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August 29, 2007

Homes without heat?

Category: Efficiency – Dan 2:12 pm

Efficiency is the ugly stepchild of solving our energy woes. While solar panels and windmills are high profile and focus on alternative sources of energy, efficiency focuses on needing less in the first place. How dull.

How do you spice this up? How about the idea that you don’t actually need any home heating. What, you say? Maybe in moderate climates, but that’s not going to cut it in Minnesota! But the hotbed (no pun intended) of this technology is in Germany, which is anything but warm in the winter.

Germany has several home heading standards in place[1].

  • A “Low Energy House” (Niedrigenergiehaus) cannot require more than the equivalent of 7 litres of heating oil for each square meter of room for space heating annually (in US terms, 15,850 Btu/ft²/yr)
  • The German Passivhaus ultra-low energy standard, is set to less than 1/3 this level, with a maximum space heating requirement of 4,755 Btu/ft²/yr. These homes are generally built with no central heating system, because it’s not needed.

Compared with buildings that follow the 2003 Model Energy Efficiency Code in the United States, these ultra-efficient homes use 75% to 95% less energy for heating or cooling.

Yes, you say, but what are the costs of building this way. Data on this varies widely, but seems to be in the 3% to 8% range. The challenge (as I saw in one article) is that the developer is generally not the owner.[2]

What to do in the near term? When buying new homes, demand higher energy efficiency! Be willing to pay the additional costs. But more important, we need to lobby for higher efficiency standards and incentives for developers to implement higher standards. The US has just come off a massive housing construction boom, and the sad truth is that a majority of those homes were not particularly energy efficient.

July 27, 2007

The Rebound Effect

Category: Efficiency – Dan 4:32 pm

Now here’s a challenge. In the recent issue of Scientific American, there’s an article about the “rebound effect”. This is something straight out of Economics 101: “If prices decline, consumption will increase”.

When applied to efficiency, what this means is that, as energy consuming devices, like cars and our homes, become more efficient, will we drive more and turn up the heat? Studies listed in the article had conflicting results, but the conclusion was that indeed there was some rebound effect. The article concludes, in part, by stating:

To compensate for the rebound effect, energy efficiency must be couples with other policy solutions to lower emissions.

On a parallel thread, I’ve seen some companies, or companies-to-be working on solutions to this of another kind. Some of the contestants in the 2007 CleanTech competition are working on ways to make your energy consumption more visible. Primarily at the home level, these folks are looking to provide a real-time monitor for your home’s resource consumption, be it gas, electricity, or water. In the presentation at the most recent CleanTech event on green building, one of the speakers mentioned a case were simply by posting daily energy use on the bulletin board of a college dorm, that day by day the usage fell as awareness grew.

So maybe the answer to the Rebound Effect is better awareness. Instead of simply seeing the monthly bill, you see a red light on the wall every time you’ve left too many lights on, regardless of how efficient they are. Food for thought.

May 12, 2007

Personal choices

Category: Efficiency,General – Dan 6:42 am

What can you do to save energy, and to move the world toward a more sustainable future? When I tell people about this site, many assume that the primary focus is on personal choices.

My initial thought here is that although there are myriad things that individuals can do to contribute to the solution, all these things are in the current context of where and how we live. And that inherently limits what we can do as individuals. For example, if you currently live in the suburbs, and your job is 30 miles away, and there is no public transit, your choices are limited. Unless you move or change jobs (both hard choices), you must drive to work, and your car choices are limited to what’s on the market.

