Problem Statement/ Solution



Eagle Bluff

Alternative Energy for the Future

Design report

Project Number

May 04-10

Client

Eagle Bluff Environmental Learning Center

Joe Deden, Executive Director

1991 Brightsdale Road

Route 2 Box 156A

Lanesboro, MN 55949

Faculty Advisors

Dr. James McCalley

Dr. Mani Venkata

Dr.Delly Oliveira

Team Members

Abdul Kader Abou Ardate

Darko Brokovic

Daniel M. Disenhouse

Lucas J Kirkpatrick

REPORT DISCLAIMER NOTICE

DISCLAIMER: This document was developed as a part of the requirements of an electrical and computer engineering course at Iowa State University, Ames, Iowa. This document does not constitute a professional engineering design or a professional land surveying document. Although the information is intended to be accurate, the associated students, faculty, and Iowa State University make no claims, promises, or guarantees about the accuracy, completeness, quality, or adequacy of the information. The user of this document shall ensure that any such use does not violate any laws with regard to professional licensing and certification requirements. This use includes any work resulting from this student-prepared document that is required to be under the responsible charge of a licensed engineer or surveyor. This document is copyrighted by the students who produced this document and the associated faculty advisors. No part may be reproduced without the written permission of the senior design course coordinator.

May 5, 2004

Table of Contents

List of Figures and Charts LOF-1

List of Tables LOT-1

List of Symbols LOS-1

List of Definitions LOD-1

Introductory Materials 1

Executive Summary 1

Recommendation 2

Acknowledgment 3

Problem Statement 4

General Problem Statement 4

General Solution Approach 4

Operating Environment 4

Intended Users 4

Intended Uses 5

Assumptions 5

Limitations 5

Expected End Product and Other Deliverables 6

Approach and Design 7

A. Design Objectives 7

B. Functional requirements 7

C. Resultant Design Constraints 7

WIND 8

Biothermal 13

Solar 15

Fuel Cells 20

Hydro 22

Microturbine 24

Load Management 27

E. Recommended Design Approach 34

F. Detailed Design 35

Current System 35

Technical Specifications of the Proposed Design 38

Final Plan 43

Recommendation 48

Resource and Schedules 49

Resource Requirements 49

Schedules 53

Closure Material 55

Project Evaluation 55

Recommendations for Additional Work 55

Lessons Learned 55

Risk and Risk Management 55

Project Team Information 56

Closing Summary 58

References 59

Appendix A – Wind Data 1

Appendix B – Load Data 1

Appendix C – Hydro Data 1

List of Figures and Charts

Figure 1: An Example of Energy Supplied by Multiple Sources 6

Figure 2: Wind capture 9

Figure 3: Betz Limit 10

Figure 4: BioMax generator 14

Figure 5: Typical solar roof design 16

Figure 6: Components of the solar electric system. 17

Figure 7: Solar Application 19

Figure 8: Fuel Cell 20

Figure 9: A single fuel cell membrane electrode 21

Figure 10: Typical Hydro Design 23

Figure 11: Water Fall of a Hydro Plant 23

Figure 12: Flow system for a microturbine 26

Figure 13: Microturbine system 27

Figure 14: Geothermal Pumps 31

Figure 15: Installed Cost 33

Figure 16: One-line diagram of the current system 36

Figure 17: One-line diagram of biothermal unit and the inter-tie 45

Figure 18: One-line diagram of wind turbine unit and the inter-tie 45

Figure 19: One-line diagram of final plan 46

Figure 20: Shifted wind curves for 2001 wind profile 47

Figure 21: Yearly power output of the wind turbines with shifted wind profile for 2001 47

Figure 22: Chart of Original Effort 51

Figure 23: Chart of Updated Effort 51

Figure 24: Actual Time Spent 52

Figure 25: Gant Chart of Projects and Deliverables 54

List of Tables

Table 1: Wind Bins Sample 9

Table 2: Average Electric kWh/year 11

Table 3: Economic Analysis 12

Table 4: Biothermal costs and generation 15

Table 5: Hydro facts 24

Table 6: Microturbine facts 26

Table 7: Single Lamp Relamp 29

Table 8: 4 vs. 3-Lamp 30

Table 9: Efficiency of different approaches 32

Table 10: Fuel Costs 33

Table 11: Campus electrical energy facts 37

Table 12: House electrical energy facts 37

Table 13: Shiitake electrical energy facts 37

Table 14: Schroeder electrical energy facts 38

Table 15: Entire Facility electrical energy facts 38

Table 16: Wind generation costs 38

Table 17: Biothermal generation costs 39

Table 18: Insurance compared to other states 40

Table 19: Generation Interconnection summary 41

Table 20: Combined generation costs 46

Table 21: Personnel Effort Requirements 49

Table 22: Revised Personnel Effort Requirements 50

Table 23: Final Individual Effort Requirements 50

Table 24: Estimated Financial Cost 52

Table 25: Revised Financial Cost 53

Table 26: Actual Estimated Project Cost 53

List of Symbols

KW: Kilo (103) Watts

KV: Kilo (103) Volts

MV: Mega (106) Volts

MW: Mega (106) Watts

kg: Kilo (103) Grams

List of Definitions

Biothermal – The use of biodegradable products such as wood and corn stalks to create electrical energy.

Grid – The transmission network that connects all power lines and nodes

Interconnection – The point of connection between a power source and the utilities distribution or transmission system.

IPP – Independent Power Producer

NEC – National Electric Code

NESC – National Electric Safety Code

Introductory Materials

Executive Summary

Eagle Bluff Environmental Learning Center requested that a study be performed to evaluate possible renewable energy resources. The following describes the project’s needs, activities, final result and the project’s recommendation.

