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Some questions I got from a listener by email
Submitted by ben on Sat, 02/09/2008 - 14:53.
Here are some questions from Larry that I got by email (perhaps they'd make some good conversation topics in the forums here):
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Here are some pressing questions that, perhaps, you can address on upcoming podcasts:
Purpose of my writing: Please consider the following questions regarding the issue of “full-cost accounting” in the following areas: transportation, alternative energy, and lighting, agriculture. Although I am asking for a cost-benefit analysis, this is the cost to the society and environment, not to the pocketbook of the investor.
Specific questions:
* transportation/alternative energy:
-What is the cost in energy, materials, pollutants, etc. in producing a new motor vehicle, relative to continuing to drive an older, less efficient model? At which “CO2 emitted/distance level would producing the new, more -efficient vehicle begin to look favorable?
- In a related question, how does the current electric storage battery technology measure-up relative to internal-combustion engines in terms of energy, materials and pollutants needed to manufacture, drive, and handle at the end-of-life?
-What is the relative energy efficiency and emissions levels of an all-electric plug-in vehicle, relative to a traditionally-powered car? What would be more efficient, to fill tanks in cars with natural gas, or to power large generators with natural gas and use this to power the cars? If the nation were to switch to a fleet of vehicles powered by one of these natural-gas options, would there be enough fuel available? Would it make sense to power the generating plants with petroleum instead of natural gas?
What are the energy and pollutant issues for recycling or discarding the various types of batteries be recycled?
* alternative energy: What’s the true story regarding the “environmental friendliness of semiconductor-based photovoltaic panels? Specifically, what is the relative cost benefit of producing the panel in energy, water, and pollutants? Regarding energy cost, my impression is that if a photovoltaic is mostly made of sand, then the 20-30 yr. payback cost for a typical house is the cost in energy needed to produce the panel. If it should fail or break over that time period, then where is the energy savings??
* lighting: Why do the utilities keep encouraging us to purchase fluorescent lights as replacements? Do they profit from the sale of the lights, or increase profit margins should the energy usage go down? What is the cost/benefit analysis of switching from incandescent to these fluorescents (compact or traditional), regarding the energy, materials and pollutants involved in producing the lights? What about the issue of dealing with the bulb at the end of life, especially given their mercury content? How does the new semiconductor-based LED lighting measure-up in terms of production, energy consumption and disposal, relative to the story with incandescent and the various fluorescents?
** In sum, given current technological capability and the accumulating environmental problems, how will the earth be able to support the current world human population, let alone the currently projected rate of population growth?
Re: Some questions I got from a listener by email
Regarding the question about batteries.
Batteries store energy so the energy to propel the car has to be produced elsewhere, preferably via renewable sources. An internal combustion engine burns fossil fuels, or biofuels, which act as the energy carrier or storage. The problems with fossil fuels are obvious relating to climate change but are multiplied by the fact that the vehicles as currently designed are incredibly inefficient, somewhere in the neighborhood of 12 to18% on average well to wheel. Most of the energy of the fuel is lost as heat, precious little is used to produce forward motion. Some of this is due to excessively heavy cars. Making cars lighter does have recyclability issues, currently there is an industry already handling heavy car recycling as the materials are currently used.
In electric cars much more more of the energy is used to produce forward motion and the vehicles are therefore substantially more efficient, up to 88% efficient. This drops substantially, down to 28%, if power plants are used to charge the batteries. (http://www.electroauto.com/info/pollmyth.shtml 02/08) 28% is still a significant improvement but simply increasing CAFE standards to 40 mpg, easily achievable with current IC technology, would be a doubling of current average and if the entire fleet were brought up to that standard US GHG emission would be reduced by 10%.
As far as environmental impact is concerned, lead acid batteries have a mature recycling industry in place and are 90% recyclable for the electrolyte, 96% for the lead. These are figures based on the EU which mandates recycling of lead acid batteries. I'm unsure about Lithium Ion batteries and recycling.
C Robb
http://sustliving.blogspot.com/
Questions for Bill Kemp
For the next podcast I'm going to be talking to Bill Kemp (who's been on the show before: http://www.thewatt.com/node/83 and http://www.thewatt.com/node/87). He wrote a new book called The Zero-Carbon Car. I'll ask him some of these questions. The conversation will revolve around personal transportation issues and how he built his car, it's very cool: http://aztext.com/zero_carbon_car.cfm, anything else I should ask?
Re: Some questions I got from a listener by email
Hello there,
I think, I have some answers or at least some hints, where to look for answers for some of the questions asked by Larry.
1. What is the relative energy efficiency and emissions levels of an all-electric plug-in vehicle, relative to a traditionally-powered car?
