**6. Discussion**

Most Polish researchers and politicians agree that the country faces significant challenges related to the energy sector. The challenge is even more challenging because the Polish economy relies on coal as the primary energy source. Nearly everybody agrees that "something has to be done". Most of these people also agree that future technology should help to build a low-carbon economy. The papers related to the subject mainly highlight the possibilities and advantages in using RES as a substitute for coal. Of course, physicists argue that it is possible; but still, researchers do not mention the disadvantages and threads that should be considered in constructing a new energy mix for Poland. As the problem

affects the entire economy, industry and economists should take part in the discussion and estimate the economic efficiency of the proposed solutions from designing to the utilization of the wastes. This should be an idea for further research. For example, the authors strongly recommend using PV systems as ecological distributed energy generation systems because of their flexibility, use, and growing efficiency. Still, it has to be mentioned that millions of solar panels installed in the last two decades will soon be ready to be disabled and recycled. Recycling is also a considerable problem of wind turbine blades, batteries used as energy storage, and nuclear waste. Making the total cost calculation could change the efficiency of the proposed solutions. This is why further research has to be carried out.
