Welcome to AS 2: Desktop Research
Welcome to your study notes for Task 1: Desktop Research, a foundational component of Unit AS 2 (Renewable Energy Technologies) for CCEA GCE Environmental Technology. In this unit, you act as an environmental consultant working on a pre-released realistic client scenario.
Before jumping into practical testing or making final recommendations, you must carry out thorough desktop research. This means gathering secondary data from technical databases, manufacturer datasheets, planning guidelines, and geographical tools. These notes will guide you step-by-step through the core concepts, calculations, regulations, and reporting techniques needed to produce a top-scoring technical report.
Quick Fact: AS 2 represents 50% of your total AS Level award (and 20% of the full A Level award). Doing solid desktop research sets the foundation for your entire coursework report!
1. Understanding the Role of Desktop Research
Desktop research is the process of collecting, analysing, and applying existing secondary information to solve a specific engineering problem. Rather than guessing what technology fits a building, you use proven data to evaluate technical feasibility, resource availability, financial payback, and environmental impact.
The Three Assessment Phases of AS 2:
• Task 1: Desktop Research (This chapter): Gathering data on resources, technologies, planning rules, and costs tailored to the scenario brief.
• Task 2: Practical Investigation: Carrying out laboratory/field tests and practical experiments on renewable energy devices.
• Task 3: Analysis, Recommendations, and Evaluation: Combining your desktop research and practical findings to present a site-specific solution for the client.
The Three Core Renewable Technologies to Investigate:
• Wind Energy: Small-to-medium scale wind turbines (horizontal and vertical axis systems, micro-wind).
• Solar Energy: Solar Photovoltaic (PV) systems for electricity generation, and Solar Thermal systems (evacuated tubes and flat plate collectors) for domestic/commercial hot water.
• Biomass Energy: Biomass boilers, wood pellet/chip systems, and anaerobic digestion/biogas systems.
Key Takeaway: Desktop research is not just copying textbook facts; it is finding targeted data that answers the specific needs, location constraints, and energy demands of the client scenario.
2. Resource Assessment & Geographical Suitability
A renewable technology is only as good as the natural resource available at the site. In your desktop research, you must evaluate geographical suitability using recognised UK and Northern Ireland data sources.
A. Wind Resource Assessment
Wind speed varies significantly across regions, topography, and heights above the ground. You must evaluate:
• NOABL Database: The Numerical Objective Analysis of Boundary Layer (NOABL) database provides estimated mean annual wind speeds in metres per second (\(\text{m/s}\)) across the UK at various hub heights (such as \(10\text{ m}\), \(25\text{ m}\), or \(45\text{ m}\)).
• Terrain Roughness: Open coastal areas and hilltop locations offer smooth airflow and higher wind speeds, whereas urban areas, trees, and buildings create surface friction (roughness) that slows the wind down.
• Obstacle Clearance & Separation: Wind turbines must be placed away from nearby obstacles to avoid turbulent airflow. As a standard rule of thumb, turbines should be sited clear of obstacles that cause turbulence and mechanical stress.
B. Solar Resource Assessment
Solar technologies depend on the amount of light energy reaching the collector surface:
• Solar Irradiance / Insolation: Measured in kilowatt-hours per square metre per year (\(\text{kWh/m}^2/\text{year}\)). This value indicates the total annual solar radiation received in a specific geographic area.
• Optimal Orientation: In the UK and Northern Ireland, solar collectors should ideally face due south (\(\pm 30^\circ\)) to capture the maximum daily solar yield.
• Roof Pitch Angle: An inclination angle of \(30^\circ\text{ to }40^\circ\) from the horizontal is typically optimal for year-round solar capture in the UK.
C. Biomass Resource Assessment
Biomass feasibility is driven by logistics and fuel quality rather than weather patterns:
• Local Supply Chain: Proximity to reputable suppliers of wood pellets, seasoned logs, or wood chips to keep transport emissions and fuel delivery costs low.
• Energy Density (Calorific Value): The amount of heat energy released per unit of mass, measured in megajoules per kilogram (\(\text{MJ/kg}\)) or kilowatt-hours per kilogram (\(\text{kWh/kg}\)).
• Bulk Storage Requirements: Biomass fuels require dry, accessible storage space (such as a dedicated fuel hopper or silo) close to the boiler.
Key Takeaway: Always cite geographical databases (like NOABL for wind) and local climatic figures rather than assuming uniform resource availability across the country.
3. Key Technical Calculations & Operating Principles
In your desktop research, you need to calculate potential energy yields and understand how balance-of-system components function.