This is an very interesting question, but unfortunately it is incomplete. If you want to compare these types of energy conversion, then you have to keep in mind, that they are more or less chains of single energy conversions. That means, to compare them you have to have a equivalent starting point and ending. So, there is not much sense in analysing and comparing the energy efficiency of an all-electric plug-in vehicle with a traditionally-powered car, because they have different starting points. One starts with the calorific value of energy of the fuel and the other with the voltage and electric charge needed. Both of them have to be produced in the first place and for this production you also have to calculate the energy efficiency, unless they aren't provided by nature for free. Like solar radiation, wind power, water power or usable geothermal heat.
Nevertheless, if you do compare them, the result is, that the all-electric plug-in vehicle has an energy efficiency somewhere between 0.9 and 0.8 for converting electricity into motion, while the car powered by a turbocharged diesel engine and a mechanical transmission would have an energy efficiency of about 0.45 to 0.4, for converting the calorific value of energy of the fuel into motion.
For a petrol engine the energy efficiency is a little less, about 0.4 to 0.3, depending on the technical level of the engine used. (At this point I did not go further into detail. If you want to know more about it, that would lead us into the priciples of thermodynamics and electrical engineering, which takes too much space here.)
So, to take a common starting point, you can start with the same fuel. No matter, if it's fossil fuel or bio fuel, or if it's natural gas, coal, wood, petrol or what ever. Then you can say the energy contained in this fuel is converted into motion in two different ways. The first one is the direct way, where the fuel is used directly in the engine of the car with the energy efficiency mentioned before and the product is mechanical energy, which is turned into motion. The second option is to burn that fuel in large power stations and convert it into electricity. This electricity is transformed several times, stored in the battery of the car and finally converted into motion. These transformations and the storage are not free of losses. So, to get an equivalent total energy efficiency compared to the direct use, the power station has to be exactly that more efficient, what the electrical system is more unefficient, compared
to the direct use. (Now things get more complicated if you say that the all-electric plug-in vehicle comes with a build in start-stop capability and regenerative braking, because they lead to an increase of energy efficiency. But their influence is hard to calculate because they are depending on the driving habits.)
So that was also, albeit indirect, the answer to your 2'nd question. Which asked, if it would be more efficient, to fill tanks in cars with natural gas, or to power large generators with natural gas and use this to power the cars?
As far as I know, today the best available solution for a large power station, regarding the energy efficiency, is a combination of two thermodynamic cycles. Namely a Joule and a Rankine cycle. Practically this is achieved by a combination of a gas- and steam turbine system, where some heat from the gas turbine exhaust gases is recovered and used for the steam production for the steam turbine. This leads to an energy efficiency of about 0.55 for the conversion of the calorific value of energy of the fuel into electricity.
Instead of starting the calculation with the same fuel, it is also possible to start the calculation beginning with a natural source and calculating the energy efficiency for its extraction, mining or growth & harvest. Like a well-to-wheel calculation for the extraction, transport, refinement & distribution of oil as a fuel.
Regarding the emission levels, one can say, that they are depending on the fuel and the technical level and combustion process of the engine. (I once did measure the emission levels of my car, at a certain operating point, because I wanted to figure out, if there's a difference when it's running on canola oil compared to diesel fuel.) So, for the all-electric plug-in vehicle, as long as the source used to produce the electricity is producing almost no emissions, you will have almost no emissions. But unfortunately in most countries it's a mixture of different sources, e.g in Germany in 2006 the electricity was produced out of 13% renewable sources, 29% nuclear fission and 58% fossil carbohydrates. It is stated that this mixture produces 530 g of CO2 per kWh. For the all-electric
plug-in vehicle this end's up somewhere between 589 and 663 g CO2 per kWh of mechanical energy. To have a comparison I calculated the average CO2 emission of my car and that's 702 g of CO2 per kWh when running on diesel fuel only and 438 g when running on a mixture of canola oil and diesel fuel (This allready includes an input of 37% of primary energy to grow the canola.) So, here it turns out, that in my situation there is no advantage in changing to an all-electric plug-in vehicle. But that's also depending on the car I drive and my driving habits. (About 70% of the distance I travel by car in one year, is on highways and has an average distance of 500 km (310 miles) per journey. The average speed is 130 km/h (80 mph). The other 30% I travel through cities and on minor roads. So you can say my car's engine is mostly driven close to its designed operating point regarding the rpm and power output.)
3. question was: Would it make sense to power the generating plants with petroleum instead of natural gas?