Project Need

Eagle Bluff’s goal is to fulfill their energy needs using cost effective renewable resources. In-order to determine the available energy resources and the feasibility of the project, a study was required. The study needed to examine the available technologies, technical requirements as well as economic feasibility.

Activities

There were number of activities involved in performing the study. These activities included research and investigation of the following technologies:

• Wind

• Biothermal

• Solar

• Fuel Cells

• Hydro

• Microturbines

• Load Management

After these technologies were researched, Eagle Bluff was presented with the economics of each resource. Eagle Bluff then requested that an in-depth plan combining wind and biothermal technologies be developed. This plan was developed by studying several wind turbines and biothermal units. A variety of wind turbines with different characteristics were discovered. However, there were few biothermal units that fit Eagle Bluff’s energy requirements.

Final Result

The final result was a plan which connected two wind turbines and a biothermal unit to the utility’s distribution system. The power produced would be delivered to Eagle Bluff over Tri-County Electric’s distribution lines. The final plan detailed the major components of the interconnection and presented an economic analysis. The figure below shows a one-line diagram of the final plan.

[pic]

The economic analysis showed that 2 turbines would be the cheapest with a project present worth cost of $634,566 for a 25 year span. With the addition of a back-up thermal unit, the cost rises to $883,458. These costs where compared with the present worth of Eagle Bluff’s usage for the next 25 years. This resulting cost known as the break-even project cost is $403,136.

Recommendation

The research and consultations with Eagle Bluff concluded that a wind turbine and a biothermal resource was the best approach. However, an economic analysis showed that the developed plan would be more than the break-even cost. As a result, this study concluded that alternative energy would only be an economically viable solution if government grants and outside donations were received.

Acknowledgment

Eagle Bluff has been very helpful in the initial consultations. They were able to identify their specific zone of interest and were more then willing to supply the necessary information for demand calculations. They provided the team with monthly electric bills and blueprints. The clients were also very cooperative and took the team on a tour through the buildings showing their main load demands. Also, Eagle Bluff initiated the collection of local wind measurements and briefed the team on the facility’s bio-energy resources.

Bob Spartz of Tri-County Electric gave access to detailed information that was received from Tom Nigon of PowerPlus Engineering. Tom provided our team with a transmission layout, as well as the services that Eagle Bluff receives.

Jerod Smeenk from Iowa State University Department of Mechanical Engineering provided the team with cost estimates and information regarding renewable resources.

Dr. James McCalley, Dr. Mani Venkata, and Dr.Delly Oliveira have provided many suggestions and expertise in guiding the team through the project. They have spent numerous extra hours in developing the project.

Problem Statement

General Problem Statement

Eagle Bluff is a residential environmental learning center located in southeast Minnesota. Its maximum energy consumption is 300 KW. The center would like to become energy self-sufficient and remove itself from the electrical grid, except for backup purposes. The center is looking for a solution that is environmentally friendly, reliable, economically feasible and cost effective. A plan that meets these criteria should provide a number of energy sources, necessary electric designs, economic analysis, and a cost analysis.

General Solution Approach

In order to provide Eagle Bluff with the required plan, a variety of energy sources and storage devices were investigated. These sources included wind generation, hydrogen production, solar cells, fuel cells, and biothermal. The electric layout needs were investigated and a proper system was designed. All governmental and industrial regulations that apply to Eagle Bluffs situation were investigated and the results were reflected in any design. At the end of the research, recommendations were given to Eagle Bluff on what systems they should implement according to their finances, location and the available resources. The expected end product is a report that includes: (1) system requirements and environment, (2) options considered and descriptions, (3) prioritized options and reasons for prioritization, (4) a detailed system design and (5) economic analysis of investment cost and future operating cost.

Operating Environment

Minnesota weather is known to range from hot to cold. Any system designed for Eagle Bluff will need to withstand wind, snow, ice, and low and high temperatures. Because of the latitude, summer daylight hours are long while winter daylight hours are short. These factors were considered when deciding on particular types of equipment for power generation. In the case of solar, wind or fuel cells, they need to be placed in particular location to best optimize the sun, wind, and temperature. Using Minnesota wind demographics as well as average solar exposures for the area needs were taken into account when performing energy calculations.

Intended Users

The plans created by the design team are intended to be used by Eagle Bluff in selecting new energy sources. The plans will allow Eagle Bluff to determine what forms and amounts of energy sources they would like to install. Also the plans will allow money to be raised to install the new generation and electrical systems. The plans will be used by potential sponsors in determining if Eagle Bluff meets the donation requirements. Visitors to the center will benefit from the implementation of the design. They will be able to view renewable resources and see energy production as it happens.

Intended Uses

Expected uses are separated into two categories:

1. The project will be used to give Eagle Bluff and understanding of the possible energy solutions. Also the project will be used to determine the best plans for producing electric energy in the most economical and environmentally friendly way. The ultimate goal of having some form of the plans implemented.

2. This project should increase education opportunities in the Eagle Bluff learning community and open awareness of energy conservation and clean energy production.

Assumptions

There are seven assumptions listed for this project:

1. The total power needed will not exceed 1 MW.

2. The protective system used will be accepted by the local utility.

3. Project provides reliability of the system and its actual dependency on the electrical grid.

4. The wind shear factor equals 0.2; a value of 0.1 for roughness length was estimated.

5. The utility’s avoided cost is $0.022/kW

6. Tax breaks and government grants are not included in the current cost analysis.

7. The monthly billing from Tri-County will be the net difference of power produced and power used plus all standard connection fees.

