Whether it is solar power, wind farms, dams, or biofuel crops, renewable energy tends to be land-intensive. Indeed, that is one of the major reasons for which improving efficiency in sectors like buildings and vehicles is some important. Improving their efficiency can allow us to reduce our fossil fuel use, both out of concern for climate change and in response to their inevitable depletion, while engaging in the decades-long project of deploying the kind of renewable infrastructure we are going to need to power human civilization in the future. If we want to have an acceptable balance between areas used for energy generation, those used for all other human purposes, and those where nature is meant to be dominant, we will need to improve the efficiency of both our energy production and our energy use.
There are many trade-offs to be considered. For instance, the best sites for wind farms and solar facilities are often far away from centres of energy demand. That establishes a trade-off between producing power at the best sites and managing losses across long distances. While there is a lot of excitement about highly distributed forms of electrical generation, it may well prove to be the case that the most economically and ecologically sound approach is based on big renewable facilities linked to cities through efficient transmission systems, such as high voltage direct current (HVDC) lines.
There are also ecosystem trade-offs: dams block rivers, biofuel plantations are generally sterile monocultures that can lead to deforestation, and solar facilities crowd the dessert. That being said, fossil fuel extraction certainly causes harm to ecosystems, a well. There is direct harm from both deliberate actions (open pit oil sands extraction, coal mining, etc), near-term indirect harm from accidents like oil and coal ash spills, and the potentially massive long-term harm associated with climate change. Indeed, that final issue alone may be a strong justification for converting large amounts of land towards renewable energy generation; in that way, ecosystem harm can be made to occur in a planned way within large but controlled spaces, rather than globally and chaotically as the consequence of temperature increases, precipitation changes, and ocean acidfication.