Monday, October 15, 2007

Blog action day

Today is "Blog Action Day," wherein many bloggers are uniting to promote environmental awareness.

Bloggers Unite - Blog Action Day

This seems like an excellent opportunity to try to answer a question posed to us some time ago by one of our good friends and loyal readers:

"...have you two done a comparison between Odyssey energy use and a single-family home with similar appliances/ features? I assume your MPG on the road are low, but how about your fridge, etc? ..."

Actually, yes, we've tried to do this. And I say "tried" because, really, it's not possible. I could go on for pages and pages about why that is, but, for the sake of simplicity, I'll just say it has to do with the fact that, while "primary" energy consumption is easy to measure (how much gasoline one uses in a year, for example, or how many kilowatts of electrical power), secondary, tertiary, etc., usage (for example, how much electricity is used to pump city water to your house) is difficult, if not impossible to measure for the average consumer.

As an example, consider the following scenario: You are currently driving a ten-year-old car which gets an average of 17mpg, uses a quart of oil every 3,000 miles, and puts out a certain level of exhaust emissions. It's otherwise in good shape and can continue to be driven, for, say, another five years and 60,000 miles. You are trying to decide whether to keep this car, or buy something more environmentally friendly, say a brand new car which gets 32 mpg, will use a negligible amount of oil, and has a cleaner exhaust system.

Looking at this only from a primary effects standpoint, it is a no-brainer: over the next 60,000 miles, you will burn 1,654 fewer gallons of gasoline, emit less exhaust, etc.. However, you will also have created a consumer demand for one additional new car, and you will have created one "scrap" or junk car as well. Probably not the car you will replace -- it will propagate downward through the consumer chain, and, presumably, a very clunky gas hog with horrible exhaust will be what gets scrapped (we hope). But, nevertheless, one new vehicle will have to be manufactured and one used vehicle will be scrapped.

So, in order to determine the net environmental effect, we need to consider how much energy is used to manufacture a new car. This includes such things as smelting and founding metals, creating the plastics (a petroleum product), mining the copper for the wiring, etc.. We also need to consider how much energy is used to scrap the used car, and what happens to the inevitable portion of the waste from that process that can not be recycled.

By the time you add up all these effects, you will have reduced the environmental "gains" of the higher-mileage, cleaner-burning car by a fair amount. It's conceivable, even likely, that some new car purchases, even of very "green" cars, have their environmental effects completely negated by the myriad second-order effects. Does that mean we should not buy newer, more environmentally friendly cars? Of course not -- if a new car is inevitably going to be manufactured and consumed, it should be as green as possible. I'm just trying to illustrate the complexity of the energy consumption (or "carbon load") calculation, and how difficult it is to really know how much impact one is having.

With that as a backdrop, imagine the complexity in trying to assign a carbon load figure to the life we lead aboard Odyssey, and to compare it to a different life we might lead in a fixed dwelling. I'm not even sure where to begin: if we assume a fixed dwelling, does that mean that we'll still do leisure travel? If so, will we be, perhaps, flying to various leisure destinations throughout the year? Will we be renting a car there? Or maybe we'll go back to touring the country on a pair of motorcycles, staying in hotel rooms, or the occasional campground where we will burn a wood fire for comfort heat and to cook food.

So, I'm sorry to say, I can not give a pat answer to the question. I can't simply say something like "our carbon load is 35 tons, compared to the national average of 40 tons per couple." In fact, I can't even calculate our carbon load, because the many, many carbon load calculators (such as this example) make several assumptions based on the average person in a fixed dwelling that simply do not apply to us. (If we try to use such a calculator -- as we have -- and just key in the data that we can, it gives a very lopsided answer that is certainly not correct.)

Instead, I'll try to run down a few of the major carbon load "hot buttons" and discuss how life aboard Odyssey pertains to each:

Direct use of fossil fuel

I'll start with this one, because it's the most obvious, and the biggest "down side," so things will only improve from here.