Limitations

There are six limitations listed for this project:

1. Alternative energy resources must be environmentally friendly.

2. The project must include a protective system, that consists of a proven technology and applicable for Eagle Bluff.

3. The project results are to be understandable by persons not familiar with energy production and distribution. It needs to be understandable so it can be used as an educational material for students visiting the Eagle Bluff learning center.

4. Limited access to wind and sunlight due to geographical location and unpredictable weather.

5. Generation size must satisfy local utilities’ interconnection requirements.

6. Wind speed data must be economically viable for wind turbines

Expected End Product and Other Deliverables

The expected end product is an in-depth plan which uses a combination of wind and biothermal. All considered resources will be discussed with reasons provided for the chosen solution. A solar unit will also be considered for educational purposes. Eagle Bluff should be able to use the plans to raise money and support for the goal of becoming energy self-sufficient. The goal of the project does not include delivering any hardware or software product to Eagle Bluff.

[pic]

Figure 1: An Example of Energy Supplied by Multiple Sources

Approach and Design

Design Objectives

The following is a list of the design objectives:

1. Minimum size of 300kW – This is Eagle Bluff’s maximum demand.

2. Renewable energy sources – This falls under the environmental friendly purposes of Eagle Bluff.

3. Final detailed plan using wind and biothermal – They fall into the guidelines of being cost affective and environmentally friendly.

4. Other options considered – A discussion on why some of the other options considered and reasons will be given for not further developing them.

Functional requirements

The following is a list of the functional requirements:

1. Meeting the demand power consumption of Eagle Bluff – The combination of power resources that Eagle Bluff can use must meet the demand needed to fully maintain their facility.

2. Minimum impact on the environment – Being an environmental friendly place with the least amount of impact on the environment.

3. Upgradeable system design – The design would allow the facility to upgrade the system to generate more power in regard to their needs and expansions.

4. Staying connected to the electrical grid and selling any excess power – The design would help to offset the costs associated with new generator as well as helping to lower costs of daily activities.

5. Back-up generator on standby – This will help if main source becomes unusable for a period of time

6. Educational use – To have the ability to show visiting people the alternative methods of power production

Resultant Design Constraints

The following is a list of the project constraints:

1. Weather resistant – extreme temperatures; wind, rain, and snow that may limit wind and solar power generation – Wind and solar are not constant which would limit their use and increase the use of backup power supply.

2. Cost – Cost of implementing the plan and cost of maintenance as well as the possible fuel supply and storage for certain types of generation should be equal to or less than the current costs.

3. Resources – Land availability and location of generator

4. Reliability of Generation –How reliable is the source of generation

5. Maintenance requirements – The amount of maintenance required and the lifespan of the generation equipment

6. Interconnection limitations – Generation should not exceed 1MW due to grid connections requirements.

7. Minimum size of 300kW – This is Eagle Bluff’s maximum demand.

D. Technical approach considerations

There are a number of energy technologies that have been investigated as possible solutions to Eagle Bluff’s needs:

• Wind

• Biothermal

• Solar

• Fuel Cells

• Hydro

• Microturbines

• Load Management

These technologies are discussed below.

WIND

The first step taken to study the possibility of having a wind turbine up at Eagle Bluff was to determine the wind profile for that specific area. Wind measurements for Eagle Bluff were available online at “Minnesota Wind Sites”. The device up at that particular site has a sensor height at 20, 29 and 30 meters and recorded wind speed and direction from 10/14/2000 to 8/4/2003 as ten minute averages (Samples of wind speed statistics are provided in Appendix A). All the wind speeds were put into spreadsheets and the time of the year each wind speed blows was calculated. Table 1 below shows the speed of the wind and the time of the year in hours this particular speed is blowing (frequency) at 30 meters height. The total number of hours for all the wind speeds sums up to 8760 hours which is exactly the number of hours in one full year.

After finding the wind speed measurements, the challenge was to calculate how much electrical energy capability such a site holds. For that, many factors of wind were introduced; roughness length, shear, Betz limit, density, elevation, height and many others that are not directly related to the wind. To fully understand the final numbers accompanied with these measurements, a simple yet clear explanation of some of the factors that had a significant influence on the calculations are presented.

|mph |Hours/year |

|0 |518.28 |

|1 |329.32 |

|2 |297.67 |

|3 |396.17 |

|4 |530.97 |

|5 |675.85 |

|6 |721.2 |

|7 |703.77 |

|8 |703.97 |

|9 |647.04 |

|10 |559.17 |

|11 |464.46 |

|12 |400.73 |

|13 |358.07 |

|14 |308.8 |

|15 |246.45 |

|16 |216.99 |

|17 |176.57 |

|18 |128.27 |

|19 |98.291 |

|20 |74.691 |

Table 1: Wind Bins Sample

Wind Shear:

The fact that wind speed decreases when moving closer to ground level is often called wind shear; more height means faster wind. This factor was introduced to the wind calculations because the wind measurements available were at 30 meters height. The wind shear formula presented below provides wind speed at any desired height

v = vref * ln(z/z0 )/(ln(z ref /z0 )) ...(equation1)

v = wind speed at height z above ground level.

vref = reference speed; known wind speed at height z ref .

ln = the natural logarithm function.

z = height above ground level for the desired velocity, v

z0 = roughness length (explained in the next section)

z ref = reference height; known height at the exact wind speed vref

assuming

z = 70 meters

z ref = 30 meters

z0 = 0.1

v/vref = ln(z/z0 )/(ln(z ref /z0 )) = ln(70/0.1 )/(ln(30 /0.1 ))

this is equal to 1.149

Roughness Length:

Is defined as the height above ground level where the wind speed is theoretically zero. This factor is important because it directly related to wind speed; the more roughness of earth surface there is, the more likely that wind will be slowed down. Since the particular site at Eagle Bluff is an open agricultural area without fences and hedgerows and very scattered buildings, a value of 0.1 for roughness length was estimated. This places the site at roughness class 2 (this is only an estimated value, a more accurate roughness length will be determined later). This value was used in equation one to determine wind speed at any desired height.

