from lower to higher elevations, a lot of energy will be required. At the same time when the pump is turned off, the liquid will flow back to the lower level. But the use of foot valves prevents this reverse flow. The foot valve maintains the liquid column even when the pump is not working.
Foot valves are basically a type of check valve that prevents the backflow of liquid. They are placed in the pick-up end of the pipe and are located at the very bottom. When the pump is started, a suction is created which opens the foot valve. Water or other liquid easily enters the pipe through the foot valve due to the pulling force of the pump. But when the pump is turned off, this pulling force is removed but still, the water level retains its level as the foot valve does not allow the water to flow back. thus the pump remains always primed.
Requirements for Foot Valves
Foot valves are used for various reasons like:
To keep the pump primed when pumping liquid from lower to higher levels.
To prevent damage to water pumps without foot valves there may be dry runs. Without a foot valve, the air will fill the pipe which will oppose the water flow and the pump will run dry.
To reduce energy wastage.
Functions of the Strainer for the Foot Valve
The strainer in a foot valve filters out the debris that may jam the foot valve and can cause damage to the pump. So, the strainers protect the valves and pumps and perform a very important function.
Features of a Foot Valve
Foot valves usually have self-tapping male and female threads that help in easy installation. They have internal balls for quick sealing and valve reaction. They are flexible enough to fit various types of water pump uses. Foot valves are cheaper compared to other valves.
Components of Foot Valves
Each foot valve consists of 4 basic components:
Screen: To remove sediments or debris.
Body: The complete mechanism is housed within the valve body.
Seat: The seat is an integral part of the body and uses o-rings to avoid leakage when the valve is closed. The valve lands on the seat when the pump is turned off.
Disc: This is the gateway of the foot valve. When the disc is raised, liquid can enter.
Materials for Foot Valves
Foot valves are usually constructed of heavy-duty cast iron, bronze, Stainless Steel, PVC, and Plastic. Foot valves are normally used for water services and these materials last longer when submerged in water.
Applications of Foot Valves
As foot valves prevent the suction column from draining when the pump is not in operation, they are widely used in all kinds of pneumatic systems. The major application of foot valves is found in pumps and because of that, they are sometimes called foot valves for pumps or well-pump foot valves. Typical applications of foot valves include:
Suction lines of the pipeline
Ponds, pools, and wells, where pumps are used to transfer water.
Sump pumps, and intake pumps, in rivers and lakes.
Foot valves can be classified based on construction and flow systems. Based on the construction of foot valves, there are two types of foot valves, Membrane foot valve, and ball foot valve.
Membrane foot valve: In a membrane foot valve, a cylindrical rubber membrane is fitted inside a steel strainer. When the suction is formed in the strainer, the membrane is displaced and the liquid flows through the valve. The cylindrical membrane closes during a reverse flow and thus prevents the backflow.
Ball foot valve: In this type of foot valve, a cylindrical inclined chamber and seating have used that guide the ball valve. When inward flow occurs, the ball is displaced with its chamber, and fluid flows. On the other hand, when the flow rate decreases, it runs down the chamber onto its seat and the valve prevents reverse flow. Ball foot valves are mostly used for contaminated water.
According to the flow system, the foot valves are classified as Microflow system valves, high-flow system valves, and low-flow system valves.
The microflow system valves are mostly made of stainless steel and used in direct push technology micro-wells and multilevel good installation.
The high-flow system valves are used on 2-inch wells or larger and can stand high pumping rates and very deep wells.
The low-flow system valves are used in small diameter piezometers which lift up to 100 feet of water.
Based on the types of threads used, foot valves are of three types:
Female threaded foot valve.
Male threaded foot valve
Dual-threaded foot valve
Selection of Foot Valves
Foot valves are selected considering various parameters like:
The task that the foot valve will perform and fluid service.
Duty of valve; whether heavy-duty or light-duty.
Load the foot valve need to carry.
Durability.
Maintaining a Foot Valve
Even though a foot valve is a small element, it must be properly maintained. Some of the steps that can be followed to increase the life of foot valves are:
Regular cleaning of debris of the foot valve.
Regular checking of corrosion signs.
Ensuring that the tank or well bottom is clean
Difference between Foot Valve and Check Valve
Even though both the check valve and foot valve serves a similar function of a non-return valve i.e, preventing backflow, there are some distinct differences between the two valves. They are:
3D models are very popular in the engineering of process and power piping industries as they graphically represent the overall plant with all equipment, piping, structures, instruments, and electrical connections in a three-dimensional view. These 3D models are close to the real plant that will be built at the site after construction. Various 3-D piping design software packages like PDMS, SP3D, E3D, etc simulate the actual plant in the 3D model that gives a better representation of the plant as compared to the age-old 2D plant models. They are the electronic equivalents of real plants. In this article, we will explore the 3D model review procedures.
What is a 3D Model Review?
A 3D model review is a design procedure to present the electronic 3D model to the client to verify that the current stage of the design meets the minimum project requirements for operability, maintainability, constructability, safety, and functionality and that it reflects every discipline’s input to the design to date. All discipline engineers review the 3D model through a walkthrough of the plant. Any design changes required are discussed and listed as Model review comments which will be taken care of after the model review.
For small projects for which 3D software packages are not used a similar philosophy of review termed Desktop Review is followed.
Stages of 3D Model Review
3D Model review, in general, is performed in three stages; 30% model review, 60% model review, and 90% model review. The percentage term used along with model review denoted the percentage completion of the design stage. These model reviews are major checkpoints and milestones in the engineering design process. Deliverables required from each discipline to achieve each of these checkpoints are defined in the model review matrix.
Typically a model review will not proceed until such time that all of the deliverables required for the specific review have been incorporated. When deliverables are missing for a particular review, the model review may only proceed provided that the associated risks and mitigations have been identified and approved by the project manager.
30% Model Review
A 30% model review means the design is complete by roughly 30% and is the 1st milestone for model preparation. All design data is not yet firm at this stage. This phase aims to lay out the major design elements of the project. It establishes the cost and timeline of the project. 30% model review generates a basis for plant layout, accessibility, and safety measures recommendation. Only the large-diameter critical lines are routed and modeled. At the 30% model review stage, the contractor and client meet to set a basis for further development of the design.
The 30% model review phase is the foundation of the project. From this point onwards the design will be developed further continuously.
