Monthly Archives: October 2013

Myth of costs

We tend to ignore the environmental impact of using cement for all construction practices and do not consider alternatives

26bgp-green-sen_26_1631331gLet us try answering a simple question. Which item among the following list is the cheapest in terms of cost per kg. – old newspaper, cement, local vegetables or packaged mineral water? While most people may consider paper or vegetable, the surprise answer is cement. A bag of cement weighing 50 kg. comes at less than Rs. 350, hence costing less than Rs. 7 per kg., while even the old newspaper costs nothing less than Rs. 9 in Bangalore. Regarding vegetable prices, the less said the better.

Next, let us look at another question in continuation of the above. Among the above list of materials, which one consumes maximum energy and produces maximum wastage? Many of us may consider paper, but zero in on cement and we are right. Cement production consumes much and also wastes much.

Finally, third and last question in the series. Possibly which material contributes maximum to greenhouse gas emissions (GHG) and has the highest carbon footprint? Of course, now we all are sure of it being cement. The construction industry contributes to nearly one-third of all GHG emissions, within which four materials in heavy demand today, i.e. steel, cement, glass and aluminium, contribute majorly to greenhouse gases.

Contradiction

The foregone paragraphs are not meant to question and denounce cement, but use it as a case in point to discuss the myth of costs in eco-friendly approaches. A hidden contradiction in the contemporary sustainable discourses revolves around a possible belief that all that is cheap is sustainable in society and all that is costly is detrimental to nature. Considering the cost as a derivative of resource consumption, this theory may appear valid in certain cases. However, materials like cement being the backbone of the construction industry worldwide, it is produced in such large quantities, bringing the prices down, thanks to economies of scale.

When materials which are harmful to nature are available at such low prices, we tend to ignore the environmental impact of using them, for they are popular, seemingly necessary and available everywhere. Any alternative, possibly an eco-friendly one, comes at a higher cost, hence becomes less of a choice for all of us.

For sustainability

How is it possible for an energy intensive item, factory-made material, transported over long distances to cost so less, despite having high carbon footprint? Every material invented by humans depends upon nature to supply the raw sources and in turn produce the manufactured ones, causing a two-way impact – decreasing the natural and increasing the artificial. Yet, why do local and natural alternatives cost more than the artificial and manufactured? We may not be able to right away understand the complex market economics to get an easy answer, but need deep introspecting into such contradictions if we have to tread the path of long-term sustainability.

One thing is clear – during our times of green talk everywhere, economic cost and ecological cost are not directly related.

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Watch the wind

Alternative energy sources like wind can never compete with heavily subsidised and often freely supplied grid power. A look at some renewable ideas by architect.

19bgp-green_GA4_19_1623264eWe are passing through a time buzzing with renewable ideas like wind and solar energy; bulbs like CFL and LED; concepts like hybrid and grid supply. While they renew our own hopes for a more sustainable future, these ideas are not without their basket of problems.

At present, wind energy is best used to compliment the electricity board grid and solar power. Grid energy will run all the 16 amp power needs and supplement when either solar or wind is not able to generate power. Wind energy can be used to charge the battery, but periodic battery replacement is not an eco-friendly option. This system is called hybrid system, with low running cost, but initial higher capital cost.

Instead, direct supply to the grid is more efficient and better, but the government has to provide for such provisions. At the higher end, there are people who have invested in large wind mills, sell the power to the government directly and then draw power from the grid wherever they want. It is a known fact that wind mills come with least of operation and maintenance costs, while solar panels produce reduced power across years, besides the need to replace batteries periodically. As such, investing in wind is a better long-term strategy.

While there are increased efforts to promote wind energy production, the idea is not without inherent problems. During times of repairs, reaching the tip of turbine is not easy. Often the turbine will be rotating but hardly any electricity would be produced due to low speeds.

Fast winds, especially during the early unexpected rains, can spoil the blades, making replacing them a cumbersome job. The components are designed for all general challenges, but not for such unpredictable extreme conditions, also due to cost factors.

Fluctuations

The fluctuating power can damage power equipment, demanding the use of inverters at additional cost and consumption. Though there will be a feel good factor, the overall looks of the tower and the apparatus below can be unpleasant in an otherwise publicly important structure. More common problems sighted refer to troubling birds, with turbine clusters virtually eliminating birds around them.

Even with the small units, the air current and sound wave affected by the rotating blades disturb the bird population. In quite neighbourhoods, the blade sound can be distinctly heard, often to the neighbour’s discomfort.

Notwithstanding all the above, energy form wind is something to watch out for. The irony is, the main obstacle in popularising wind energy is none of the above. Alternate energy sources like wind can never compete with heavily subsidised and often freely supplied grid power (which our government does), hence people tend to prefer grid power to wind or solar power. Only when we are made to pay realistic prices for the power we consume, hopefully we may attempt the alternatives and live a more sustainable life.