We consume approximately 3,300 gallons of diesel fuel, 30 gallons of gasoline,and 15 gallons of LP gas per year. The diesel not only moves the bus, but also provides some of our electricity, most of our home heat, and some of our hot water. (Most of our hot water, and a good bit of our home heating, comes from waste heat from the main engine -- we designed it that way to reduce costs and to provide a direct environmental benefit.) The gasoline powers our scooters, which are very fuel efficient (80-100mpg) and serve as our around-town transportation (although we also use mass transit whenever we can). The LP, which is mostly propane in this country, is used strictly for cooking on both our indoor stove as well as our outdoor grill.

By comparison, the average American couple (by which I mean two times the individual average) consumes about 2,300 gallons of refined petroleum products and about 2,000 gallons of LNG. The refined petroleum products includes motor fuel and heating oil. So we use more oil, but less gas than the average.


Now, bear in mind that some of the electricity we use is generated by burning diesel fuel, and so it is included above. That includes not only the electricity that comes from our generator, which is (in the global scheme of things) very fuel-inefficient, but also electricity that comes from our engine alternator, which does the lion's share of our battery charging. The alternator is much more efficient than the generator, for reasons I will not delve into here.

Some of the electricity we use is generated by our solar panels. We have 330 watts of panels on our roof, and I would guess that they are, on average, 30% efficient (accounting for cloudy days, parking in the shade, the fact that they are flat, etc.) for about eight hours of every day. In any case, it merely serves to reduce the diesel load, described above, or the amount we draw from the grid, which I will get to in a moment. Also, it's important to remember that even solar energy has a carbon load: the panels have to be manufactured in a factory, and ultimately scrapped when they no longer produce energy. But we can say we derive about 300 KWH per year from solar.

We do spend some time plugged in to commercial power. Since we don't have a kilowatt-hour meter as most homes would have, again I have to make an estimate. I estimate that we use about 2,000 KWH of commercial electric power each year. That compares to the average couple's residential use of about 10,000 KWH per year. However, bear in mind that total per-capita electric usage is actually higher, because most people spend time at work, the mall, the skating rink, etc. and those spaces need to be lit, air conditioned, cleaned, and so forth. We do, too, of course (well, except for that pesky work part, outside of our Red Cross assignments), but we spend less time inside of those kinds of commercial spaces than most folks. How much less? I can't say.

One final note about electricity: we need to "smooth" our demand function by using batteries. We have over a thousand pounds of them, and we're on our second set. Without the batteries, the solar panels would be all but useless, and we'd need to run the diesel-guzzling generator far more often. Our actual electric demand/usage would not go up, but the carbon load certainly would. But the batteries themselves have an environmental cost -- they had to be manufactured, and they will need to be recycled (the good news is that batteries are highly recyclable these days).

With regard to the specific question about our fridge, and, by implication, our other appliances, the need to be able to run from batteries demands that our appliances be highly efficient. Our refrigerator is a 24-volt model, a mere 7.5 cubic feet in capacity, with no automatic defrost. It uses a tiny fraction of the energy of the typical house refrigerator. Likewise, our diesel heating is high-efficiency hydronic, we have a very efficient induction stove to reduce our propane consumption when on commercial power (or the generator is running anyway), and our coffee maker is the thermal carafe type, with no hot plate. Even our TV is an energy-efficient LCD model. We have high-efficiency xenon/halogen lighting for when we need it, but mostly use super-efficient LED lighting to get around after dark.


This is an area where Odyssey really shines. Our total water consumption is about ten gallons per day -- less than 4,000 gallons per year. By contrast, the average couple's domestic water usage is over 100,000 gallons per year.

While water use doesn't sound like a big carbon-load contributor, the fact is that each gallon of water has to be pumped, filtered, treated, and stored -- all of which have carbon-producing energy impacts, and then every gallon becomes sewage, which also must be treated, producing more carbon.

Incidentally, on the subject of water, we don't generally use bottled water (or soft drinks). Not counting milk (about 30 bottles worth each year), we perhaps go through four dozen or so beverage bottles per year, both home and away. When we do get bottles, we reuse them. A water or beverage bottle typically lasts us a month or two. We have a good filtration system aboard Odyssey, and we simply refill our water bottles from the tap. I drink powdered beverage mix, which, admittedly and annoyingly, is highly over-packaged (Crystal Light and its knock-offs, which come in plastic tubs, six in a plastic tube -- at least the tubes are recyclable). But still, I get more than half a gallon from each packet.

