Alternative Energy Supply vs. Supplemental Energy Supply

I’m sure you’ve all seen headlines, articles, columns and blog posts about how the United States (or whatever country you live in) needs to move away from traditional fossil-fueled (or whatever energy source your country uses) energy supplies to environmentally friendly renewable, or ‘alternative’ energy supplies; i.e. wind, solar, bio-mass, etc. Let’s capture this all in the term “Green Energy.” The latest buzz from both the Obama administration and the main stream media is about the creation of “green jobs” … but only if we give up our addiction to carbon-based energy sources.

I suspect most of the people advocating this position have absolutely no experience with, nor do they understand, the chaos that is present in large dynamic systems.The US electric system covers almost all areas of the nation and consists of what would be most simply described as three separate but interconnecting grids. According to the US Department of Energy’s web site,

The economic significance of electricity is staggering. It is one of the largest and most capital-intensive sectors of the economy. Total asset value is estimated to exceed $800 billion, with approximately 60% invested in power plants, 30% in distribution facilities, and 10% in transmission facilities.

The above statement captures the economic boundaries of the grid, but it doesn’t begin to address the engineering and physical aspects of one of the largest and most complex systems humans have ever created.

What I would like to convey within this post is that moving the existing grid to this vision of a Green Energy world will not happen within the lifetime of my six year old grandson. There are such huge issues to resolve and such massive costs to completely redesign and rebuild the system from generating plants to distribution systems to meters.

I’ll start by excluding myself as a an expert (recognized or self-professed) of the US, or any other national electric grid. My sole claim to experience in energy and power systems is as a customer of these systems and their prevarications, a consultant for the past 30 years developing and implementing energy efficiency programs for utilities and large commercial and industrial electric and natural gas customers, and not lastly a student of engineered systems.

The primary generation systems on today’s grid are made up of very large generation plants, capable of generating 1,000 megawatts (MW) or more of power. To put this in layman’s terms, a megawatt is 1,000 kilowatts or 1,000,000 watts. In other words, one of these plants can create enough power to light 10,000,000 (ten million!) 100 watt light bulbs (or more than 40,000,000 curly-que/compact fluorescent light bulbs).

The Western Systems Coordinating Council is the grid that servers the Western 11 US states and parts of Western Canada and Northern Mexico. In the WSCC there are more than 80,000 miles of transmission lines at or above 115,000 kilovolts (115 kV), more than 180 generating plants larger than 200 MW, and more than 19,000 substations, and many control areas, just to mention a few statistics. I’ll return to these issues later.

Power is the rate that energy is used (or consumed) and is measured in watts. Electrical energy is a measurement of work and measured in joules, calories or watt-hours. The two are not necessarily related. I can use one million kilowatt hours (kWh) over a period of several years in my home, or I can use the same one million kWh in one day in an arc furnace at my steel mill.

Grids are immensely complex, and controlling such a system is truly art. The one element that makes these power systems (yes, I meant power system and not energy system) so different than any other distribution system is storage. Unlike natural gas, oil, or for that matter tissue paper, there is no reasonable or cost effective way of storing power. It is used at the very moment it is produced!

There are several methods of storage in a power system, but little in relation to to overall size of the system, and as I said, it is generally much more expensive than most any generating technology. Probably the most used storage approach is pumped hydro, which utilizes generators and water storage, releasing water during summer afternoons when demand is high and pumping the water back up the hill at night when demand is at it’s lowest. Regardless … very expensive!

So … power is generated and used at the same instant. This in itself creates significant challenges to introduce Green Energy. Solar produces power only when the sun shines, and I’m not just referring to night and day. Below is a graph of a large photovoltaic array located in the Inland Empire area of Southern California showing hourly production for several days in early May, 2009:

Even in an area that isn’t normally affected by the marine layer so often seen along the coast of Southern California in June (the notorious June gloom), clouds have significant influence on the power output of a PV array. The same thing can be said for wind turbines and their power output if the wind stops blowing … or blows to hard. These issues are among several that eliminate wind and solar as viable alternatives to conventional power generation … supplemental, yes but not an alternate.