Betz Law (limit):

Betz Law simply states that a wind turbine can only convert 59% of the wind kinetic energy of the wind into mechanical energy. Assuming that one can capture 100% of the wind striking the rotors of the wind turbine, the move-away air would have a zero speed (v2=0); rotors will not rotate. On the other hand, if we capture none of the wind (v1=0), rotors will not turn either. However, there is a way

Figure 2: Wind capture

in-between the two extremes to capture the maximum

possible amount of wind energy.

Using Newton’s second law:

P = (1/2)*m*(v12- v22) = (1/2)*([pic]*A*(v 1 + v 2 )/2)*(v12- v22)…(equation2)

P = the power extracted from the unit by the rotor

m = the mass of the air streaming through the rotor during one second

[pic] = the density of the air (1.2 Kg/m3)

A = the wind turbine blade area

v1 = wind speed in front of rotor

v2 = wind speed behind rotor

P0 = ( [pic]/2)* v 1 3 *A…(equation3)

Where P0 is power from the wind through the same area with no rotor to block the wind

Now Cp = P/ P0 = (1/2)*(1 - (v2  / v1 ) 2 ) (1 + (v2  / v1 ))…(equation4)

Plotting Cp verses v2/v1 shows that Cp reaches its maximum value of 59%when the ratio v2/v1 is 1/3.

From here, it is obvious that the effectiveness of any wind turbine is measured by the power coefficient Cp which is defined as the power delivered by the rotor divided by the power in the wind striking the area swept by the rotor.

Figure 3: Betz Limit

Wind Turbines:

Wind turbines vary in sizes and shapes, one aspect of wind turbines that is very helpful in determining the electrical energy output of a wind turbine is the power curve. A power curve of a wind turbine determines how much power in Watts (W) is produced at a certain speed (mph or m/s).

Extensive research has been done on wind turbines to describe the best turbine to meet Eagle Bluff needs; electrical and economic wise.

The shear coefficient is estimated from equation1 to be about 0.2. This coefficient provides a conversion between the annual generation of power at reference height to the annual generation of power at desired height

G2 = G1*(z/z ref)^(shear coefficient) = G1*(z/z ref)^(0.2)…equation5

Calculations for the power output for several wind turbines are conducted provided using the following calculated and given numbers:

a. The power curve of the wind turbine to be considered (see Appendix A)

b. The frequency of wind at Eagle Bluff (see Table 1)

The power output corresponding to each wind speed is multiplied by the hours per years that particular speed is blowing which gives: kW*hours/year = kWh/year. This Total generation of electric power is assumed at air density of 1.225 kg/m3.

Wind turbines considered and their outputs

Four generators have been considered and analyzed last semester. However, closer look at the wind profile of Eagle Bluff shows that wind is between .25 and 24, with an average of 8.22 mph for the major amount of time in the year. This gave the team an indication that a wind turbine that can reach its rated capacity at low wind speeds would be more efficient for the location at Eagle Bluff. The best wind turbine found by the group is Suzlon 1 MW rated capacity. The five wind turbines considered were

1. Fuhrlander 250kW 30m rotor

2. Vestas 660kW 47m rotor

3. Micon 750kW 48m rotor

4. Mitsubishi 1000kW 56m rotor

5. Suzlon 1 MW 64m rotor

Using the power curves provided in the appendix, the annual power generation for each wind turbine was calculated for 2001 and 2002 (calculations for 2003 were not possible due to the lack of wind speeds after 8/5/2003). The values initial obtained were actually at the reference height z ref = 30 meters. Using equation5 with the estimated shear coefficient of 0.2, the desired output was calculated at the desired height z = 70 meters. The annual kWh generations for years 2001 and 2002 are presented in the table below

Table 2: Average Electric kWh/year

| |2 Fuhrlander 250kW 30m |Vestas 660kW 47m |Micon 750kW 48m rotor|Mitsubishi 1000kW 56m |Suzlon |

| |rotor (kWh) |rotor (kWh) |(kWh) |rotor (kWh) |1000kW 64m rotor (kWh) |

|2001 |429,040 |447,923 |568,320 |704,144 |1,064,065 |

|2002 |505,125 |539,792 |673,630 |839,001 |1,251,174 |

Since a 250 kW wind turbine is actually less than the average instantaneous consumption of electricity at Eagle Bluff, two 250 kW wind turbines are considered. This step actually has a very important reliability advantage. In case one of the turbines should stop functioning, the second turbine would, the facility would still be getting half the initial power. This is a very important point that Eagle Bluff personal should consider.

Costs and Economic Analysis

The prices of wind turbines have decreased by 80% in the past 20 years. And the

wind market of production of energy increases by 30% each year. With the new regulations, the wind energy is growing so fast that NERC is already making changes in the distribution of energy throughout the whole nation.

Prices of wind turbines vary in-relation to the power rating of each of them, the blades diameter and also the tower height. But the average cost of turbines is about $2000/kW. Adding installation costs and maintenance costs raises the price up to about $2250/kW. Operation costs of wind turbines are very low of about $0.01/kW.

