Question: what are two advantages and two disadvantages of hydrogen fuel cells?
Answer: It is readily available. As mentioned earlier, hydrogen is a basic earth element and it's very abundant. ... 
It doesn't produce harmful emissions. ... 
It is environmentally friendly. ... 
It can be used as fuel in rockets. ... 
It is fuel efficient. ... 
It is renewable. ... 
It is expensive. ... 
It is difficult to store.