Design for the Environment/Off-Grid Electricity for Cottages



Spending weekends at a cottage with families and friends has become an increasingly popular lifestyle for the Ontario urban populations. Ever since the economic boom of the 1980s, a part of central Ontario known as “cottage country” had seen a constant growth and development in the resort and cottages industry. This implied that large amount of urban populations decided to get away from the fast pace city momentum and spend quality time with their families in rural area on weekends as the quality of life increases resulting from the steadily increasing average household income. As the demand for cottages increases and easily accessible lands are taken up by previously built cottages, new cottages have to be built in increasingly remote locations, posting a major logistical problem: the lost of connection with the utility grid. In this analysis, only electricity generation was analyzed.

Although power lines that distribute electricity to cottage country exist according to, connecting a remote cottage to the utility grid is not economically sound in some cases. According to, one Georgian Bay, Ontario cottage owner estimated that the cost for connecting her cottage to the electricity grid to be $60,000 (CAD) since a cable of over 1 km long has to be run from her cottage to the nearest utility outlet.

The life-cycle of three small scale off-grid electricity generation methods: diesel generator – the baseline for comparison, solar panel (PV cells), and micro-hydro system were analyzed based on a typical Ontario cottage setting.



Project Information
Analysis conducted by:

Section 02 Group 11 (B11)
 * J. Lau (JLau)
 * E. Zhuang (j.zhuang)
 * J. Sin (Ckjackysin)
 * B. Wong (Bwong)

Highlights
The cottage analyzed was assumed to be located in a remote area adjacent to Lake Muskoka. The power consumption of the cottage was assumed to be 170 kWh/wk and 6.9 kWp. As a result, actual commercial products that met the functional requirements were selected to conduct the analysis. Based on the expected life span of each alternative, a study period of 300 years was used. Read more on the major assumptions made in this analysis.

From the technical side of the alternatives, micro-hydro turned out to be the most efficient alternative with an efficiency of 65% in converting gravitational potential energy from the water into electricity. Followed closely behind is diesel generator with an efficiency of 45%. When the availability of the energy is considered, however, diesel generator is superior due to the fact that diesel is available as long as petroleum is available. Solar panel lacked behind in both of this category with an availability of energy of only 22% and an efficiency of only 17-20%. Yet, solar panel is easier to be implemented than micro-hydro while diesel generator requires very little effort in its implementation.

The Streamlined Lifecycle Assessment (SLCA) concluded that micro-hydro system have the least environmental impact with a score of 56/80. Diesel generator scored the lowest due to its heavy dependency of petroleum product during its use stage and the existence of petroleum residue at its end of life. Solar panel also got a relatively low score due to its energy intensive pre-manufacturing and manufacturing stage. The delivery stage of all three alternatives was ignored because they are the same and therefore will not affect the score.



From an Economic Input-Output (EIO) LCA, a decision on the the system with least environmental impact was very hard to be made. During the manufacturing stage, solar panel emits less conventional air pollutants than micro-hydro system. Yet, the Gross Energy Requirement (GER) and Global Warming Potential (GWP) for solar panel is higher than micro-hydro. Diesel generator lacked behind in all categories except for lead emission and Solid Waste Burden (SWB) because manufacturing it does not require silicon or copper as a source material.

Based on an economical assessment, micro-hydro system is the most economical alternative with only half of the cost required to buy and run a diesel generator. The cost of a solar panel over the entire study period is also slight lower than a diesel generator, but its capital cost is almost 14 times the capital cost of a diesel generator. The capital cost of a micro-hydro system, on the other hand, is only 3 times a diesel generator.

Recommendation
After considered all aspects of the analysis with environmental impact receiving the biggest weight and the technical aspect receiving the lowest weight, the micro-hydro system was considered as the best off-grid electricity generation alternative and diesel generator was considered as the worst off-grid electricity generation alternative. Although the amount of lead emission during the manufacturing of a micro-hydro system is 7 times greater causing a SWB to be 9 times greater when compared to diesel generator, micro-hydro scored much higher in the other categories than the other two alternatives.

Another recommendation is to combine a diesel generator with PV cell or micro-hydro to create a hybrid system as suggested by. Although this recommendation will not decrease the environmental impact of the system and will yield a system with a higher cost, the reliability of the system will be significantly increased. Since both PV cell and micro-hydro system depends on the weather, the diesel generator will be used to act as a backup power source.

