The rapid growth of cities has become the most striking feature of human civilization. Cities have depleted earth’s resources by draining the fertility without replenishing it. They have exhausting the forests, watershed and in the process discarding vast quantities of waste and pollution.
Sustainability needs to be addressed if mankind is to continue to live in cities and continue to flourish on this planet. We need to find a viable relationship between cities and the living world – a relationship not parasitic but symbiotic, or mutually supportive (Girardet, 1992).
In this essay an attempt has been made to describe the situation of Thimphu city and the type of strategies that will make the city sustainable. While the city will never be entirely sustainable this attempt at reducing use of natural resources, reusing resources, use of additional renewable energy source aims to reduce the impact of the city on the environment and in the process also combat climate change.
Bhutan is a land-locked country in the Himalayas having a population of 672,425 people (PHCB, 2005). Bhutan has an area of 38,394 Km2 and borders China in the North and India in the South, East & West.
The Capital City Thimphu is located in the western region with a population of 98,676 (PHCB, 2005).
The Government has a policy of maintaining 60% of areas under forest cover. In 2005, 68% of total area was under forest cover (NECS, 2002).
The back bone of the economy is hydropower. Export of hydropower to India accounts for 60% of total revenue.
Bhutan is a signatory to the Kyoto protocol under the United Nations Convention on Climate Change. Bhutan’s annual emission of CO2 per-capita was 0.2 ton as compared to the world average of 4.5 ton in 2004 (UNDP, 2007).
While no targets have been set for reduction of Carbon Dioxide, Bhutan is committed to reducing GHG (NEC, 2000). Mitigation programs currently being implemented:
- Renewable energy technology options
- Improved technology to reduce fuel wood consumptions
- Introduction of fuel-efficient vehicles
- Improvement of imported fossil fuel quality
Bhutan has till date successfully constructed and commissioned a 70 kW Clean Development Mechanism micro hydropower project in Chendebji village with the objective to reduce GHG. The project commission in 2005 has reduced CO2 emission by 593 tons, by replacing the need of kerosene, firewood and diesel by the villagers.
Bhutan generates about 1488 MW of electricity from hydropower of which it consumes 152 MW (BEA, 2005). However with global warming and glaciers receding fast, there is a need to depend on other renewable energy sources in the future.
According to the Population and Housing Census 2005, the main sources of fuels are firewood (37.2%), electricity (30.6%), LPG (25.5%) and the remaining from other sources.
While Bhutan has an abundant clean source of energy there is still abundant use of fuel wood. Even though Carbon dioxide is a GHG, fuel wood burning is not considered a GHG as it is absorbed when trees are planted. However, the burning of wood results in deforestation which damages the environment, effects the water shed (water source) and at the same time reduces the carbon sink potential.
It was found that most of the 6,982 households and over 1000 institutions in Thimphu still use fuel wood for cooking and heating purposes. For example on an average each school consumes about 15 truckloads of firewood every year (GEF, 2006).
Some of the strategies to reduce fuel wood demand:
- Replace traditional stoves with efficient improved cooking stoves will reduce the consumption of firewood. Such stoves can save up to 40% of fuel compared to traditional stoves. This puts less pressure on forest & energy recourses in addition to reducing GHG (Shrestha, S.K & Thapa, R. 1999).
- Use of sawdust briquette as an alternative fuel source
- Switch to electrical appliances instead of wood stoves
- Use of alternative renewable energy source such as solar energy
- Most institution use fuel wood as a source of energy for heating water for having bath
- Switch to solar hot water system (SHWS) would result in decrease of demand for fuel wood
- For example a nunnery in Thimphu used to use five truck load of fire wood per year. With use of SHWS, three truckloads of fuel wood use is reduced a year (GEF, 2006)
- Solar power generation is considered a prominent form of clean energy that avoids GHG Emissions
- One KW of Solar power capacity avoids one MT of annual CO2 emissions (Kaur, R. 2008)
Houses in Thimphu are poorly designed. Improving the designs of house can result in saving of energy and money in the long run.
