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March 30, 2007

A deeper look at energy transmission

Category: Transmission/Storage – Dan 2:06 pm

In my recent post “The Energy Big Picture” I argued that there are four components to the energy big picture: Sources, Transmission, Storage, and Use. If you consider the big picture, you must consider all of these together. In this post, I’ll take a closer look at the transmission part of the picture, and show why it’s closely tied to the other three components.

Energy Distribution in the US Today

There is a vast infrastructure today providing energy transmission. Too often we think only of the electricity grid, but transmission today includes:

  • Natural gas transmission – There are 300,000 miles of natural gas transmission lines[1] in the United States. Note this doesn’t count the local distribution network, which adds another million miles or so of pipes.
  • Oil transmission – There are about 200,000 miles of liquid oil pipelines [1] in the United States. However, unlike natural gas, most local distribution (except airports) is handled by tanker trucks.
  • AC High Voltage Electric Grid – There are about 154,000 miles of high voltage (>230kV) electric transmission lines[2]. The electric grid is divided into three major segments: the Eastern Interconnection, the Western Interconnection, and the Texas Interconnection. As with natural gas, this doesn’t count local electric distribution systems.
  • DC High Voltage Electric Transmission – This is a relatively small component of the electrical distribution system, comprising only about 3,300 miles today[2]. With DC it is possible to transmit higher voltages over long distances. The best known line in the US is the Pacific Intertie, which transmits 3,100 MW of power from the Dalles Dam on the Colombia River to Southern California.

Source and transmission relationships

If we look down the list of new energy technologies, they have to be taken in context of source and transmission. Here are some examples:

  • Wind power – There’s enough wind power available in the plains states to power the entire country. But to tap it, we would need to extend the electric power grid throughout the region.
  • Concentrating Solar – There’s enough space in the southwest to generate at least 25% of US demand. But while the markets in southern California and Arizona are nearby, moving the rest of this power across the country requires major grid investments.
  • Hydrogen – Hydrogen is an energy carrier. Whether we use it to power cars (I’ll reserve my opinion here for another post), as a means to store energy generated by wind or CSP, or as a major energy carrier, we’ll have to create a new pipe distribution infrastructure equivalent to the natural gas system.


What this means, is that we have to think about energy transmission at the same time we think about new sources. Wind, CSP, geothermal, and biomass advocates have to take into account how the power gets to the markets where it will be used.

Carbon credits? What do you think?

Category: General – Dan 1:13 pm

OK. If I’m going to talk the talk, I guess when I fly I’d better walk the walk. So on my trip to Las Vegas several weeks ago, I clicked the button to select the “Terra Pass Short-Haul Flight” carbon offsets for $5.99.

What did I buy really?

Booking another trip today, this time I a) kicked myself for not saving the good article I read on this sometime in the last 48 hours and then b) spent enough time on-line to decide that TerraPass wasn’t a bad choice, and bought it again.

I have the nagging feeling that I don’t understand this well enough yet. I feel pretty confident about understanding and explaining the technology, pros, and cons of various alternative energy sources, distribution means, and storage methods. But this one leaves me wondering.

What I found so far was a portion of the But I’m going to keep looking. Any comments, thoughts, or suggestions on this topic are welcome!

Mythbusters – Hurdles remain for Plug-In Hybrids?

Category: Efficiency,Mythbusters – Dan 9:05 am

Argh. Yet another fountain of misinformation slowing adoption of what should be a no brainer technology. In this case, I’m referring to the forces aiming to divert attention on plug-in hybrids.

In an earlier post, I talked about why plug-in hybrids are a hot technology. Clearly I’m not the only one with this point of view. Look at what Austin Energy is doing in Texas.

Under the direction of the Austin City Council, the City of Austin and Austin Energy are leading Plug-In Partners, a national campaign to demonstrate to automakers that a market exists today for plug-in hybrids.

This initiative was recently written up in the Wall Street Journal (look here for a copy of the article where you don’t need a subscription to view). This is great news in terms of spreading the word, but the article is full of industry misinformation…to quote:

Big hurdles remain. The cars require expensive lithium-ion batteries that haven’t been perfected.

“Plug-ins will have a niche market,” says Red Cavaney, president of the American Petroleum Institute, which represents the oil industry. “They’re certainly not going to replace the family car.”