So here are two lists, one of things that are relatively easy to do, and the other a list of things that will have a greater impact but will require a change in habits:

Easy to do
Big impact
  • Install energy efficient light bulbs – Just do it. These CF lights are now inexpensive and save money and carbon.
  • Drive less – Think about the trips you make, and combine them. Cut out unnecessary trips. For most people, cutting driving by 20% is relatively easy.
  • Unplug your extra freezer or refrigerator – If your extra fridge is only used occasionally, unplug it the rest of the time. You might save 10% on your overall electric bill.
  • Choose clean power – If you can specify power source when you buy electricity, spend the (usually small) extra money and specify you only want green power.
  • Choose Energy Star appliances – There is usually an incremental cost, but again it is relatively small and the cost savings and impact (especially with refrigerators) can be quite large.
  • Get a home energy audit – Of course you should then implement the suggestions. Some will be small and make a big difference, others will be an investment that will pay off over time.
  • Buy locally produced food and products – One of the big hidden energy costs is transportation for the things we eat and consume.
  • Use less water – What’s water got to do with energy you ask? For starters, water is heavy to move. If you live high on a hill, you may already be paying a surcharge, because pumping water up the hill costs more than delivering to people on the flatlands. It takes lots of energy to deliver water, and it also takes energy to treat the water.
  • Buy carbon offsets – Again, these are not too expensive. Effectively you are investing in projects to reduce carbon use, and carbon offsets allow that investment to be tied to your personal carbon use.
  • Install solar hot water heating – Solar hot water makes sense in so many places. The incremental cost is small, and the benefit is that your hot water heater hardly ever comes on, and you don’t have to feel guilty about long showers!
  • Get an efficient car – The car you drive is your most important personal climate decision.
  • Fly less – From a personal perspective, air travel is the #1 carbon producer. If you fly for business, look to how you can reduce trips and do more on the phone. When you do fly, make the trip count — stay longer and make one trip count for two.
  • Move downtown – Cities are energy efficient. You have transit options, you can walk to shops and businesses. A bicycle becomes a practical means of travel.
  • Downsize – Smaller homes consume less energy. And (as one article puts it), you’ll have less space so you’ll buy less junk.
  • Become a vegetarian – This is hard, but meat production is energy intensive, so eating less meat has a big impact on carbon use. One list also recommends loosing weight (every 50 pounds you loose will give you a 1% improvement in gas mileage).

In general, I’m not in favor of preaching sacrifice — it doesn’t work for the population at large and won’t solve the problem. But from a personal perspective, you can make a difference. And there is an aspect of changing the culture of energy consumption. In the Nov/Dec issues of Stanford Magazine, there was an article “A Crude Awakening”, documenting a debate of energy experts. One quote stands out here:

This has to become a public policy issue. It’s not right now. Think about the way the market for cigarettes worked in this country 50 years ago, and think of how it is structured now. We have not just taxes but regulation – they can’t be advertised on television – and a national campaign trying to educate people about the health concerns. We need a similar effort on this issue.

Cigarettes have almost become socially unacceptable in many parts of the country. At least it’s a start if you develop energy saving habits and lifestyles, and show others the way forward.

April 18, 2007

LEED – A big deal for building efficiency

Category: LEED – Dan 8:34 pm

Lately I’ve been reading a lot about LEED™ — which stands for “Leadership in Energy and Environmental Design”. Buildings (residential, commercial, and industrial) are responsible for an estimated 43% of U.S. CO2 emissions[1], and LEED™ is the nationally accepted benchmark for design, construction, and operation of green buildings.First LEED Platinum Home in US

Next time you’re at a developer’s presentation (as I was a couple weeks ago for a proposed mountain community development), raise your hand and ask “Will you be LEED certified?”. If more and more developers hear this question, it will absolutely have an impact. These guys want to be perceived as green (or more to the point, the don’t want to be perceived as not being green…there is a subtle difference here). Make this an issue for every developer out there.

What is LEED™?

Let’s start with the words directly from the LEED™ section of the U.S. Green Building Council website.

LEED provides a roadmap for measuring and documenting success for every building type and phase of a building lifecycle. Specific LEED programs include:

  • New Commercial Construction and Major Renovation projects
  • Existing Building Operations and Maintenance
  • Commercial Interiors projects
  • Core and Shell Development projects
  • Homes
  • Neighborhood Development
  • Guidelines for Multiple Buildings and On-Campus Building Projects
  • LEED for Schools
  • LEED for Retail

LEED has many complex components, but what provides a common language and is something everyone can use is LEED Certification. You want to ask “Will this project be LEED certified?”. If the answer is yes, you can follow it with “At what level?”