One of the main sources of CO2 is energy required for space heating. Improvements in building design can reduce energy consumption. In a new house, windows typically account for 15% to 30% of the total heat loss. With good design, large areas of glass window can save energy through passive solar heating gains. While initial cost of glazed window is high they will eventually pay for itself – for example, window with low energy coating cost about 10-15% more than conventional double glazed units, but they reduce energy loss up to 18% (Woolley, T & Kimmins, S. 2000).
In the same way using advance insulation materials can actually reduce the energy consumption of buildings by as much as 90% (Girardet, H. 1992).
Bhutan has a strict procedure to approve building designs prior to construction. In addition to checking structural integrity, the government agency should encourage eco-friendly practices. While initial cost might be more, building with good energy saving features can be viewed as an eco-friendly house and will eventually have greater market value as energy saving would compensate for the higher investment. This is in contrast the current practice of poorly insulated houses being constructed at the lowest possible cost. The result is that building owners also charging minimal rent but energy consumption of individual households are high. While the financial outcome may be same, there is more energy use in the latter which emits more GHG.
The documentation of design and materials used in building now, is a good practice. This provides the ideal opportunity for incorporating building efficiencies. In addition during demolition of buildings it helps in efficiently sorting materials which can be later be used for recycling (Lawson, B. 1996).
Use of energy saving devices
Most buildings in Thimphu use incandescent bulbs. Switching to use of low-energy fluorescent light can save 70% power. Although they cost more initially they last longer and soon pay back the extra cost in the energy saving they make (Elliott, D. 2003).
Environment preserved by:
- better fuel efficient stoves
- better building design
- reduced use of fuel wood due to use of alternate energy
- decrease in health hazard from indoor air pollution
- improved quality of life
- While initial economic costs of these investments are high, in the long run they will pay back / benefit the community
- government can play a major part in influence the demand by affecting the supply cost by either taxation or subsidy such as by:
- No tax on electrical heaters and rice cooker appliances
- Subsidy on energy saving appliances
- Subsidy on briquette stoves to encourage use of sawdust briquette
- Subsidy on house insulation materials
- Increase in royalty on fuel wood
- Cost sharing basis by government for renewable energy
Bhutan imported about 70,047 metric tons of oil equivalent in 2005 which were used for transportation, lighting, cooking and heating purposes (DOE, 2005).
With inadequate public transport, cars have been an essential means of mobility by which individuals commute. As per the Road Safety and Transport Authority (RSTA), there are 19,000 vehicles in Thimphu in 2008 with the number increasing at 17% annually (RSTA, 2003).
A major source of air pollution in Thimphu is the combustion of fossil fuels from vehicle emission. Study conducted by the National Environment Commission (NEC) found that emission levels was found to be high in vehicles with 60% of petrol and 96% of diesel engine vehicles not meeting Indian emission standards (BSoE, 2001).
In fact, it was found that pollutants of vehicle as one of the main causes for acute respiratory tract diseases in Thimphu. A health study showed that acute respiratory tract disease had increased from 10.08% in 1990 to 14.02% in 1998 (BSoE, 2001).
More cars mean more pollution. In addition use of cars has a disadvantage to community. Cars not only pollute the atmosphere but also take away valuable space. It is estimated that “one hundred people in a bus need only 40 square meters of road space” whereas “one hundred people in cars travelling by themselves need some 2000 square meters” (Girardet, 1992).
Car based planning are destroying public spaces, and detaching bonds within community. High volume and speeding traffic causes people to retreat from street-based community. This results in social disintegration and isolation. Reliable public transport is therefore the only option to give back more public space to the community.
Vehicles not only need resources for production but also needs energy during operation. Pendakur (cited in Girardet, 1992) reports that “cars use 1860 calories per passenger mile, bus 920, rail 885, walking 100 and bicycles 35 calories per passenger mile”. Hence we can see that the bus uses much less energy than car and should be the mode of travel.