Economic analysis is conducted for a life span of 25 years, which is the expected operational time of the wind turbines and the biothermal unit. The salvage values of all machines are estimated at 10% of the capital cost. The net present worth (NPW) and the internal rate of return for investments (IRR) is calculated for all the different options and combinations of wind turbines and the biothermal unit as well as the increased cost over the $0.06/kWh that Eagle Bluff is currently paying.

Table 3: Economic Analysis

|Machine Used |Capital Cost |NPW (6%) |IRR % |Increased Cost $/kWh |

|2 Fuhrlander 250kW 30m rotor |$1,000,000 |-$ 634,566 |-2% |$ 0.051 |

|Biothermal |$ 60,000 |-$ 68,680 |-15% |$ 0.010 |

|Vestas 660 kW 47m rotor |$1,320,000 |-$ 918,667 |-3% |$ 0.069 |

|Micon 750 kW 48m rotor |$1,500,000 |-$ 1,065,550 |-3% |$ 0.064 |

|Suzlun 1 MW 64 m rotor |$2,000,000 |-$ 1,429,063 |-9% |$ 0.046 |

|2 Fuhrlander 250kW 30m rotor + Biothermal |$1,060,000 |-$ 883,458 |-5% |$ 0.046 |

|Vestas 660 kW 47m rotor + Biothermal |$1,380,000 |-$ 1,188,915 |-6% |$ 0.060 |

|Micon 750 kW 48m rotor + Biothermal |$1,560,000 |-$ 1,335,799 |-6% |$ 0.058 |

|Suzlun 1 MW 64 m rotor + Biothermal |$2,060,000 |-$ 1,699,311 |-5% |$ 0.045 |

Break- even

In Table 3 above, the present worth of each combination of machines is calculated. These values represent the present worth of the cost for the project with a 25 year life span. These values can be compared with the present worth of what Eagle Bluff would pay the utility over the next 25 years given its present usage assuming a 6% return on investment. The present worth of Eagle Bluffs bill for the next 25 years is as follows:

• Average kWh usage per year = 525,600 @ $0.06 per kWh = $31,536

• The NPW (6%) = $403,136

From these values, we can see that the NPW Break-even investment cost is $403,136

So, the less costly option is the 2 Fuhrlander 250kW wind turbines that have a NPW of the cost after 25 years of $634,566.

Disadvantages of wind turbines

There are a few disadvantages accompanied with the wind turbines.

• Neighbors don’t like them because they are noisy, the blades constantly make noise when rotating

• They take a lot of land space to install, this is a major concern especially to farmers because they prefer to use that land space for agricultural purposes

Biothermal

Biothermal is one of the many technologies that are being considered as an energy source for Eagle Bluff. As with all sources of energy, there are a number of factors that must be examined:

• Fuel source

• Types of technologies

• Power output

• Installation cost

• Operating cost

• Equivalent annual cost

Each of these factors is briefly discussed below and the biothermal technology that is currently being considered for Eagle Bluff is presented.

Fuel Source

Biothermal energy is energy that is obtained from biodegradable products. This technology covers a wide territory and includes a number of fuels:

• Wood

• Switch grass

• Rice hulls

• Manure

• Corn

These sources can be burned to obtain heat directly or the heat can be use to produce electricity by using a turbine. As discussed in technologies, some devices use some of the energy as direct heat and the rest produces electricity. This is system is used to increase total efficiency

Types of Technologies

There is quite of variety of technologies that come under the heading of biothermal. Some systems burn the fuel source directly to produce heat while others gasify the fuel and then burn the gas to produce heat. Another method is used in the case of manure. The methane from the manure waste is collected, cleaned and burned. In all of these cases, the energy output is either used to directly produce heat or the heat is used to produce electricity. Under a co-generation system, both heat and electricity are collect and used from the output.

Power Output

Biothermal generating units vary in size from a 5kW to 20MW. The larger units tend to be co-generation systems that act much like a typical coal plant; the burned fuel is used to operate a steam generator. Small generation units are often used to produce heat for room or a small building. As a result of some government sponsored studies, some generating units that produce 10kW to 30kW are being developed. Some of these units are gasifying fuel such as wood to produce heat. Currently there does not appear to be many technologies that produce electricity in the 100kW to 500kW range.

Costs

There are a number of costs that must be examined when studying biothermal units. The technologies that produce electricity have an investment cost of $2,000 per kW. The annual operating and maintenance cost are estimated to be $.08 to $.12 per kW if fuel costs are not included. Combining investment costs and operational cost, an estimated equivalent annual cost of $.20 per kW is obtained. These are rough industry estimates and subject to the technology type and tax breaks.

Figure 4: BioMax generator

Technology Considered for Eagle Bluff

Based on the discussed factors, the unit that is currently being examined which will help stratify Eagle Bluff’s needs is a 30kW BioMax generator produced by Community Power Corporation. This device is a self contained unit that gasifies wood to produce electricity. While the unit does not meet all of Eagle Bluffs peak demand, it will supply energy for the small buildings and a series of them can be used to produce more power. The BioMax system power output and cost currently follow the industry trend. However, as more units are produced these costs will come down.

Table 4: Biothermal costs and generation

|Biothermal Plan(assuming no fuel cost) | |

| |Size(kW): |30 |

| |Lifetime (years): |30 |

| |Installation Cost: |$60,000.00 |

| |Operation and Maintenance ($/kW) |$0.085 |

| |Yearly kWh output |262800 |

| |Annual Cost (6% interest) |$26,696.93 |

| |Cost ($/kWh) |$0.19 |

| |(Cost if installation not considered($/kWh) |$0.085 |

Solar

Solar generation technology does not date way back like the other energy generation technologies. It has been in experimenting and developing phases since 1970’s. However it is just recently technological advancement in the field of solar power allowed more solar system usage than ever before. This trend is growing and solar systems are becoming more and more popular and widely available every year now.

