James Madison University Department of Engineering Eric J. Leaman Jack R. Cochran Faculty Advisor: Dr. Jacquelyn Nagel

Size: px

Start display at page:

Download "James Madison University Department of Engineering Eric J. Leaman Jack R. Cochran Faculty Advisor: Dr. Jacquelyn Nagel"

Constance Harrison
5 years ago
Views:

1 James Madison University Department of Engineering Eric J. Leaman Jack R. Cochran Faculty Advisor: Dr. Jacquelyn Nagel

2 Overview Background Problem Statement Broader Impact Literature Review Design Approach Energy Storage Concepts Models and Calculations Model Validation and Experimental Results Conclusions Future Work 2

3 Background 22% of total energy consumed in the United States is used in residences Electricity accounts for 41% Only 10.6% of energy generation is from renewable resources Residential solar energy systems help to reduce dependency on fossil fuels for electrical energy If 15% of Shenandoah Valley households utilized PV systems, carbon emission would be reduced by the equivalent of removing 5,000 passenger vehicles from the road [1] 3

lead) More than 200,000 tons is nonrecyclable Off-gassing is another danger They are expensive averaging $115 to

4 Problem Statement Typical small-scale solar systems use chemical batteries for energy storage Lead acid batteries account for more than 2 million tons of total waste each year Comprised of regulated toxins (sulfuric acid and lead) More than 200,000 tons is nonrecyclable Off-gassing is another danger They are expensive averaging $115 to $160 per amp-hour capacity at 12V Lifespans are short and discharge to below about 80% capacity damages battery [3] [2] 4

5 Technical Social Environmental Economic Broader Impact Advancement of renewable energy systems and greater incentive for skeptical adopters Inexpensive, safe, and lowmaintenance system for remote and poor locations Reduction in waste, toxins, and emissions Improvement of costfeasibility for residential PV system 5

maintenance Low environmental impact Disadvantages High start-up costs Typically

6 Pumped hydroelectric energy storage (PHES) Accounts for over 99% of worldwide bulk energy storage Up to 85% efficient Advantages Good reliability Low maintenance Low environmental impact Disadvantages High start-up costs Typically used in large-scale systems such as power plants PHES Reservoir in Rönkhausen, Germany [8] [8] 6

7 Compressed Air Energy Storage (CAES) Published overall efficiencies typically around 50% Highly reliable Greater complexity than comparable storage methods Typically used on very large scales [10] 7

8 Design Approach 8

9 System Architecture 9

10 Functional Model 10

11 Concept Generation 11

12 PHES Architecture House (Not to scale) 12

Concept Selection High-level Analysis Published efficiency values for water turbines range from 60% to 90% Published efficiencies for generators range from 80% to 95% At minimum efficiency, this

13 Concept Selection High-level Analysis Published efficiency values for water turbines range from 60% to 90% Published efficiencies for generators range from 80% to 95% At minimum efficiency, this translates to a reservoir of about 5.6% the volume of an Olympic swimming pool at 62 m to meet power and energy requirements System Parameters to Provide 1 kw Power for 11.4 h Using an 11 mm Nozzle 13

14 Results of High-level Analysis Stored energy is a function of both reservoir height and volume E = mgh = ρvgh Power is a function of height: P = de dt = mgh Needed Volume vs Height for 1 kw Power and 11.4 kwh Energy for No Loss, Max. Expected Efficiency, and Min. Expected Efficiency 14

15 Compressed Air w ov = n n 1 Pin 1 P out Pin w ov = Specific work that can be stored n 1 n n = value related to the conditions of the system P out = the pressure outside of the tank P in =denotes the pressure inside of the tank.

16 Compressed Air w ouv = n n 1 P m 1 P out P m n 1 n P m = working pneumatic pressure Replacing P in with P m w ouv = wasted energy density

17 Tank Storage Needed w oev = w ov w ouv V int = E st w oev

18 Compressed Air System Efficiency η stor = E 2 E 1 = 43% η x,t = W t E 2 = 36% η stor = Efficicency of the Storage Tank η x,t = Efficiency of the Turbine E 1 = Energy from Storage Inlet E 2 = Energy from the Storage Outlet W t = Turbine Work

19 Energy Conversion Turgo and Pelton turbines operate in air Francis and propeller turbines operate submerged (From Williamson, et al. [11]) [12] All shown practical at a smallscale 19

