Design for the Environment/Power Generation Alternatives for Off-Grid Homes

From Wikiversity
Jump to navigation Jump to search

one might take for granted the fact that we live amongst a full infrastructure of power distribution and we can find electricity wherever we go. However, in some remote locations, this luxury may not be available. There is a need for alternative methods of power generation to supply electricity to a home operating off-grid. In order to shed light on the options available, a comparison between power generation options for a single family home located in Port Sydney, Muskoka will be made. Off-grid power is not cheap, and unfortunately empty pockets are not the only cost. In the age of limited sources of energy, strict regulations and an increasing awareness for our impact as humans on our planet, this analysis will compare each alternative over a 15 year life-cycle and focus on the environmental impacts.

Three options for generation will be considered: a diesel generator (baseline), a micro hydro system, and a solar/wind combination system. The common function is to supply 8,900kWh[1] of power annually to the home - the average power consumption of a household in the United States. Each option has been carefully selected to satisfy this requirement.

The diesel generator is one of the most widely available methods of off-grid generation. The combustion of diesel fuel converts chemical potential into kinetic energy which in turn spins a generator to create electricity. The micro-hydro system implements a water turbine system to harness gravitational potential and kinetic energy of a river and convert it into rotational motion of a turbine and subsequently electricity. The solar/wind combination system utilizes sources of renewable energy to generate power through solar panels and a wind turbine.

Each source relies on inputs which are intermittent in nature. The diesel generator must be refilled, the river is not always flowing at its peak, and some days are calm and cloudy. In order to provide a continuous source of power, a battery bank system to store the electricity will be implemented. However, as this bank is required in each case, it does not aid in our comparison of power generation technologies.

Project Information[edit]

  • Section: 01
  • Group: 8A
    • Vuk Dulanovic (Vdulanovic)
    • David Grant (David.grant)
    • Andrew Demeter (Andrew.demeter)
    • Adam Debowski (Adam.debowski)

Highlights and Recommendations[edit]

Major Highlights[edit]

Functional[edit]

The micro-hydro generation system and the solar/wind combination both rely on a natural source of energy. Specifically, the micro-hydro depends on the flow rate of the river which varies seasonally, and the solar/wind combination depends on sunlight and wind speed, respectively. These natural sources are not consistent and therefore decrease the reliability of the two systems. The diesel generator is the most reliable system since it is not dependant on natural variables.

Cost[edit]

The table below summarizes the life cycle costs for each option. Based strictly on direct costs, the micro-hydro alternative is the best choice. Click on the links below for a detailed cost breakdown of each alternative.

System

Life Cycle Costs

2008 $USD

Diesel Generator

Initial

$7,049

Maintenance

$2,713

Operating

$15,475

Total

$25,236

Micro-Hydro

Initial

$9,618

Installation

$4,440

Maintenance

$5,162

Total

$19,100

Solar/Wind

Initial

$26,090

Maintenance

$2,714

Transportation

$1,016

Total

$29,820

EIOLCA[edit]

The economic input-output life cycle assessment (EIOLCA)[2] is designed to display the amount of releases produced from a 1997 dollar amount of activity in a given sector. For example, by calculating the cost of a product and entering that amount into the appropriate EIOLCA sector, one can obtain the release values for toxins, green house gases and energy consumption that results from the economic activity. Using the life cycle costs for each alternative, appropriate sectors were selected within the EIOLCA software and results were obtained.

EIOLCA proved to be a strong determining factor in the comparison. By considering the environmental impacts of each system, we can gain a quantitive understanding of how each system affects our ecosystem. The EIOLCA allows us to pinpoint downfalls of each alternative and consider ways in which they may be improved.

The following is a graph of the releases/consumptions for each alternative as a percentage of the total releases/consumptions for all alternatives.

EIOLCA.JPG

The following are the totals obtained from the EIOLCA analysis for each alternative. The values in bold are the worst amongst each of the alternatives.

Alternative

SO2 ( mt)

CO ( mt)

Nox ( mt)

VOC ( mt)

Lead ( mt)

PM10 ( mt)

Diesel

0.035

0.131

0.028

0.026

0

0.004

Micro Hydro

0.0247

0.1662

0.0473

0.0192

0

0.0055

Solar/Wind

0.059

0.256

0.044

0.029

0

0.012

Alternative

GWP (MTCO2E)

Total (TJ)

Tot Air Rel. (kg)

Water Rel. (kg)

Land Rel. (kg)

U'ground Rel. (kg)

Diesel

17.437

0.146

2.098

0.629

11.423

0.578

Micro Hydro

6.3788

0.0718

1.8126

0.2616

4.4070

0.3685

Solar/Wind

15.724

0.178

4.151

1.022

29.576

0.854


Based on the results obtained above, Micro-Hydro performs best overall as it imposes the least stress on the environment through harmful emmissions. Solar/wind has the most toxic releases, and the highest energy consumption due to the significant energy inputs required in the manufacturing phase. In addition to this, the diesel generator option contributes the most to global warming as it is the only option that burns fossil fuels.

