Monday, February 23, 2009

The Electric Grid. Answering question #2: What determines the capacity of power plants and #3: Why not a DC grid?

Again this week I would like to thank everyone for responding to my Electric Grid Questions. This week I will address the other two questions:

2- What determines the capacity needs of the power plant? Is it the installed capacity in the network (each appliance and circuit in each house, office and factory) or is it the historic average consumption of electricity?

3- Why can’t we have a direct current (DC) grid? Many alternative energy technologies struggle with the conversion from DC to AC (alternative current). Why do we need to use AC everywhere?

First of all, about the capacity. This question was difficult to formulate and it was also misunderstood on several responses. The reason for this question is to find out if there is something that can be done regarding Watts and Amperes of new appliances and alternative power sources to minimize the required capacity of new power generation.

At the end of the day my understanding is that even with the most efficient appliances in the grid, power generation and distribution is still a statistical game, and this is EXACTLY where the so called "smart" grid will contribute to energy savings. Power plants generate at constant preset levels and additional capacity is turned on or off based on "peak demand"

Regarding DC vs AC I gather that the big problem of DC is the inefficiency of transporting this current from the source to the user. But, I definitely see an opportunity in generating locally DC power and using it in DC appliances without wasting electricity in DC to AC conversion.

The other problem of the DC power is that many appliances relay on the frequency of the AC electricity to work properly. Many people also mentioned the fact that DC components are much more expensive than AC components. I believe the answer to both this issues relies on the fact that AC has been mainstream while DC has been kept in the dark. If we inject new force in the DC solution then we will find that the market will generate new ideas and better pricing for DC applications.

Some of the answers received:

"2. The capacity needs of the power plant should be based on total load installed [maximum consumption] + some allowance for VAR correction + anticipated or estimated future augmentation [load additions]
3. DC generation & distribution equipments are far more expensive than the AC equipments like generator, transformers, safety devices etc. Its comparatively cheaper to convert it at user end [the converter modules with the chord would not be more than $30 each"

"Dumb Grid allows double digit percentages of electricity to escape and a new Smart Grid would not.
The U.S. will need to install a new Smart Grid system if there is any chance of going to electric cars.
AC vs DC: AC technology is much more flexible and has a strong economic advantage as DC requires very thick copper."

"...why is there no DC? First, there are increasing uses of DC power in parts of the grid that consumers don't see. DC power can be used now for relatively long distance power transmission. But to switch the entire grid and each and every device that uses electricity from AC to DC would clearly be impossible. There may be room for DC in some applications; but not on a widespread basis."

"#2 - I think plant size is governed by politics, dollars available and demand.
#3 DC does not travel well. over distances the voltage drops. not true with ac. ac losses are in current - not volts."

"We could have a DC grid, and yes it would be much more efficient, but it is highly unlikely to happen in our lifetime because no one will accept going without power long enough to switch the system around and highly unlikely investors or the government would pay to do it."

"2) Make the consumer more mindful of their power usage by forcing them to look at the data in the power distribution console/display or connected smart appliances designed to take advantage of data communications technologies built into both appliances, devices and the smart meter interface"

"2)There are additional needs to consider, including extra reserve capacity, based on rules from NERC/FERC. No one wants to experience a blackout or brownout, so the generators/systems/transmission lines all have extra capacity designed in

3)There are several examples of HVDC in North America. When it is most economically feasible, HVDC is used"

"2.There are no ideal figures for per capita electricity consumption as the same can be open ended.At the household level,one could consume as much electricity as one wants depending on availability.At the industry level,one could keep setting up newer manufacturing units once again depending upon availability of electricity.The best way is to link it to nominal and per capita GDP growth rate which the government plans to achieve.Growth in electricity generation must lead GDP growth by a factor of about 1.4 to 1.5.
3.This goes back to epic debate of AC vc DC between Nikola Tesla and Edison.AC won over DC and hence AC grids were set up.A DC grid needs inversion equipment which adds to the cost. However there is a realization that DC is more economical with lesser losses than AC over distances longer than 800 kms.There are now quite a few HVDC grids being set up."

