Well the total energy of an object can be written as $$E=(\gamma-1)m_0c^2$$where $\gamma$ is the realativistic factor $$\gamma=\frac{1}{\sqrt{1-\frac{v^2}{c^2}}}$$ $m_0$ is the rest mass and $c$ is the speed of light. From this you can see that $$\lim_{v\to c}\gamma=\infty$$
This means that the energy tends towards infinity as you get faster. Obviously we have no concept of infinite energy - and neither do we have to, as you can't reach the energy required to get to $c$.

Hope this helps :)