That does not make too much difference regarding the relative energy efficiency. The difference is less depending on the fuel you use, but more on the thermodynamic cycle, the technical level and complexity of the power plant. That means if it's an gas turbine, steam turbine or a combination of both. Or if it is a diesel engine. (By the way also diesel engines can run on natural gas, only the injection system is a little more complicated and thus a little more expensive.) Then the question is if your plant has some kind of waste heat recovery or if it provides a district heating system.
4. If the nation were to switch to a fleet of vehicles powered by one of these natural-gas options, would there be enough fuel available?
Well, this question is a really philosophical one. Without notice it implies, that the word "enough" is correlating with a certain period of time and amount of consumption, unless this resource is not endless. Even if you think in a period of another 100 years and the same consumption as today, there will surely not be "enough" natural gas.
So I think there will not be a big one-fits-all solution regarding everyones energy demand, especially when it's about transportation. I think in the futur there will be a greater variety of fuels and therefore the future engines have to be able to run on "multi-fuel". And not at last people have to reduce their energy consumption, by changing their habits and way of live, to solve the energy shortage and climate change problem.
So long
Ernesto
Re: Some questions I got from a listener by email
Here are some of my comments:
Question 1:
The CO2 content of gasoline is 8.9kg CO2/gallon or for a 30 mpg car, you would be producing 296 g CO2/mile or 185 g CO2/km (note: Prius produces 104 g CO2/km). Or, put another way, the energy content of gasoline is roughly 37 kWh/gallon and this would mean that CO2 produced from gasoline is roughly 268 g CO2/kWh.
In the US, the grid produces on average 606 g CO2/kWh, in Canada, the grid produces on average 255 g CO2/kWh, The efficiency of an electric car using Li-ion batteries is ~0.21kWh/km producing 127 g CO2/km in the US or 53 g CO2/km in Canada (BEV info comes from Ulf Bossel's presentation Note: Here's a podcast interview with Ulf Bossel, it's a good one).
So, to summarize:
30mpg gasoline car: 0.77 kWh/km, 185 g CO2/km
Li-ion BEV: 0.21 kWh/km, 127 g CO2/km in the US or 53 g CO2/km in Canada
I'll take a stab at the other questions a bit later ;).
Re: Some questions I got from a listener by email
I'm curious about the difference between the US and Canadian grid. Why such a difference?
In my comment about battery powered vehicles I mentioned that the efficiency goes down significantly if charged from the grid. Using widely deployed battery powered powered vehicles to store and make available energy from renewable sources, vehicle to grid (V2G), not only makes the vehicles more efficient but also helps to solve the problems of intermittency from renewables. Zero Carbon Britain estimates, and recommends, that if the entire fleet were replaced with electric cars using V2G technology, 27 million vehicles with capacity of 50kWh, a storage capacity of 1.65 TWh could be added to the grid, 1.6x the daily household electricity use in Britain. Cars in Britain are used on average 1 hour/day, the rest of the time they would be hooked to the grid. Until the time when that technology is large enough to make a difference I'm of the opinion that electric vehicles should be charged from dedicated renewable sources whenever possible.
Re: Some questions I got from a listener by email
Hi Robb, I completely agree, I love the idea of vehicle-to-grid. When you look outside at the parking lot, and consider that each of those cars is essentially a 100kW power plant (for electric vehicles it'll probably be less than 100kW but still significant), it makes perfect sense that they could smooth out intermittent power supplies on the grid.
I have been thinking how this would work practically though. You charge your "mobile power plant" (aka your plug-in electric car) at night to take advantage of off-peak electricity (which eventually may become peak-electricity if everybody plugs in their cars), drive to work discharging your battery, plug-in at work to supply electricity to the grid to make up for peak-demand, discharging your battery some more, then drive home, discharging your battery, and plug-in at home, charging your battery. I think this would only work if there are lots of cars supplying the grid during peak-hours, since you don't want to discharge your batteries too much because you still have to drive home.
The other possibility of course is that you could bump up your base load electricity supply (such as nuclear) so that it meets traditional peak demand, and then during the tradition off-peak demand you'd have to find something to do with the excess nuclear energy, and so you'd charge your batteries.
If V2G was implemented there would be a huge boom in demand for computer scientists / controls people who have to write the software which figures out how many cars are plugged in, how much juice should be supplied/taken from the grid.
To answer your question about the differences in the grid CO2 content between Canada and the US: The US is 50% coal, Canada is 60% hydro.
To be a bit more specific:
Canada: hydroelectric (58%), coal (16%), nuclear (12%), natural gas (6%) , and fuel oil (3%), other (2%)
US: Coal (49%), nuclear (19%), natural gas (18%), hydroelectric (6.5%), fuel oil (3%), other (3%)
Vehicle to grid and a bit of a rant
Hello Ben,
It would really be a shame to create so many jobs to implement V2G, along with all the PV industry jobs it might just finally prove Bush wrong that addressing climate change is bad for the economy, never mind that Spain, Japan, Germany, and Denmark are already proving that point.