"I believe that as alternative energy evolves, as more and more end users are using solar power, as LED lighting becomes the norm, that AC will eventually become extinct. The "grid" concept will be redundant"

"Transmission losses are the big dirty secret of centralized power."

Until next week... SHALOM!

Thursday, February 12, 2009

The Electric Grid. Answering question #1: Centralized vs Distributed power

First of all I would like to thank everyone for responding to my Electric Grid Questions and throwing light into this subject which I find fascinating. Here is the compiled version of the answers I received for the first of the three questions plus some research of my own (the other two questions I hope to address in the upcoming weeks):

1- What is the best strategy for the future of power? Is it to generate electricity in each home, or neighborhood, or community; or to maintain the current system where a series of big power plants inject their product into a complex network that distributes the electricity to large geographic areas?

To help me answer this question I turned to Amory B. Lovins' newest article "Does a Big Economy Need Big Power Plants?" (it turns out we both wrote about this particular subject at the same time, therefore proving that great minds think alike!)
Amory is 100% for distributed power: “Central thermal stations have become like Victorian steam locomotives: magnificent technological achievements that served us well until something better came along.”

Some interesting facts mentioned in Amory's article: "The U.S. lags with only about 6 percent micropower: its special rules favor incumbents and gigantism. Yet micropower provides from one-sixth to more than half of all electricity in a dozen other industrial countries. Micropower in 2006 (the last full data available) delivered a sixth of the world’s total electricity (more than nuclear power) and a third of the world’s new electricity. Micropower plus “negawatts” — electricity saved by more efficient or timely use — now provide upwards of half the world’s new electrical services. The supposedly indispensable central thermal plants provide only the minority, because they cost too much and bear too much financial risk to win much private investment, whereas distributed renewables got $91 billion of new private capital in 2007 alone"

Even though I would also prefer to see a distributed power system I am not as optimistic as Mr Lovins (and neither were some of the people who responded). There are some important efficiency and market issues with distributed energy generation that we have to face right now. Take wind power for example: the newer generation of wind farms has more and bigger turbines than their predecessors. I credit this to several factors:

  • Turbines become more efficient as they grow in size - bigger turbines (this is true up to certain limits)
  • Wind farms benefit from economies of scale as they become larger (more turbines)
  • As wind farm owners become more comfortable with the investment, higher capacity plants are being proposed and funded.
  • Most important of all: Selling and installing ONE wind farm that produces a Mega Watt per hour is easier (and more commercially viable) than selling thousands of smaller kilo watt turbines. This point in particular affects the whole chain of development of power plants:
      • 1. Developers of new technologies aim towards bigger pockets (centralized plants). Therefore, creating newer and more efficient generators for the centralized system and neglecting the distributed option.
      • 2. Investors, distributors and installers aim to reduce their risk by concentrating their investment and effort into more focused and less mass market trend-changing technologies. When we talk about creating a new wind power plant, we understand the limits and the risks better than if we would talk about selling wind turbines door to door.

The same efficiency and market issues hold true for other renewable energy generation methods (with perhaps the exception of solar PV, being the one with the most distributed systems to date). Furthermore we are leaving hydro and nuclear out of the equation. Forget the impossibility of having distributed hydro power and the danger of having distributed nuclear power!

Finally, I am including some answers I received via email or LinkedIn (I am reserving the names of the authors awaiting for their approval):

· "we need to break away from centralized power...and as it happens - while that's not a common opinion with the big power companies - it is the common opinion of electrical generation engineers"

· "technology and wisdom will dictate the answers...Now that science is finally focusing on the problem of sustainability and innovation, breakthroughs will be coming within a few years based on existing "future-tech" inventions and unimagined ones"

· "With the move to wind and solar power it will be necessary to maintain a large grid system because of the instability of the energy production"

· “I think the "smart grid" has the potential in the 2010s to duplicate the same type of transformation of our everyday lives as did the Internet in the 1990s… New technologies are making small generating facilities (solar, wind, biomass, even natural gas) sufficiently economic that they can compete with the large central station generators… The smart grid can help here also. It will be able to control the micro generating device you install at your house. When you are away or not otherwise using your full capacity for your own house, the smart grid will pump your electricity into the grid for others to use. This lets your system operate on a useful basis closer to 100% of the time with the resulting efficiency gain”