Major obstacle to faster development of the solar energy production was and still is the cost of the equipment. This cost is rapidly decreasing, with increased efficiency and better standards that are in use in the solar systems today. However, solar energy is still not able to seriously compete with cost and amount of conventional power produced from hydro, coal or nuclear power plants. Nonetheless, solar power is the power of the future, with constantly increasing efficiency, generating capacity and rapidly decreasing costs.

Solar energy is widely used in the nature for a long time. Plants use it for the process of photosynthesis; some of the animal species use it for the managing body temperature. It is a natural way of providing light to earth.

Idea behind the conversion of the energy from the sun to the electricity is simple one. Light waves from the sun are captured by solar panels where electric current is produced. Process is as follows:

Light comes in the form waves from the sun to the earth. Waves are constructed out of the tiny particles, called photons. Since they are moving in the waves and traveling towards earth, photons carry kinetic energy and when they hit the solar panels they transfer their energy to the valance electrons. Energy absorbed by the electrons make them to move and soon after, valance electrons are leaving their positions, creating flow of the current.

However, size wise, a photon is much smaller than an electron. Therefore, a much larger number of photons is needed to move the electron from its valance position. Simplified, this means that the panel needs to be in good sunlight and angle of the impact needs to be as close to the ninety degrees as possible for the best efficiency. If there is no sun light, during night or cloudy day, there will be no electricity produced from solar system.

[pic]

Figure 5: Typical solar roof design

The solar panel position is very important. Good sun tracking monitor that positions panel towards the sun all the time greatly improves efficiency, but this device also adds to the price. A solar panel that has been positioned at 15 degrees inclined towards south by latitude in the fixed position will produce as much as 30% more energy than the horizontally flat fixed panel and about 20% less than the panel with a sun tracking device.

Installation of such additional devices such as sun tracking device do increase the efficiency and capacity of produced energy, but they also add to the price and the complexity of the system. The economic wisdom of installing a sun tracking device will be determined by comparing cost of device over the energy gained with it over life time of the system. However, complexity of the system is more important aspect. Fixed systems without tracking devices are usually more dependable and maintenance free. They can withstand greater storms and winds up to 120 miles per hour. Therefore, almost all of the systems installed today are fixed horizontal systems with certain degree of inclination. Angle of inclination will depend on the geographical position. At the equator there will be no angle and plate should be absolutely flat, which makes exactly 90 degrees, and best efficiency.

Currently produced in the solar panel is the direct current, and to be used in the home, for example, it needs to be converted to the alternating current. Inverter does this, which is the next component in the solar system. There are different kinds of inverters offered on the market today and they range in the price, relative to its size, capacity and efficiency. Size of the inverter is determined by the amount of the energy that is produced by the solar panels. If the panels are not able to produce rated value of the inverter, it is waste of money to buy bigger inverter. Bigger area needs to be covered by solar panels or their inclination needs to be adjusted. Efficiency of the inverter is very important since not much energy is produced by solar panels and it needs to be conserved as much as possible.

However, the sun does not shine 24 hours a day. Depending on the part of the year, location, sun radiation and cloud index, approximations of solar energy can be made. During a night or cloudy days, solar panels do not output any energy. To sustain the needs, one more component is necessary in the solar system. That component is a battery, and not just one, banks of the batteries. Again, depending on the size of the solar system, appropriate size of the battery bank can be determined.

[pic]

Figure 6: Components of the solar electric system.

Battery banks add extra cost to the already expensive system. They also add complexity and maintenance cost over the period of time. This option is not absolutely necessary, but is preferable to collect any excess energy produced by the solar panels during a day when usage is not big and production exceeds the demand. If electrical power is not used instantly, it is lost. This process of matching generation with demand is a load balance. During a night and clouds there is no energy produced. By installing battery banks, overall reliability of the system and operational time are greatly improved and any excess energy produced can be used in time of need, such as during a night or longer periods of the cloudy days.

By adding all of the necessary components, system greatly suffers on the efficiency side. It is important to state that in recent years advance of technology made solar systems possible to at least effectively use, but still, overall efficiency of the system is somewhere in the neighborhood of 10-15 %. This is constantly improving but it is still low to be adequately competitive with other alternative or conventional sources.

However, no matter how much system is effective and how much it can save, one thing is important. It is absolutely necessary to conserve energy. It is up to Eagle Bluff, consumers, to use energy wisely and not waste it. Installation of the energy efficient loads is one way to conserve. Use natural gas heating instead if electric heating. Do not use electric heating and other heavy motor loads at the same time. Improve lightning efficiency, by using more efficient neon lamps instead of conventional light bulbs.

In recent years awareness of the global warming prompted development of the alternative sources in U.S. Now there are loans and certain government subsidizes to help and ease the cost of the solar power. Over a million households around the U.S have installed solar systems on their roofs and that number is growing every day. Due to deregulation, power companies are obligated to by any excess energy produced form alternative sources, back to the grid.

Still with all of the advancement, solar energy is still most the expensive. Cost of electric energy produced by the solar system is around 25 cents per kilo Watt-hour which is about 3 times higher than the cost for conventional energy on national average. Of course this is installation cost divided by the expectancy of life of the solar system. Maintenance and running costs are almost zero, but initial investments are usually higher that average total return over lifetime of the system which is usually around 20-25 years.

