Results of the sustainability analysis for the selected system for Pangboche
This stage is in accordance with the fourth stage of the proposed methodology: Sustainability Analysis. This stage follows on from Energy System Design and is the final stage of the methodology. The methodology is concluded in Project Conclusion.
A range of technically feasible systems have been designed in the previous stage. Social, economic and environmental impacts and implementation models were then considered to determine the optimal system. This section details the methods and results for Sustainability Analysis for Pangboche, according to Stage 4 of the proposed methodology.
The capital costs, O&M costs and cost of energy to the consumers for the electrical system were determined using HOMER. Costs were determined over the system’s life span (25 years) using a discounting rate of 10% [1]. The table below provides a summary of the cost analysis.
The table above suggests that return on investment is possible within 15 years of operation without subsidy support and 10 years of operation with subsidy support. The proposed tariff is consistent with other case studies of other systems looked at in literature [2]. A typical family in Pangboche would potentially use about 3.75kWh a month on average and would therefore pay about $1.31 per month for using the electricity. Comparing this to grid charges, a family would pay about $1.11 for a grid connected system [3], inclusive of the minimum service charge. This tariff charged for the mini-grid system is therefore competitive to grid connection and therefore reasonably priced.
Unlike the thermal system where each household would be responsible for financing the system, the community would collectively need to raise the funds required to install and maintain the system. One requirement for a community to qualify for subsidies for community scale renewable energy systems is that 10% of the financing should be in the form of credit [4]. The subsidy provisions are enough to fund the initial capital costs of the project. The remaining costs are from installation and O&M. The cost of installation and part of O&M for the first year could be covered by the loan. The system would then generate enough revenue over the consequent years to pay the loan and set up a fund for O&M costs over the system’s life span.
Grid Architecture
Grid architecture was first considered. As discussed in Energy System Design – Electrical the potential for grid connection is highly unlikely and not desirable. Of the remaining grid architecture options (microgrid, battery charging station and nanogrid) were then considered for the 116 households in the community. The layout of the village economically favored microgrid architecture. Back-of-the-envelope calculations are shown below which support this statement. It should be noted that the values used are intentionally favorable to battery charging station architecture and unfavorable to microgrid architecture:
The overall costs of the thermal system components were determined by a review of literature on system costs in Nepal. A majority of this information was retrieved from non-government organisations promoting clean technologies in Nepal, such as Practical Action [5], World Wildlife Fund [6], the Sustainable Technology Adaptive Research and Implementation Centre, Nepal (STARIC-N) [7], as well as the government publications such as reports from the Alternative Energy Promotion Centre (AEPC) [8]. The Nepal government has a renewable energy subsidy policy that has provisions for subsidies for capital costs and transportation costs particularly for remote hard to reach areas [9].
The table below details the capital costs and annual Operation & Maintenance costs of the thermal system, including subsidy provisions.
Each household would incur just over $1,000 to implement the thermal system. As mentioned in the project definition stage, the average GDP per capita is about $427. It is assumed that households only spend money on kerosene, since fuel wood and animal dung are available for free. Assuming families use 0.2 litres a day on kerosene and the average price of kerosene going for $0.82/litre (calculated as average from February 2015 to February 2017) [10], then a family would use $ 0.16 per day on fuel, which translates to $59.86 annually. If it is assumed that only one member of the family is the bread winner, then this translated to about 8% of total income per capita.
If the biogas and improved cook stoves replace kerosene use by 100%, then each family would potentially have about $59.86 available to pay for the thermal system. From the table above, subsidies would contribute to about 30% of the total system costs and households could potentially contribute at least 6% of the total system costs from their income (excluding personal savings). The remaining 64% would need to be sourced elsewhere.
One way to reduce the costs is by households providing labour to install the thermal system. For the cook stove options, the SNV & WWF promoted cook stove was found to be the most suitable since it is easy to assemble without the need to pay a technician to install it. This therefore saves the user some money. For the biogas system, it is possible for individuals to be involved in installing the system, therefore saving some costs as well. Savings from installation was assumed to be about 10% in labour costs. Therefore, only 54% of the total system costs would need to be sourced. This can done through micro loans from micro finance institutions, cooperatives and savings and loans associations [11].
From the estimates above, a typical household would need to contribute an additional 8% from its annual income to pay for the thermal system, for a period of 5 years. After that the family would start saving from using the system, particularly biogas. It is therefore possible to save at least $590 over the system’s life span.
The final design for Fabric Improvements was chosen to be locally sourced 200mm thick wool quilt for loft insulation based on the results from the thermal energy system design stage. From the range of options available it was seen that there was a greater reduction in demand based on investment costs from installing loft insulation that you would get from wall insulation. Using the final design of 200mm wool loft insulation can potentially reduce space heating demand of a household by a third or increase the internal temperatures by 4°C across the entire day.
The importance of ensuring that the energy system does not effect the surrounding environment is particularly relevant for Pangboche as it is located in a world heritage site. Agriculture & tourism are also an important activity for residents, so it is important to ensure there are not conflicts in land use. The potential environmental impacts were analysed for each technology in the system and are discussed below.
In rural off-grid developing communities such as Pangboche the implementation of new technologies within the community can have a number of social impacts on the residents. For Pangboche these impacts have been split into four main areas of consideration: Results for impacts on health, employment, community acceptance, comfort & wellbeing are displayed below.
Measures to be taken:
Black soot from cooking is an indicator of air pollution
Houses can get very cold at night
The implementation model ensures that there are people responsible for the use and maintenance of the energy system in place. Pangboche already has a community in place, therefore they were ideally placed to be the oversight. Facilitators could be either NGO's or Governmental Organisations such as AEPC (Alternative Energy Promotion Centre) in Nepal, but must be able to provide the support and infrastructure for system use. Finally, the implementers for the system in Pangboche can be the community themselves, as the system is designed to be discreetly operated by the end-users in this case.
Below is a summary of the energy system that was proposed for Pangboche.
This is the result of an iterative design process and running the system through a sustainability analysis to test its robustness in meeting the community's holistic needs.
Hydro & solar PV are very complimentary in nature, as when there is low rainfall in winter, there is high solar irradiance and vice versa. The battery system can be used to store energy, to provide electricity when supply is low, such as in the night. The biogas digester and improved cook stoves provide cleaner fuel and better combustion efficiency respectively, therefore improving air quality. And the locally sourced insulation will ensure there are improved comfort levels in the cold weather.
The analysis of the proposed system shows a total of $32,000 for the electrical system that would be borne by the entire community and just over $1,000 per household for each household for biogas and ICS.
Finally we will conclude our project