The size of the investment for energy-saving modifications of air compressors depends on several factors, including the type, scale, and usage of the existing air compressors, as well as the energy-saving technologies and solutions chosen. Let's take a look at these factors in general:

Condition of the existing air compressors: If your air compressors are old or have low efficiency, energy-saving modifications may require a larger investment. Newer and more efficient compressors may require less modification cost.

Energy-saving technologies: Different energy-saving technologies come with different costs. Some common energy-saving technologies include replacing compressors with high-efficiency ones, improving the insulation of piping and gas transmission systems, and installing variable frequency drives. The specific technical solution will affect the investment amount.

Expected energy savings: The anticipated reduction in energy consumption after modifications also affects the size of the investment. The more significant the energy savings, the shorter the payback period, and the higher the potential investment.

Energy costs: The level of energy costs also influences whether it is worthwhile to invest in energy-saving modifications. In regions with high energy costs, there may be more incentive for energy-saving investments.

Policy support: Some regions may offer policy support and subsidies for energy-saving modifications, which can help reduce the investment burden.

Overall, the size of the investment for energy-saving modifications of air compressors varies by region. It is best to conduct detailed research and consultation first to understand your specific investment budget and potential energy-saving benefits. Energy-saving modifications are generally a worthwhile investment for long-term energy consumption and operational cost savings.