Installation cost is about 8-12 dollars per Watt, which is $8000-$12000 per kWh. Government subsidizes for about 2-4 dollars per Watt on the installation cost but still even with this help, for the decent 2.5 kW system installed in the home ballpark of $20,000 needs to be devoted. System as this one installed in the Midwest, for example, will save around 300 dollars per year in the energy cost. It is easy to see that in 20 years, solar system is not even able to pay for itself.

However, solar energy is a way of investing into the future. It is good to have system like this in case of power outage. With battery banks it makes truly remarkable back-up system in case of emergency and it generates certain revenues.

It is more than evident that solar energy is the energy way of the future. Its impact that is already done may not be so obvious, but people do depend on this kind of power. Cell phones, GPS, satellite television is transmitted over satellites. However, satellites that orbit around earth and are powered by the solar energy, because it is the best solution for the situation. It is secure and constant source of the energy as long as the full view of the sun is possible.

[pic]

Figure 7: Solar Application

Finding and implementing the ideas for the alternative energy sources for the Eagle Bluff learning center in Minnesota, solar energy was one of the options. However, by studying the load curve and average usage it become obvious that solar energy regarding for the moment its cost, will not play any vital role in the energy needs of the learning center. Wind and bio-thermal will have impact on the bills, and solar would do almost not noticeable impact.

In the southern Minnesota sun radiation index is on yearly average about 4kWh/m^2/day, taking that national average is about 6-7kWh/m^2/day, and in southern parts of U.S is even close to 10kWh/m^2/day. This means that solar energy in this part of the country is not very applicable, but it is possible. Cloud index is also above national. This means less sunny days than on the national average. Winters are longer farther north from the equator, the incident angle is getting smaller than 90 degrees which added to already low efficiency of the system, and it makes clear why there are not many solar panels on the Midwest roofs. All of those factors combined limit possibilities for the solar generation in that area, and initial costs prevents any bigger developments.

However, solar energy generation is not entirely impossible at the Eagle Bluff learning center site. As the mater of fact, there would be even better opportunity by displaying this system as a learning objective than in generation purposes. Whole site would benefit tremendously from the impact that students and teachers would have as the display of value for the renewable energy. This would ignite students to think appreciate and conserve energy. It would also increase awareness to the students of how hard is to produce renewable energy.

Eagle Bluff would benefit from additional power it gets but most of the credit would be ability to show and explain to the students something that other schools are not able to. After all this is the environmental learning center. Therefore, as a displaying purpose, solar system should be used at the Eagle Bluff.

One thing is certain, renewable alternative energy is here to stay. It is the energy of the future. Just the matter of time is before science and technology further increase capacity and efficiency of the solar energy conversion. Prices will most certainly rapidly to decrease just as they did in the past decades. All of those factors will contribute to fact that solar energy will take us to the limits of our universe and on the other side provide lightning and other needs in the future. It is clean, sufficient energy source. It does not add to the green house gasses and global warming. The best of all, after installation costs, it is absolutely free, with minimum close to zero maintenance requirements.

Fuel Cells

A fuel cell operates at an efficiency of 40-50%, significantly higher than conventional power generators. A steam power plant is typically 35% efficient, while the efficiency of an internal combustion engine in most vehicles is only about 15%. The Proton Exchange Membrane (PEM) type fuel cell would be best suited for Eagle bluff. PEM fuel cells are compact and produce a powerful electric current relative to their size. They operate at a lower temperature (less than 100 degrees Celsius or 212 degrees Fahrenheit) which allows for faster start-up and rapid response to changes in the demand for power (load following).

[pic]

Figure 8: Fuel Cell

The core of a PEM fuel cell consists of a membrane electrode assembly (MEA), which is placed between two flow-field plates. The MEA consists of two electrodes, the anode and the cathode, which are each coated on one side with a thin catalyst layer and separated by a proton exchange membrane (PEM). The flow-field plates direct hydrogen to the anode and oxygen (from air) to the cathode. When hydrogen reaches the catalyst layer, it separates into protons (hydrogen ions) and electrons.

The free electrons, produced at the anode, are conducted in the form of a usable electric current through the external circuit. At the cathode, oxygen from the air, electrons from the external circuit and protons combine to form water and heat. PEM fuel cells use a solid polymer membrane (a thin plastic film) as an electrolyte as opposed to a liquid or high-temperature ceramic.

[pic]

Figure 9: A single fuel cell membrane electrode

Hydrogen

Hydrogen flows through channels in flow field plates to the anode where the platinum catalyst promotes its separation into protons and electrons. Hydrogen can be supplied to a fuel cell directly or may be obtained from natural gas, methanol or petroleum using a fuel processor, which converts the hydrocarbons into hydrogen and carbon dioxide through a catalytic chemical reaction. This will obviously not be environmentally friendly, but at the same time will be more cost-effective than the current system in use.

Membrane Electrode Assembly

Each membrane electrode assembly consists of two electrodes (the anode and the cathode) with a very thin layer of catalyst, bonded to either side of a proton exchange membrane.

Air

Air flows through the channels in flow field plates to the cathode. The hydrogen protons that migrate through the proton exchange membrane combine with oxygen in air and electrons returning from the external circuit to form pure water and heat. The air stream also removes the water created as a by-product of the electrochemical process.

Flow Field Plates

Gases (hydrogen and air) are supplied to the electrodes of the membrane electrode assembly through channels formed in flow field plates.

