the heating system in your house,

房子裡的暖氣設備、

your gas stove.

你的瓦斯爐、

Most of the energy you use

大多數你使用的能源

comes from fossil fuels,

都來自化石燃料

which present a couple of problems.

這造成了一些問題

First, there are limited supplies of fossil fuels,

第一、化石燃料供應量有限

so the more we use, the less we've got.

我們用得越多、地球存量越少

And second, the use of fossil fuels

第二、燃燒化石燃料

is the main cause of climate change

是造成氣候變遷的主因

because it releases large amounts

因為它釋放出

of carbon dioxide into the atmosphere.

大量二氧化碳到大氣中

Biofuels come from natural, renewable sources like plants,

生質燃料來自大自然，是再生資源

so they have the potential to reduce our reliance

有可能減少我們

on those limited supply fossil fuels

對有限化石燃料的依賴

and reduce the risk of climate change.

並降低氣候變遷的風險

Most biofuels today are made from corn grain

目前生質燃料主要來自玉米

that is fermented into ethanol.

發酵後得到乙醇，也就是酒精

But we have a limited supply of this corn,

但玉米供應量有限

so it's not a solution to the limited supply

並非解決能源供應的好方法

part of the quandary.

這是問題一

It also takes a lot of resources to grow corn grain.

還有，種玉米需要很多其他資源

Strike 2!

兩好球了！

A potential solution:

一個可能方案：

Using cellulose instead of corn grain to make ethanol.

利用纖維素代替玉米製造乙醇

Cellulose is far more abundant than corn grain

纖維素供應量比玉米多很多

and takes less energy to produce.

生產所需能量也較低

In fact, it's the most abundant organic molecule on the planet!

事實上，它是地球最豐富的有機物

Cellulose is the main ingredient

纖維素是構成

found in a plant's cell wall.

植物細胞壁的主要材料

Plants generate cellulose from water and carbon dioxide

植物用水、二氧化碳合成纖維素

during photosynthesis.

這過程叫光合作用

So, where as using fossil fuels produce carbon dioxide,

燃燒化石燃料會產生二氧化碳

using cellulose-based ethanol might help remove

利用纖維素製造乙醇卻有助於

carbon dioxide from the atmosphere.

清除大氣中的二氧化碳

The main obstacle is that the cellulose molecule,

最主要的困難在於

a long, connected chain of glucose sugar

纖維素由長鏈葡萄糖組成

protected by a tough, molecular sheath,

它的官能基，遮蔽了碳骨架

is difficult to break apart.

非常難分解

Creating cellulose-based ethanol

用纖維素製造乙醇

means first unwrapping that protective sheath

必須先突破這層保護

and then chopping up the cellulose

才能將纖維素

into its individual glucose molecule.

分解成個別的葡萄糖分子

Only once we have unpacked each glucose molecule,

分解成葡萄糖分子以後

can we begin fermentation.

才能進行發酵

But some microorganisms,

但有些微生物

like bacteria or fungi,

如細菌或真菌

break down cellulose for energy all the time.

不斷分解纖維素以獲得能量

For example, dairy cows eat foods

如乳牛吃進乾草、

like hay or alfalfa, which are full of cellulose.

苜蓿等富含纖維素的食物

Microbes that live in their stomachs

牠們腸道中的微生物

produce an enzyme called cellulase,

會生產纖維酵素

which breaks apart the cellulose molecules

可分解纖維素分子

so that the cow can use what's left for energy.

牛即可利用分解後的產物 產生能量

Researchers are now studying

研究人員目前

these kinds of microorganisms

正在研究這類微生物

in the hopes of finding better ways

希望能找到更好的方法

to break down cellulose

分解纖維素

so we can use it for our own energy needs.

以解決我們的能源問題

The solution, they think,

他們認為解決問題的關鍵

lies in finding microbes in nature that can produce

在於從自然界找到一種微生物

the kinds of cellulase enzymes that we need.

可生產我們所需的纖維酵素

This process of searching for species in nature

這種由自然界中尋找生物

that can produce valuable products

生產高價值產品的過程

is called bioprospecting.

叫做「生物探勘」

To test whether or not a sample of microbes

為了測定樣本微生物

can break down cellulose effectively,

能否有效分解纖維素

researchers first grow the microbe in a test tube.

研究人員用試管培養微生物

Then, they add a source of cellulose

並加入纖維素

as the sole form of energy.

作為唯一能量來源

If the microbe can't produce cellulase

如果微生物不會製造纖維酵素

and break down cellulose,

就不能分解纖維素

the test tube will remain unchanged.

試管內會維持原狀

But if the microbe produces the enzymes

如果微生物可以製造

we are looking for,

我們想要的酵素

it will be able to break down cellulose,

微生物就可以分解纖維素

use it for energy,

作為能量來源

and thrive in its test tube environment.

並在試管中繁衍成長

If our microbial sample can break down

如果樣本微生物

the cellulose in the test tube,

可在試管中分解纖維素

there is a chance we could use it to create

就表示我們有機會用纖維素

a renewable and sustainable source of fuel

製造再生性、永續性的燃料

for our cars from cellulose.

以供汽車使用