Functional Analysis
The major components of a diesel generator include a diesel engine and an electrical generator – actuator. The diesel engine generates power through an internal combustion process in which the fuel would be ignited by direct injection into a chamber filled with compressed high temperature air. The efficiency of a diesel engine is around 45%, where each gallon (3.8 L) of diesel fuel contains approximately 20x106 J more than each gallon of gasoline. Therefore diesel generator may be deemed an efficient way of generating electricity, and had been commonly used for industrial purposes as well as certain residential needs. The diesel generator is also a highly reliable method of electricity generation due to its readily available potential energy in diesel fuel, as compared to other methods that may rely on natural conditions.

Product Selection
In determining a suitable size of the diesel generator, a 6kW power output was arbitrarily chosen for the purpose of this analysis. Based on the estimation of 679.549kWh/month energy requirement of the cottage and energy density on diesel fuel of 10.11 kWh/litre, a 6kW diesel generator shall only need to operate for 3.78 hours a day and consume approximately 150 litres of diesel each month. Therefore a 70 litres fuel tank should be considered as an accessory so that the user can reduce the frequency of refilling diesel generators, since the generators’ fuel capacities are usually only around 10-15 litres. This fuel tank will add $336.75 on top of the capital cost.

A battery will be used to store energy from the generator. It will allow the generator to only operate when energy is needed and not produce excessive electricity to be wasted. However, this is identically implemented in the other two alternatives (micro hydro and solar); hence its effect will not be evaluated in the analysis.

Functional Analysis
A solar electric system generates electricity directly using Earth’s most sustainable and abundant energy source – sunlight. PV system has the advantage of generating “free”, clean and emission-free (no noise, smell and GHG) electricity. Also during its useful life, a PV module requires very little maintenance. However, this method of converting energy into electricity is not as efficient as other methods such as hydroelectricity generation; typical module efficiency from today’s technology ranges from 16% to 21%. Moreover, the performance largely depends on the weather (sunny hours). The average peak sunlight hour (from May to October) estimated from insolation data is 5.2 hours, 22% availability a day.

Product Selection
The initial cost of such system is however relatively high. For example, according to our power consumption estimation, the cottage requires 680 kWh per month and a maximum of 6.9 kW at anytime from a PV off-grid system. Estimating from the sizing sheet provided by, a 7 kW system is needed. Mitsubishi Electric PV-UD185MF5 which claims to have 185W peak power is selected for the analysis. Full specification can be found in. It costs $833 each and 38 such modules are required for the desired output. The total cost is $31,654. Another important performance measurement is the average cost per kW-h generated over its life span, which was estimated to be about 35 cents per kWh, shown later in Cost Analysis, assuming the system fully satisfies the power consumption. The PV modules can be placed on the roof of a cottage to save space; nevertheless, space requirement for the PV system is calculated to be 52.5 m2 in total, using module’s specification.

Functional Analysis
The micro-hydro system is hydroelectric power installation with 65% efficiency which normally generates up to around 100kW of power. It transfers potential energy into electricity continuously as long as water stream runs along the river at which the system is installed. It is one of the most environmental friendly energy conversion alternatives available, because running water is a renewable energy source and unlike large-scale hydro power, it does not interfere with water flows significantly. It also operates quietly and without odour. Moreover the aesthetic problem can be basically solved by careful design of pipeline route. For the purpose of this analysis, our micro-hydro system will be asuumed built at a 50 feet head and 600 foot long creek, and the cottage is located 200 feet from the creek. This scenario allows a micro-hydro system to generate up to 110kW .A micro-hydro system can normally last for at least 20 years if maintenance is performed regularly. However, there are certain disadvantages: 1. the size and the flow of the river constraint the expansion of the system as the electricity demand increases. 2. In some regions, the climate will affect the speed and the amount of water flow in the river. An example is solidification of the water during winter. 3. Construction of the system will affect the ecology and the civil infrastructure of the area around the system.

Product Selection
In order to maximize efficiency, micro-hydro system is generally custom made to fit the specific terrain. The space occupied by the water turbine is approximately 12 x 12 x 12 ft3, and the typical price of such system ranges from $1,000 to $20,000 CAD.

