More than 68% of New European Electricity Capacity Came From Wind and Solar in 2011

[kristopher]

31. What does the term "operational characteristics" mean to you?

In this case it refers to the way the limitations and advantages of a power source cause it to be operated. It is a combination of technical and economic factors that define when a grid operator decides to put energy from the resource onto the grid.

Those factors for coal and nuclear are very similar. Addressing your question specifically, economically coal and nuclear both have large, up front capital costs and both require fuel, therefore both have fuel costs.
In comparison geothermal has a much smaller up front capital cost and no fuel cost at all.

The technological characteristics of these sources are shaped by economics. Coal and nuclear are most profitably built by making individual generators very large. The size of a geothermal generator is limited by the less concentrated nature of underground heat. A geothermal facility is made larger by building multiple smaller units (it is similar to hydro in this respect). What happens as a consequence is that the shafts of the generating turbines for coal and nuclear plants are very large while the shafts for geothermal and hydro plant generators are much smaller.

These "characteristics", in turn, affect how each of the energy sources are best used from the grid operators point of view. Coal and nuclear are designed to run 24/7 at a constant speed. Their large individual size has the consequence of making them poorly suited to ramping up and down quickly, or shutting down and restarting quickly.

That is why natural gas has been exploited for electrical generation. Its smaller size makes it more nimble and able to respond to the variability in demand. Since the variability we see with wind and solar presents itself operationally as the same problem we see with variable demand, the natural gas that is already in place now is sufficient to handle a much higher level of renewable penetration.

The smaller size of natural gas turbines also means that the up front capital costs are far, far lower than that of nuclear and coal, but it has traditionally had far higher fuel costs than coal and nuclear, a fact that limited its economic viability. Fracking has changed that and made NG competitive with coal and nuclear; but even with fracking, there is still a significant fuel cost relative to renewables. If fracking is severely curtailed it will, at this point in time, probably benefit renewables more than it would nuclear or coal.

Due to past high per unit manufacturing costs determined by limited deployment, the zero fuel cost advantage of renewables is only now beginning to be felt. The amount of new generation capacity installed last year is most significant in that it is a leading indicator of future price declines brought about by a growing manufacturing base.

Each resource in the renewable portfolio has its own set of characteristics. As renewable penetration increases, the needs that grid operators are meeting when they select the power source required at the moment is going to be increasingly determined by the zero-fuel cost of renewables instead of the merely low fuel costs of nuclear and coal.

That also applies to natural gas. While there is currently a glut, no one expects that to continue. As the backbone renewable manufacturing continues to ramp up, their zero fuel costs will to some degree displace all sources that have fuel costs. The degree that each specific fuel will be a loser will vary by region.

I hope this helps make the situation more clear. It will take decades but we are in the process of building a distributed grid based on the operational characteristics of renewables. This is why I reject spending money to build or extend the life of nuclear plants. The larger the percentage of renewables on the grid, the more the decision-making of grid operators is guided by the needs of renewables and the more zero-fuel cost renewables are deployed to meet those needs.


A report documenting the way nuclear (or coal if it were supported like nuclear) crowds out renewables can be downloaded here:
http://www.vermontlaw.edu/Documents/IEE/20100909_cooperStudy.pdf