Objectives of 30% model review
The 30% 3D model review is performed to serve the following objectives:
To discuss and agree on overall plant layout qualifying hazard recommendations and other project requirements.
To fix the equipment location considering the available information.
To identify primary operational/assessable/maintenance points or platforms.
To identify improvements considering the safety and operation aspects.
To release foundation loads for structural design.
To finalize the equipment nozzle orientation and send the information to the vendor.
To finalize the main underground isometrics for fabrication.
Important points that are usually included and discussed during any model review are usually decided by the model review matrix. The model review matrix outlines the preparedness required by each discipline at each stage of the design review and the items to be reviewed at that stage. A sample model review matrix explaining the piping items is provided in Table 1 below.
60% Model Review is the second milestone of the model review process and serves the utmost importance of the project. All the doubts raised during the 30% model review are clarified during this phase. In this stage, the team focuses more on the analysis of constructability, budget consideration, modification, and potential issues or concerns. The model review team discusses the constructability of the drawings and any preferred equipment and material needed to build the project during this stage.
60% model review phase is also considered to be a good time for value engineering. Any changes or modifications after a 60% model review will significantly impact the schedule, cost, and overall design. In general, the 60 % model review is carried out and closed out prior to issuing the piping isometrics for construction.
Objectives of 60% model review
The main objectives of the 60% model review process are:
To check if the design is at par with the safety philosophies and requirements.
To determine the location of secondary fire/safety equipment
To find out if the main equipment locations are in order and updated.
To review the location of minor equipment.
To review the secondary operability/accessibility/maintainability as required.
To review and release buried isometrics for IFC.
To release the updated nozzle orientation information to the vendor.
90% model Review
This is the final model review and the design is almost final with all data and information. 90% model review finalizes the total design of the model. All the comments from the 60% model review stage are resolved and incorporated into the 90% model review. All drawings and specifications are ready with the design team for issue as final. 90% model review is the last stage for the client to suggest any minor changes. The construction schedule, phasing plan, logistics plan, etc are finalized at this stage.
During the 90% model review stage, the model must be substantially complete, including instrumentation and all Manufacturer/Supplier information, to allow final comments to be made.
Objectives of 90% model review
The main objectives of the 90% model are:
To ensure that the final design is acceptable to the client and agree to IFC issues of all drawings and specifications.
To ensure that operational and maintenance access has been provided to all required items.
To ensure the construction feasibility of all plant components.
To ensure all safety philosophies and recommendations are implemented prior to the publication of drawings.
To ensure the model reflects all project requirements.
3D Model Review Responsibility
3D Model Review is the joint responsibility of the piping lead, the designer/drafter, the project engineer, and other related disciplines. The piping engineer and the project engineer are the primary organizers of the model review. In most cases, the piping leads show the plant by walk-through of the complete plant. All comments are recorded in a proper project format for resolution and incorporation. Any necessary changes and comments are agreed upon and immediately recorded and marked with reference numbers and model pictures to allow follow-up and avoid misunderstanding.
The main responsibilities of the primary organizers are as follows:
Responsibilities of the project engineer:
Project engineers
Decides the required attendees, and schedules and manages the formal model reviews.
Ensures that the design progress meets the requirements for the review as defined in the model review matrix.
Prepares and issues an agenda for the review.
Coordinates the discussions and documents resolutions and action items.
Ensures proper filing of all documentation.
Distributes the model review comments to the attendees.
Responsibilities of the piping lead:
The piping lead engineer
Coordinates with CAD support for the assembly of the 3-D models required for the review.
Operates or designates a team member to operate the computer “walk-through” during the review.
Ensures that an interference check has been completed prior to the review.
Ensure that a “snapshot in time” of the 3-D model files used for the review is archived for future reference and record-keeping after each review.
Captures all comments/action items in the software package.
Maintains a hard copy binder and logs and distributes the action items to the designers.
The important activities and responsibilities can be listed as follows:
Schedule for model review: Project Manager
Model review document preparation: Project Engineer
Distribution of review document and agenda to the client: Project engineer
Organize model review venue: Project engineer
Review tools and create a model file: Design Administrator
Report status of 3D CAD model: Lead piping engineers
Report of hold item list: Lead piping engineers
Coordination during model review meeting: Project engineer
Preparation and Summarize of the action list: Project engineer
Review, reconciliation, and distribution of action list report: Project manager
Follow up and Updation on Action list: Project engineer/Lead piping engineer
Review model and Status files: Design Administrator
Supporting Documents and Drawings for Model Review
Various documents may be required during the actual model review process. Hence the following documents with their latest approved revision should be made available during the model review session. These drawings are usually marked as “Model Review master“. These important documents and drawings are:
For each model review session, the contractor notifies the client and all other disciplines about the venue and time of each model review session. Usually, the following professionals participate in the model review session:
Instrument/Electrical engineer: As per requirement
Structural Engineer: As per the requirement
Safety Engineer: Full time
HVAC: As per requirement
Civil Engineer: On-call
3D Model Review Checklist
Checklists of 3D model reviews are prepared to ensure that important checkpoints are discussed and not missed during the session. The 3D model review checklist varies with the stages of the model review. Some typical points that are included in the 3D model review checklists are listed below:
30% Model Review Checklist
The 30% model review checklist usually considers the following checkpoints:
Location of all equipment and their orientation
Major critical piping routes
Separation distance within plots
Constructability
Drainage philosophy
Access to major valves
As-built coordinates of tie-ins with existing pipe or equipment.
Major wall and floor penetrations.
Equipment status
60% Model Review Checklist
The 60% model review checklist emphasizes the following major points:
Pressure regulators play a critical role in ensuring the safe and efficient operation of equipment and processes in the oil and gas industry. From drilling to refining, maintaining optimal pressure levels is essential for the smooth functioning of systems that involve the handling of volatile substances.
What Are Pressure Regulators?
A pressure regulator is a device designed to maintain a desired output pressure by controlling the flow of gas or liquid from a high-pressure source to a lower-pressure environment. It automatically adjusts the pressure to the required level, ensuring consistent performance of the downstream equipment.
In the oil and gas industry, pressure regulators are used extensively to manage the pressure in pipelines, storage tanks, and processing equipment to ensure safety, reduce risks, and improve efficiency.
Pressure regulators are devices used for controlling fluid pressures within a range. The main function of a pressure regulator is to reduce a high input pressure to control lower output pressure. Pressure regulators can even find applications in situations where constant output pressure is required to be maintained.