SLCA[edit]

Slca.JPG

The Visual SLCA chart helps us see which alternatives are stronger in each category (the higher the score, the more environmentally friendly). In the Materials Provisioning stage of the process of power generation, the diesel generator ranks the lowest due to the amount of mining and refining required. The other alternatives require significantly less metal components. Another interesting thing to note is that the micro-hydro and solar/wind hybrid systems score the same in the Primary Process category. The reason for this is because they both satisfy the same functional requirement while affecting the environment at the same level (during the primary process). The diesel generator, on the other hand, satisfies the same functional requirements while negatively affecting the environment via the combustion of a fossil fuel. During the Secondary Process, all of the alternatives rank the same. The reason for this equality is associated with the nature of the Secondary Process, itself. In the case of supplying an off-grid home with power, the use of a battery bank to store the generated power (which will be supplied to the home in periods of wind/sun/river current lull or when the diesel generator is off) is necessary. Within the scope of this project, therefore, the Secondary Process refers to the management of power within the batter bank. Due to the fact that every alternative (within the scope of this report) is designed to function with the same batter bank, the Secondary Process for each alternative bears the same, and relatively low, impact on the environment.

Societal[edit]

Each of the three systems has some sort of societal effect that should be accounted for to make the best possible decision. Some possible impacts include generated noise, smell, ecological effects, increased water temperature, excavation and natural aesthetics. For the case of the diesel generator, noise was not an issue because the chosen model was part of the Quiet Diesel(QD) series. However, the smell given off by the diesel generator could perhaps be an issue to the surrounding neighbours. The societal impacts caused by the micro-hydro generation system include river damming and destruction of the surrounding ecosystem. Fish are often killed travelling down stream into the turbine or intake mesh. The increased water temperature causes changes in the biotic makeup of the water in the river. This can cause plants and algae to grow at the site. Excavation can also cause problems for the environment because pipelines must be installed underground and may disrupt animal homes or plant roots. The solar/wind combination system has very few societal effects. The most significant is the noise given off by the wind turbine during operation. This effect could be minimized by installing the fan away from the house.

Final Recommendation[edit]

The final recommendation for providing off-grid electricity for the cottage owner in Port Sydney, Muskoka is the micro-hydro generation system. This decision is based on the conclusion from the functional, cost, streamlined life cycle, economic input/output life cycle, and societal analyses.

The major downfall of this system is observed when considering the functional analysis. This system seems to be the hardest to implement because of the excavation for the pipelines. However, when looking at the EIOLCA, micro-hydro has the least amount of GWP and also releases the least amount of toxins. Along with this system being the most environmentally friendly, it is also the cheapest. The initial cost for this system is fairly large but because it harnesses natural energy and requires no other costs other than regular maintenance. With an overall cost of $19,100 USD, micro-hydro is the cheapest of the three alternatives, with diesel costing approximately $25,000 USD and the solar/wind combination being the most expensive at approximately $30,000 USD.

When taking into consideration the societal effects, a minor downfall is that it disrupts the ecology of the nearby river. However, large amounts of fish are killed only when major hydro power sites are present. In our client’s case, this is a simple and small water turbine that will not cause a large enough effect for it to be deemed dangerous.

Additional Information[edit]

Baseline: Diesel Generator[edit]

Functional[edit]

The average American household uses 8,900kWh of electricity every year . The diesel generator which has been chosen (Onan 8.0 HDKAU) will output 6kW of power when running, and will burn a quarter gallon of fuel every hour .In order to supply 8,900kWh of electricity annually, the diesel generator must be left running for four hours every day. Estimating the price of fuel to be $3.75 per gallon, the generator would burn $1,500 of diesel annually.

Cost[edit]

Initial Cost
The Onan generator has an initial cost of $7000 USD (this figure includes installation costs). The shipping cost, however, is not included in the purchase price. The location of the off-grid home (120km away from the nearest Onan distribution site) introduces a cost of roughly $300 USD[3].

Maintenance Cost
The cost of maintenance has been estimated to be roughly $150 annually. The estimation has taken into account the need for very little maintenance during the first few years of the generator’s life, and an increased amount of maintenance as the generator ages.