America's obsession with bottled water, and individually bottled beverages in general, is a huge source of needless carbon load. And, as long as I am ranting, let me just say that the state of recycling in many parts of the country is appalling. As much as we try to recycle everything we can, in many (most?) states it's just not possible to recycle anything but aluminum cans. Environmental costs be damned, but when the base material is worth real money, then we'll put a program in place. Bah.


Not generally included in many carbon-load formulae, but I think it's important.

Since our storage space is at a premium, we try not to buy anything that is excessively packaged. Unfortunately, we also cannot buy in bulk (the 36-roll package of Costco toilet paper is out), so there are tradeoffs here. But we often spend extra money for a product simply because the packaging is more minimalist.

In any case, we try to minimize our trash, and there is an energy component to dealing with trash that is thus also minimized.

This brings me around to the last subject:


Living in a 300 square foot space means that one simply can not accumulate "stuff." If I buy three new shirts, then three old shirts have to go to the Goodwill (or the trash -- I tend to wear my clothes out). When we bought a new pot recently, the old one went on eBay.

Since we have mostly nice things, and we are mostly happy with them, the idea of giving or throwing them away is a powerful disincentive to bringing anything different into our lives. As a consequence, we have generally "checked out" of the American consumer culture. We simply do not buy very much "stuff." When we do, it is a real treat -- I just bought a new GPS to replace a five-year-old unit that wouldn't fit where I needed it (the old one, and all its clunky accessories, was sold on eBay). Louise treated herself to new towels for her birthday yesterday (the old ones will be donated someplace).

I mention this here because American consumer culture is one of the key reasons that Americans generate six times the carbon emissions of the world average. All of these consumer goods take energy and raw materials to produce, and then, generally, become just so much garbage at some later point in time.

The bottom line

I wish I could come up with a number here, but I can't. That said, I would have to guess that our total impact on the environment here aboard Odyssey is somewhat less than the national average, yet still far and away above that of the rest of the world. We are, after all, Americans, and have become accustomed to a certain standard of living that Americans in general take for granted, and people in developing nations don't even dream of.

We have a higher direct usage rate for motor fuel than most Americans, but the inherent energy- and water-efficiency of Odyssey and the limitations it imposes on our behavior likely completely offset that and then some.

I'm certainly not trying to sell anyone on the green benefits of an RV lifestyle -- this is a form of luxury consumption, after all (nobody really needs to see the country, and few need to travel). But we try to keep things as green as we can within the confines of what we've decided to do with our leisure time at the moment.


  1. Fantastic, thoughtful article. It is hard to compute the indirect costs but they are HUGE. My gut tells me tho that living on the road is less impact than living in a medium to large house. OTOH, if you keep the house and just go on the road now and then w/ the rig, you really have a huge carbon footprint.
    Do not be swayed by the sarcastic comments elsewhere. I like your thinking.

  2. Very well written. I've done the same exercise on our travel and come to nearly the same conclusions. But I "rounded off" the secondary and tertiary energy and resource impact rather than trying to dig that far down. My assumption has been that (overall) we use public facilities & utilities nearl as much as we did before, and so that doesn't need to be compared. Our primary usage of resources, especially consumer consumption of material goods, is dramatically lower than our use prior to full-timing. Rather than trying to evaluate yourself against the average American, try evaluating yourself against your former lifestyle ... I think that's more relevant and quite enlightening.

  3. thank you for replying! you help raise awareness through your thorough response.

  4. Hi,
    I know this is an old post, but it has answered many of my questions. I am Jim and Pat Shepherds daughter, Judy, and asked my dad for a little help with a question I posted on my own blog ( battery charged items in my truck (ie: Sirius radio and phone chargers), he sent me to this post. Between the two of you, I am able to answer my own burning question! Thank you for making this readable for every type of reader. My parents really enjoy their time with you.
    Thanks again,
    Judy Jeute
    (pronounced Judy Judy)


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