The Role of Pressure Regulators in Oil and Gas Operations
Oil and gas extraction, processing, and transportation involve highly pressurized fluids and gases, making pressure regulation essential at various stages. Below are some key areas where pressure regulators are indispensable:
Drilling Operations: During the drilling phase, pressure regulators are used to control the flow of drilling mud and prevent blowouts. This ensures that the well remains under control even in high-pressure reservoirs.
Gas Distribution: In natural gas distribution systems, pressure regulators manage the flow of gas from high-pressure pipelines to lower-pressure delivery systems that supply consumers.
Processing and Refining: Refineries use pressure regulators to maintain the optimal pressure within reactors, distillation columns, and other equipment. Proper pressure regulation ensures that chemical reactions occur efficiently and that safety is maintained in case of overpressure.
Pipeline Transportation: Long-distance transportation of oil and gas requires precise pressure control to minimize energy loss and ensure the integrity of pipelines. Regulators help manage pressure drops across pipelines and maintain steady flow rates.
Storage: Pressure regulators control the pressure inside storage tanks, especially when storing liquefied natural gas (LNG) or other compressed gases. This prevents hazardous conditions, such as over-pressurization, which could lead to explosions.
Other applications of pressure regulators are:
gas grills,
heating furnaces,
dental equipment,
pneumatic automation systems,
automotive engines,
aerospace applications,
hydrogen fuel cells,
reclaim driving helmets
pressure cookers and pressure vessels,
welding and cutting,
gas-powered vehicles,
mining and natural gas industries,
hyperbaric chambers,
inflating tires, etc
Functions of a Pressure Regulator
As already stated the main purpose of installing a pressure regulator is to reduce the pressure. However, they can effectively be used to perform the following functions:
Regulating the back-pressure
As pressure switching valves in pneumatic logic systems.
As vacuum regulators, to maintain a constant vacuum.
Components of a Pressure Regulator
All pressure regulators are characterized by the reduction of the inlet pressure to lower output pressure. There are three main components that help a pressure regulator perform its intended function are:
A loading element like an actuator or spring to apply the required force
A sensing element like a piston or diaphragm.
Refer to Fig. 1 below which shows the schematic diagram of a typical pressure regulator.
Fig. 1: Schematic of a Typical Pressure Regulator
The pressure-reducing valve is also known as the restricting element. It provides a variable restriction to the flow. Examples include a globe valve, butterfly valve, poppet valve, etc.
The loading element is a part that can apply the needed force to the pressure-reducing valve. A weight, a spring, the diaphragm actuator in combination with a spring, or a piston actuator can act as the loading element.
The measuring element or sensing element determines when the inlet flow is equal to the outlet flow. Often, the diaphragm itself works as a measuring element; it can serve as a combined element.
Types of Pressure Regulators
Depending on the number of stages employed to get the final reduced pressure, there are three types of pressure regulators.
Single-Stage Pressure Regulator: For relatively small pressure reduction in the range of 100 to 150 psi. Used for machine tools, test stands, linear actuators, automated machinery, leak test equipment, etc.
Dual Stage Pressure Regulator (Suitable for large variations in the inlet pressure), and
Three-Stage Pressure Regulator: They provide a stable outlet pressure and are able to handle larger pressure reduction. Typical examples are UAVs, medical devices, analytical instruments, hydrogen fuel cells, etc.
Again, based on the working methods they can be broadly categorized into the following two classes.
Self-operated Pressure Regulator: Simplest design. They have greater accuracy at lower pressures and lower accuracy at higher pressures. They do not require external sensing lines for effective operation.
Pilot Operated Pressure Regulators: They are complex in design but can handle larger pressure fluctuations. Pilot-operated pressure regulators provide precise control of pressure.
Based on the application of pressure regulators they are sometimes termed as:
Water pressure regulator
Gas pressure regulator
Fuel pressure regulator
Working of Pressure Regulators
A pressure regulator matches the gas flow through the regulator to the gas demand placed upon it. At the same time, they maintain a sufficiently constant output pressure. When the load flow decreases, the regulator flow also decreases. Again, when the load flow increases, then the regulator flow also increases and thus keeps the controlled pressure from decreasing due to a shortage of gas in the pressure system. The pressure regulators are so designed that the controlled pressure does not vary greatly from the set point for a wide range of flow rates. At the same time, the flow through the regulator is stable and the regulated pressure is not subject to excessive oscillation.
Pressure Regulator Materials
The material of pressure regulators varies depending on the operating environment and compatibility of the fluid handled. Common materials that are used in typical pressure regulators are:
Brass
Aluminum
Stainless Steel
Plastic
Stainless Steel and sometimes carbon steel are used for spring materials. Seal material is usually Fluorocarbon, EPDM, Perfluoroelastomer, or Silicone.
Selection of Pressure Regulators
Even though pressure regulators are found in various sizes and constructions, Some parameters must be considered for proper selection. Common parameters that influence the selection process of pressure regulators are:
Operating temperature and pressure range (Both inlet and outlet temperature and pressure)
Fluid service medium and properties (Gas or liquid, Corrosive or Non-corrosive, Hazardous or Non-toxic, Explosive nature, etc)
Capacity or flow required (Maximum, minimum, and flow variation)
Material requirements
Accuracy required
Connection Size
Dimension, weight, and size
Installing Pressure Regulators
Installation of pressure regulators must be performed considering manufacturer guidelines. In general, the following steps are followed for pressure regulator installation:
Step 1: Connect the pressure source to the inlet port and the reduced pressure line to the outlet port. These ports are usually marked, else contact the manufacturer.
Step 2: Turn on the supply pressure gradually to avoid any shock.
Step 3: Set the regulator at the desired outlet pressure. Slight adjustments can be done to get the desired pressure.
Pressure regulators are fundamental to the safe and efficient operation of oil and gas systems. From wellheads to refineries, these devices help control the flow of gases and liquids, protect equipment, and ensure worker safety. By selecting the right type of pressure regulator and maintaining it properly, oil and gas companies can optimize their processes, reduce risks, and comply with environmental and safety regulations.