· “the best strategy isn't a single approach. By combining efficiency at the demand end of the grid (homes, business, etc) and allow the demand to sell the ability to reduce further during peak periods we can avoid building some amount of new generation. This alone isn't enough. Technology on the supply side with newer more efficient means of generation also play a role”

· “Imagine rental properties or tightly packed suburban neighborhoods. These folks would find it difficult if not impossible to erect a wind turbine or solar panel. Also, many consumers would not be able to generate enough alternate source power individually to run their homes and most businesses would not either”

· “Think how consumption is accomplished - locally in homes and local businesses, and there are some large energy intensive industries that require huge amounts of energy, like metal foundries and smelting, and they need the massive generation power of wind farms and solar farms and hydro dams (for overnight storage, and base load power)”

· “Part of the problem with local generation is that no one wants to live next to a power plant”

· “Electricity tends to be a natural monopoly. Established industrial groups especially the utilities owning and operating generating stations on fossil fuels and large dumb grids and super highways supplying energy at low tariffs were hitherto getting away with murder by not paying for externalities (carbon footprint increase).”

· “for most sources local generation is impractical, and you still need a grid to even out supply and demand even for solar”

· “The moving of energy from point A to B, and often back again, is a huge drain on efficiency. Keeping it all close by to where it was generated and will be used would be great. However are there good options for the consumer and/or the business that want to store the power? I've read about some custom hydrogen fuel cell methods. There is always batteries I guess”

Until next week…SHALOM!

Wednesday, February 4, 2009

The Electric Grid. Questions?

I come here before you to seek for answers!

Now that the words “Smart Grid” is in our everyday lives. I would like to better understand how the current “Dumb Grid” works. In this world full of information I have not been able to find satisfactory answers to the following questions regarding the Electricity Grid. Excuse my ignorance!

1- What is the best strategy for the future of power? Is it to generate electricity in each home, or neighborhood, or community; or to maintain the current system where a series of big power plants inject their product into a complex network that distributes the electricity to large geographic areas?

2- What determines the capacity needs of the power plant? Is it the installed capacity in the network (each appliance and circuit in each house, office and factory) or is it the historic average consumption of electricity?

3- Why can’t we have a direct current (DC) grid? Many alternative energy technologies struggle with the conversion from DC to AC (alternative current). Why do we need to use AC everywhere?

What I have learned recently is that the existing network of power plants works under a demand / cost of production basis. The power plant that is cheapest to run is producing 24/7 (Base Load Power Plant); as the demand grows during the day (or the week) additional plants start generating to produce the needed electricity. Therefore creating a different (cost and) price for electricity at different times of the day (or the week).

Will this complex network be needed if (and when) we obtain electricity from the sun or the wind (or any other renewable source)?

The real core of the matter is whereas new alternative energy technologies will flourish in the home or neighborhood scale, or will they replace existing power plants in the power grid? In other words, who will be the pioneer of renewable energy? Will it be the average Joe or the big utility companies?

Regarding the capacity of the power plants:

This question seems simple, but I have found is not as straightforward as it seems.

According to me, there are two "measurements" of electricity in your home, commerce, office or factory: the installed capacity and the actual electricity being consumed.

When you build a house and install the main electricity "box" you have to do so according to a calculation of the power needs for that house. This calculation is based on the number of outlets, appliances, lights and other power consuming devices the house has built into it (or may be able to support). The breaker box in the house reflects the need of each room or appliance for the power capacity (voltage).

The question is: does the power plant need to generate according to the installed capacity of the aforementioned house, or can the power plant generate based on the actual use of electricity in the house? In other words, if we reduce the installed capacity of all the houses in a city, but these houses consume the same amount of electricity as before; will we save any power?

Finally, I am puzzled by the lack of DC alternatives in today’s wind, and solar power generation world. I am aware of the “War of Currents” between AC and DC (won by AC). But I wonder what would happen if today’s technological advances were applied to a DC network with alternative energy as a power source and DC applications everywhere.

I want to apologize for the time gap between my previous posting and this one. It turns out that having a third child, traveling and keeping up with three different types of businesses in three different countries does take time!

Until next week: SHALOM!