Operating Cost
The cost incurred during the operation of the generator is attributed only to the cost of diesel fuel consumed by the generator. At $3.75 per gallon, the generator consumes $1,500 annually.

Disposal Cost
A diesel generator will generally last longer than 15 years (which is the lifetime of each alternative within the scope of this project). Therefore, there will be no real cost associated with its disposal. In fact, our cottage owner would probably be able to sell the generator for a profit, or simply have the generator taken away at no cost. If the generator was not functional at the end of its life, it would either be recycled or refurbished, neither of which have strong environmental impacts.

EIOLCA[edit]

Sector

Component

SO2

mt

CO

mt

NOx

mt

VOC

mt

Lead

mt

PM10

mt

Motor and generator manufacturing

Generator

0.008

0.032

0.006

0.005

0.000

0.002

Truck Transportation

Transportation of

Generator

0.000

0.052

0.004

0.004

0.000

0.000

Commercial machinery repair

and maintenance

Maintenance

0.002

0.009

0.001

0.001

0.000

0.000

Advertising and related services

Diesel

0.000

0.001

0.000

0.000

0.000

0.000

Petroleum refineries

Diesel

0.006

0.009

0.004

0.004

0.000

0.000

Oil and gas extraction

Diesel

0.019

0.028

0.013

0.012

0.000

0.002

Total

0.035

0.131

0.028

0.026

0.000

0.004

GWP

MTCO2E

Total

TJ

Air Rel.

kg

Water Rel.

kg

Land

Rel.

kg

Under

Grnd.

Rel. kg

Motor and generator manufacturing

Generator

2.92

0.035

0.961

0.258

9.45

0.217

Truck Transportation

Transportation of Generator

0.847

0.007

0.020

0.004

0.054

0.005

Commercial machinery

repair and maintenance

Maintenance

0.635

0.008

0.136

0.030

0.574

0.034

Advertising and related services

Diesel

0.175

0.002

0.036

0.004

0.044

0.005

Petroleum refineries

Diesel

3.29

0.037

0.403

0.134

0.382

0.079

Oil and gas extraction

Diesel

9.57

0.057

0.542

0.199

0.919

0.238

Total

17.437

0.146

2.098

0.629

11.423

0.578

Societal[edit]

Noise
The largest societal concern of an internal combustion generator would normally be the noise pollution. A diesel generator, however, is generally quieter than a gas powered generator because it outputs the same power at roughly half of the speed. Furthermore, the Onan 8.0 HDKAU is a part of Onan’s QD (Quiet Diesel) series which create much less noise pollution than other diesel generators with comparable power ratings. In fact, the 8.0 HDKAU has a decibel rating of 67dB (heard 10 feet away from the generator), which is just slightly louder than a normal conversation between two people.[4]

Smell
Another societal concern is the smell of burning diesel fuel. If there are neighbours nearby, they may complain about the odour. If a home is off-grid, however, there is a high probability that the area is not very populated.

Alternative 1: Micro-hydro[edit]

Functional[edit]

A micro hydro power generation system harnesses both kinetic and gravitational potential of a river. These two sources of energy come from two characteristics of the river, the head and the flow rate. These will be discussed further in the Site Definition section. The moving water from the river is directed into a pipeline through the use of an “intake”, and fired through water jets which in turn spin a turbine blade. This rotational motion can be easily converted into electricity and stored in a battery storage system.

Site Definition and Power Potential

The river this micro-hydro generation system will be installed on has the following characteristics:

Head: 140ft (the vertical distance from the intake to the turbine)

Peak Flow rate: 300gpm (the amount of water flowing through per unit time)

Microhydroplan.JPG


In order to calculate the net head of the micro turbine system, we must subtract the head losses in the piping used from head provided by the elevation change.

Net head = 140ft – (300ft x 17.90ft/100ft of piping) = 86.3 ft

Estimated Power (W) = (Net head*Flow rate)/ Efficiency Factor [12]

Typical efficiency Factors range from 9 to 14 depending on the system employed. For the purposes of this analysis we will use a factor of 10 which equates to ~53% system efficiency[5]. This efficiency also includes the losses in the transmission lines, battery storage system, and AC inversion processes, and thus the estimated power below should be close to what the system will produce in reality.

Estimated Power = 1036 Watts

Annual Energy Output (kWh) = 9071.856 kWh

Since the annual energy requirement was set at 8900kWh per year, based on the analysis above the micro hydro system is able to meet this demand.