There are four levels of LEED™ certification: Certified, Silver, Gold, and Platinum. Certification is determined based upon a points system, with investments in different green elements contributing to the overall score. LEED is unique in that it quantifies most of the “green credits”, for example 5% of the building materials must be from salvaged materials to earn a point for the “salvaged materials credit”. Points can be earned in six different topic areas[2]:

  • Site development (did you minimize stormwater runoff, increase urban density, include green space, …)
  • Water efficiency (what’s been done to reduce water consumption)
  • Energy efficiency (what’s been done to reduce the building’s energy needs)
  • Material selection (did you minimize construction waste, re-use an existing facade, use recycled or salvaged materials)
  • Indoor environmental quality (did you incorporate daylighting, use low off-emitting materials, provide operable windows)
  • Innovation in Design (did you incorporate innovative environmental features not covered in other areas)

LEED™ has a 69 point scoring system. Get 26 or more points to be Certified, 33 or more to get a Silver rating, 39 or more for Gold, and 52 or more for Platinum. What’s also interesting is this table available on Entermodal Engineering’s website that shows estimated costs and payback for different levels of LEED certification:

LEED™ Rating Certified Silver Gold Platinum
Energy Savings> 25 to 35%> 35% to 50% 50 to 60% >60%
Annual Utility Savings 40¢/ft2 60¢/ft2 80¢/ft2 $1/ft2
Typical Payback Under 3 yrs 3-5 yrs 5-10 yrs 10+ yrs
Incremental construction cost
Small Buildings 3% 7% 10% 15%
Small Buildings 1% 3% 5% 8%

What’s the bottom line on LEED™?

  • Ask for it! If you’re buying a home, if you’ve involved with a development, if you’re going to a citizen’s meeting on a new project, ask if they intend to get LEED certification!
  • Talk about it! If you see the certification plaque on a building, tell your friends. If a developer is seeking LEED certification, complement him on his choice to go green. Encourage your city government to demand that all new city buildings be LEED certified.
  • Get LEED certified. If you’re a building professional, look into getting LEED certification. Believe me — this is going to be a good career move!

Want to read more? Check out these sites:

April 13, 2007

Cars, electric motors, and batteries – an in-depth look

Category: General,Plug-in Hybrids – Dan 8:58 am

Ever since I wrote the Mythbuster’s post “Hurdles remain for Plug-in Hybrids?“, I’ve been thinking more about the engineering logic of electric and plug-in hybrid vehicles. Here’s a quick rundown.

Batteries – Bad news *but*…

First, in doing the research for the earlier article on Hydrogen for Cars, I looked up information on energy density and found a complete table[1] showing both “volumetric density” (energy content for a given volume) and “gravimetric density” (energy content for a given mass) for a long list of common and not so common energy storage choices. Here’s a few lines of data based on this table:

Material Volumetric (kwH / liter) Gravimetric (kWh/kg)
Diesel 10.9 13.8
Gasoline 9.7 12.2
Ethanol 6.1 7.9
Liquid H2 2.6 39
Lithium-Ion Batteries 0.3 0.1

In terms of conventional fuels, Diesel and Gasoline deserve their popularity rating — they have high energy density, both in terms of volume (taking up a smaller part of your car) and weight (less mass to accelerate). And frankly, battery energy density stinks. How is it possible to even conceive of an electric car? Fortunately, battery energy density is the only bad news in this article.

Electric motors – A big win

When you do the comparison of electric motors to gasoline or diesel engines, you get an entirely different picture, in numerous dimensions.