Power from Terrace

A wind energy unit is a one-time investment. So, across years of operation, the cost per unit goes on reducing, making it a sustainable source of energy.

12bgp-green_GA9_12_1615992eIf we think energy from wind mills is new technology, we are totally wrong. They existed in Babylonia 2,500 years ago, Persians tried them out 1,200 years ago and Europe in general has had windmills for over 700 years. Generally, the rotating blades were used to move simple mechanical parts for lifting water, pounding grains or extracting oil in mills. Wind power to move sail boats and later to explore the world by larger ships has been in vogue for thousands of years. During the 20{+t}{+h}century, it caught up in the U.S. and rest of the world for more diverse applications.

While there are wind turbine clusters with hundreds of them dotting the landscape, we are discussing here mainly the small-scale unit practical for typical urban public buildings. They supply power for lights, TV, battery charging and such needs. With blade diameter ranging from 0.5 to 7.0 metres, and average wind speeds upwards of 2.5 metre per second, we can generate power in the range of 0.5 kW to 10 kW per hour.

For routine household needs, even smaller units with blade diameter less than 3 metres, generating up to 2 kW, can be considered. DC generators in the 12 to 24 volts range are adequate for household needs.

For such small scale, magnetic alternator-type generator serves the function. Also, horizontal axis devices deliver maximum coefficient of efficiency. These can be easily mounted atop any well-designed building. The legs of the tower cannot be directly placed on a slab, but preferably need RCC pillars or an inverted beam arrangement to transfer the load down.

Technically speaking, periodic records of wind speed across one year taken through anemometer is required to accurately assess the power generation. Altitude, air density, topography, speed, wind direction, trees, buildings and such others increase the air turbulence, reducing the power generation. Using scientific formulae based on density, velocity and wind sweep area, technical experts can advice on the installation of the turbine.

The choice of rotor depends upon the purpose of generation – slow running multiple blades are good enough for water pumps while the fast running ones with fewer blades, with wind blowing perpendicular to the blades, are required for electricity.

If the wind can create a drag and lift effect, it further boosts power generation. Of course, there will be the tail vane to rotate the blades in wind directions. Generally, the blades need to have aerodynamic design, good strength and light weight material. Accordingly, aluminium and fibre are preferred over steel.

India, on an average, has around 3 metres per second speed, making it a viable nation for tapping wind energy. Of course, this average has no meaning, for the spot speeds are important. Wind energy unit is a one-time investment, so across years of operation the cost per unit goes on reducing, making it a sustainable source of energy.

A clean energy called wind

Much work has been focused towards sourcing energy from alternative sources such as geothermal, bioplants, ocean tidal, hydro-electricity, solar, and wind. Not all of them can be produced in the context of a building.

05HAB-greensens_05_1607969eAmong the many concerns of sustainable development and possible solutions to the present day crisis, renewable energy is among the critical. Justifiably so, for if we burn out the limited stocks of coal, gas, timber and such sources, our civilization would perish for lack of energy resources. As such, much work has been focused towards sourcing energy from alternate sources such as geothermal, bioplants, ocean tidal, hydro electricity, solar, and wind. Not all of them can be produced in the context of a building, where presently solar water heating leads the list. Next to it, much has been discussed about generating power from the wind, with the generator located atop or by the side of the building.

Enigmatic

While experts feel power from the wind has unlimited potential, they equally feel we cannot tap it all. The technology required to harness the power is simple, but often it can get so costly that the savings may get wiped out. As such, it needs careful evaluation before installation.

Wind is always in motion due to surface temperature variations, day and nights, oceanic conditions and many such factors, simultaneously producing kinetic energy. This energy can be converted into electricity by letting the wind rotate a fan of blades which rotates a shaft where the shaft is connected to the wheels of a generator. Power thus produced can be connected to a transmission system in case of large-scale generation; or in small-scale operations, stored in a battery for later usage. Considering the fact that wind speed varies, leading to intermittent supply, wind energy for buildings is always coupled with solar and main grid, called hybrid power system. Periodic replacement of batteries creates waste and demands expenses, but the supply to grid option is yet to be finalised for small-scale units.

Components

The major components of the system are tower to support the rotor blades, rotor to turn the turbine, gear box to control speed, charge controller and regulators to divert excess load to dump load and save battery, fuses and resisters to regulate electricity flow, battery to hold power, inverter to convert DC to AC power, brakes to control blade rotation and, finally, outlet sockets. Though this sounds complex, most of these can be fabricated in any small town. In case of small-scale building level units, they are better done locally rather supplied by branded units from far off places, to keep the costs low and quick referrals for maintenance.

Wind power has evoked much interest in India, yet it lies largely untapped. Without energy by wind, the Egyptian ships would not have sailed and civilization evolved; the Romans, Cholas and Vikings would not have had victories overseas and the medieval explorations across the high seas would not have connected the world before phones and planes did. May be, wind power now holds the key to another chapter of the future world.