What is a Shut-Off Valve? It’s Working, Function, Types, and Selection
A shut-off valve is a valve that safely manages the flow of hazardous fluids (liquids, gases, slurries, and fluidized solids). Shut-off valves are also known as on-off valves, cut-off valves, lockout valves, stop valves, etc. They safely stop or continue the fluid flow. When not in use they isolate the sub-system.
Shut-off valves belong to a large family of valves. Various types of valves like ball valves, globe valves, gate valves, pressure valves, temperature control valves, solenoid valves, instrument valves, etc may work as a shutoff valves. Shut-off valves are widely used where system safety is of importance as they represent a positive action safety device. Some examples of shut-off valve applications are:
Air preparation unit.
Industrial Automation Process.
Fuel units
Pneumatic industry.
Water Industry
Working of Shut off Valves
Each shut-off valve consists of two fundamental components.
The valve body through which the fuel, liquid, slurry, or gaseous fluids pass and
The control device, which is equipped with a sensitive element.
The control element ensures the required closing and opening of the valve. When everything works correctly, the fluid passes through the valve smoothly. However, when any anomaly (for example excessive fluid expansion, breakage of capillary, etc) arises the control device closes the flow passage inside the valve.
Selection of a Shut-off Valve
Based on the application there are various types of shut-off valves. So, the selection of the appropriate shut-off valve is not easy. Various parameters need to be considered while selecting the shut-off valve for a specific service and operation. The important factors to consider are:
Type of application
Size and weight
Temperature and Pressure
Range
Working Environment
Port size, position, and type
Types of Shut-off Valves
Shutoff valves are categorized based on various parameters like working, configuration, application, etc. Depending on the turning of the handle there are two types of shut-off valves;
Multi-turn shut-off valve and
Quarter-turn shut-off valve
Depending on configuration shut-off valve types are:
Straight shutoff valve
Angle shut-off valve
Again, depending on the applications they are popularly categorized as
Water shut-off valve
Gas shut-off valve
Fuel shut-off valve, etc
Various materials are used to manufacture shut-off valves based on fluid service compatibility. Common shut-off valve materials are Brass, Carbon Steel, Stainless Steel, Alloy Steel, etc. For low-pressure temperature applications in the water industry plastic or polypropylene, valves are used.
Functions of a Shut-off Valve
All shut-off valves are designed to provide fully on or fully off functionality. So they function similarly to an electric switch, either stopping the flow completely or allowing it fully.
Shut off Valve Symbols
All valves are indicated in P&ID and isometric with specific symbols. Shut-off valves also have their symbols. The symbols of shut-off valves are decided based on the specific valve type used as a shut-off valve. So, the shut-off valve symbols differ from ball valve to angle valve or globe valve.
Fig. 1 below shows some typical images of shut-off valves.
Fig. 1: Typical Shut off valves
What is Pressure Drop? Piping Pressure Drop Equations and Calculation
Pressure drop is a widely used term that is frequently used in design engineering, process industries, etc. So it is very important to have a thorough knowledge of pressure drop. Pressure drop is the difference in pressure between two points provided that there is a fluid flow between those points. So pressure drop occurs when a fluid (gas/liquid) material enters one point of the piping system and exits through the other points. In that case, process piping systems should have losses of pressure, and this phenomenon is known as pressure drop.
Pressure drop occurs due to friction caused by fluids rubbing against the pipe surface and the internal walls of a pipeline.
For a system, pressure drop can be calculated with engineering equations that require the type of fluid, flow rate, fluid properties, plot plan, and piping material specifications (including thickness, schedule number, and pipe diameter).
Why does Pressure Drop important?
If the pressure drop in a system is high then the process fluid temperature rises, and energy consumption will be high. Overall system pressure also increases for the high-pressure drop. The high-pressure drop also increases wear on components and causes potentially dangerous & over-pressure scenarios. Lastly, a large pressure drop may render some piping component systems disable due to insufficient operating pressure.
Process engineers should have a clear understanding of the pressure drop of the whole network associated with a fluid to be handled so that they can determine the size, capacity of the pump and motors, and piping diameter required to carry the specific fluid through the piping system.
The larger the pressure drops in the pipeline, the larger the energy required to retain the required process flow, requiring a higher horsepower motor. On the other hand, for low, pressure drop in a pipeline, less energy is required, providing the potential to use a smaller hp motor. Pressure drop also governs the overall pressure of the system or head requirements.
What is a Pressure Head?
In short, the pressure head is defined as the height (m/ft) to which a selected pump can bring a column of water that is usually expressed in meters.
It is the magnitude of the force the pump exerts on the fluid that is being pumped. From the Pump vendor, data pressure heads may be available or they can be calculated from the formula.
What factors affect the Pressure Drop?
The following factors affect the pressure drop in a fluid-carrying network,
Fluid Component
Various fluid parameters like Density, Heat capacity, Temperature, and Viscosity affect the pressure drop of the fluid.
Some products change their viscosity drastically while being pumped through a pipeline due to shear. These kinds of products will become due to frictional effects caused by the passing through the pumps and the internal surfaces of the pipes. This type of fluid is called the thixotropic fluid which is a time-dependent fluid. Thixotropic fluids are usually viscous fluids in stagnant conditions. But it gets thinner or low viscous during movement while shaking or mixing & it returns to its normal state while the means of mixing is removed.
On the other hand, some others are called Newtonian fluids under certain processing conditions. Newtonian fluids are not thixotropic fluid, and it is not subjected to vary their viscosities upon exposure to shear force. Fluids that show Newtonian characteristics may add to higher pressure drop while being pumped through a piping system because their viscosity will not vary as it passes through the system.
Mechanical Component
The mechanical elements in a piping system that imparts pressure drops are valves, strainers, flow meters, couplings, fittings, bends, and tubing. Excluding pumps, all of these other elements commonly available in a process piping system contribute to an overall pressure drop of the system as they remove pressure energy from the process fluid, rather than adding to it.
This dynamic pressure drop depends on the cross-sectional area of the piping system as well as an internal surface roughness (roughness factor), the equivalent length of the pipeline.
Changes in Elevation
Changes in elevation in the Piping system significantly affect the pressure drop. The additional pressure drop will occur if the starting elevation of a pipe is lower than its end elevation. This elevation difference is measured in the fluid industry in terms of the fluid head.