Critics of plug-in hybrid technology generally attack on three fronts:

  • The battery technology isn’t there
  • The costs will be too high
  • It shifts polution to dirty coal fired facilities

Let’s look at each of these in turn…

The battery techology isn’t there

I’ll start by arguing that, although the perfect solution isn’t here, there are good enough solutions in place. The real question is “how far do you want your plug-in hybrid to go before the engine comes on?”. Indeed, today’s Toyota Prius, running on battery alone, can go roughly 10 miles. Given that 50% of all U.S. vehicles travel less than 20 miles per day[3], if you tripled the size of the Prius’ battery you’d be at a good-enough point for half the US drivers. Today’s batteries really are adequate to the task.

In addition, the next generation of batteries is considerably better — to quote:

Advanced lithium-ion batteries now becoming available for automotive use are smaller and lighter than the metal-hydride cells we have so far employed, which will allow for lighter vehicles with the same electric range or ones that can go even farther before they begin to use gasoline. At the moment, the main roadblocks to lithium-ion cells are higher cost, reduced longevity and concerns about safety, but some battery makers claim to have solved these issues with their newest designs. … I fully expect that lithium-ion cells of one variety or another will eventually replace metal-hydride batteries in hybrid cars, offering a two- to threefold increase in energy storage for a pack of a given weight, along with a greater ability to absorb energy quickly during regenerative braking and, perhaps, with adequate durability to last for 15 years and 150,000 miles.[2]

As battery technology improves, and if plug-in hybrids are successful, the high-volume production of batteries could lower their price. This would make it affordable to increase battery-pack size in successive generations and rely even less on gasoline. Eventually, the internal combustion engine could be made smaller and be used exclusively to recharge the batteries on long trips in a configuration called a “series” hybrid.[1]

The costs will be too high

Purchase price of a plug-in hybrid will indeed be higher. Face it — the batteries will add to the cost. How much more?

The Electric Power Research Institute (EPRI) estimates that, with mass production, the cost of a PHEV battery will add $2,000 to $3,000 to the cost of a conventional hybrid. EPRI studies project that after considering the lower costs of fuel and maintenance, a mass-produced PHEV should provide better overall economics than either a conventional hybrid or a conventional vehicle. Battery costs are the primary reason for this incremental cost, and battery prices are likely to fall with increased production.[3]

I’ve also seen the number “add 10% to 20% to the cost of the vehicle”.

Is this too much to pay? I picked (at random) the Ford Explorer Hybrid to look at the cost of other options. the base price of this car is $25,740, so I’d presume the extra batteries will cost something on the order of $3,000. What do some other options cost? We see:

Option Cost
4WD $1,750
Navigation System & CD Changer $2,695
Leather Seats $695
Chrome Trim $195
Side step bars $345
Moonroof & satellite radio $995

So yes, the additional batteries would cost a bunch – but no more than adding say 4WD plus Leather Seats. And if your equivalent gas use goes from say 25MPG to 100MPG, at $3/gallon (less than I’m paying now) and you drive 15,000 miles/year, you’ll save over $1,000 year in fuel cost (even counting the electricity), which , by the way, is far more saving’s than you’ll get from having the moonroof!

It shifts polution to dirty coal fired facilities

Ok, this was what I first thought when considering electric cars and plug-in hybrids. But there’s scientific data on carbon emissions for plug-in hybrids this in the ASES Climate Change report[3]:

Technology> Per Mile
Gasoline Engine 0.22 lb
PHEV/Modern Coal-Fired Power Plant 0.19 lb.
PEHV/Gas Combined-Cycle Power Plant 0.08 lb.

So even in states with a predominance of coal-generated electricity, there’s some advantage in carbon emissions.

But the opportunity to reduce carbon here is huge. Why is Austin Texas so jazzed about plug-in hybrids? The wind blows like crazy in West Texas at night. What use is all this wind power at night? Well, it could be charging the batteries in a Texas-sized fleet of plug-in hybrid vehicles.

What’s more, Penney says, “if millions of these things were produced 20 years from now, it would really enable renewable energies like wind to take off.” Wind power requires ways of storing energy generated when demand for electricity is low, he says. The cost of the storage makes it hard for wind to compete with other sources of electricity. Millions of plug-in vehicles charging at night would essentially provide free storage.[1]

Bottom Line

The bottom line is that plug-in hybrids make sense today. I get angry when people try to dismiss this as some far out future technology that “someday might be practical and cost effective”. Do your part in helping dispell this myth!

Want to do more? You can:

March 28, 2007

What about Hydrogen?