Streamlined Life Cycle Assessment
Figure on the right shows the scores of each stage in the life cycle for three alternatives studied. Overall, micro-hydro scores the highest and diesel scores the lowest of the three. The following highlights the reasons behind the scorings:

Pre-manufacturing
PV receives relatively lower scores than the other two mainly because extraction of silicon requires both virgin materials and intensive energy input ; however, for diesel and micro-hydro, recycled materials such as scrap steels can be used to reduced various impacts such as energy consumption and air pollutions.

Manufacturing
PV is rated the lowest because in the production of PV cells, hazardous chemicals, intensive energy are required and significant amount of toxic materials is released. On the other hand, production of diesel generator and micro-hydro turbine utilize recycled materials and require less energy input and release either no or negligible toxic materials.

Use
Diesel is rated the lowest because during use phase, diesel generator requires the use of highly toxic and hazardous consumables such as fuel and oil etc. Also, large amount of GHG and toxic air pollutants are released during generator’s internal combustion process. PV and micro-hydro are rated perfect because they require little maintenance during their respective useful life.

End of Life
Diesel receives relative lower scores than other two alternatives because most of the components in PV module and micro-hydro system can be recycled yet diesel generator is turned into scrap and it requires considerable amount of energy during disposal.

Methodology
Since the scale used in the EIOLCA model on www.eiolca.net is quite large, an economic activity of 1000 systems is used for the input. For each alternative (Diesel, PV, Micro-hydro), EIOLCA is only performed on the diesel generator, PV module, micro-hydro turbine and copper piping respectively. Diesel Sectors selected: 1. Other engine equipment manufacturing sector 2. Petroleum refineries sector Respective economic activity at 1997 Dollars: 1.5 Million and 10.6 Million Life span: 15 years  PV Sectors selected: Semiconductor and Related Device Manufacturing Economic activity at 1997 Dollars: 24 Million Life span: 25 years  Micro-hydro Sectors selected: 1. Primary smelting and refining of copper sector 2. Turbine and turbine generator set units manufacturing sector Respective economic activity at 1997 Dollars: 3.8 Million and 2.5 Million Life span: 20 years 

Results from EIOLCA
Conventional Air Pollutants

Diesel has the most impacts on SO2, CO, NOx and VOC emissions, accounting annually for 3.2 Mt, 5.1 Mt, 1.9 Mt and 2.0 Mt respectively, but least in lead (0.0005 Mt). This is the result of cracking and coking chemicals required during refinement. PV contributes the least of the conventional air pollution except lead, 0.86 Mt, 2.0 Mt, 0.6 Mt, 0.5 Mt and 0.18 Mt for SO2, CO, NOx, VOC and PM10 respectively. Nevertheless, the semiconductor sector itself contributes negligible impact on conventional air pollutants emission. Micro-hydro poses moderate impact on most of the pollutant emissions except for Lead where it contributes most of the three. Yet the impact of lead is considerably small for all three alternatives, annually accounting for only 0.0005 Mt, 0.001 Mt, 0.003 Mt respectively.

GWP – Global Warming Potential Annually, Diesel poses the largest GHG emissions and thus the most GWP among the three alternatives, accounting for more than 1500 MTCO2 of GWP while PV and Micro-hydro contribute only around 400 MTCO2 and 200 MTCO2, respectively. These result from the fact that the diesel fuel needed during the use stage constitutes 64.3% of the total GWP while PV and Micro-hydro require no input during the use phase; their GHG is mostly incurred during production and delivery stages. 

GER – Gross Energy Requirement Diesel requires the most energy input, accounting for 18.3GJ annually. Over 55% of the energy is consumed in petroleum refineries, which indicates the great impact of the diesel fuel during use stage. The other engine equipment manufacturing sector itself however consumes relatively much less energy. On the other hand, PV and Micro-hydro requires relatively the same amount of energy input, annually 4 GJ and 3 GJ respectively. Nevertheless, production of PV and Micro-hydro system is also very energy intensive as they require 100 GJ and 60 GJ respectively to produce one system.

SWB – Solid Waste Burden  Micro-hydro has the greatest toxic release of all three alternatives, producing total of 6550 Kg toxic releases/transfers annually. This is due to the requirement of copper piping in the system which induces the majority of the toxic releases from mining and primary smelting of copper. Moreover, they are primarily concentrated on the land releases because the dust and solid residues from the mining dumps. Diesel and PV produce negligible toxic releases compared to Micro-hydro because they do not require extraction of materials that produces lots of wastes.