From Pendakurs report we can see that bicycles use the least energy. To encourage bicycle usage, and to ensure that it is save and convenient as possible, it is vital that roads and facilities are of suitable standards. Hence Roads Authorities should constructed or rebuilt road with minimum recommended lane width so the bicycles can be safely included in the general flow of traffic (Healey, K. 1996).
The strategy for a sustainable city aims to reduce energy demand, reduce pollution & free more space for the community.
Policy strategies for transport are listed below:
- Impose high tax on import of cars
- Policy to import fuel efficient vehicles
- Import good quality fuel
- Legal framework to control vehicle emissions
- Introduce reliable public transport system
- Subsidy for buying bicycles
- Improved footpath for pedestrians
A good public transport for Thimphu can be a bus or tram system that runs on electricity as the source of energy from renewable hydropower is within Bhutan.
- With less car pollution there will be decrease in health related illness, which will decrease health expenses of the government as health care in Bhutan is free
- Government health sector resources could be invested into the transport sector
- Higher tax on cars can help fund public transport
- class barriers are not created, which will allow for an environment for interaction between people
- No financial pressure to invest limited resources in expensive vehicle. Hence it frees resources of people to be used in other meaningful ways
- Use of public transport and bicycle will put less pressure on the atmosphere
- Decrease in demand for non renewable petroleum based fossil fuel
With a population of 98,676 people (PHCB, 2005) and with water demand at 125 liters per person per day (DUDES, 2006), Thimphu required 12,335.5 cum of water per day.
Thimphu’s two water treatment plants supply of 15,000 cum per day is more than adequate currently.
However with the population growing rate of Thimphu of 10% per annum (NEC 1998), the current water supply of 15,000 cum per day will only be able to provide water for a population above 120,000. Hence water conservation measures have to be taken to ensure that water is available in the future.
Some of the strategies that can be taken are listed below:
- Rain water harvesting systems
- Thimphu is an ideal city for rain water harvesting as most building have Corrugated Metal Sheet roofing
- rainwater harvesting is sustainable as there is rainfall throughout the year
- Government needs to promote rainwater harvesting by inculcating social acceptance and pride in technology that preserves the environment
- Financial investment is minimal with building owners required to purchase gutter for channeling of water to tank, a tank, and an electric motor to pump the water from lower tank to existing tank
- Saving on water is an economic incentive for people
- Less energy is required to treat water thereby benefiting the environment
- The government can influence the demand by affecting the supply cost by either taxation or subsidy.
- Increasing the tariff on water to discourage use
- Subsidize water saving devices such as efficient shower heads, shower timers etc.
- Policies could be implemented such as all new construction being required to use dual flush toilets, water less urinals, all gardening to be done by grey water
Thimphu was establishment in 1955 as the capital of Bhutan. Since then Thimphu has undergone many changes. The town plan of 1998 was to make Thimphu a dream city with a vibrant culture which is people and environment friendly.
With rapid increase in automobile numbers and pressure on public health infrastructure in the town centre, a new plan called the Thimphu Structural Plan was implemented in 2003. This plan after implementation would ensure Thimphu to be a sustainable and livable city.
This new structural plan put restriction on plot coverage as well as building height. While the objective was the reduce pressure at the center this also allowed for other considerations:
- With residential buildings restricted to three floors, lifts are not needed thereby elimination the use of electricity
- Concept of elders residing on ground floor, middle class on second floor and young couples at the top floors encourages older generation to live in cities
- With no lifts there is more free space
The structure plan being implemented is aimed at improving the access of people to services. This structural plan requires the creation of 15 urban villages which is created through participatory land pooling. All villages will have its own village square with shopping centers, playground, gardens and an express bus link connecting it to the urban centre. This ensures a local communal environment where all activities are close together and walking and cycling can be the mode of transport (DUDES, 2003).