Category: Hydrogen – Dan 10:00 am

Hydrogen is often quoted as a new alternative energy source, particularly with respect to what we’ll put in our gas tank. I will argue that hydrogen is a likely part of the energy future. But it is not a new energy source, and using it as an automotive fuel is not a smart use for hydrogen.

Hydrogen compared with Natural Gas

The closest equivalent to hydrogen today is natural gas, with respect to it’s potential uses and behavior. The obvious difference is that natural gas is a fossil fuel that can be extracted from the earth, whereas elemental hydrogen does not naturally exist in commercially available quantities and so has to be generated. Here’s a simple chart to show the similarities and differences:

Natural Gas Hydrogen
Normal state Gas Gas
Highly compressable Yes Yes
Energy Content 1040 BTU/cubic foot 320 BTU/cubic foot
Practical to transport in pipes Yes Yes
Practical to store underground Yes Yes
Sources Underground extraction Electrolize water or reform natural gas

We all think of natural gas as an energy source. But beyond being a source, natural gas is also an energy carrier, allowing practical energy distribution from source to consumer, and it serves as an energy storage mechanism. Indeed, to balance seasonal demand, natural gas suppliers regularly store natural gas in salt caverns during slack periods to have energy in reserve during peak times. It’s no wonder natural gas is in favor.

Hydrogen can serve as a natural gas alternative for two of these three crucial characteristics: transmission and storage.

Pairing hydrogen with alternative energy sources

Alternative energy sources like wind, concentrating solar power (CSP), or geothermal energy, all share the same good-news/bad-news characteristics:

  • The good news – There’s a huge power potential. We could supply the entire US energy needs by wind power from the midwest or CSP in the desert southwest.
  • The bad news – These sources are intermittent, and they are hundreds or thousands of miles from the demand. In the industry, these are known as “stranded” sources.

Here’s where hydrogen can, and perhaps should, play a staring role. Given a source of energy and a supply of water, it’s fairly straightforward to generate hydrogen. If it’s practical to pipe hydrogen long distances, and store it until needed, one could almost redefine a large wind farm as a hydrogen generation facility.

This topic has considerable depth. I first came to understand some of these ideas after a conversaton over dinner at the PowerGen conference with Bill Leighty of the Leighty Foundation, which has been funding research into this area for some time. I’ll provide more on these ideas, with more information sources in future posts!

March 22, 2007

The energy big picture

Category: General,Transmission/Storage – Dan 7:44 am

I want to return to a theme I touched on a week ago in the “What’s the answer? Yes” entry. Too often we look at a potential solution like wind or concentrating solar power (CSP), and say “won’t solve the problem — it’s intermittent”, or “it only works in the desert”.

This issue touches directly on energy policy. We need to think of the energy big picture. And I’m going to argue that there are four components to that big energy picture: Sources, Transmission, Storage, and Use.

  • Sources – Wind, CSP, Photovoltaic — these are all sources. There’s a lot of data that shows that there’s plenty of environmentally benign energy to be had. For example, the TREC project (a Club of Rome initiative) shows that a CSP facility covering a fraction of the Sahara desert could provide power for the entire world. The challenge here is that these great CSP sites are far from the major population centers. This leads us to…
  • Transmission– Our current major power sources, coal and oil, are cost effective today in part because of elaborate transmission and distribution systems. The US is crossed by a network of pipelines, an electric power grid, and coal fired plants either are colocated with the mine or at the other end of a major rail line connecting mine to plant. Indeed one enormous energy use in the US is energy transmission. No energy strategy is complete without considering the investment required to get that energy to market.
  • Storage – As important as transmission is the ability to store energy for use when it’s needed. Why is gasoline a great transportation fuel? Because a relatively small and lightweight quantity can be stored easily in a gas tank until it’s needed. Indeed, you can think of fossil fuels as a giant tank of stored solar energy that, for the past century, we’ve been drawing down. The piles of coal outside a coal-fired utility, and the tanks of gasoline at your local filling station are all examples of functional and cost effective energy storage. The big challenge with many alternative energy sources is storage; it’s easy and cost effective to convert wind to electricity, but it’s not so obvious how to store it until it’s needed. As our energy strategy evolves, we have to address this storage challenge.
  • Use – Finally, the nature of delivered energy is important. Electricity is a wonderful and flexible energy medium, but without better batteries (a.k.a. chemical storage), it can’t power automobiles. There are industrial processes that require specific fuel sources. I cook, and believe me a gas stovetop is superior.