Note I said ‘eliminate?’ Sure … you could add these generating sources to a grid, but they would have to be backed up 100% by conventional generation sources to insure continuity and reliability. There are two primary reasons for for the need for 100% backup. These “Green” sources cannot be relied upon to produce power when needed (remember … power is used at the instant it is produced). Additionally, and more difficult to envision, power grids are inherently unstable.

First, as I intimated earlier, the grid is really one machine with many parts. The power flows within each section of the grid depend upon synchronization between the hundreds of generators. The interconnects between the three sections are not capable of carrying as much power as the transmission lines within each section. The graphic below shows most of those connections.

Second, the instability of the grid is challenging to control. For an AC power grid to remain stable, the frequency and phase of all power generation units must remain synchronous within narrow limits. A generator that drops 2 hertz (Hz) below 60 Hz will rapidly build up enough heat in its bearings to destroy itself. So circuit breakers trip a generator out of the system when the frequency varies too much. But much smaller frequency changes can indicate instability in the grid. In the Eastern Interconnect, a 30 mHz drop in frequency reduces the power delivered by 1 gigawatt.

Introducing thousands, or as dreamed by the Enviros’, hundreds of thousands of small, distributed generating plants driven by variable “energy” sources such as wind or solar radiation will make control of the grid more difficult by several magnitudes. Further, even if all this new Green Energy were added to the grid, all of it would have to be backed up by more reliable sources of generation.

This would double the capital costs and some of the backup generation would have to run at the same time the Green Energy was running just to control flows within the grid. This doesn’t even address the requirement for generation running in a standby mode, commonly referred to as spinning reserve, in the event of the loss of a generating unit or an entire plant.

When more power is being generated than is being used, the excess is turned into heat and is wasted. Again recall … power is used at the instant it it produced. If not used on the load side … instant waste heat! This in turn would cause higher system operating costs.

I’ve thought long and hard for an analogy to an electric grid that can make all this more understandable to the layman … and the best I’ve come up with so far is an ocean. Open your mind and think of the Pacific Ocean; it has currents, swells, waves, temperature variations, and other phenomenon that create and drive its parts. Likewise, an energy grid has generation systems, transmission systems, distribution systems and finally, the load, or if you prefer, the air conditioners, refrigerators and other electric appliances in your home.

A large underwater earthquake that causes the sea floor to shift, or a massive underwater landslide will cause a column of water to suddenly rise which in turn produces a tsunami or tidle wave, as occurred off the coast of Indonesia on December 26, 2007. Humans can do nothing to stop the resulting force; only move to higher ground until the sea settles.

Likewise in the grid, something seemingly so small as a transmission line sagging as it heats and then touching, or grounding, against a tree can cause much of the grid generation to disconnect (move to higher ground) to protect itself, thereby shutting down large pieces of the grid … as happened in Ohio on August 14, 2003, resulting in a blackout that affected over 55 million people in the US and Canada for hours.  That cascade is similar to the power outage that occurred in 1965 as a result of a failed relay at a power station in New York, darkening the Northeast for 12 or more hours (and purportedly causing a spike in the birthrate nine months later).

What does all this have to do with Green Power? Our current grid is not sophisticated enough to be able to control the immense vagrancies imposed by massive numbers of generating sources distributed across the grid and therefore outside the control of the artists responsible for making this immense machine work. One of the current buzz-phrases is “smart grid” (of which I’ll discuss in another post). The cost to make the grid “smart” will be ginormas all by itself … over and above the cost of all the Green Energy!

… and that doesn’t include the need for Obama to declare the second and third laws of thermodynamics unconstitutional!

Related posts:

1. When the wind blows, the cradle will fall
2. A Better Mouse Trap?
3. Radicals Kidnap EPA, Declare Ransom Demands
4. California Heading for a ‘Green’ Train Wreck