For a general piping system, the overall pressure drop is usually calculated using equations similar to the following:
P(end)= P(start) – friction loss- fittings loss -component loss + elevation (start-end) + pump head
Pressure Drop Equations/ Pressure Drop Calculation
Due to different elevations, turbulence caused by changes in flow direction and frictional losses while flowing through piping and losses due to fittings pressure drop or head loss is caused. The widely used methods used to calculate the head loss in glass pipe are Manning, Darcy-Weisbach, and Hazen-Williams, equations. The applicability of each method governs by the flow pattern (gravity flow or pumped flow).
Hazen-Williams Equation
The Hazen-Williams equation is normally used for water pipes while the flow is fully turbulent flow. It has achieved a wide range of acceptance in the water and wastewater industries as it is very simple to use. The equation is as follows,
V=0.85 C R0.63 J0.54
where
v = velocity, m/s
C = Hazen-Williams Coefficient
R = Hydraulic mean radius, m
J = Hydraulic gradient, m/m
Hazen-William coefficient, C for ADPF fiberglass pipe is taken as 150.
Manning Equation
For gravity difference flow, the Manning equation typically is used to solve gravity flow problems where the flow partially fills the pipe under the influence of changes in elevation. The equation is as follows,
V= (1/n) R0.667J0.5
where
v = velocity, m/s
n = Manning’s Coefficient
R = Hydraulic mean radius, m
J = Hydraulic gradient, m/m
Manning’s Coefficient, n for ADPF fiberglass pipe is taken as 0.01.
Darcy-Weisbach Equation
This equation states that pressure drop is directly proportional to the square of the velocity and the length of the pipe. This equation is applicable for all fluids for both laminar as well as turbulent flow. The disadvantage of this equation is that the Darcy-Weisbach friction factor is a variable that can be found in the standard chart available. The equation is as follows,
The table given below determines the type of flow of fluid from the Reynolds number.
Type of Flow
Reynolds Number
Laminar Flow
Re≤2200
Transition Flow Zone
2200≤Re≤4000
Turbulent Flow
Re≥4000
Types of Fluids as per Reynold’s Number
If the flow is Laminar, f = 64 / Re If the flow is Turbulent, the friction factor can be determined from the Moody diagram found in most fluid mechanics texts or calculated from the Colebrook equation.
1/√f=-2Log(ε/3.71D+2.51/(Re√f))
where
ε = Roughness.
Re = Reynolds number
The Colebrook correlation friction factor for fiberglass pipe is determined as 0.04 mm which includes the head losses over joints.
Pressure drops in Pipe Fittings
Head Loss or pressure drop in Pipe fitting is usually defined as the equivalent length of pipe that is added to the straight run of pipe. This approach is mostly associated with the Hazen-Williams or Manning’s equations. This method does not consider the effect due to turbulence and subsequent losses caused by different velocities.
Equivalent Length (in m)
Pipe Fittings
150
200
250
300
350
400
450
500
600
700
800
900
1000
90ᵒElbow
8.5
6.4
7.9
9.4
10.7
12.2
14.0
17.0
23.0
28.0
32.4
37.1
42.3
45ᵒElbow
3.5
3.4
4.2
5.0
5.7
6.5
8.2
10.9
13.6
16.2
20.1
23.5
25.6
Tee
11.0
14.4
17.8
21.1
24.0
27.5
32.8
38.3
49.5
61.5
72.9
84.6
96.8
Equivalent Length for Pipe Fittings in m
For a more accurate calculation, head loss in fittings can be determined using loss coefficients (K-factor) for each type of bend & fittings. In this method, K-factor is multiplied by the velocity head of the fluid flowing through the bends and fittings.
The relevant equation is H=K x (V2/2g).
where,
H = Head loss, m
V = Velocity of flow, m/s
K-Factors for Pipe Fittings
Type of Pipe fittings
K-Factor
90ᵒElbow, standard
0.5
90ᵒElbow, single miter
1.4
90ᵒElbow, double miter
0.8
90ᵒElbow, triple miter
0.8
45ᵒElbow, standard
0.3
45ᵒElbow, single miter
0.5
Tee, flow to branch
1.4
Tee, flow from branch
1.7
Reducer, single reduction
0.7
K-factors for various Pipe Fittings
Water Hammer
It is caused due to pressure surge or internal shock, resulting from a sudden change of velocity within the system. As a result, these shock waves can reach a sufficient level to rupture or collapse a piping system irrespective of the material of construction. The surge pressure is the faster moving wave that increases as well as decreases the pressure in the piping system that depends on the source of the direction of the shock wave travels. Fast valve closure can result in the building-up of shock waves as the kinetic energy of the faster-moving fluid is converted to the potential energy that must be accommodated. These pressure waves traverse throughout the whole piping system and may cause mechanical damage far away from the source of the shock wave.
The effect of the water hammer depends on,
Physical properties of the fluid
Volumetric flow rate
Elastic modulus of the pipe material
The equivalent length of the pipeline
Rate of change of momentum
The lower value of elastic modulus fiberglass generates a dampening effect as the pressure wave moves along the piping system. As the elastic modulus of piping material is very high so the pressure waves generated in the pipeline are very high in magnitude. Additionally, due to the fast closure and opening of the valve, sudden air release, and start-up or shut down of the pump can cause water hammer.
Talbot formula gives:
P= (a.w.V)/(144.g)=(a/g).(SG/2.3).V
where,
a=Wave velocity (ft/s)
P = Surge Pressure (psi)
v = fluid velocity (ft/s)
w = Density of fluid (lb/ft³)
SG = Specific gravity of the fluid
K = Bulk modulus of fluid (psi)
E = Hoop modulus of elasticity (psi)
d = Inside diameter of the pipe (inch)
t = Pipe wall thickness (inch)
g = Acceleration due to gravity (ft/s²)
How to prevent water hammer?
Standard design practices can avoid water hammers in most systems.
Rapid opening and closing of valves are to be avoided.
The Greenhouse Effect and the concept of achieving Net-zero Carbon Emissions are critical topics in the context of climate change and environmental sustainability. In this comprehensive explanation, I’ll provide detailed insights into both these subjects to equip you with a thorough understanding.
The greenhouse effect is a natural phenomenon that warms the Earth’s surface. It occurs when the sun’s energy reaches the Earth, and some of that energy is reflected back to space while the rest is absorbed and re-radiated by greenhouse gases. This process is crucial for maintaining the temperatures necessary for life on our planet. However, human activities are amplifying this effect, leading to climate change and a host of environmental challenges.