Much of the challenge to move to a carbon-free energy economy is how to evolve the current entrenched system to adapt to new cleaner sources, while addressing the new problems that arise with transmission, storage, and use. This will be a focus on ongoing posts.

March 19, 2007

The solar variety show

Category: Concentrating Solar,Photovoltaics – Dan 7:38 am

Like many people, what I knew about solar power was limited, and in particular was limited to knowing about flat panel solar collectors. Oh, and one article that I’d read years ago about a “power tower” being built somewhere in the southwestern US with a bunch of heliostats (sun tracking mirrors).

Turns out that solar is an area with not only vast potential, but extensive innovation on a number of different approaches to turning solar energy into useful power. Here’s my list:

  • Flat panel technologies – All flat panel technologies have some key characteristics. They do not require direct sunlight, and generate energy regardless of where the light source is located. As a result, they don’t need to track the sun (although efficiency will be higher if they do), and they generate some power even on cloudy days. There are several types of flat panel collectors:
    • Flat panel crystalline silicon solar cells – These are what most people think of when they think solar. Cystalline silicon is grown into rods, which are sliced into wafers that form the cells. Arrays of the cells are built into flat panels.
    • Thin film technology – The high cost (both dollars and energy) of crystalline solar cells prompted development of a new approach where thin films of semiconductor materials are deposited. Although these generally have lower efficiencies than crystalline cells, the costs are also significantly lower, both in terms of manufacturing the active material, and in terms of the required support structures (thin film cells are much lighter). Thin film cells are also flexible, and can therefore be bonded directly to roofing materials; an example of this is the BIPV Solar Electric Roofing produced by SolarIntegrated.
    • Non-traditional photovoltaics – There is a new generation of semiconductor solar cell devices that work differently than the above two options. Companies doing this development include Konarka Technologies, Nanosolar and Nanosys.
  • Concentrating Photovoltaics – If the most expensive component of a traditional solar cell is the collector itself, then why not use mirrors or lenses to concentrate sunlight on the collectors. The advantage of this approach is lower costs. This does, however, make it more important that the collectors track the sun, and this technology clearly works better in southwest locations that have relatively cloudless skies. Companies working on concentrating photovoltaics include SolFocus, Silicon Valley Solar, and Sharp Electronics.
  • Solar Thermal Technologies – If what you need is heat and hot water, why go to the trouble of converting sunlight to electricity? This is the theory behind various solar thermal technologies. Solar thermal has been around for generations, and unfortunately this seems to be the unglamorous stepsister of solar technology. Solutions range from basic arrays of black tubing on the roof to help heat swimming pools, to modern sophisticated devices using glass evacuated tubes coated with advanced materials and integrated with ethanol-filled heat pipes. This is worth an entire article, so I won’t write more here.
  • Concentrating solar power – If you think big, it’s possible to create facilities that gather sunlight over a large area to create high heat that then is used to generate electricity. The three primary types of facilities here are:
    • Parabolic Trough – Long parabolic trough-shaped mirrors focus sunlight on tubes that heat a fluid to well over 500 degrees F; this heat creates steam to power a turbine generator and produce electricity.
    • Power Tower – A circular array of sun tracking mirrors focus sunlight on a central receiver on tower, heating a fluid which powers a generator.
    • Dish Engine systems – A mirrored dish focuses sunlight on a stirling heat engine at the focal point that directly generates electricity.

Why so much investment in PV?

Category: Photovoltaics – Dan 5:46 am

Photovoltaics (PV) have always baffled me. While they clearly make sense for applications in remote locations, other options like wind and concentrating solar power are far more cost effective for industrial scale power generation. Why then is there so much venture capital investment in PV? Looking through the publications, there are at least a dozen companies developing new PV technology, and major investments are being made in fabrication facilities to create hundreds of MW of PV panels each year.

Then I saw my copy of “Inside the Tornado” on the bookshelf an the the light went on in my head.

Most alternative energy sources — Wind, concentrating solar power, geothermal, and biomass — are industrial scale sources. If your not a utility, you’re not likely to be making a major investment in any of these sources.

Photovoltaics are entirely different. An individual can install them on his home. A business can install them on the roof of their warehouse. PV panels can work anywhere there is sufficient light. And while having a grid connection is useful, you don’t need the utility’s permission or cooperation to generate PV power.

