Penurunan Level Permukaan Tanah di Jakarta

Permukaan tanah di beberapa daerah di Jakarta mengalami penurunan setiap tahunnya. Ahli Tehnik Tanah, Chaidir Anwar Makarim, menyatakan penurunan tersebut karena tanah Jakarta yang sebagian besar berupa lapisan lunak yang terbentuk atas lempung dan lanau.

"Bukan hanya karena pengambilan air tanah apalagi oleh bobot gedung," katanya kepada Tempo di kantornya, Jakarta. Dia mencontohkan jalan di Bandara Soekarno-Hatta yang mengalami penurunan 1,2 hingga 1,5 meter sejak dibuat tahun 1983. "Dilewati mobil saja sudah turun sedalam itu, bagaimana jika dibangun gedung," katanya.

Tanah Lunak ini tersebut tersebar di Jakarta Utara, Jakarta Barat, dan sebagian Jakarta Pusat. Daerah Jakarta Utara antara lain meliputi daerah Sunter, Ancol, Kelapa Gading, Pluit, Cilincing, dan Kapuk.

Tanah lunak di Jakarta Barat meliputi Kecamatan Taman Sari, Tambora, Grogol, Jalan Daan Mogot, dan lain-lain. Sementara kawasan Jakarta Pusat diantaranya terdapat di Jalan Gatot Subroto, Sawah Besar, sebagian Bundaran HI, Sarinah, serta Cideng Barat dan Timur. "Tanah di Jakarta Selatan dan Timur relatif bagus," katanya .

Menurut Chaidir, tanah lunak terbentuk dari bekas rawa, bekas aliran sungai atau berbatasan dengan bekas aliran sungai, serta timbunan sampah organik yang lama kelamaan membentuk lapisan tanah.

Jika dibiarkan, tanah di atas lapisan lunak tersebut akan mengalami penurunan jangka panjang dengan kecepatan bervariasi. "Sekitar empat hingga sepuluh sentimeter per tahun," katanya menjelaskan.

Efek bagi membangun di atas lapisan lunak adalah bangiunan terancam turun yang lama kelamaan akan menimbulkan keretakan pada tembok dan akhirnya merobohkan bangunan.

Untuk mengantisipasi, Chaidir menjelaskan, tanah lunak tersebut harus dipadatkan. "Jika lapisan lunaknya kurang dari tiga meter, sebaiknya tanahnya diganti," katnya. Untuk gedung tinggi, mutlak harus menggunakan tiang fondasi yang mencapai lapisan tanah keras.

Pemukiman di daerah Pluit,yang berdiri di atas tanah lunak, sebagian besar dibangun dengan pondasi cerucuk. Tiang pancangnya cukup panjang tapi tidak mencapai lapisan tanah keras. Akibatnya, menurut Chaidir, bangunan akan tetap tidak stabil.

Bagi bangunan yang sudah terlanjur berdiri di atas tanah lunak, beban pondasi harus dialihkan ke lapisan tanah keras dengan tehnik under pinning. "Kendala antisipasi dan solusi cuma satu, biaya," kata Chaidir.


Penurunan permukaan tanah tersebut disebabkan oleh adanya penyedotan air dalam skala besar. Untuk mengantisipasi semua ini pemprov jakarta akan memberikan pasokan air yang cukup banyak agar tidak terjadi penurunan permukaan tanah di DKI Jakarta yang merupakan menjadi salah satu sebab terjadinya banjir.

Compost, a solution to soil quality decline

Compost  is composed of organic materials derived from plant and animal matter that has been decomposed largely through aerobic decomposition. The process of composting is simple and practiced by individuals in their homes, farmers on their land, and industrially by cities and factories.

Compost can be rich in nutrients. It is used in gardens, landscaping, horticulture, and agriculture. The compost itself is beneficial for the land in many ways, including as a soil conditioner, a fertilizer, addition of vital humus or humic acids, and as a natural pesticide for soil. In ecosystems, compost is useful for erosion control, land and stream reclamation, wetland construction, and as landfill cover



How to make compost based on observation and research:

1.      Seperate the trash between the organic and the inorganic

Organic trash: leaves, plants, dry leaves.

Inorganic trash: plastics, products incapable of decomposing.

2.      After seperated, add the organic trash some fertilizer.

3.      Apply  formula F4(microbe destroyer formula)to the mixed organic-fertilizer trash.

4.      After 1 week, turn and churn the mixture. Do this for 1-2 months, every week.

5.      After 1-2 months, the organic compound will be destroyed completely, becoming black, soft, and humid soil-       like matter mixed with rocks and other biomasses.

6.      The soil-trash fertilizer is then filtered by a round hand-powered filter.

7.      The filtered soil-trash after filtered is compost that is ready to be used almost by all kinds of plants.

Solar Cell : renewable Energy

A solar cell is a solid state device that converts the energy of sunlight directly into electricity by the photovoltaic effect. Assemblies of cells are used to make solar modules, also known as solar panels. The energy generated from these solar modules, referred to as solar power, is an example of solar energy.

