constraint (n)
/kənˈstreɪnt/

something that limits the range of a person’s actions or freedom

contamination (n)
 /kənˈtæm.ɪ.neɪt.ʃən/

the process of making something dirty, polluted, or poisonous by adding achemical, waste, or infection

deplete (v)
/dɪˈplit/

to reduce something in size or amount, especially supplies of energy, money, etc.

dispose of (phrasal verb)
/dɪˈspoʊz əv/

to get rid of something; throw out or destroy

elementally (r)
/ˌel·əˈmen·təl.li/

fundamentally or essentially

emission (n)
/iˈmɪʃ·ən/

gas, etc. that is sent out into the air

extinction (n)
/ɪkˈstɪŋkʃn/

a situation in which a plant, an animal, a way of life, etc. stops existing

reservoir (n)
/ˈrez·ərˌvwɑr/

a large amount of something that is available to be used

shrink (v)
/ʃrɪŋk/

to become smaller or cause something to become smaller

stable (a)
/ˈsteɪ·bəl/

firmly fixed or not likely to move or change

consumption (n)
/kənˈsʌmp·ʃən/

the use of something such as fuel or energy, or the amount that people use

crude oil (n)
/krud ˈɔɪl/

oil from underground that has not yet been made into other products

reserve (n)
/rɪˈzɜrv/

something kept for a particular purpose or time, or the state of being kept for future use by someone

underground (a)
/ˌʌn·dərˈɡrɑʊnd/

below the surface of the earth; below ground

biodiesel (n)
/ˈbaɪ.oʊˌdiː.zəl/

fuel made from vegetable oils or animal fat

modification (n)
/ˌmɑː.dɪ.fɪˈkeɪ.ʃən/ 

the process of changing something slightly

engine (n)
/ˈɛndʒən/

a machine with moving parts that uses a fuel to produce movement

blend (n)
/blend/

a mixture of different types of the same thing

witness (v)
/ˈwɪt·nəs/

to see something happen

petroleum (n)
/pəˈtroʊ.li.əm/

oil that is found under the ground or the ocean and is used to produce gasoline, paraffin, diesel oil, etc.