A scientific analysis by Benjamin Sovacool of 123 countries over 25 years published in 2020 concluded that adoption of renewables tends to be associated with significantly lower carbon emissions while larger-scale national nuclear fission energy attachments is not. Tensions between these two national energy development strategies can reduce their effectiveness in terms of climate change mitigation due to factors such as different infrastructure requirements and negative association between the scales of national nuclear and renewables attachments. However, an analysis of the same data by another group of scientists came to a different conclusion: "nuclear power and renewable energy are both associated with lower per capita CO2 emissions with effects of similar magnitude". Societal allocation of resources to nuclear energy production-related efforts may compete with resource allocation for research, development, construction, expansion and improvement of renewables-related technologies and structures such as energy grid systems, energy conservation technology and methods, efficient energy use, energy efficiency, energy storage, load balancing, sustainable design, novel renewables technologies – such as of the hydrogen economy – and smart grids.