Photovoltaics is the field of technology and research related to the practical application of photovoltaic cells in producing electricity from light, though it is often used specifically to refer to the generation of electricity from sunlight.

Cells are described as photovoltaic cells when the light source is not necesssarily sunlight. These are used for detecting light or other electromagnetic radiation near the visible range, for example infrared detectors), or measurement of light intensity.

Solar cells are long lasting sources of energy which can be used almost anywhere. They are particularly useful where there is no national grid and also where there are no people such as remote site water pumping or in space.


Solar cells provide cost effective solutions to energy problems in places where there is no mains electricity. Solar cells are also totally silent and non-polluting. As they have no moving parts they require little maintenance and have a long lifetime. Compared to other renewable sources they also possess many advantages; wind and water power rely on turbines which are noisy, expensive and liable to breaking down.

Rooftop power is a good way of supplying energy to a growing community. More cells can be added to homes and businesses as the community grows so that energy generation is in line with demand. Many large scale systems currently end up over generating to ensure that everyone has enough. Solar cells can also be installed in a distributed fashion, i.e. they don't need large scale installations. Solar cells can easily be installed on roofs which means no new space is needed and each user can quietly generate their own energy.

source: wikipedia, http://www.chm.bris.ac.uk/webprojects2003/ledlie/advantages_of_solar_energy.htm

Geothermal Energy

Geothermal energy (from the Greek roots geo, meaning earth, and thermos, meaning heat) is thermal energy stored in the Earth. Thermal energy is energy that determines the temperature of matter. Earth's geothermal energy originates from the original formation of the planet, from radioactive decay of minerals, from volcanic activity, and from solar energy absorbed at the surface. The geothermal gradient, which is the difference in temperature between the core of the planet and its surface, drives a continuous conduction of thermal energy in the form of heat from the core to the surface.

From hot springs, geothermal energy has been used for bathing since Paleolithic times and for space heating since ancient Roman times, but it is now better known for electricity generation. Worldwide, about 10,715 megawatts (MW) of geothermal power is online in 24 countries. An additional 28 gigawatts of direct geothermal heating capacity is installed for district heating, space heating, spas, industrial processes, desalination and agricultural applications.

Geothermal power is cost effective, reliable, sustainable, and environmentally friendly, but has historically been limited to areas near tectonic plate boundaries. Recent technological advances have dramatically expanded the range and size of viable resources, especially for applications such as home heating, opening a potential for widespread exploitation. Geothermal wells release greenhouse gases trapped deep within the earth, but these emissions are much lower per energy unit than those of fossil fuels. As a result, geothermal power has the potential to help mitigate global warming if widely deployed in place of fossil fuels.

The Earth's geothermal resources are theoretically more than adequate to supply humanity's energy needs, but only a very small fraction may be profitably exploited. Drilling and exploration for deep resources is very expensive. Forecasts for the future of geothermal power depend on assumptions about technology, energy prices, subsidies, and interest rates. Geothermal power requires no fuel (except for pumps), and is therefore immune to fuel cost fluctuations, but capital costs are significant. Drilling accounts for over half the costs, and exploration of deep resources entails significant risks. A typical well doublet (extraction and injection wells) in Nevada can support 4.5 megawatts (MW) and costs about $10 million to drill, with a 20% failure rate.

In total, electrical plant construction and well drilling cost about 2-5 million € per MW of electrical capacity, while the break–even price is 0.04-0.10 € per kW·h. Enhanced geothermal systems tend to be on the high side of these ranges, with capital costs above $4 million per MW and break–even above $0.054 per kW·h in 2007. Direct heating applications can use much shallower wells with lower temperatures, so smaller systems with lower costs and risks are feasible. Residential geothermal heat pumps with a capacity of 10 kilowatt (kW) are routinely installed for around $1–3,000 per kilowatt. District heating systems may benefit from economies of scale if demand is geographically dense, as in cities, but otherwise piping installation dominates capital costs. The capital cost of one such district heating system in Bavaria was estimated at somewhat over 1 million € per MW.Direct systems of any size are much simpler than electric generators and have lower maintenance costs per kW·h, but they must consume electricity to run pumps and compressors. Some governments subsidize geothermal projects.