Crucial Difference: Power vs. Energy
Don't worry if this seems confusing at first—just remember this simple analogy: Power is the speed of your car at any single instant, while Energy is the total distance you have travelled over time.
• Power (\(P\)): The rate of doing work, measured in kilowatts (\(\text{kW}\)).
• Energy (\(E\)): The total work done over a period of time, measured in kilowatt-hours (\(\text{kWh}\)).
The standard energy formula is:
\(E = P \times t\)
Where:
• \(E\) = Electrical energy yield in kilowatt-hours (\(\text{kWh}\))
• \(P\) = Power rating in kilowatts (\(\text{kW}\))
• \(t\) = Operating time in hours (\(\text{h}\))
Kinetic Power in the Wind
The theoretical power available in the wind passing through the swept area of a turbine rotor is given by:
\(P = \frac{1}{2} \rho A v^3\)
Where:
• \(P\) = Power in watts (\(\text{W}\))
• \(\rho\) (rho) = Air density (standard value is approximately \(1.225\text{ kg/m}^3\) at sea level and \(15^\circ\text{C}\))
• \(A\) = Swept area of the rotor blades in square metres (\(\text{m}^2\)), calculated as \(A = \pi r^2\)
• \(v\) = Wind velocity/speed in metres per second (\(\text{m/s}\))
Notice the velocity cubed (\(v^3\)): If wind speed doubles, the power in the wind increases by a factor of eight (\(2^3 = 8\))! This is why site wind speed is so critical.
Thermal Heat Output Formula
For solar thermal systems or biomass heat transfer, heat energy is calculated using:
\(Q = mc\Delta T\)
Where:
• \(Q\) = Thermal energy transferred (in joules, \(\text{J}\), or kilojoules, \(\text{kJ}\))
• \(m\) = Mass of the fluid being heated (in \(\text{kg}\))
• \(c\) = Specific heat capacity of the fluid (for water, \(c \approx 4180\text{ J/kg}^\circ\text{C}\) or \(4.18\text{ kJ/kg}^\circ\text{C}\))
• \(\Delta T\) = Change in temperature in degrees Celsius (\(^\circ\text{C}\) or \(\text{K}\))
Balance-of-System (BOS) Components
Generating power is only part of the system. Your desktop study must research the supporting hardware:
• Inverters: Convert direct current (\(\text{DC}\)) generated by solar PV panels or small wind turbines into alternating current (\(\text{AC}\)) for domestic appliances or grid export.
• Charge Controllers: Regulate the voltage and current coming from renewable sources to prevent battery storage systems from overcharging.
• Generation & Export Meters: Measure the exact quantity of electricity generated and the surplus exported to the electrical grid.
Key Takeaway: Master the distinction between \(\text{kW}\) and \(\text{kWh}\), and remember that the power in the wind depends directly on the cube of the wind speed (\(v^3\)).
4. Planning Permission, Regulations & Grid Standards
A renewable system cannot be built without complying with national legislation, local planning laws, and electrical safety standards.
A. Permitted Development Rights (PDR)
In Northern Ireland and the wider UK, certain microgeneration installations do not require a full planning application if they meet specific Permitted Development thresholds:
• Solar PV / Thermal: Panels mounted on a building roof must generally not protrude excessively above the roof plane and must not exceed the highest part of the roof.
• Wind Turbines: Micro-wind systems often have strict constraints regarding total height, rotor diameter, and mandatory separation distances from neighbouring site boundaries to minimise visual and noise impact.
B. Building Regulations Compliance
Any renewable installation must meet standard Building Regulations:
• Structural Integrity: Ensuring roof trusses can take the dead load of solar collectors and dynamic wind uplift forces.
• Ventilation & Flue Discharge: Biomass boilers must have appropriate flues for exhausting combustion gases safely and must adhere to clean air requirements.
• Electrical Safety: Wiring must comply with national electrical wiring standards.
C. Grid Connection Standards (DNO Approvals)
Connecting generation equipment to the local distribution network (operated by Northern Ireland Electricity Networks / DNOs) requires formal notification or permission:
• Engineering Recommendation G98: Applies to fully type-tested, small-scale microgenerators (up to \(16\text{ A}\) per phase, which is \(3.68\text{ kW}\) single-phase) connected in parallel with the low-voltage network (often a "fit and inform" procedure).
• Engineering Recommendation G99: Applies to larger installations exceeding the G98 rating threshold, requiring formal prior application and approval from the network operator before commissioning.
Key Takeaway: High-scoring technical reports never overlook planning and grid regulations. Always state whether your proposed system falls under Permitted Development or requires full planning and DNO approval (G98/G99).
