Hi as part of my mechanical engineering design course,

We have been asked to design an electric tractor that is powered by Wind energy.

The details are as follows:
The tractor will be used on a small scale forestry and pasture farm.
We have a budget of €25,000
We have decided to design a tractor with 35hp ~ 25kwh
To be able to pull a load of 2,000kg

We are modelling the tractor similar to this one

What we need help on is battery choice, size, cost and amount as we are struggling to find solid information dealing with this.
Is there any way you can help?

A NiMh battery seems to be the best value at the moment.