Human World’s Population

Human world’s population has grown vigorously in two hundred years and until today, the world population had reached more than seven billions. Besides, the suitable lands that are now used for farming purpose are also degraded at a fast rate. Food crisis might happen if the food we have now is not enough for the world population. So, we should not convert the agriculture land for feedstock biofuel production. Due to this reason, people started to find new land instead of using the cropland and most of them have chosen rainforest, peatland and grassland. When these lands are converted for feedstock plantation, it lost its function as a world climate stabilizer, raw material and medicines source or protecting human from the natural disasters. Besides, the living habitat for many plant and animal would turn into concentrated monocultures. For example, large area of the Amazonian rainforest has converted to plant soybean and also the lowland rainforest of Malaysia was turned into oil palm plantation. The land conversion has caused living species loss their habitat and brought damage to the microorganism ecology (Biofuel.org.uk, 2018). Taking the case happened in Malaysia and Indonesia as an example, some animal species would face extinction crisis, for example Malayan tigers, Sumatran rhinoceros, and Borneo elephant when the forest is converted into palm oil plantation. It also caused the extinction of living species. In South America, Alagoas curassow has become extinct because its living habitat was demolished for sugarcane biofuel production in Brazil. Carbon Debt The land use changes brought by biofuel production have also unintentionally causing carbon debt.

The term carbon debt or can be referred as Greenhouse debt can be defined as the amount of greenhouse gases which are released during the land conversion for the biofuel production (Fargione et al, 2008). According to some research, the land conversion in Southeast Asia, Brazil and United States of America to feedstock plantation produced around 17 to 420 times more carbon dioxide than the yearly greenhouse gases reduction which the biofuel would released by displacing the fossil fuels. Initially, the biofuel acted as a renewable energy, aim to replace fossil fuels and mitigate climate change. But, it turned out that the biofuel production created more greenhouse gases emission. Nowadays, the carbon debt is accumulated until up to more than hundred years is needed to repay the debt. For example, in order to repay the carbon debt created when the Amazonian rainforest is transformed into soybean field for the soybean biodiesel production, it needs about 300 years. While in Malaysia and Indonesia, it has to take about 400 years to repay the carbon debt for the palm oil production. Most of the greenhouse gases are released mainly through the deforestation, the growth of feedstock and the usage of fertilizer. These three factors will be further discussed in the next topic. Greenhouse Gas Emission Greenhouse gases (GHG) are the one percent gases that absorb and release radioactive heat radiation from sunlight. Some examples of greenhouse gases are carbon dioxide, methane and chlorofluorocarbons.

These gases can be emitted though several ways such as deforestation, growth of feedstock and usage of fertilizer. Deforestation Deforestation is defined as the removal of the forest or other trees, causing by exploitation of natural resources for human population development. Figure 1 shows the causes of deforestation. According to a study conducted by United Nations Framework Convention on Climate Change (UNFCCC) secretariat, agriculture sector contributes the most in causing deforestation. Biofuel production can be related to commercial agriculture and fuel wood removal as rainforest, grassland, peatland and savanna are converted to plant feedstock such as corn, canola, potato, sugarcane, soybean, poplar tree and willow tree (UNFCCC, 2007). Figure 1: Causes of Deforestation Trees are the gift from the mother earth as a human protector. It can capture the carbon dioxide through photosynthesis process. The tree itself contained about 50% of carbon and some of it will be emitted through respiration process. But, when there is deforestation activities, tones of carbon dioxide are released through the microorganism metabolizing the dead wood or other organic matters. It is believed that the forest in United State of America can help to offset 20% until 46% of GHG emission as the trees absorb up to three million metric tons of carbon dioxide annually. Taking the land conversion for maize biofuel production in United State of America as an example, 1.8 tons of carbon dioxide is released per hectare annually. According to a study, the deforestation of grassland will produce 300 tons per hectare of carbon dioxide while deforestation of forest will produce two to three times stronger than conversion of grassland. Growth of Feedstock Trees are expected to be an atmosphere cleaner, absorbing the carbon dioxide and reduce the greenhouse gas emission.

At the same time, it can used to replace the fossil fuels. But, trees can actually make the condition even worse. Study shows that Perennial lignocelluloses plants such as poplar, willow and eucalyptus trees will release a kind of dangerous chemical substances called isoprene. These plants are used as a renewable wood fuel. They grown faster than other normal tree and can plant on low quality land. Poplar, willow and eucalyptus trees also required less management and low input of fossil fuel. Due to these reasons, they are widely use nowadays. But, as they grown up, they released great amount of isoprene. The isoprene will react with air pollutants such as carbon dioxide and methane in the sunlight to form ozone. A research is conducted and they estimated that the ozone produced from wood fuel energy in order to achieve European Union’s 2020 goal will cause 1400 premature deaths annually (Smith, 2013). The red spots in Figure 2 clearly show the number of death is likely to increase due the increase in number of tree plantation for biofuel production. Figure 2 : Death due to increase in tree plantation for biofuel production in Europe. Usage of Fertilizer Fertilizer contained three main macronutrients element which are nitrogen, potassium and phosphorus. It is mainly used for providing nutrients to plants and increasing the crop yields. Fertilizer did provide lots of benefits but fertilizer especially nitrogen based fertilizer released more hazardous greenhouse gas called nitrous oxide(N_2 O) which has a Global Warming Potential about 310 times greater than carbon dioxide. It means that one kilogram of nitrous oxide will warm the Earth around 310 times stronger compared to one kilogram of carbon dioxide.

Nitrous oxide can be formed through two microbiological processes which are nitrification and de-nitrification. After nitrates (NO_3) produced by ammonium (〖NH〗_4) during nitrification, the nitrates will then reduce to nitrogen gas(N_2) during de-nitrification process. Nitrous oxide is then produced in the intermediate step of these processes and it will escape to the atmosphere in gas state (Millar et al, 2014). The production of nitrous oxide can be considered as natural phenomena but the usage of fertilizer, is making the nitrous oxide being converted by microorganism at a faster rate. Adding more nitrogen nutrient to the soil stimulated the nitrification and de-nitrification process. Nitrous oxide not only heating up the atmosphere, it can also destroy the stratospheric ozone that protect the Earth from the ultraviolet rays. Figure 3 below shows the nitrogen based fertilizer consumption kept increasing and Asia countries contributed the most. Relate to a research that conducted few years before, it is shown that the nitrous oxide level has increased from 270 ppb to more than 320 ppb since 1750. It rose about 20% and still kept increasing until today. Thus, the increase of nitrous oxide level can be related to the usage of nitrogen fertilizer.