Fuel Cell Stack

In order to obtain the desired amount of electrical power, individual fuel cells are combined to form a fuel cell stack. By increasing the number of cells in a stack will increase the voltage, while increasing the surface area of the cells increases the current.

Amount of fuel used will depend on how many times they go to the back-up system per year; this will depend on the wind speeds throughout the year.

Hydro

The hydro system that would most fit the Eagle Bluff need is a run-of-the-river hydro project, in which a portion of a river's water is diverted to a channel, pipeline, or pressurized pipeline (penstock) that delivers it to a waterwheel or turbine. The moving water rotates the wheel or turbine, which spins a shaft. The motion of the shaft can be used for mechanical processes, such as pumping water, or it can be used to power an alternator or generator to generate electricity.

The amount of electricity a hydropower plant produces depends on two factors:

How Far the Water Falls

The farther the water falls, the more power it has. Generally, the distance that the water falls depends on the size of the dam. The higher the dam, the farther the water falls and the more power it has. Scientists would say that the power of falling water is "directly proportional" to the distance it falls. In other words, water falling twice as far, has twice the energy. 

Amount of Water Falling.

More water falling through the turbine will produce more power. The amount of water available depends on the amount of water flowing down the river. Bigger rivers have more flowing water and can produce more energy. Power is also "directly proportional" to river flow. A river with twice the amount of flowing water as another river can produce twice as much energy.

A simple diagram of the system will look like this

Figure 10: Typical Hydro Design

[pic]

Figure 11: Water Fall of a Hydro Plant

In order to calculate the amount of electricity the Root River can produce they need to obtain the elevation drop (head) from the entry of the penstock to the exit. In addition we needed to find the average river flow at spot in the river or one closest upstream and extrapolate the data to that spot. The Root River data is shown in Appendix C. The equation that engineers use to calculate the power generated is shown as the following

Power = (Height of drop in river elevation) x (River Flow) x (Efficiency) / 11.8

Table 5: Hydro facts

|Power |The electric power in kilowatts (one kilowatt equals 1,000 watts). |

|Height of Dam |The distance the water falls measured in feet. |

|River Flow |The amount of water flowing in the river measured in cubic feet per second. This data was extrapolated |

| |from Pilot Mound and found to be a yearly average of 162.5 cubic feet per second |

|Efficiency |How well the turbine and generator convert the power of falling water into electric power. For older, |

| |poorly maintained hydro plants this might be 60% (0.60) while for newer, well operated plants this might |

| |be as high as 90% (0.90). |

|11.8 |Converts units of feet and seconds into kilowatts. |

For the Root River in the Eagle Bluff area, assuming they buy a turbine and generator with an efficiency of 85%. Then the power for the river will be:

Average Power = (20 feet) x (162.5 cubic feet per second) x (0.85) / 11.8 = 234.11 KW

Peak Power = (20 feet) x (203.3 cubic feet per second) x (0.85) / 11.8 = 292.88 KW

The approximate costs involved with this project are as follows given the following assumptions:

Capital cost $/kW: $1700-2300/kW cap.

Operation cost/kWh: (0.4¢)

Maintenance cost/kWh: 2 (0.3¢)

Total cost/kWh: (2.4¢)

Operating life: 50+ years

There is no water storage required because it is a run-of-the-river hydro plant

Microturbine

Microturbine generators can be divided in two general classes:

1) Recuperated microturbines, which recover the heat from the exhaust gas to boost the temperature of combustion and increase the efficiency,

2) Unrecuperated (or simple cycle) microturbines, which have lower efficiencies, but also lower capital costs.

The average microturbine costs $650-1000/kW

Most microturbines are considered not environmentally friendly because of the use of non-renewable fuels

The benefits of the Micro Turbine are:

Extreme low emissions

The MicroTurbine has the lowest emissions of any non-catalyzed fossil fuel combustion system: the NOx emissions (on natural gas) are as low as 9 ppm (about 10 gr/GJ)

Virtually maintenance-free

The MicroTurbine has only one rotating part, using innovative air bearing technology. So the unit does not need an oil system or a liquid coolant system, so reducing drastically the maintenance necessary.

Plug-and-play

Using smart power electronics the unit is ready to run when you connect the fuel line and the power cables: no synchronization equipment, no electronic safety devices, no transformer are needed! The unit can also be remotely monitored and controlled.

Compact and light

The Microturbine is about the size of a refrigerator and weighs roughly 500 kg.

Fuel diversity

The Microturbine can handle a wide range of fuels: natural gas, biogas, flare gas, wet gas, propane, diesel, kerosene, etc.

Multi-pack capability

The product range consists of a 30 kW unit and a 60 kW unit. But the MicroTurbine has a multi-pack capability (up to 10-pack units): so a 10-pack 30 kW system acts as one 300 kW unit.

Various applications

Applications like electricity (grid connected or standalone), power quality, resource recovery (like waste gas to electricity), cogeneration, cooling, drying processes, direct CO2 fertilization, hybrid electric vehicles (like busses), marine (like yachts), rental, etc.

With only one rotating part and no liquids for cooling or lubrication, the Microturbine requires very little maintenance: the unit basically requires service once every 8.000 hours, so at continuous operation once a year. At the first service interval it's only required to change-out the air and gas filter: this is a job of about 15 minutes. This makes the microturbine a reliable power source, requesting little attention and causing very limited down time.

Table 6: Microturbine facts

|Microturbine Overview |

|Commercially Available |Yes (Limited) |

|Size Range |25 ñ 500 kW |

|Fuel |Natural gas, hydrogen, propane, diesel |

|Efficiency |20-30% (Recuperated) |

|Environmental |Low ( ................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download