For high-head (above 20ft) applications, it is ideal use a turbine with a Turgo–type blade[6]. This type of turbine blade allows for water jets to be angled at the blade instead of firing straight on. This makes it possible to increase the number of water jets, which in turn allows the turbine to handle higher flow rates.

Energy Systems and Design produces a Turgo blade turbine called the Stream Engine ESD-SE-4. They are a Canadian company and therefore the prices used in the cost analysis represent a real solution that can be purchased in Canada, and not an item that is from U.S. or other markets.


EIOLCA[edit]

Sector

SO2 (mt)

CO (mt)

Nox (mt)

VOC (mt)

Lead (mt)

PM10 (mt)

Sheet Metal work manufacturing

0.0001

0.0004

0.0001

0.0000

0.0000

0.0000

Plastics plumbing fixtures and all other plastics products

0.0046

0.0170

0.0042

0.0048

0.0000

0.0007

Turbine and turbine generator set units manufacturing

0.0129

0.0204

0.0059

0.0025

0.0000

0.0026

Truck transportation

0.0010

0.1132

0.0087

0.0086

0.0000

0.0004

Machinery and equipment rental and leasing

0.0008

0.0020

0.0038

0.0004

0.0000

0.0002

Other maintenance and repair construction

0.0053

0.0132

0.0246

0.0029

0.0000

0.0016

Total

0.0247

0.1662

0.0473

0.0192

0.0000

0.0055

 

GWP (MTCO2E)

Total (TJ)

Tot Air Rel. (kg)

Water Rel. (kg)

Land Rel. (kg)

U'ground Rel. (kg)

Sheet Metal work manufacturing

0.0340

0.0004

0.0083

0.0034

0.0559

0.0018

Plastics plumbing fixtures and all other plastics products

1.9183

0.0247

1.2820

0.0950

0.9521

0.2734

Turbine and turbine generator set units manufacturing

1.8263

0.0224

0.3763

0.1433

3.1106

0.0704

Truck transportation

1.8610

0.0147

0.0444

0.0090

0.1194

0.0105

Machinery and equipment rental and leasing

0.0982

0.0013

0.0135

0.0014

0.0225

0.0016

Other maintenance and repair construction

0.6410

0.0082

0.0880

0.0094

0.1466

0.0107

Total

6.3788

0.0718

1.8126

0.2616

4.4070

0.3685

Societal[edit]

Eco-system

The main societal impact of any micro hydro generation system is the disruption of the eco-system it is implemented in. Although micro hydro systems are generally safe, and environmentally friendly, whenever a man made object is installed in nature, there are always undesirable consequences. Fish are often killed as they travel downstream and get caught in the turbine or intake mesh. It is estimated that in major hydro power sites, turbines eliminate 25-73% of the juvenile and adult fish.[7]

River damming

One issue that is important to address with micro hydro systems is the effects of river damming. Although the system being implemented above only uses an intake system and does not dam the river, similar effects are experienced - on a smaller scale. There is often an increase in temperature of the water around the dam. This results in changes to the “biotic-makeup” of the water in the river. This can affect what kind of plants and algae grow at the site.

Excavation

In addition to the river effects of the micro hydro system, there are also effects from the installation of the system due to substantial excavation for pipelines. The grading and removal of soil can disrupt animal’s homes and drive them out of an area. The running of a pipeline may also damage the root systems on trees and other plants, and may even cause them to die.

Alternative 2: Solar/Wind[edit]

Functional[edit]

A wind and solar energy system can prove to be a quite effective source of energy to supply a small home. Typically, when it is sunny, it is calm, and when it is cloudy, it is windy. In this case, these hybrid components work hand in hand with each other to use natural power in any weather. Using only natural elements to harness energy, this system is very environmentally friendly during the usage stage of its life. Each windmill produces 1600kWh/year[8] at a wind speed of 8mph[9] (typical average for Muskoka). Each solar panel produces approximately 254kWh/year[10] under an operational efficiency of 13.3%. In order to power a house demanding 8900kWh of energy per year, one needs 4 windmills and 16 solar panels to operate at minimal output all day long.

Cost[edit]

The cost of both the windmills and the solar panels is quite expensive. The price for one windmill is $2,425 and for one solar panel is $999. Due to the number of each needed, the total initial cost for these mechanisms becomes $25,684. This is quite expensive for an energy alternative. However, after the initial cost has been paid, the system becomes cheaper to maintain in latter years of use.

