Minnesota’s Solar Pathway

By Paul Homewood

 

 

A reader sent me this recent study, claiming to show how a high level of wind and solar generation could be integrated into Minnesota's grid.

 

http://mnsolarpathways.org/spa/#finding1 

Its main finding was that solar and wind could supply 70% of Minnesota's electricity by 2050, and at a cost comparable to natural gas:

 

 

I was expecting some technically sophisticated solutions, but there is actually very little new in it.

Having said that though, the authors have developed a clever toolkit for analysing hourly generation and demand patterns, to test out various scenarios.

But to put the above numbers into perspective, we need to look at Minnesota's current demand load:

Below is Figure 8 from the report. Ignore the red line for the moment, it is the black line which denotes demand:

 

What we see is that for most of the year, demand hovers around 10 GW, except for summer, presumably when air con kicks in. Even in summer, it only occasionally gets anywhere near 15 GW.

This raises an interesting question right away – what do Minnesotans do for heating in winter? I presume most must use gas or oil. If Minnesota wants to do away with fossil fuels, how will they replace these from the electrical grid, particularly when solar generation peaks in summer?

Now let's look again at that earlier chart:

 

 

Relying on so much wind and solar only works by retaining enough standby capacity from reliable sources to cover virtually all of the demand profile.

The summer time peaks can be catered for, because of the higher solar generation then. Night time demand in summer is partly met battery storage.

There is however another aspect to note. To get to the 70% solar/wind target, the plan calls for massive overengineering of solar and wind capacity, so that even on calm, winter days there is still a reasonable amount of generation. The plan calls this "Additional Capacity"

This however causes a fresh set of problems. For much of the time, solar and wind generation will be much more than total demand. So what do you do with the surplus?

The answer is to throw it away, or as the plan calls it "curtail".

Of course, if you don't use all of the generation from wind and solar, the unit cost of what you do use rises considerably. Optimistically, the plan says this is still economical, because wind and solar will be so cheap by then.

I remember hearing similarly optimistic claims about nuclear power in the 1950s!

In fact, the plan assumes massive cost reductions from current costs, down to a level of $20/MWh. And it is on these cost assumptions that they claim solar and wind can match the cost of new gas generation. Without such reductions, the whole plan falls apart.

Whether such reductions are feasible in the long run, I have no idea. But the whole question is immaterial anyway.

If the costs come down sufficiently by 2050, the market will take over. Generators will quickly react by building solar and wind farms, if it is economic for them to do so.

What you most definitely don't do is start working towards a new power mix on the basis that costs might fall in the future.

In summary then, Minnesota can only run on a high level of wind and solar power if it retains on standby enough dispatchable power to supply demand at all but peak periods.

And it can only run the system economically as long as the cost of wind and solar power falls drastically from current levels.

from Climate Change Skeptic Blogs via hj on Inoreader http://bit.ly/2SVmPZ3