  • Power efficiency – Gas and diesel engines get hot. They require complex cooling systems to eliminate waste heat. The result is that a gas engine typically only uses about 15% of the potential energy in the gasoline to drive the car, whereas electric motors are 75% efficient or higher. Tesla claims their engine is 85% to 95% efficient.
  • Full torque at zero speed – Gas and diesel engines don’t produce power unless they are spinning, and thus require a clutch to get things moving. Electric motors can generate full torque at a stand still. Indeed this is the reason that modern powerful railroad trains are pulled by “Diesel-electric” engines — in effect a hybrid engine with electric motors powering the wheels and no clutch.
  • Regenerative braking – Once you’ve burned the gas, the only thing you can do with excess energy is to use conventional brakes to convert the car’s kinetic energy to heat. With an electric motor, you can slow down and recover the kinetic energy, and put it back into the battery. Typically you can recover over 40% of a car’s kinetic energy in this fashion. This is why a Toyota Prius gets such superior city gas mileage — nearly half of the energy “lost” when the car stops at the light can be reused to start it again.
  • Fewer moving parts – The typical DC electric motor, as would be used in these cars has only a dozen or so mechanical parts, and only the main wheel bearing has friction and wear from mechanical contact. Contrast this with typical gas or diesel engines, that have literally thousands of mechanical parts and hundreds of bearings. Can you say “reliability”?
  • No extra rotating stuff – Typical gas powered cars have hundreds of pounds of rotating steel. When you step on the gas to accelerate, you not only have to get the car up to speed, you have to get all this rotating steel in motion. This huge rotating inertia means you need a bigger engine. A car powered by an electric motor can four small electric motors, one for each wheel, eliminating all this rotating metal.
  • No clutch, no transmission, no differential – We already pointed out that you can get rid of the clutch because electric motors produce torque at zero speed. They also produce relatively flat torque throughout up to several thousand RPM. Unless you want an ultra high performance electric car (like the Tesla for example), you don’t need a transmission. And if you put one motor on each wheel, you don’t need a differential or a transfer case. Four wheel drive comes along for free!
  • Less weight – A Tesla has one electric motor, which weighs about 70 pounds and is designed for a high performance sports car. Compare this with a typical gasoline engine, which can easily weigh 300 to over 500 pounds[3]. Not to mention the weight of the clutch, transmision, and differential, which can easily add up to another 300 pounds or more.
  • No oil changes – Without the many moving parts, and without the high heat, explosions, and pressures of a gas engine, and you eliminate oil and oil changes. Yes, there is lubrication in the bearings of an electric motor — it’s generally good for the life of the motor.

Bottom line here is that electric motors offer huge advantages over gas and diesel engines.

So there’s good news and bad news

So batteries have terrible energy density, while electric engines are great. So what?

Let’s do some math.

Working from the gas tank forward with the gasoline powered car…

  • A typical car has a 15 gallon gas tank.
  • Gas weighs between 5.8 and 6.5 lbs/gallon, so our tank will hold about 90 pounds of gasoline.
  • Gas has the energy equivalent of 12.2 kWh/kg, which means our tank of gas has about 450 kWh of energy.
  • The gas engine is only about 15% efficient, so the useful energy we have on board is about 67 kWh.

Now let’s work backwards to see how much battery we really need on board for the electric.

  • First, the electric motor is about 90% efficient, so whereas the gas car stored about 450 kWh of energy in gasoline, we’d only need to store about 75 kWh (67 / 90%).
  • Then we can factor in regenerative breaking, which in city driving provides us with another 40+ percent. So we can reduce the needed 75 kWh by 40% to 45 kWh.
  • We’ve run out of efficiency magic, and it’s time to buy batteries. 45kWh of batteries, at 0.1 kWh/kg, yields a battery pack weight of 450 kg, or about 990 lbs.
  • While 990 lbs sounds like a huge weight, remember to subtract the weight of the gas (90 lbs) and the weight of the gas engine, transmission, differential, and clutch. So we’re really only off by about 300 pounds.

The point here; yes, batteries don’t have anywhere near the energy density of gasoline, and that is and issue. But electric engines are so efficient, and they allow you to eliminate so much weight, that they compensate for a good portion the battery’s weakness.