What is the Greenhouse Effect?
Warming of the Earth’s surface and troposphere (the lowest layer of the atmosphere) in the presence of water vapor, carbon dioxide, methane, and other specific gases in the air is called the greenhouse effect. Of these gases known as greenhouse gases, water vapor has the greatest impact. The atmosphere penetrates most of the sun’s visible light and reaches the surface of the earth. Since the surface of the earth is heated by sunlight, part of its energy is radiated into space as infrared rays.
Unlike visible light, this radiation is absorbed by greenhouse gases in the atmosphere and raises their temperature. The heated atmosphere then radiates infrared rays to the surface of the earth. Without greenhouse warming, the average surface temperature of the Earth would be only about -18 ° C (0 ° F). On Venus, the concentration of carbon dioxide in the atmosphere is so high that it has a very high greenhouse effect, with surface temperatures up to 450 °C (840 °F).
The greenhouse effect is a naturally occurring phenomenon, but its effects can be amplified by the release of greenhouse gases into the atmosphere as a result of human activity. From the beginning of the Industrial Revolution to the end of the 20th century, the carbon dioxide content in the atmosphere increased by about 30% and the methane content more than doubled. This global warming can change the Earth’s climate, create new patterns and extreme droughts and rainfall, and disrupt food production in certain regions.
Greenhouse Effect
Mechanism of greenhouse effect
So, the mechanism of the greenhouse effect can be summarized as follows:
Solar Radiation:
The Earth receives energy from the sun in the form of solar radiation. Approximately 30% of this radiation is reflected back to space by clouds, atmospheric particles, and reflective surfaces (like ice and snow). The remaining 70% is absorbed by the Earth’s surface and oceans.
Infrared Radiation:
As the Earth absorbs solar energy, it warms up and re-emits this energy in the form of infrared radiation. This radiation is then either absorbed by greenhouse gases or escapes into space.
Heat Trapping:
Greenhouse gases absorb and re-radiate the infrared radiation, trapping heat in the atmosphere. This process keeps the Earth’s surface significantly warmer than it would be otherwise—approximately 33 degrees Celsius (59 degrees Fahrenheit) warmer.
What are greenhouse gases?
Greenhouse gases (also called GHGs) are gases in the Earth’s atmosphere that trap heat. During the day, the sun shines through the atmosphere, warming the surface of the earth. At night, the earth’s surface cools and radiates heat into the atmosphere. Part of the heat is however trapped by greenhouse gases present in the atmosphere. Greenhouse gases on Earth trap heat in the atmosphere and warm the Earth. The main gases responsible for the greenhouse effect include carbon dioxide, methane, nitrous oxide, water vapor (all of which are naturally occurring), and fluorinated gases.
Carbon Dioxide (CO2): Released from various natural processes like volcanic eruptions and human activities such as burning fossil fuels and deforestation.
Methane (CH4): Emitted during processes like enteric fermentation in livestock, rice cultivation, and the production and transport of fossil fuels.
Water Vapor (H2O): The most abundant greenhouse gas, its concentration varies greatly with location and climate.
Nitrous Oxide (N₂O): Emitted during agricultural and industrial activities, as well as during the combustion of fossil fuels and solid waste.
Why is it called greenhouse gas?
Greenhouse gases are so named because they absorb infrared rays from the sun in the form of heat, which circulates in the atmosphere and eventually is lost to space.
Greenhouse gases in the atmosphere act like a blanket around the Earth. When the Earth’s surface emits infrared radiation, greenhouse gases absorb some of this heat energy, preventing it from escaping directly into space. Instead, they re-radiate the heat energy in all directions, including back toward the Earth’s surface.
This process of re-radiation effectively traps heat energy in the Earth’s atmosphere, warming the planet. Without this natural Greenhouse Effect, the Earth’s average temperature would be significantly colder, making it inhospitable for most forms of life.
Why CO2 is a greenhouse gas?
Carbon dioxide molecules in the atmosphere absorb far-infrared energy (heat) from the earth and then re-emit it, and some of it returns. This effectively traps the heat around the earth. Carbon dioxide (CO2) is one of several greenhouse gases in the atmosphere.
What are greenhouse gases made of?
Greenhouse gases are water vapor, methane, ozone, nitrous oxide, and carbon dioxide. Some of these gases may not be very present in our atmosphere, but they can have a significant impact. Each greenhouse gas molecule is composed of three or more loosely bonded atoms.
Is ozone a greenhouse gas?
Ozone is technically a greenhouse gas, but it can be useful or harmful depending on where it is in the Earth’s atmosphere.
Is H2 a greenhouse gas?
H2 is an indirect greenhouse gas that reacts with other greenhouse gases in the atmosphere to increase its Global Warming Potential (GWP).
The Importance of the Greenhouse Effect
Natural Regulation of Climate
The greenhouse effect plays a vital role in regulating the Earth’s climate. Without it, the average surface temperature would be about -18 degrees Celsius (0 degrees Fahrenheit), making life as we know it impossible. This natural warming allows for liquid water to exist on the planet, which is essential for all known forms of life.
Biodiversity and Ecosystems
A stable climate facilitated by the greenhouse effect supports diverse ecosystems. Plants, animals, and microorganisms all rely on specific temperature ranges and weather patterns to thrive. Disruptions to this balance can lead to biodiversity loss, habitat destruction, and extinction events.
Enhanced Greenhouse Effect
Human Impact on the Greenhouse Effect
Industrial Revolution and GHG Emissions
Since the Industrial Revolution in the late 18th century, human activities have significantly increased the concentration of greenhouse gases in the atmosphere. The burning of fossil fuels for energy, transportation, and industry has led to a dramatic rise in CO₂ levels.
Deforestation
Forests act as carbon sinks, absorbing CO₂ from the atmosphere. Deforestation, whether for agriculture, logging, or urban development, reduces the planet’s capacity to sequester carbon and contributes to higher atmospheric CO₂ levels.
Agriculture and Livestock
Agricultural practices contribute significantly to methane and nitrous oxide emissions. Livestock production, rice cultivation, and the use of synthetic fertilizers are key contributors to the rise in these potent greenhouse gases.
Urbanization
The expansion of cities leads to increased energy consumption and emissions. Urban areas are often characterized by higher temperatures (urban heat islands) due to human activities and reduced vegetation.
