One thing before I start. The reason I am focusing on North Carolina in these posts (other than the fact that I live here) is that the Eastern United States, as a region, has some of the highest per capita fuel use in the world. So if we can reduce fuel use here to a sustainable level it should be possible to do it any where.
Moving on - I am obviously interested in biofuels but the reason for this is not that I am particularly concerned about climate change, which is what most people think about in regards to reasons for using biofuels (climate change could be a major a problem, don’t get me wrong). I am interested in biofuels because our civilization is reliant on abundant fuel for its very survival.
I don’t say that to be dramatic, I really mean it. As oil becomes scarce and more expensive it won’t simply be a matter of it being inconvenient or expensive to get from point A to point B when you want to. Which is the second thing most people of think of when we talk about fossil fuel depletion. It is a lot more serious than that. When oil becomes scarce and expensive people will be unable to commute to and from work, period. This will also cause serious economic disadvantage for people with lower income and those in outer suburbs or rural areas and the functioning of the economy will be impaired.
Additionally, and more seriously in my opinion, we need fuel to grow and transport food. The large population of humans on Earth is in part due to the fact that we can use farm machinery to cultivate vast areas of land. We could conceivably grow the same amount of food with higher labor inputs but imagine, for example, planting and harvesting the entire Australian wheat crop by hand. This would probably raise food prices substantially. Then how do we move the huge volumes of produce to people? If you think about this for a moment you will start to see my point.
In the previous post I looked at the ability of different biofuels to meet our energy demands. I concluded that we will need to dramatically reduce our energy needs in the future to live within a renewable resource base. The point of this post is to look at how we can reduce our energy use. This is a complicated subject so to make things easier I will focus on petrol use.
The data for this post comes from the following US government statistics websites http://www.bts.gov/ and http://www.census.gov/ .
To begin, lets look at the annual fuel usage of North Carolina if everyone traveled 400 kilometers a week (which is our weekly average travel distance) and drove either 1) a car getting 11 kilometers per liter, which is the national average fuel efficiency of an American car, 2) a car like our little Hyundai that is more efficient, 3) a hybrid like the Toyota Prius or 4) a magic car that gets twice the fuel efficiency of a Prius. Then let’s see how much of our fuel demand we can meet using 50 % of North Carolina’s pastoral land to grow Switchgrass, using all the same assumptions from my previous post.
This is what you get:
So, even if we all drove cars with magic efficiency we are still 80 % away from meeting our fuel needs with one of our best-prospect biofuels. So even though driving fuel efficient cars is important it is not going to lower fuel consumption sufficiently.
So what other options do we have to reduce fuel use?
Of course not everyone has to drive as far as I do each day which means my estimates are not exactly correct. So let’s look at some real figures.
The following table shows the breakdown of different types of commuting for people in the US. Assuming people in North Carolina conform to the national average then you can calculate the number of people in the state who use each form of transport:
This shows that about 7 million people a day drive to work. Of course nearly a million of these carpool so lets assume there are two people in a carpool car and divide this by 2. So people undertake about 6.6 million car trips in a working week.
This tells us that a simple way to reduce fuel use is to get some of the 76% of people who drive alone to carpool. I will deal with that later though.
The average national commuting speed in the US is 51 kilometers an hour so from that you can calculate how far people are driving using average commute times. Using the average fuel efficiency of 11 kilometers a liter you can estimate the amount of fuel used by these different length trips. This is what you get:
What is interesting about this graph is that the total fuel use amounts to 6.7 thousand megaliters a year, when the average petrol use in North Carolina is 16 thousand megaliters a year. My figures are estimates which may in-part explain this discrepancy, but it doesn’t explain all of it. I think what this shows is that over half the petrol in North Carolina is not being used for commuting/domestic use. So simply reducing domestic fuel use is not sufficient to reduce total fuel use, but lets not worry about that for the moment.
What is also interesting is that over 60 % of trips are less than 30 minutes one way, which is approximately 18 kilometers or less. I personally think anything less than 10 kilometers is easy to do on a bike. Perhaps not for a trip to the shops but for regular commuting to an office, for example, where you can access showers and a change of clothes, it is easy. I used to commute 12 kilometers to work by bike with no problems. According to the previous table a paltry 0.3 % of commutes are done by bike so increasing bike use could be one way to drastically reduce fuel consumption.
Another way to reduce fuel use could be to increase public transport use. A standard diesel bus gets about 4 kilometers per liter of diesel. So if we assume a bus has an average of 20 people on it this works out as about 260 L of diesel per person annually. Diesel and petrol use are not directly comparable but that aside people catching a bus use about 13 % of the petrol of an average car, this is vastly more efficient than a Prius. A train might be even more efficient but I don’t have that data at my fingertips.
And, as I mentioned before, a big way is too reduce fuel use per capita is to increase car pooling (i.e having two people in a car uses half the fuel per head).
So, lets say 60 % of people do something other than drive just themselves to work. If only 20 % of trips less than 30 minutes were by bike, only 20 % of trips were by bus and only 20 % of people you could save about 3.5 thousand megaliters of petrol, or 50 % of total petrol used for commuting purposes. Now THAT starts to be a big saving of fuel.
If everyone else not using these alternative transport options started using cars with twice the fuel efficiency the petrol used in commuting would be around 1.7 thousand megaliters a year. We COULD potentially meet this using biofuels if we used things like switchgrass and woody waste.
Of course there is the outstanding problem of fuel used in non-commuting applications - about 9.3 thousand megaliters worth of it. Of course part of this is non-commuting car use, so it will be in part met by increases in fuel efficiency. I haven’t found any information about where else the fuel is used, so I can’t recommend how to reduce the amount used. It could also be things like lawn mowers for example, which we could find alternatives for. If anyone can tell me that would be great.
So perhaps I can conclude this post by saying that in North Carolina we MIGHT be able to meet energy requirements currently met using petrol by using biofuels. This is without using crop land needed for food and not cutting down extra forests to grow things. However this can not be done with increases in fuel efficiency! People will need to change their lifestyles (oh no!) by using alternative transport options and working closer to home. Appropriate town planning might provide one way to do this, such as by providing convenient public transport, and more urban consolidation.
Stay tuned for the next post, where I will try to get my head around fuel needed for farming and transport of goods.