How do you go the last mile (pun intended) to make batteries adequate? Plug in hybrids! Reduce battery size by half or more (say 300 pounds max), put in an ultra efficient gas engine to recharge the batteries (it can run at a constant speed, it needs no clutch, it needs no transmission), and most of the time your car can run happily on battery power, and when you need the extended range, you have your on board charging unit. Smart, green energy.

Note there were a couple articles that were especially useful to write this post:

Tesla Motors white paper “The 21st Century Electric Car”
Aurica Labs paper “Building the World’s Fastest Electric Car”

April 11, 2007

Efficiency vs. Conservation? Is there a difference?

Category: Efficiency – Dan 8:24 am

Too often, I hear “efficiency” and “conservation” in the same breath. What’s worse, I often hear that to solve the climate crisis, we need to get people to conserve energy: drive less, turn their thermostats down to 65 (or lower!), turn all the lights off, and more.

I want to put a stake in the ground with my opinion on this subject.

Note I’m not going to argue that we, as a nation, have a tendency to waste energy. I’ll often see houses where every light is turned on (even near my home here in the SF Bay Area). People still drive 1/4 mile to pick up one food item. And don’t get me started on the commute, where 1,000s of people all sit, by themselves, in bumper-to-bumper traffic.

But getting people to conserve, to cut back on energy use by changing their behavior, requires a change in personal habits. Yes, many concerned and committed citizens will take these measures, but the majority of Americans will not. Conservation — belt tightening — is not going to cut carbon emissions or change how we as a nation use energy.

Efficiency is not the same thing. My home office, formerly a dark cold room in the downstairs of our home, is now brightly lit and a pleasure to work in. Usually I have four lights turned on – a desk light and 3 recessed ceiling lights. All compact florescents, they use a total of 52 watts. As a committed environmentalist, I still turn out the lights when I’m leaving, but I don’t have to work in the dark because I invested in efficient lighting.

Efficiency continues to be the best energy investment of all, because it doesn’t require that anyone develop any new habits to be effective. My food stays just as cold, my rooms are just as well lit, and I save energy because I have efficient appliances and lighting.

My opinion: If you’re an environmentalist, and you want to really address the challenge of global warming, you need to get the nation moving. If you begin by telling people they have to conserve, cut back, and do without — you’re off to a bad start because inherently that doesn’t seem like the American way. But efficiency is good business, and good business is an American trait that we can and should exploit to solve this problem.

March 30, 2007

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 12, 2007

Hot Technology Series – Plug-in Hybrids

Category: Efficiency,New Technology – Dan 9:52 am

There’s quite a bit of information already available on plug-in hybrids, so rather than provide a detailed explanation, I’ll provide a quick summary. Yes plug-in hybrid cars are efficient, and they extend gas mileage and reduce emissions, but in my view there’s a bigger benefit that outweighs all of these: plug in hybrid vehicles provide fuel flexibility. Keep reading…

A high level view – hybrids and plug-in hybrids
Typical hybrid cars today power the car using a combination of gasoline and electric engines. At low speeds when the batteries are relatively full, the cars will use only electric power, and at higher speeds or when the batteries are low, the gasoline engine is used to help power the car and recharge the batteries.

A plug-in hybrid car has three key differences:

  • A larger battery, which enables the car to travel a greater distance (typically 50 to 80 miles) on battery power alone>
  • The ability to run (and perform) on battery power alone, so that for trips within that 50 mile range the gasoline engine may not be needed at all.
  • The ability to recharge the battery either by plugging it into a standard outlet, or when driving by the on-board gasoline engine

For many people who commute daily to work, the majority of their trips could be done on battery power alone, and the gas engine only comes on during longer trips to recharge the battery. Effectively, a plug-in hybrid behaves like an electric car, except that it can be charged up by either grid power (by plugging it in), or by gasoline.