Cost Assessment
 In order to compare the life-cycle costs for diesel generator, PV cell, and micro-hydro, it is necessary to divide the life-cycle cost by the life span for each alternative and then evaluate them.

 The capital cost of diesel generator consists of the retail prices of diesel engine and a 70L fuel tank which sum up to be $2330.75 CAD. . Diesel generator is much cheaper than PV cell because its capital cost is solely consisted of solar panels with $31,654 CAD. On the other side, the capital cost of micro-hydro is $6380.43 CAD which is intermediate among the alternatives. It includes the retail prices of Copper Pipeline and micro-hydro turbine.

 Due to the 25 year warranty of the solar panels, PV cell generation does not require any operation cost. In contrast, extensive of diesel fuel is needed for the operation of diesel generator; moreover, transportation of the fuel to the cottage and engine oil refill also contribute a significant amount to the operation cost. Thus, the total operation cost of PV cell generation is $16,418.89 CAD. The maintenance cost of Micro-hydro is is the maintenance of copper pipeline and turbine and it is assumed to be $4624.25 CAD based on the replacement of piplines and turbine.

 For the disposal stage of micro-hydro diesel generator, since it is assumed that disassembly of the system is done by the cottage owner, there is only the cost of the transportation of the scrap materials. The price of gasoline in 2028 is assumed to be the same as the price in 2008 excluding inflation of the currency for simplicity. Thus, $31.20 CAD is required to dispose micro-hydro system and diesel generator. It is assumed that the cost of processing recycled modules (silicon wafers effectively) is about ¼ of the cost to produce new wafers. Silicon wafer is responsible for 50% of the cost of manufacturing a module. Thus, $1,168.44 CAD is the total disposal cost for PV cell and it is the highest among the alternatives.

 Indirect costs include health and environmental costs are calculated based on the output of EIO-LCA and the cost per emission obtained from the research in University of Alberta. . As a result, the total indirect cost for diesel generator is $5005.42 CAD, PV cell is $3292.61 CAD, and micro-hydro is $2747.29 CAD. Thus, micro-hydro costs the least to the environment and health in a financial point of view.

 Finally, as the direct cost and indirect cost are added together, this becomes the total life cycle cost.

Other factors
There are some concerns excluded from the analysis. The implementation of diesel generator would have minimal effect on society due to cottage's afar location from city. However, there is still a minor probability of ignition of spilled fuel, or unexpected particle in combustion chamber causing ignition, which could lead to burn down of trees nearby. This highly improper situation would result in serious environmental damage. Residents living near by may as well oppose the installation of micro-hydro system due to its destruction of natural aesthetic of the river as well as potential recreation area. Approval from the residents in the area and government permission are therefore needed prior to its installation. Technological advancements and environmental/climate changes can also affect the performances of above alternatives, in effect changing the available power output, lifespan, operation cost etc. These factors are difficult to account for yet may significantly affect the accuracy of this analysis.

Topographical and Geographical Assumptions
The cottage is assumed to be located at a site next to Lake Muskoka in central Ontario. Terrain and geographical features includes: The above assumptions resemble a typical remote cottage that allowed the possibility of all three alternatives after studying geographical features of central Ontario using.
 * Open field suitable for large scale PV installation
 * Minimal trees coverage allowing exposure of cottage roof top to solar radiation
 * Next to a small creek of 20 m elevation over a distance of 200m that transports runoff water into adjacent Lake Muskoka
 * Nearest gas station that offer diesel is 10 km away

Power Consumptions Estimate
Based from the table above, the weekly energy consumption of the cottage is 170 kWh with a peak power consumption of 6.9 kWp. This peak consumption is based on the power required when using all of the following appliances concurrently: Clothes Dryer, Computer, Air Conditioner, Hair Blow Dryer, Lighting, Refrigerator, and Television. This power consumption simulates a possible evening setting. All power consumptions data are based on, and. The cottage was assumed to be only in use during weekends while only the refrigerator will be on during the week. The cottage will only be used during cottage season which is from May to October.

Other Assumptions
The off-grid electricity generation system was assumed to follow the remote area power supply (RAPS) system model which contains an electricity generation method, an AC/DC converter for converting electricity into DC for battery storage and back to AC for household use, and batteries. Please refer to Figure A-2 for a diagram of RAPS system. Since the RAPS system is the same for the diesel generator and micro-hydroelectricity alternatives, and only required minor modification for the PV alternatives, the AC/DC converter and the battery will not be included in the LCA.