The urban villages provide communal public areas which are essential for people to interact. Young people especially require public meeting space where they can strengthen their links with people around them. Otherwise they may turn to crime and increasingly to suicide (Healey, K. 1996).
Strategy to improve the life of the community:
- Coordinate social gathering that ensures communal spirit and bonding
- Initiate communal service centers such as washing machine services. Instead of each individual buying a machine, communal washing machine can still serve the needs of people and ensure optimal use. These actions reduce GHG.
The establishing urban villages are being implemented. As the urban villages get completed the villages remove the pressure on the urban center, which will allow the city centre to also become more livable.
Thimphu has grown rapidly in the last few decades. With rapid urbanization, rural-urban migration, change in consumption habits and the high population growth rate have resulted in increase of waste generated.
Thimphu which generated 10 tons of waste daily in 2000 (USPS, 2000) is currently generating 64.5 tones of waste daily (Penjor, 2008). The waste generation of 0.3 kg per capita per day in 2001 (BSoE, 2001) has risen to 0.56 kg per capita per day in 2007 (Penjor, 2007). These wastes are being disposed of at Thimphu’s only landfill site.
The tariff charged by the Municipal Corporation for the disposal of Solid waste is low. There is no limit restriction to the amount of waste disposed. Being a cheap method for waste disposal, there is no incentive for other viable economic methods of waste management.
As per a survey by Penjore (2008), the composition of waste by weight was 25% organic, 14% cardboard, 12% paper, glass 10%, plastic 5%, metal 4% and other the remaining. This revealed that recycling of waste at household level was minimal. In addition organic and green wastes are not composted. The decay of organic matter in absence of air also releases methane a harmful GHG.
The success of management of solid waste is crucial in the attitude and behavior of humans to the environment. The strategy for solid waste management should be to reduce waste to the landfill:
- Tariff for the waste for landfill should be charged based on quantity
- Increasing tariff would result in people reducing waste to land fill. Only waste with no value will be disposed as it cost people money to dispose of it. Waste such as paper, glass, metal, organic waste which have value could either be sold off for recycling
- With increased tariff for waste disposal, recycling option can become economically viable. Recycling will:
- preserve the environment as the recycled resource does not require new raw materials
- uses less energy in processing recyclable materials than processing from raw materials
- With increased tariff for waste disposal composting options can become economically viable
- Composting of organic matter and greens can produce manure
- Composting done properly would not generate methane, a GHG
- Manure can be sold
- Effective composting requires a right Carbon to Nitrogen (C/N) ratio of about 25-30:1. For example the mixing high C/N ratio such as sawdust, with low C/N ratio such as glass clippings or vegetable peels resulting with C/N ratio of 30 would allow compost activity to take place at optimum rate (Mason, J. 2003, p.43, 44).
- Waste such as sawdust from sawmill could be used in composting or converting to alternate source of fuel such as briquette.
- This would also encourage reduction of waste disposed into landfill and in the process promote value from waste material
- Government should finance and provide technical expertise to encourage private business to take up recycling and composting
- Cost of purchasing different bins for different waste should be subsidized. This will encourage segregation of waste at source
- Increase in cost of disposal of construction waste will have positive impact on initiative to reuse old material
- most current industrial practices and systems are currently ecologically unsustainable
- Tucker and Treloar (1994) recommends that from an energy conservation and CO2 emission viewpoint, recycling of building materials should be encouraged based on research
- It is essential to make use of resources a more natural systems, which are typically characterized by cyclical process (Lawson, 1994) and symbiotic, mutually dependent relationships (Allen,1994) for sustainability
These methods will:
- conserve materials and energy;
- generating less waste for landfill
- With the increase in tariff of disposing waste to the landfill, it becomes economically viable to compost which is valuable nutrient that has economic value
- people can eat food from natural nutrients and not artificial fertilizers
- With composting, valuable nutrients which could other wise have been lost is replaced back into the soil, closing the nutrient cycle
As per L. M Austin and S. J. Van Vuucen, human being excretes 500 liters of Urine and 50 liters of faeces per year.
