According to the theory of relativity, as an object with mass approaches the speed of light, its energy and momentum increase significantly. As a result, it becomes increasingly difficult to accelerate the object further. In fact, as an object with mass approaches the speed of light, its energy requirement for additional acceleration becomes infinite.
To provide a specific answer to your question, let's assume we have an object with mass that is already moving at the speed of light. According to the theory of relativity, the energy required to accelerate this object by any amount, even by half again, would be infinite. This is because the object already possesses the maximum energy allowed by its mass at the speed of light, and any further acceleration would require an infinite amount of energy.
It's worth noting that the theory of relativity breaks down when it comes to objects with mass traveling at or faster than the speed of light. Therefore, discussing the energy requirements for accelerating an object beyond the speed of light is not meaningful within the current scientific framework.