Energy consumption

Since the seventies of the 20th century mankind has slowly become aware that from the time of the industrial revolution she has gained a large and potentially disastrous influence on the planet's climate. The main source of trouble is the emission of greenhouse gases by burning fossile fuel reserves. It is clear that our ever growing hunger for energy has to be curbed and drastically too. The world is looking towards its politicans to take measures, but as is common with politicians they are cautious and slow to act. If change is to be effected, it has to come up from the bottom. So what can the average world citizen do?
One thing is to take a look at your personal energy consumption and make cuts where they really count. This article helps in quantifying personal energy consumption. Compare the numbers with your personal situation and decide where to strike.

Energy is measured in various units: cubic meters of gas, kilowatthours electricity, liters gasoline, etc. That is confusing and therefore all energy numbers in this article are supplemented with conversions to the SI-unit Joule. One joule is the amount of energy used at 1 Watt power during 1 second of time. Numbers are listed in J (Joule), kJ( = kiloJoule = 1 thousand Joule), MJ (= MegaJoule = 1 million Joule), GJ (= GigaJoule = 1 billion Joule) or even PJ (= PetaJoule = 1 trillion Joule).

Energy consumption Netherlands

Here are the numbers for the total energy consumption in the Netherlands.

Sector	energy in PJ
Energy companies	454
Industry	1393
Other (incl. agriculture, government)	558
Traffic	504
Households	424

Source: CBS (2008)

The numbers for industry, agriculture, government and the like show our indirect energy consumption: the energy needed for production, transport and distribution of food that we eat and products that we use. These numbers are hard to translate to one's personal situation because one person consumes more than the other. Also a lot of what we produce is exported and many things that we consume are imported.
Here you must use common sense: How long do you let your electrical equipment last? Do you eat plenty of meat or are you a vegetarian? The numbers for housholds and traffic are easier to tackle.

Natural gas

The most important energy source for houses in the Netherlands is still natural gas. Gas consumption is usually measured in cubic meters (m3). One m3 aardgas yields 31.7 MJ energy.
In 2009, the average Dutch household used 1608 m3 gas (51 GJ) per year. Again on average this was split into heating 81%, warm water 15% and cooking 4%. The lionshare, heating, depends a lot on type of house, degree of insulation, personal warming behavior and severity of the winters. Here is a table of averages per type of house:

House type	gas in m3	energy in GJ
Freestanding house	2396	75.95
Two onder one roof	1785	56.58
Cornerhouse	1722	54.59
Sandwiched house	1453	46.06
Apartment	1016	32.21

Source: Nibud (2009)

Electricity

The second major energy source is electricity. Usually this is measured in kilowatthours (kWh). One kWh electricity equals 3.6 MJ energy.
In 2009, the average Dutch household used 3430 kWh electricity (12.3 GJ) per year. Again on average this was split into washing and drying machines 21%, refrigerators 17%, lighting 16%, warm water 15%, other electric devices 31%. Electricity use depends mostly on the size of the household, so here is a table with averages for that:

Number of persons	electricity in kWh	energy in GJ	energy / person
6	5430	19.54	3.26
5	5292	19.05	3.81
4	4604	16.57	4.14
3	4092	14.73	4.91
2	3424	12.32	6.16
1	2317	8.34	8.34

Source: Nibud (2009)

Traffic

People do not just use energy at home. Another great consumer of energy is travel, either for business or recreation purposes. About 45% of the total fuel consumption of traffic in the Netherlands comes from personal cars; 1% from motorcycles; the energy needed for trains is alsmost neglegible. These numbers exclude ships and trips outside the country, which are significant.
Below are listed averages for different modes of transport. They can be used to compute one's own travel energy consumption and make comparisons.

The cruiseship Queen Elizabeth II is claimed to use 306 liters of diesel fuel (11143 MJ) per km at cruising speed. When fully loaded with 1777 passengers that is 6.27 MJ / km / person.

A jumbojet airplane cruising a long distance, say crossing the Atlantic ocean, uses 14.8 liters of kerosine / km, which is 520 MJ / km. Full loaded with 450 passengers that boils down to 1.15 MJ / km / person. On shorter flights the efficiency dramatically goes down, because of the higher relative proportion of the high energy required at takeoff to gain altitude.

Fuel consumption of cars depends heavily on size, engine power, speed, driving environment and driving behavior. An "efficient" gasoline car uses about 0.08 liters of fuel (2.7 MJ) per km at highway speed. With only one driver that is 2.7 MJ / km / person, fully loaded with 4 people that is 0.7 MJ / km / person. Fuel consumption goes down a lot at lower speeds, except in the city, where frequent short bursts of acceleration actually lower the efficiency about 20% - 25%. Larger and heavier cars use more fuel, especially in the city.
A city bus uses more fuel, about 0.5 liters (18.2 MJ) per km, but as it can carry about 40 passengers, fully loaded it can achieve an efficiency of 0.455 MJ / km / person.

A train that drives 14 km between towns, accelerating from standstill to a top speed of 140 km / hour and breaking back to zero, uses about 302 MJ, or 21.6 MJ / km. During low hours it may have only 10 passengers, resulting in an efficiency of 2.16 MJ / km / person. But fully loaded it has 372 passengers, for 0.058 MJ / km / person and during peak hours it may be stuffed with 800, resulting in 0.027 MJ / km / person.
Intercity and long distance trains achieve higher efficiency because they do not need to accelarate so frequently. High speed trains are less efficient because of their higher speeds. A high speed train that accelerates to 300 km / hour and does not decelerate until it has covered 100 km, uses 6.96 GJ, or 23.2 MJ / km. Fully loaded with 377 passengers that comes down to 0.062 MJ / km / person.

Pedestrians and bicyclists use energy too, though not in the form of petrol but of food. A pedestrian walking at 4 km / hour uses about 0.3 MJ / km; a cyclist driving at 20 km / hour sitting straight up about 0.06 MJ / km. Cyclists can reach higher efficiency by driving racing bicycles (less drag from wheels and chain and also from air), lie-down bicycles (much less drag from air) or driving two-person bicycles.

The numbers above take only into account the fuel consumption to cover distance. If one also considers the energy needed to mine and refine fuel and materials, construction and maintenance of vehicles, energy costs for every mode go up (even pedestrians a little, who wear out their shoes).

Energy consumption