The analogy I’d use here is the automobile. There were other ways to get around in the early 1900’s, and public transit was highly developed in many parts of the country. Although early automobiles were a pain (they weren’t reliable, gas stations were few and far between, the roads were poor), they offered a way to take transportation into your own hands and not rely on the railroads and public transit agencies. In the terms of “Inside the Tornado”, cars were a disruptive innovation. They changed the paradigm, and the result was huge growth of the automotive industry, and the decline of the railroads.

PV has the same potential — to change the entire nature of the energy supply business. If PV became cost competitive, companies and consumers could take control of their power generation away from the utilities. The upside opportunity for companies here is far greater than the upside of other alternative energy sources (wind, CSP), which rely on existing organizations (utilities, oil companies, etc) to drive adoption and investment.

What do you think? Is this what’s driving PV investment? And will it work?

March 15, 2007

New FAQ section

Category: General – Dan 8:05 pm

I’ve started a new section for “Frequently Asked Questions“. So far, there’s only questions addressed for Solar and Wind power, but my intention is to continue to gather questions that I hear, research the answers, and post the results in this section.

If you have questions, feel free to e-mail me or post them in the comments section of the particular blog entry.

March 14, 2007

Solar Power FAQ

Category: Uncategorized – Dan 9:09 pm

Q: I’d love to install solar cells, but the up front cost is simply too high. What can I do?

A: Before you consider solar, take all practical efficiency and conservation steps to reduce your electrical usage. You may find that your electricity needs drop to the point where solar is affordable.

The second step is to look not only at the initial up-front cost of the investment, but at the money you’ll save over time. If you finance the investment over time, you may find that the energy saved will cover most or all of the monthly payments. Indeed, some solar installation companies will provide this financing as part of the package reducing or eliminating the net incremental cost of installing solar power.

Q: What is the practical potential and limitation of solar power?

A: Because solar power is intermittent, it must be complemented by other energy sources, or some kind of storage must be available. One advantage of solar is that the maximum generating capacity (the most sunlight) is generally available during peak demand periods (when you need the most air conditioning). Note that concentrating solar power located in the desert southwest is less intermittent because the hot working fluid can be stored in insulated tanks providing ongoing power for hours after the sun sets.
From a cost perspective, power from photovoltaic cells is still expensive because the manufacture of cells is costly. New photovoltaic technologies hold promise of reducing these costs. Electrical power from solar concentrating devices is cost effective today with fossil fuels.

Q: Are there any alternatives to solar power besides solar cells?

A: While solar cells (photovoltaic cells) are the most visible solar solution today, there are other solar technologies that are practical and cost effective.

  • Solar water heating – Relatively low technology solar water heaters are inexpensive to install and can reduce and in some case eliminate energy used for domestic water heating.
  • Concentrating solar power facilities – Just as a nuclear or coal fired power plant uses heat to generate steam to turn a turbine, solar plants have been built that use sun-tracking mirrors to focus intense sunlight onto a working fluid that drives a turbine. See the section in the blog on concentrating solar power for more information.

Wind Power FAQ

Category: Uncategorized – Dan 9:03 pm

Q: What is the practical potential and limitation of wind power?
A: Because wind power is intermittent, it must be complemented by other energy sources. In practical terms, wind power can likely provide at least 25% of a region’s overall electricity supply; indeed in Denmark, wind power now accounts for close to 20% of electricity consumption.

Q: Wouldn’t providing this much wind power mean windmills would be everywhere?
A: Providing 25% of US electricity requirements (250GW) would require on the order of 125,000 wind generators, which would cover about 12,500 square miles. This sounds huge, but it’s about 12% of the state of Kansas. Germany (which is roughly the size of Montana) today has over 16,000 turbines.

Given that wind generators can be deployed across existing farmlands and at offshore sites, the impact of 125,000 windmills is minimal. Compare this with the land affected by strip mining coal; it has been estimated that by the time all the coal is mined out, Wyoming alone will have 40,000 square miles of area affected by coal mines. [Harvard Gazette 02.20.2003]

Q: Don’t windmills kill birds?

A: While early wind farms were criticized for killing birds, this has been shown to be primarily an issue with poor site selection. While windmills still kill birds (existing US, onshore and near-shore turbines kill an estimated 70,000 birds per year), this is a minor impact compared with bird deaths by cars (57 million/year) or by collisions with plate glass (97 million/year). See the article in the Mythbusters section of this site on this topic.