As with most solutions we need to look at the situation in a more holistic way. V2G in Britain would be more effective earlier due to the smaller distances driven on average, as well as already having smaller lighter cars. North America has so many challenges to face, not least of which is creating a society less dependent on driving overall and in huge wasteful vehicles. As Bill Kemp said in your interview we are going to have to get used to driving much less. The less we drive the more likely V2G can be of assistance. Because it makes implementation of grid scale renewables more effective, storage is widely agreed to be necessary, it should be part of an overall strategy and not looked at in terms of would it work in todays context. Also, all electric cars should covered in PV, most cars sit in the sun all day. With millions of lightweight electric cars all covered in PV the amount of electricity produced and stored 2 feet away from the panels, even if only 2% of the cars needs, would be significant. As an aside, I think we need to shift to an ethos of producing power where we use it.
We have to create a new context of overall improvements in sustainability in all sectors. I think we are deceived when we look at technologies and solutions in isolation. An example; here in Britain everyone is going on about the 4 million new homes we are going to need by 2050 and that we need to create new eco towns, using up valuable farm land and carbon sequestering green space in the process. Enormous amounts of planning and training are going into this effort, not least of which is my own MSC course. I see a couple of problems with this. All this effort is going into housing for 2% of the population. The other 98% of us will continue to live in highly inefficient 50 to 200 year old houses. We are intent on maintaining the look of these homes and are therefore unwilling to externally clad them to bring them up to standard. Addressing this issue isn't really of interest to developers, architects, and the other industries of growth that control the dialogue. So we expend most of our effort on what will be small improvements in our carbon footprint. I like Architecture 2030's approach much better.
Housing in Britain is already out of reach for all but the upper middle class and higher. Who will be able to afford these 4 million new homes? Everyone seems to ignore that the world by 2050 will be a very different place. The simultaneous challenges of peak oil, soil erosion, environmental refugees, and water scarcity will have a profound effect on our economies.
I realize the purpose of this website is to discuss energy solutions to the dilemma facing us but we need to keep in mind that the very first thing we all need to do is use far less of it, less driving, less television watching, less purchasing of pointless consumer goods, even less eating for many of us is going to be required. Purchasing a V2G car to replace a 10 year old SUV when personal resources are stretched to the limit by the effects of peak oil is not going to be affordable for large percentages of blue collar people in 10 years. They will be focusing on producing food, generating energy, and procuring safe water for their families.
We apparently have less than a decade to make huge changes, planning new more efficient methods of consumption in order to not rock the boat of growth is folly. We can't consume our way out of overconsumption. This not to say we shouldn't address the changes needed like V2G. I can see California mandating it sometime in the next 15 years and the rest of the nation following suit within 10 years later, but only if it is well planned and the technology worked out. We musn't lose sight of the overall context.
"Nothing is less productive than to make more efficient what should not be done at all." -- Peter Drucker
Re: Some questions I got from a listener by email
Hi Ben,
thank you for checking my comment. After reading your reply I first was a little bit surprised of the difference in the calculation. But then I found out what the reason for that is. And guess what?
It's this tricky changing-the-point-of-view-thing.
In your 30-mpg-gasoline-car-example, the "kWh" with which the 268 g CO2 correlate, are not the same as the "kWh" with which my 702 or 438 g CO2 correlate. Yours is the energy content of the gasoline and mine is the energy contained in the kinetic work of the car. So, they are very different types of energy and between them there is this conversion, which my engine does with an energy efficiency of approximately 0.39. And now we can close
this circuit by saying, that CO2 produced from diesel fuel is about 270 g CO2/kWh and that diesel fuel contains about 37 kWh/gal or ~42500 kJ/kg.
So, we are both right, only the point of view is a different. I took the kinetic work of the car as a common reference point, because if both cars have almost the same size, weight and shape, their kinetic work will be the same, as long as the resistance and time are the same.
Now, if I take my car's consumption and the energy content of the diesel fuel multiplied with the energy efficiency of my car, I get 0.23 kWh/km, which sounds quit realistic to me.