20 Dynamic System-level Model T L I e ω = T T L cω c I armature I turbine T, ω k b ω i a (R L + R a ) = 0 V a R L L R a V b T L = k T i a = k bk T R L + R a ω i a 20

21 The force on a vane of the turbine is: F = m b v j v b β And: m b = ρa n (v j v b ) Then the torque on the turbine is: T = Fr = m b r v j v b β = rρa n β v j rω 2 Where: m b = mass flow rate into turbine bucket v j = velocity of jet v b = tangential velocity of turbine β = 1 + cos(γ) γ = 60 (angle between center of bucket and bucket wall) ρ = density of water A n = cross-sectional area of nozzle outlet r = radius of turbine v b = rω (From Thake [15]) Leading to: I e ω = rρa nozzle βv j 2 2v j r 2 ρa nozzle β + k bk T R L + R a + c ω + r 3 ρa nozzle βω 2 21

22 Experimental Set-up The model was validated by simulating a raised reservoir using a fluid bench and pump 22

Model Validation 6, 8, 10, 12, and 16 mm nozzles tested Model accurate within 7% of results on average for 10 and 12 mm nozzles Accounting for loss due to air resistance and the

23 Model Validation 6, 8, 10, 12, and 16 mm nozzles tested Model accurate within 7% of results on average for 10 and 12 mm nozzles Accounting for loss due to air resistance and the support bearing brings model within 6% of results Ns/m added to damping coefficient Smaller and larger nozzles less accurate: 27% average for 6 and 8 mm 14% average for 16 mm 23

24 Experimental Results Measured efficiency up to about 40% power output ( ) total kinetic jet power 10 mm nozzle Flow rate of 15.8 GPM Total hydraulic head of 10.4 m Max. Overall efficiency of about 32% ( power output ) power potential 24

25 Design of Experiments What factors most significantly impact efficiency? Parameter Gross head Effect Flow rate Pipe diameter Frictional losses at pipe walls Pipe components Number of nozzles Nozzle geometry Water jet position Load on generator Frictional losses due changes in flow direction Total power input to turbine Flow rate, jet velocity Total power input to turbine Induced torque on turbine Level Nozzle Size Motor Speed Load 1 8 mm 40 Hz 35 Ω 2 10 mm 45 Hz 50 Ω 3 12 mm 50 Hz 65 Ω 25

26 Modeled efficiency for 250 W target with optimized load and nozzle diameter at 20, 30, and 40 m 26

27 Conclusions and Future Work Target of 1 kw power output may be difficult to achieve with great efficiency Expectation is that residence is grid-connected System is most cost effective by providing little power for a long time System could be implemented in poor or remote locations, especially where local topography permits low-cost installation of raised reservoir Further analysis and concurrent optimization of generator and turbine efficiency 27

28 References 1. Zimmerman, D. L., Residential Solar Energy in the Valley: A Feasibility Assessment and Carbon Mitigation (Master s Thesis). Retrieved from James Madison University files database Nagel, J. K., (2012). Two-phase Energy System (Project proposal to Valley 25x 25). Source provided by Dr. Nagel. 5. October 25, Basic Tutorials: Storage Batteries. Free Sun Power. 6. October 25, Packing some power. a. The Economist. 7. Levine, J. G., Pumped Hydroelectric Energy Storage and Spatial Diversity of Wind Resources as Methods of Improving Utilization of Renewable Energy Sources (Master s Thesis). Retrieved from University of Colorado Boulder files database Young-Min K., Jange-Hee L., Seok-Jeon K., Favrat, D., Potential and Evolution of Compressed Air Energy Storage: Energy and Exergy Analyses. Entropy 14 (8), Williamson, S., Stark, B., Booker, J., Low head pico hydro turbine selection using a multi-criteria analysis. Renewable Energy 61, Proczka, J., Muralidharan, K., Villela, D., Simmons, J., & Frantziskonis, G. (2013). Guidelines for the pressure and efficient sizing of pressure vessels for compressed air energy storage. Energy Conversion and Management, 65, Retrieved October 30, 2013, from the Science Direct database. 14. Elmegaard, B., Brix, W. Efficiency of Compressed Air Energy Storage. Retrieved from Thake, J., The Micro-hydro Pelton Turbine Manual. ITDG Publishing, London. 28

Micro Hydro Turbine Test Facility at the NERDC

International Conference on Small Hydropower - Hydro Sri Lanka, -4 October 007 Micro Hydro Turbine Test Facility at the NERDC T.A.Wickramasinghe and M.Narayana Department of Renewable Energy, National