# Renewables, homework help

Humanities

Q1. (85%) Based on the discussion in the last lectures on Renewable Energy Systems, and from your point of view, what would be the optimum renewable energy system to proceed with in the next two decades? Support your argument by statistical analysis, potential advances for the system considering the sustainable criteria of:

1. Environmental impact ( i.e. less emissions to air , water, land; less depletion of resources,…etc)
2. Economical Impact (i.e. cost, economy of resources, viability,…etc)
3. Human well-being, acceptance

Please remember that for the system to be sustainable there is compensation between the 3 previous attributes, so do not hesitate to choose any system you see has potential applications,  fast wide-spreading, environmentally sound,…etc. Support your argument with examples, initiatives, more governmental support than the others. You can choose from Biomass, Wind, Hydrogen, Solar PV, Geothermal, Tidal, Hydro power, or a new promising system you see (must provide strong evidence for brand-new systems). You will have a brief presentation (15 slides) on your chosen system (please see class schedule) for 10 minutes.

Q2. (15%) You have a client in Norfolk, VA (36.9 o N Latitude). She asked you to design a small scale house with basic appliances (refrigerator, washer, microwave, stereo, fan, and TV) and the lighting fixtures will be energy efficient (fluorescent bulbs, high efficient incandescent, no sodium or halogen lamps). One of the ideas was to power the house with a grid-connected PV system since the weather is good and sunny she will use fans and cross ventilation in cooling the house (no ACs) to minimize energy consumption.

Make a rough estimate of the PV array area required for the house and the annual energy production giving the following equations (please refer to resources on D2L, Chap 17: system sizing, p.163 – p.172 for more information, equations and other illustrations:

1. Area (PV) [m2]  = Power PV [kW]  / η PV

2. Power PPV [kW]  = Daily load [kWh/day] / Lowest insolation on PV array [(kW/m2) / day] / wiring loss factor

3. Annual Energy E = η whole system x K x PPV [kW] x Annual insolation (S) [kWh/m2]

Assumptions:

1. The system will operate all year long since the weather is good

2. η PV    : efficiency for Polycrystalline silicon module   = 20% (0.2)

3. η whole system   : losses in wires and inverter     = 85% (0.85)

4. K  : safety factor     = 0.9

5. Tilt angle     = 30o (i.e. slope of the roof)

6. Azimuth angle    = 0 (true south)

8. Wiring loss factor   = 0.9

9. Daily Load     = 3 kWh/day

10. Safety factor   = 0.9 (You use the most advanced module available)

11. Solar Insolation and energy is given according to the following table:

 Month Horz’l Array plane Horizontal Insolation x Tilt angle (30), azimuth,shade factor for 36.9o N = Insolation at 30o x Days per month kWh/m2.month kWh/m2.day kWh/m2.day Jan 2.1 x 1.5 = 3.36 x 31 104.16 Feb 2.9 x 1.4 = 4.06 x 28 113.68 Mar 4.0 x 1.2 = 4.8 x 31 148.8 Apr 5.3 x 1.0 = 5.3 x 30 159 May 6.0 x 0.9 = 5.4 x 31 167.4 Jun 6.3 x 0.9 = 5.67 x 30 170.1 Jul 5.8 x 0.9 = 5.22 x 31 161.8 Aug 5.3 x 0.9 = 4.77 x 31 147.8 Sep 4.4 x 1.1 = 4.84 x 30 145.2 Oct 3.4 x 1.3 = 4.42 x 31 137 Nov 2.6 x 1.5 = 3.9 x 30 117 Dec 2.0 x 1.5 = 3.0 x 31 93 S: Annual insolation on PV array [kWh/m2] 1665

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