If you are interested in, here are some facts about the car:
Its a 1995 Peugeot 306 1.9 Diesel
dead weight: 1130 kg
rated power: 50 kW or 68 bhp
at rpm of 4600
max. speed: 160 km/h (100 mph)
measured average consumption: 6.1 ltr/100km or 38.5 mpg (on diesel fuel) and 6.5 ltr/100km with mixture of canola oil & diesel fuel (ratio: 3/4 canola oil to 1/4 diesel fuel) due to higher density and lower calorific value of energy of the mixture
energy efficiency: ~0.39, when run with ~30 kW load at ~3500 rpm
(This load is approximately the same as traveling on an even highway at a speed of 130 km/h or 80 mph. The input of fuel energy is then ~77 kW continously.)
CO2 output per km: 162 g (110 g with canola oil)
Actually the energy efficiency is bad for a diesel engine. It could easily be better if it had a turbocharger and thus the option to recover some waste heat from the exhaust gases. Then the engine could be of a smaller size, let's say 1.5 ltr and would easily have the same rated power, but less consumption. (perhaps it would then reach ~0.49)
But unfortunately this was not the case, because the understanding of a turbocharger in the automobile industry was a different one. They used this device to boost up engines to be more powerful, instead of downsizing them. Probably this attitude is changing now, but it's a very slow process.
Now to come to another subject. I saw that you and Robb were discussing this vehicle-to-grid thing and I believe this is a very interesting point and I totally agree with what both of you said.
I encountered this problem of the grid and its intermittent load or input on a smaller scale. I'm studying "ship's operation" which is a kind of technical engineering, dealing with ships and their technical operation and maintenance. And I've allready worked onboard ships for about 5 years.
So, in this business we face the same problems. For example onboard of a standard containership we also have an electrical grid, even though its a very small one. Probably comparable with a small town. We have something like a power plant for the base load, which is the main engine. We have several smaller power plants, called the auxillary engines. They can be used in case of a peak load or if the main engine is not in operation. And of course
we have lots of different consumers. We have a bow thruster, which is a very big consumer. We have all the electric motors of pumps, winchen and so on. And we have the lighting system and lots of reefer containers, which also need to be supplied by the grid. Now our advantage, compared with the engineers managing the grid ashore is, that our consumers are very patient machines. They are not getting angry, if we switch them off for half an hour
just because we don't want to start an auxillary engine, while our main engine cannot provide the full power to the grid, due to navigational manoeuvring.
So, in our small grid we are in full comand of the supply and demand of electrical energy and we can plan ahead the production and use of electricity. Ashore things look a bit different. I suppose, today the large grids are managed almost only from the production side, apart from the few large consumers. And once in a while this allready ends up in a blackout, because the electrical processes on the consumer side are much faster than the
mechanical processes, which provide the electricity. So, there's no doubt, that we need better management on the consumer side, if we want to add our vehicles to the grid as consumers. And of course we need this management more than ever, if we decide to use the vehicles as a storage place in the grid. But I'm not sure, if the majority of us is then ready to accept this management regarding our mobility, because it might interfere with our understanding of using mobility when ever we want it. I believe people will change their attitude towards this point more quickly, if there are enough incitements.
And that brings me back again to the efficient use of energy. As Robb said we all need to reduce our consumption of energy. In the matter of transportation I observe that this is allready happening. Within the last 10 years the growing use of the internet and the increasing fuel costs made instant ridesharing very popular among a certain part of our society, which has a special profile or habit of traveling. For example students like me. Here in germany
the students have to buy a special ticket for the local traffic for each semester they are studying. Because of the obligation the price is very low. Ok, probably there is also a little subsidy. But the point is, that this ticket makes us need no cars for traveling through our city and its close by surrounding. Of course the supposition is, that we live in range of the local traffic. So the only reason for people like me to use a car is to travel long distances.
Now the problem occurs, that the less often I use the car, the more expensive its use get's, due to the fixed costs. So one solution is to reduce the variable costs, by increasing the utilization. So, I do this instant ridesharing and on average the car is transporting 3 people. Sometimes 4 and sometimes only 2, but rarely only one person. In the end this leads to 54 g CO2 per km and capita (or 37 g when running on canola oil). Of course it could be less if I had an more efficient car, but at the moment this is a financial problem. So that's one fast solution to reduce the consumption, but to induce people to do this it need's the right conditions and incitements, because not everyone has a good imagination of this problem. So it's the job of our politicians to set up these conditions and incitements and of course the people have to get a better imagination of the problems related to the use of energy. But I guess this is one purpose of this website. ;-)
Ernesto
Re: Some questions I got from a listener by email
I just noticed that I made a little misstake, when I was talking about ride sharing. I said "instant ride sharing", but it's just ride sharing and not the dynamic version, which is still to be developed.
I found an interesting study carried out by Nokia, which deals with this matter. I can find it with the following URL:
http://research.nokia.com/tr/NRC-TR-2007-003.pdf
Ernesto
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