5. Economic and Environmental Feasibility
A. Financial Appraisal Metrics
Clients need to know both the setup cost and the long-term economic return of their investment:
• Capital Expenditure (CapEx): The upfront purchase, delivery, and installation cost of the equipment (panels, turbines, inverters, pipework, and labour).
• Operational Expenditure (OpEx): Ongoing maintenance, servicing, fuel purchasing (e.g., biomass pellets), insurance, and component replacement costs.
Simple Payback Period
The time taken for an installation to pay for itself through energy savings and/or revenue generated is calculated using:
\(\text{Payback Period (years)} = \frac{\text{Capital Cost (\pounds)}}{\text{Annual Net Cost Savings (\pounds/year)}}\)
Worked Example:
A solar PV array costs \(\pounds 6,000\) to install (CapEx). It saves the client \(\pounds 1,200\) per year in electricity bills, with annual maintenance (OpEx) of \(\pounds 200\).
• Annual Net Savings = \(\pounds 1,200 - \pounds 200 = \pounds 1,000\text{ per year}\)
• \(\text{Payback Period} = \frac{\pounds 6,000}{\pounds 1,000/\text{year}} = 6\text{ years}\)
B. Environmental & Carbon Metrics
Desktop research must quantify the carbon reduction benefits of the system:
• Embodied Carbon: The total greenhouse gas emissions generated during the raw material extraction, manufacture, and transport of the renewable technology.
• Grid Displacement Factor: Measuring how many grams of carbon dioxide equivalent are avoided per kilowatt-hour of renewable energy generated (\(\text{g CO}_2\text{e/kWh}\)) compared to drawing fossil-fuel electricity from the national grid.
• Net Lifecycle Carbon Savings: The net reduction in \(\text{CO}_2\text{e}\) achieved over the full operational lifespan of the system.
Key Takeaway: Always calculate financial payback using net annual savings (savings minus OpEx) and account for carbon savings using \(\text{g CO}_2\text{e/kWh}\).
6. Report Structure, Referencing & Common Pitfalls
Technical Report Structure
Your AS 2 coursework report (approx. 3,500–4,000 words total across all 3 tasks) should follow a clean, professional engineering layout:
1. Title Page & Executive Summary / Contents
2. Introduction & Scenario Analysis: Breakdown of the client brief, site location, and annual energy demands.
3. Task 1: Desktop Research (Technology Reviews & Site Data): Detailed analysis of wind, solar, and biomass options using local data, planning constraints, BOS hardware, and financial/carbon estimates.
4. Task 2: Practical Investigations: Experimental data collection and laboratory testing.
5. Task 3: Analysis, Recommendations & Evaluation: Final synthesised proposal and critical reflection.
6. References & Appendices: Full academic citations and supplementary datasheets.
Academic Referencing Standards
Every datasheet, planning document, and web database used in Task 1 must be cited using standard academic conventions (such as Harvard referencing: Author, Date, Title, Publisher/URL).
Examiner Pitfalls: What to Avoid!
• Pitfall 1: Generic Textbook Dumps: Do not write general descriptions of how solar panels work. Always apply the data directly to the site conditions and client demands in your brief.
• Pitfall 2: Confusing \(\text{kW}\) and \(\text{kWh}\): Power is instantaneous rate (\(\text{kW}\)); energy is total volume over time (\(\text{kWh}\)). Mixing these up invalidates your yield and payback calculations.
• Pitfall 3: Blindly Trusting Peak Manufacturer Claims: A \(4\text{ kWp}\) solar array does not produce \(4\text{ kW}\) all day long! Always account for capacity factors, weather variations, and seasonal solar hours.
• Pitfall 4: Forgetting Regulations: Forgetting to check Permitted Development limits or DNO connection standards (G98/G99) will cost easy marks.
• Pitfall 5: Missing Citations: Omitting source references for datasheets or the NOABL database makes data unverified.
Quick Review Summary Checklist
Before moving on to Task 2 (Practical Investigation), check that your Desktop Research contains:
• Evaluated wind (NOABL database, terrain), solar (insolation, tilt, orientation), and biomass (calorific value, supply chain, storage) resources.
• Correct energy and power calculations using \(E = P \times t\), \(P = \frac{1}{2} \rho A v^3\), and \(Q = mc\Delta T\).
• Detailed Balance-of-System components (inverters, charge controllers, meters).
• Northern Ireland / UK planning considerations (PDR, Building Regulations) and grid standards (G98 / G99).
• Financial appraisal including CapEx, OpEx, and Simple Payback Period.
• Carbon impact assessment (\(\text{g CO}_2\text{e/kWh}\) and lifecycle offset).
• Fully formatted Harvard-style references for all secondary sources.