Plug-in hybrid advantages and disadvantages
There’s a long list of reasons why plug-in hybrids make sense, and one big reason that plug-in hybrids are in my top 3 critical technology list:

  • Cleaner fuel source – Gasoline is quite a dirty fuel when burned in internal combustion engines, both in terms of carbon dioxide and other undesirable effluent. Plug-in hybrids, for much of their use, are powered by electricity from the grid. Even with electricity from a traditional coal plant, running a car from electricity is cleaner than gasoline.[1] Why? Because stationary power sources are easier to make clean and efficient. As the power grid includes more and more renewable sources, cars powered by electricity will effectively become cleaner as well!
  • Lower costs – If we assume gas costs $2.77/gallon and electricity costs 8 cents/kWh, a typical (21 mpg) car will cost about 13 cents/mile running on gas, but only 3 cents/mile running on electricity.[1]
  • Great driving range – One of the disadvantages of current electric car technology is that the driving range is limited. Even the best cars and prototypes today (for example the new Tesla) get about 250 miles per charge, which is at the low end of a typical gasoline powered car’s range. But a plug-in hybrid gives you the best of both worlds – for short trips you don’t even burn gas, but when the battery runs low, you can keep on driving and driving.
  • Refuel at home or at any gas station – When you’re commuting to work every day, just plug your car in every night and recharge. Since the average commute is within the range of what plug-in hybrids will be capable of, the gas engine may never come on. But you have the flexibility to take longer trips, and fill up at any gas station.
  • Fuel flexibility – I’ve saved the best for last, and as mentioned in the opening paragraph, this reason trumps all the rest, as I explain in the next section.

Fuel flexibility – Key to ending oil addiction
Gasoline has one big advantage; it has a high energy density (energy content per unit weight) so it makes an ideal fuel for vehicles. An article titled “A Crude Awakening” in the Nov/Dec’06 issue of Stanford Magazine states this well:

There is no easy substitute for gasoline.

The reason ethanol is getting so much attention is because it has many (but not all) of the advantages of gasoline, and therefore makes a good substitute. But every day we use a vast quantity of gasoline; replacing it all with current ethanol technology would require 8 times today’s entire US corn crop.[2]

Plug-in hybrids provide the needed fuel flexibility. The majority of trips made by cars (and many trucks and vans) are short local trips; trips that are within the 50 to 80 mile range. These trips consume no gasoline. And the gasoline (or alternative liquid fuel) plays a key role when you need the flexibility of making a longer trip. Plug-in hybrid cars are the smart solution that combines the best of both worlds.

March 7, 2007

Hot Technology Series – Power Efficiency

Category: Efficiency,Exciting Companies,New Technology – Dan 3:34 pm

While checking out the exhibits at the Power-Gen Renewable Energy and Fuels conference yesterday, I spoke at length with Chuck Rusch of Power Efficiency Corporation. This is a company that has been languishing in the backwater for years, and has a hot technology that deserves to be on the front page.

While wind and solar are the high-visibility technologies, it seems that conservation and efficiency always gets a seat in the back. Industrial efficiency seems especially dull, despite the fact that industry consumes 30% of more of the nation’s energy. Electric motors are estimated to be a huge portion of this consumption – I’m recalling 20% (but should look this up!).

Power Efficiency’s product, Power Genius, is a next generation “soft-start” product. Now a traditional soft-start product moderates the start power used by an electric motor, ramping up the power as needed to avoid the huge start-up electric surge. Once the motor is up to speed and full voltage, the soft-start’s job is done.

Unlike traditional solutions, Power Efficiency’s product constantly senses the workload of AC induction motors. when the workload is lower than the motor’s rating, the circuits reduce the energy (voltage and current) to only what the motor needs. The engine still runs at it’s rated speed, and if the load increases the power is raised up in microseconds to ensure sufficient torque and a constant motor speed.

Savings on energy costs are typically 20-40% because most motors work well below rated levels much of the time. An additional benefit is that the motor runs cooler, because it’s not consuming energy that it doesn’t need. This provides an additional energy savings for motors in enclosed temperature controlled environments, reducing the required cooling load.

Even I’ve fallen into the trap in thinking that efficiency is boring. Here’s a company with a product that provides proven savings for a vast number of industrial and commercial motor applications — check it out!