@Carter I was wondering how long it would take someone to ask! 
39 years does seem like a long time from now but there are so many issues that have to be taken into account:
- The current infrastructure of the electric grid wasn’t really designed for two-way power flows that we will be seeing with distributed energy resources (DERs) like solar, wind, etc. Consistent and steady power flows are an issue with DERs as they are not always “on” but energy storage is getting better to help in that regard. The combination of these is just not ready to be able to replace the entire grid though. It does work pretty well for microgrids though.
- Loads will be drastically different. In a lot of suburban neighborhoods in the US, a single distribution transformer serves about 4-5 houses. If all of those homes now have an electric vehicle (or several) and they plug up to charge at the same time, that transformer will most likely fail as it wasn’t designed for that level of inrush current.
- Software to control the grid today isn’t effective for a lot of DERs being attached to the grid. We have done some studies in our group and once DER penetration hits a certain percentage, that software will no longer work effectively. There are a lot of people working on this though.
- Rules and regulations are messy and take a really long time to change. With all of the DER for green energy, we have to determine how grid infrastructure will be paid for as usage patterns will not be the same as today. Currently, we bill mostly on kWh usage, sometimes kW peaks and sometimes VAR. That may not be the case in the future. Being regulated means we serve everyone, not just the ones that can afford it and our utility commissions hold us to that. Just recently, it took nearly 2 years to get a rate case approved to make sure it was fair for everyone.
Let’s put some of the above into a little bit of context with an example. A portion of what we all pay for our energy bills goes into the maintenance of the electric grid. If the everyone who can afford to go green and get off the grid does that, revenue coming in to maintain the grid goes down. If maintenance can’t be done, the grid as a whole will start experiencing more problems and there will be outages. Who suffers in this scenario? The folks who can’t afford to “go green” yet. This is where this balancing act needs to come into play so it is fair for everyone.
These are just a few the issues that I’m aware of and I’m nowhere near the C-suite! 
We are actively working on what it will take to “go green” but it just takes time to change the infrastructure of the grid that has been built over the years. In the process, we are making sure that everyone can “keep the lights on” as things change for this new energy world we are moving towards.
Hope this helps and makes some sense.