surajgoel5 wrote:Is there any way I can make it more efficient?
I can't answer your question because you didn't tell me how you harvested the energy.
surajgoel5 wrote:Is there any circuit necessary for this?
You must have used some circuit to harvest the energy in your experiment, so there would have to be a circuit involved.
Typical DC to DC converters are designed for a constant input voltage source. You don't have a constant input voltage source so the typical DC to DC converter isn't going to work for you.
How did you come up with 800v? I have a hard time believing that your igniniter is only producing 800v. 800v won't jump a 3 to 4 mm gap.
Typical piezo electric igniters are in the 14Kv range for a 3-4mm spark gap. Designing and building circuits to handle 14Kv is challenging and is well beyond what we can help you with remotely. You are going to have to find somebody local to help you through that kind of a project if it gets to the building circuits phase.