Human activities, especially the burning of fossil fuels (coal, oil, and natural gas), deforestation, and industrial processes, have increased the concentration of greenhouse gases in the atmosphere. This enhanced Greenhouse Effect results in a stronger trapping of heat energy and leads to global warming, which is a major driver of climate change.
Consequences of the Enhanced Greenhouse Effect
The consequences of the enhanced Greenhouse Effect are numerous and severe:
Global Temperature Rise: The Earth’s average temperature has been steadily increasing due to the enhanced Greenhouse Effect, leading to phenomena like global warming.
Melting Ice and Sea Level Rise: Warming temperatures cause ice caps and glaciers to melt, contributing to rising sea levels, which can lead to coastal flooding and the displacement of communities.
Extreme Weather Events: Climate change intensifies extreme weather events such as hurricanes, droughts, heatwaves, and heavy rainfall, causing damage to ecosystems and human infrastructure.
Disruption of Ecosystems: Many species struggle to adapt to rapidly changing climates, leading to shifts in ecosystems and potential extinctions.
Ocean Acidification: Increased CO₂ levels are not only warming the planet but also leading to higher levels of dissolved CO₂ in oceans, causing ocean acidification. This affects marine life, particularly organisms with calcium carbonate shells, such as corals and shellfish.
Impact on Agriculture: Climate change affects agricultural productivity. Changes in temperature and precipitation patterns can lead to reduced crop yields, threatening food security, especially in vulnerable regions.
Mitigation Strategies
Reducing Greenhouse Gas Emissions
Transition to Renewable Energy: Shifting from fossil fuels to renewable energy sources like solar, wind, and hydroelectric power can significantly reduce CO₂ emissions.
Energy Efficiency: Improving energy efficiency in buildings, transportation, and industries can lower energy consumption and emissions.
Carbon Capture and Storage (CCS): This technology captures CO₂ emissions from sources like power plants and stores it underground, preventing it from entering the atmosphere.
Sustainable Agriculture: Adopting practices like agroforestry, organic farming, and improved livestock management can help reduce emissions from the agricultural sector.
Reforestation and Afforestation
Restoring forests and planting new trees can enhance carbon sequestration, helping to absorb CO₂ from the atmosphere. Initiatives like REDD+ (Reducing Emissions from Deforestation and Forest Degradation) aim to incentivize forest conservation.
Promoting Sustainable Transportation
Encouraging public transportation, cycling, and electric vehicles can reduce emissions from the transportation sector. Urban planning that prioritizes walkability and green spaces can also contribute to lower emissions.
Policy and Legislation
Governments play a crucial role in addressing climate change. Implementing policies like carbon pricing, emissions trading systems, and regulatory measures can incentivize emissions reductions.
Public Awareness and Education
Raising public awareness about climate change and the greenhouse effect is essential. Education can empower individuals and communities to take action, from reducing personal carbon footprints to advocating for systemic change.
The Role of International Agreements
The Paris Agreement
Adopted in 2015, the Paris Agreement aims to limit global warming to well below 2 degrees Celsius, with efforts to keep it below 1.5 degrees. Countries are required to set and communicate their nationally determined contributions (NDCs) to reduce emissions.
Other Global Initiatives
Various global initiatives, such as the Kyoto Protocol and the Sustainable Development Goals (SDGs), aim to address climate change and promote sustainable development. Collaboration among nations is crucial for effective action.
Net-zero Carbon Emission
The urgency to combat climate change has never been more pressing. With increasing global temperatures, rising sea levels, and extreme weather events becoming commonplace, the need for substantial action is clear. One of the most critical strategies in this fight is achieving net zero carbon emissions. But what does it mean to achieve net zero, and how can individuals, businesses, and governments work towards this goal?
Net-zero carbon emissions, often referred to as carbon neutrality or net-zero greenhouse gas emissions, is a critical concept and goal in addressing climate change. Achieving net-zero emissions is central to mitigating the effects of the enhanced Greenhouse Effect. Let’s delve into the details:
What does net-zero carbon emission mean?
Net zero means balancing the greenhouse gases released into the atmosphere with the greenhouse gases removed. Think of it like a bath-turn on the faucet, add more water, and pull out the stopper to let the water flow out. The amount of water in the bath depends on both the input from the faucet and the output from the drain. To keep the amount of water in the bath at the same level, it is necessary to balance the entrance and exit. Reaching net zero applies the same principles. It needs to balance the number of greenhouse gases we emit with the amount we remove. If you add only what you remove, you reach net zero. This condition is also called climate neutrality. However, zero emissions and zero carbons are slightly different because they usually mean that no emissions occur at all.
How you can make difference between gross zero and net zero?
Given the impact of carbon emissions on the planet, you may be wondering why we are not aiming for zero or gross zero instead of net zero. Gross zero means stopping all emissions, but this is not realistically achievable in all aspects of our lives and industry. Even with the best efforts to reduce them, there are still some emissions. Net zero makes it possible to look at emissions as a whole and eliminate all unavoidable emissions. From aviation or manufacturing. Greenhouse gas removal can come from nature, new technologies, or modified industrial processes, as trees absorb carbon dioxide from the atmosphere.
Why is net zero important?
Net zero is a condition in which greenhouse gases flowing into the atmosphere are offset by removal from the atmosphere. At least for CO2, the term net zero is important because this is where global warming stops. So, the main Importance of Net Zero are
Climate Stabilization: Achieving net zero is essential to limit global warming to 1.5°C above pre-industrial levels, as outlined in the Paris Agreement. This temperature threshold is crucial to avoiding catastrophic climate impacts.
Economic Opportunities: Transitioning to a net zero economy can stimulate economic growth by creating jobs in renewable energy, energy efficiency, and sustainable industries.
Public Health: Reducing carbon emissions can lead to cleaner air and water, ultimately improving public health and reducing healthcare costs associated with pollution-related diseases.
Pathways to Achieving Net-zero Carbon Emissions
Achieving net-zero carbon emissions involves a combination of strategies and actions. Here are some key components:
Reducing Emissions: The primary focus is on reducing emissions of greenhouse gases. This includes transitioning to renewable energy sources (solar, wind, hydro, etc.), improving energy efficiency, and implementing sustainable practices in various sectors like transportation, agriculture, and industry.