Cost

2008 $USD

Wind Mill Initial

$9,700

Solar Panel Initial

$15,984

Maintenance

$200/year

Transportation (once)

$1,000

Total

$29,820

EIOLCA[edit]

Sector

Component

SO2

CO

NOx

VOC

Lead

PM10

 

 

mt

mt

mt

mt

mt

mt

Turbine and turbine generator

set units manufacturing

Wind Turbines

0.036

0.057

0.017

0.007

0.000

0.007

All other electronic component

manufacturing

Solar Panels

0.020

0.064

0.015

0.011

0.000

0.005

Electronic equipment repair and maintenance

Maintenance

0.002

0.006

0.002

0.001

0.000

0.000

Truck Transportation

Transportation

0.001

0.129

0.010

0.010

0.000

0.000

Total

0.059

0.256

0.044

0.029

0

0.012

GWP

Total

Tot Air Rel.

Water Rel.

Land Rel.

U'ground Rel.

MTCO2E

TJ

kg

kg

kg

kg

Turbine and turbine generator

set units manufacturing

Wind Turbines

5.13

0.063

1.06

0.402

8.74

0.197

All other electronic component

manufacturing

Solar Panels

7.78

0.090

2.86

0.581

19.6

0.607

Electronic equipment repair and maintenance

Maintenance

0.694

0.008

0.180

0.029

1.10

0.038

Truck Transportation

Transportation

2.12

0.017

0.051

0.010

0.136

0.012

Total

15.724

0.178

4.151

1.022

29.576

0.854

Societal[edit]

This system has very little societal impact. The noise given off from the windmill is the main disturbance to the homeowner using the device. To reduce this sound effect, one must deter from mounting the windmill on the roof or in close proximity of the house. Instead, securely placing the windmill on a nearby long steel tower and mounting it into the ground is a better idea. It is wise to secure the standing windmill tower with steel wires that are staked into the ground.

Battery Bank[edit]

In order to power our client’s home, the electricity generated by the different alternatives (diesel generator, micro-hydro, and wind/solar hybrid) will be stored in the battery bank. The purpose of this battery bank is to store the extra energy generated by each alternative so that power may be continuously supplied to the home by the batteries during the times when the diesel generator is not running, there is a weak current in the river, or there is minimal wind/sun. This is due to the intermittent nature of the sources. There are three possibilities for the flow of electricity within the system as shown below.

Batterybank.JPG

Exclusion from Comparison
The battery bank has not been included in the individual analysis of each alternative because the battery bank that will be used is not dependent upon the method of power generation. That is, each alternative will function with the very same battery bank, and therefore no matter how ‘good’ or ‘bad’ the various impacts of the battery bank are, the consideration of these impacts will not aid in the comparison of the three alternatives of power generation discussed in this report. This section of the report is dedicated to providing a potential off-grid home owner with the necessary economic information and environmental impacts pertaining to the implementation of a battery bank.

Functionality and Cost
For backup and emergency purposes we will require that 2 days worth of electricity must be stored in a battery bank to supply the home when power is not being generated. In order to satisfy this requirement, 21 AGM sealed batteries[11] will be used. Totaling to an initial cost of nearly $20,000[12], the battery bank is not a cheap component of off-grid power generation. However, it should be noted that the AGM batteries are rated to last over 20 years.

Notes and References[edit]

  1. Edited by Glenn Elert, “Power Consumption of a Home”, The Physics Factbook, [Online document], 2003, [cited 2008 March 22]
  2. “eiolca.net” [Online document], Carnegie Mellon Green Design Institute, [cited 2008 March 27]
  3. Get a Quote”, Freight Monster, [Online document], 2008, [cited 2008 March 20]
  4. “Fuel and Energy Source Codes and Emission Coefficients”, Energy Information Administration, [Online document], 2000, [cited 2008 March 21]
  5. P. Cunningham and I. Woofenden, “Microhydro Electricity Basics” [Online document],[cited 2008 March 27]
  6. “Fact Sheet: Microhydro”, Western North Carolina Renewable Energy Initiative, Appalachian State University, [Online document], 2007 January, [cited 2008 March 15]
  7. “UN Atlas of the Ocans” [Online document], 2008, [cited 2008 March 26]
  8. “Southwest Windpower wind turbines”, [Online document], [cited 2008 March 23]
  9. “Average Wind Speed”, Climatology, [Online document], [cited 2008 March 23]
  10. “Sharp ND-208UI Solar Panel”, Wholesale Solar, [Online document], [cited 2008 March 24]
  11. “Energy Alternatives”, [Online document], Energy Alternatives, [cited 2008 March 21]
  12. “Energy Alternatives”, [Online document], Energy Alternatives, [cited 2008 March 21]