Mendinginkan Ruang dengan Memanaskan Bumi?

Terletak di daerah tropis menjadikan Indonesia adalah tempat yang cukup hangat (dan nyaman sebenarnya). Kondisi iklim membuat sebagian orang merasa tidak nyaman (gerah) karena temperatur rata-rata memang lebih tinggi dibanding negara lain.

Mengatasi kondisi alam yang "tidak sesuai", orang banyak menggunakan pengatur suru ruangan (Air Conditioner) untuk membuat ruangan menjadi lebih nyaman. Memang sekilas ini adalah cara yang paling mudah untuk kenyamanan. Tapi sadarkah kita bahwa dengan menggunakan AC untuk mendinginkan ruangan, kita telah berperan dalam memanaskan bumi. AC memerlukan fluida yang dapat menguap pada suhu rendah, kebanyakan masih berupa CFC (sering disebut freon). Freon adalah zat penghancur lapisan ozon (lapisan pelindung bumi yang terbuat dari tiga atom oksigen yang saling berikatan lemah) yang paling efektif. Freon menjadi katalis dalam proses penguraian ozon menjadi oksigen, akibatnya, lapisan ozon akan terkikis dan energi matahari akan dapat dengan mudah sampai di bumi, dan yang terjadi berikutnya adalah naiknya temperatur rata-rata bumi (pemanasan global).

Selain berbahaya karena freonnya, penggunaan AC yang berlebihan juga menyedot banyak energi listrik. Listrik sendiri kebanyakan dibangkitkan dari proses pembakaran batu bara, minyak, ataupun gas, yang tentu saja menghasilkan CO2 yang juga berperan dalam pembentukan efek rumah kaca.

Dari segi kesehatan sendiri, sebenarnya penggunaan AC juga tidak dianjurkan karena udara yang ada di ruangan hanya disirkulasi saja. Memang teknologi yang ada sekarang dapat menghilangkan kotoran, debu, bakteri, bahkan virus yang ada diudara, tetapi udara yang kita hirup dan disirkulasi terus-menerus tentu saja kadar CO2 nya akan meningkat. Tingginya kadar CO2 dapat mempengaruhi kondisi kesehatan.

Menyiasati kondisi iklim tropis dapat dilakukan dengan menanam vegetasi yang cukup di sekitar tempat tinggal dan rancangan bangunan yang sesuai dengan iklim tropik. Bukan dengan memasang AC kapasitas besar yang selain tidak sehat juga merusak lingkungan. Mendinginkan ruang dengan memanaskan bumi?

• Hindari penggunaan AC yang berlebihan. Hindari menggunakan AC hingga temperatur rendah, tetapi jaket/selimut tetap dipakai
• Gunakan pakaian yang menyerap keringat dan nyaman, pakaian yang gerah akan memaksa kita menekan tombol AC lebih sering
• Gunakan vegetasi disekitar rumah/kantor untuk mengatur temperatur ruangan, sekaligus menyediakan udara segar yang cukup
• Desain rumah/kantor sesuai dengan kondisi iklim tropis. Gunakan atap yang cenderung tinggi dan ventilasi/sirkulasi udara yang bagus untuk membuat suasana menjadi lebih segar.
  

Bioethanol, an Introduction

Bioethanol is alternative fuel to gasoline that made from renewable resources. There is three kind of resource: sugar base (sugar cane, molasses, sugar bit, etc), starch base (corn, cassava, sago, etc), and cellulose base (wood, rice musk, grass, etc).

Sugar base bioethanol is the most simple process. Sugar source can directly fermented by yeast to produce ethanol. Brazil produce ethanol from molasses, side product from sugar cane processing. Brazilian have perfect geographical condition to expand their cane farm. Cane should be farmed at sun rich land, mostly country at earth equator suitable for cane farm.

Difference with Brazil, US produce ethanol from starch base. US climate is not suitable for cane farm. They produce ethanol mostly from corn. There is two step corn to ethanol, liquefaction and fermentation. Liquefaction aimed to convert starch to sugar, and the next step (after liquefaction) is mostly same with sugar base ethanol.

Cellulose base bioethanol is the most complex and difficult technology since there is quite hard to crack cellulose into more simple molecule like carbohydrate or starch. Some scientist study to find more simple way to reduce molecular length by acidification. Cellulose treated with strong acid to produce simpler starch molecule, this process also produce some by product like carbon, carbon dioxide, volatile matter, etc. Simpler starch molecule then seeded to liquefaction and fermentation process to produce ethanol. Even though it is the most difficult, but cellulose base ethanol can be one of solution to produce cheap environment friendly fuel since its can convert cellulose from wood waste, farm waste, etc to ethanol.

Indonesia have much source for ethanol. Indonesia have tropical climate that suitable for cane farm, Indonesia climate also suitable produce starch or cellulose. The only problem is its productivity. Cane should have around 12% yield to sugar cane, but in Indonesia it is only 6-7%.

Other problem to develop renewable energy in developing country is competition with food. Producing ethanol from starch will disturb food supply and demand. The effect is starch for food price is increasing because starch demand increasing. This effect can be shown at crude palm oil case. Before hegemony of renewable energy, crude palm oil price is only 200-300 USD per tons, but now CPO price can reach up to 900 USD per tons. This problems can be solved with government regulation in market quota.

Bioethanol from cassava

Cassava root is one of source for starch. Cassava plant can growth well, even without any maintenance and fertilizer, at tropical climate, like in Indonesia. Cassava plantation can be found in Lampung, around 200 km from Jakarta.

Cassava can be converted to ethanol by fermentation. Cassava starch slurry must be treated with enzymatic process to convert most of starch to fermentable sugar. This process called liquefying. In this process, cassava slurry is heated to remove any microbial contaminant, then add liquefying enzyme to convert starch to sugar. Starch will be very viscous at high temperature, called gelatination, so viscosity reduction enzyme is needed.

Converted starch then can be easily to fermented to produce ethanol. Fermented sugar (ethanol) can be purified in distillation and dehydration process to produce fuel grade ethanol.

Ethanol have similar characteristic compared with gasoline, and even better. Ethanol have octane number (performance parameter of gasoline) higher than 100 while gasoline only around 88. This properties is very important to engine performance. Ethanol can also mixed with gasoline to improve its quality without addition of lead anymore. As we know that lead is very dangerous pollutant in fuel. Lead can decrease children intelligent.

Ethanol fuel also very clean to burn and have renewable resource. CO2 from combustion of ethanol process came from CO2 in the atmosphere that converted into starch by cassava or other starch source plant, so burning bioethanol will not affected to CO2 balance in the atmosphere. That why bioethanol is called environment friendly fuel.