While 50 liters of faeces is not difficult to manage, the mixing of faeces and urine when flushed with water as sewerage becomes a problem. That means 50 liters of faeces becomes 550 liters of polluted and unpleasant sewage.
The sewerage of Thimphu is piped into a sewerage treatment plant which currently has a treatment capacity of 3,060 m3/day (TCC, 2005). With increase in population, there is increase in demand of water for flushing and increase in energy needed for treating sewage.
One strategy to reduce water demand for flushing in toilets and reduce energy demand for treatment of waste is to introduce the Urine Separating toilets (UST). What UST does is that, it separate urine (nutrients N,P,K) from mixing with faeces matter.
Advantage of the UST is:
- Lower water use with 0.1 to 0.3 liters of water is required to flush urine (Johansson et al., 2002) which is 90% reduction compared to half flush from standard 3/6 dual toilet
- Nutrients from Urine (N,P,K) can be used as concentrated fertilizer with only limited treatment prior to land application
- Energy consumption for nutrient removal at Sewage treatment plants can be reduced by source separation technology resulting in lower nutrient wastewater for treatment.
Based on calculation presented in Annexure A, there is potentially a saving of 2250 m3 of water per day. In addition there is a reduction of 2250 m3 of sewage that does not require treatment per day and hence less energy use.
In addition to water saving and energy reduction, a life cycle analysis of different removal and recovery technology (Table 1) found that nutrients can be recovered energetically at source more efficient that either their removal at the Sewage Treatment Plant or from new production from natural source (Maurer et al. 2003).
|Nutrients||Specific Energy required (de-nitrification and precipitation) at Sewage Treatment Plant||Specific Energy for production of traditional fertilizer|
|N||13 kWh/kg||13 kWh/kg|
|P||14 kWh/kg||8 kWh/kg|
Table 1: Comparison of energy required for treatment at Sewage treatment plant & production of fertilizer
Source: Maurer et al. 2003
Hence, nutrient segregation at source is the most environmental friendly approach as it require the minimal energy demand, which reduces GHG emission which otherwise would be emitted during the sewage treatment or during production of new fertilizers.
In effect UTS closes the nutrient circles as nutrients can again be put back into the fields as fertilizer.
- Practical problem is difficulty in collection of urine separately. With the existing sewage network, what can be done is that the urine is stored separately during the day. At night, the urine could be released and collected separately at the sewage treatment plant. This method does not require infrastructure investment
- Concentrated Urine with minimal treatment can be sold as fertilizer
- Urine separating toilet with flush provision can be easily retrofitted in standard toilet
- Additional land not required for expansion of sewage treatment plant
- Urine separation with flush provision will make it more appealing
- Reduces demand for water, making it cheaper for people
- While use of urine as fertilizer may seem revolting, people are very adaptable in Bhutan and cheap cost will be a major incentive for use
- Reduces discharge of nutrients to sewage treatment systems
- Reduce volume of water demand
- Reduces demand for energy to treat waste
- It potentially closes the nutrient cycle by returning nutrients to the field, which contributes to sustainability
According to the International Union for the conservation of Nature, “sustainable development improves people’s quality of life within the context of the earth’s carrying capacity’.
While Thimphu is a relatively small city by modern standards, the demands and impacts of the city’s existence is clearly visible. This essay has identified issues that are crucial in making the city more sustainable:
- Energy efficiency
- Energy and water conservation
- Use of more renewable energy
- Efficient public transport
- Urban planning and livability of citizens
- Recycling of solid waste
- Solid waste composting
By reducing the demand on the natural resources and improving the living condition of people, the city will not only have a circular metabolism existence for sustainability but also have a livable city where people can live in harmony with the environment.
Prepared by: Jigme T Tsering