Geothermal power is highly scalable: from a rural village to an entire city.
Chevron Corporation is the world's largest private geothermal electricity producer. The most developed geothermal field is the Geysers in California

source:wikipedia

Wind Power - Wind Turbines

Wind power is derived from the conversion of the energy contained in wind into electricity. A wind turbine is similar to its forerunner the windmill. However, windmills are typically used to directly power a piece of machinery for example: a pump or a grinder for grain; wind turbines are dedicated to the production of electric power for use off-site.
Wind turbines, like windmills, are mounted on a tower to capture the most energy. At 100 feet (30 meters) or more aboveground, they can take advantage of the faster and less turbulent wind. Turbines catch the wind's energy with their propeller-like blades. Usually, two or three blades are mounted on a shaft to form a rotor.
A blade acts much like an airplane wing. When the wind blows, a pocket of low-pressure air forms on the downwind side of the blade. The low-pressure air pocket then pulls the blade toward it, causing the rotor to turn. This is called lift. The force of the lift is actually much stronger than the wind's force against the front side of the blade, which is called drag. The combination of lift and drag causes the rotor to spin like a propeller, and the turning shaft spins a generator to make electricity.
Wind turbines can be used as stand-alone applications, or they can be connected to a utility power grid or even combined with a photovoltaic (solar cell) system. For utility-scale sources of wind energy, a large number of wind turbines are usually built close together to form a wind plant.

source:Mary Bellis, About.com Guide

Hydrogen Fuel Cells

In 1839, the first fuel cell was conceived by Sir William Robert Grove, a Welsh judge, inventor and physicist. He mixed hydrogen and oxygen in the presence of an electrolyte, and produced electricity and water. The invention, which later became known as a fuel cell, didn't produce enough electricity to be useful.   In 1889, the term “fuel cell” was first coined by Ludwig Mond and Charles Langer, who attempted to build a working fuel cell using air and industrial coal gas. Another source states that it was William White Jaques who first coined the term "fuel cell." Jaques was also the first researcher to use phosphoric acid in the electrolyte bath.
In the 1920s, fuel cell research in Germany paved the way to the development of the carbonate cycle and solid oxide fuel cells of today.
  In 1932, engineer Francis T Bacon began his vital research into fuels cells. Early cell designers used porous platinum electrodes and sulfuric acid as the electrolyte bath. Using platinum was expansive and using sulfuric acid was corrosive. Bacon improved on the expensive platinum catalysts with a hydrogen and oxygen cell using a less corrosive alkaline electrolyte and inexpensive nickel electrodes.
  It took Bacon until 1959 to perfect his design, when he demonstrated a five-kilowatt fuel cell that could power a welding machine. Francis T. Bacon, a direct descendent of the other well known Francis Bacon, named his famous fuel cell design the "Bacon Cell."
  In October of 1959, Harry Karl Ihrig, an engineer for the Allis - Chalmers Manufacturing Company, demonstrated a 20-horsepower tractor that was the first vehicle ever powered by a fuel cell.
During the early 1960s, General Electric produced the fuel-cell-based electrical power system for NASA's Gemini and Apollo space capsules. General Electric used the principles found in the "Bacon Cell" as the basis of its design. Today, the Space Shuttle's electricity is provided by fuel cells, and the same fuel cells provide drinking water for the crew.
  NASA decided that using nuclear reactors was too high a risk, and using batteries or solar power was too bulky to use in space vehicles. NASA has funded more than 200 research contracts exploring fuel-cell technology, bringing the technology to a level now viable for the private sector.
  The first bus powered by a fuel cell was completed in 1993, and several fuel-cell cars are now being built in Europe and in the United States. Daimler Benz and Toyota launched prototype fuel-cell powered cars in 1997.
The fuel cell is a very potential cheap energy source to power homes, transportation, and others. We should start looking to the alternative energy to revive the planet. The Fuel Cell is one example of the many alterative energy sources which exist in this world.

source: H-Powers, Fuel Cell 2000, The Hydrogen Fuel Letter

AirPod - Car Runs On Air

In the past hour, worldwide consumption of petroleum exceeded 100 million gallons. In the United States, there are 200,000 miles of pipeline, 170,000 gas stations and 243 million vehicles using petroleum fuels.
Guy Nègre, a former aeronautics and formula one engineer is hoping to change all that. He has invented a compressed air technology for cars.
Nègre is the founder and CEO of Motor Development International (MDI SA) based in Luxembourg, with research and development facilities in Nice, France.
The AirPod is a small four-wheel mini-car that uses compressed air to move pistons in a 5.45 hp internal combustion engine.
It has a range of 60 miles on a single tank of air and uses a small motor to compress outside air to keep the tank full.
The compressor can operate on gasoline, diesel, biodiesel, ethanol or vegetable oil, but can also be plugged into an electrical outlet for recharging. With regular gasoline fueling the compressor, the Airpod averages an amazing 106 mpg with a range of 800 miles.
With the demand for inexpensive, user friendly, ultra high mileage vehicles that have zero emissions related to global warming - the Airpod is getting a lot of attention.
Air France and KLM airlines are using AirPods to transport passengers between arrival and departure gates at airports in Paris and Amsterdam.
Automaker, Tata Motors has purchased the manufacturing rights for India. Zero Pollution Motors has purchased the rights for the U.S. market and beginning in 2011 expect to manufacture 8,000 vehicles a year in the United States.
Licensing arrangements for other countries are currently in progress.

Source: mdi.lu/english