Carbon Offsetting: For emissions that cannot be completely eliminated, such as those from certain industrial processes or transportation, carbon offsetting is used. This involves investing in projects that remove or reduce an equivalent amount of greenhouse gases from the atmosphere, such as reforestation, afforestation, and carbon capture and storage (CCS) projects.
Technological Innovations: Developing and deploying innovative technologies like CCS, direct air capture (DAC), and low-carbon transportation options are essential for achieving net-zero emissions.
Behavioral Changes: Encouraging individuals and communities to adopt sustainable practices, such as reducing energy consumption, changing dietary habits, and using public transportation, contributes to emissions reduction.
Policy and Regulation: Governments and international bodies play a crucial role in setting policies and regulations that incentivize emissions reduction and support the transition to a low-carbon economy.
Importance of Net-zero Carbon Emissions
Achieving net-zero carbon emissions is vital for several reasons:
Mitigating Climate Change: By stabilizing the concentration of greenhouse gases in the atmosphere, we can slow down and eventually halt the progression of global warming and its associated impacts.
Preserving Ecosystems: A stable climate is crucial for preserving biodiversity and ecosystems, as many species are sensitive to changes in temperature and habitat.
Protecting Vulnerable Communities: Many communities, particularly in developing countries and coastal regions, are disproportionately affected by climate change. Achieving net-zero emissions can help protect these vulnerable populations.
Sustainable Development: The transition to a low-carbon economy can drive innovation, create jobs, and promote sustainable development while reducing reliance on finite fossil fuel resources.
Strategies for Achieving Net Zero
1. Transitioning to Renewable Energy
One of the most effective ways to achieve net zero is by transitioning from fossil fuels to renewable energy sources.
Solar Power: Harnessing sunlight to generate electricity. Technological advancements have significantly reduced costs and improved efficiency.
Wind Energy: Utilizing wind turbines to generate electricity, which has become one of the fastest-growing sources of energy.
Hydropower: Generating electricity from flowing water, though care must be taken to minimize environmental impacts.
2. Energy Efficiency
Improving energy efficiency across all sectors can drastically reduce emissions.
Buildings: Retrofitting buildings with better insulation, energy-efficient appliances, and smart technology can lower energy consumption.
Transportation: Promoting electric vehicles (EVs), improving public transportation, and encouraging non-motorized transport can reduce reliance on fossil fuels.
3. Carbon Capture and Storage (CCS)
CCS technologies capture carbon emissions from sources like power plants and store them underground to prevent them from entering the atmosphere.
4. Sustainable Agriculture
Shifting agricultural practices can significantly reduce emissions:
Regenerative Farming: Practices that enhance soil health and increase carbon sequestration.
Agroforestry: Integrating trees and shrubs into agricultural landscapes to improve biodiversity and carbon capture.
5. Afforestation and Reforestation
Planting trees and restoring forests are critical for absorbing CO2 from the atmosphere.
Urban Green Spaces: Creating parks and green roofs can also contribute to local carbon sequestration efforts.
6. Behavioral Change
Encouraging sustainable lifestyle choices can help individuals and communities reduce their carbon footprints.
Dietary Changes: Reducing meat consumption and increasing plant-based diets can lower agricultural emissions.
Waste Reduction: Minimizing waste and promoting recycling can help reduce methane emissions from landfills.
Challenges and Considerations
While the concept of net-zero carbon emissions is essential, achieving it poses several challenges:
Technological Limitations: Some technologies required for large-scale emissions reduction and removal are still in the early stages of development and may not be economically viable yet.
Behavioral Change: Convincing individuals and businesses to adopt sustainable practices and change their behavior can be challenging.
Equity and Justice: Achieving net-zero emissions must be equitable, taking into account the historical contributions of different countries and the needs of vulnerable populations.
Transitioning Energy Systems: Transitioning from fossil fuels to renewable energy sources requires significant investment and infrastructure changes.
Monitoring and Verification: Accurately measuring and verifying emissions and removals is essential for ensuring that net-zero targets are met.
What is climate change?
According to the World Meteorological Organization, the 20 hottest years on record were in the past 22 years, and the four hottest years were all very recent: from 2015 to 2018. The average global temperature is now 1℃ higher than the previous time. One degree may not seem like much, but the reality is that this gradual warming seems to be having a negative effect. Furthermore, if recent trends continue, it is expected to worsen, with global temperatures predicted to rise to 35℃ by 2100. Despite a slight increase in global temperatures, we are feeling the effects of climate change and have the following unstable weather patterns: Floods and hurricanes; polar ice loss; and sea-level rise. This is only getting worse as global warming increases.
What is causing climate change?
It is widely recognized by scientists and governments that climate change is caused by higher amounts of greenhouse gases in the atmosphere. Their name comes from the greenhouse effect they create by heating the Earth’s surface and the air above it. Carbon dioxide is the most abundant and dangerous of greenhouse gases, so reducing carbon emissions, creating a carbon footprint, or finding proposed low-carbon alternatives are ways to combat the change. climate.
How can we stop climate change?
Excess greenhouse gases in the atmosphere cause harmful global warming. Therefore, reducing the number of these gases will contribute to combating climate change. Stopping climate change can be done in two ways:
reduce the emissions we send into the atmosphere from activities such as industrial processes, power generation, transportation, and intensive agriculture
remove greenhouse gas emissions from the atmosphere, for example by capturing carbon produced in industrial processes before being released or by planting more trees.
What is green energy?
Green energy comes from natural sources like the sun and wind.
What’s the difference between renewable energy and green energy?
Renewable energy comes from sources of continuous and natural self-renewal (hence the name), such as wind power and solar energy. Renewable energy is also commonly referred to as sustainable energy. Renewable energy sources as opposed to fossil fuels, such as coal and gas, are finite sources of energy. In addition, the burning of fossil fuels to release energy is a cause of climate change.
The terms “green energy” and “renewable energy” are often used interchangeably, but there is one key and sometimes confusing difference between them. Although most green energy sources are also renewable, not all renewable energy sources are considered completely green. Take for example hydroelectricity. While hydroelectricity – the energy generated from fast-flowing water – is renewable, some argue that the process of generating large amounts of electricity from water is not green, given the associated industrialization and deforestation related to the construction of large hydroelectric dams.
What are the basic differences between green energy, clean energy, and renewable energy?
Clean energy is energy that, when used, does not pollute the atmosphere; produces little or no greenhouse gases. Again, there is a clear intersection between clean energy, green energy, and renewable
