What Is the World’s Most Energy-Efficient City?
Sorry, I don’t know the source of this, but the answer is Reykjavik, Iceland …
All of the energy and heat used by the citizens of Reykjavik, Iceland come from geothermal plants and renewable hydropower making it the most sustainable and energy efficient city in the world. This city has also been replacing traditional buses with hydrogen-fueled buses, from which the only emissions are water.
It certainly looks as though that city has the lowest CO2 emissions per capita and it does look sustainable. However, whether it is the most energy efficient city is a different matter. Basically it is a matter of definition. Do we really know that per capita it is using less energy than any other city? Regardless of the source of the energy, it is still energy.
Probably their sources of food should also be considered. If any of their food is imported, it is necessary to consider the energy used to produce that food and how much CO2 is emitted in the process. For example, beef is energy intensive and results in considerable CO2 emissions.
Regardless of the above, their good example should be emulated wherever it is practical to do so.
Reykjavik, Iceland is an energy fortunate city. However, I have to agree with Frank, that this topic may hinge on a matter of definitions. “Efficiency” has not only a scientific definition but a very broad connotative definition that ranges from an approximation of the scientific definition to simply something that is “good.”
Many cities put out media that makes some claim on renewable energy or efficiency. NYC makes a claim partially based upon its extensive subway system and the resulting 80% of the people in Manhattan who therefore find no need to own a car.
Youtube is full of more promo’s for several cities. One has been purposely build from the ground up for energy efficiency. Masdar an overwhelming impressive example of what can be done for energy efficiency: https://www.youtube.com/watch?v=NIaz61zpLfs
For a list of the top ten “smart cities” in the world look here: https://www.youtube.com/watch?v=E6l0wLG7c9I
Yes. “Efficiency” isn’t the word I would have chosen either.
I was surprised to see that Iceland is using hydrogen buses. But after a bit of digging I found this article that clarified that while hydrogen is made from fossil fuels in most places Brazil and Iceland anticipates using renewable energy. http://www.sciencedirect.com/science/article/pii/S0301421504002472
With cheap electricity hydrogen can be made using electrolysis of water. With present technology a hydrogen fuel cell electric car can have more range than a battery EV but the vehicle is more expensive and the battery EV is more than 50% more efficient using the same electrical energy (scientific definition useful work over enery input.)
There is also this: http://alpha.chem.umb.edu/chemistry/ch471/evans%20files/Hydrogen%20-%20Reality%20in%20Iceland%202002.pdf It seems that hydrogen buses in Iceland are part of a “full scale demonstration project” That has been funded with money from outside the country. The government or corporate source of that funding is not immediately apparent.
And then there is this article updated a few days ago that says after 14 years there remains only 3 hydrogen buses in Iceland fueled by one hydrogen station. http://www.worldwatch.org/node/4664
Perhaps I missed something but it is not clear to me what technology the Iceland H2 busses are using. They could be using fuel cells, but they could also be running IC engines on H2. And, as has been pointed out, they are probably getting the H2 by electrolyzing water. That is very inefficient but if electricity is cheap and generated without CO2 emissions the fact that electrolysis is inefficient doesn’t matter.
However, H2 is not exactly problem free. Because it cannot be liquified except at cryogenic temperatures, storing it is difficult. It also tends to embrittle metals and, because of its small molecular size, it is hard to prevent it from escaping. Probably it would be more practical to use NH3 (ammonia) than H2 because NH3 can be liquified at convenient pressures and temperatures making it easier to store and transport. And, NH3 can easily be made from atmospheric N2 and H2 from any convenient source.
There are problems with running engines on NH3 because NH3 is a bit difficult to ignite and it burns slowly. Normal IC engines can be run on NH3, but engines designed to run specifically on NH3 would run better. An engine designed for NH3 would be long-stroke because the slow burning of NH3 would preclude high speed operation. It could be heavily turbocharged because NH3 doesn’t knock easily and the high pressure turbocharging would enable the engine to develop plenty of power at low speeds. The ignition difficulty could be solved by special spark plugs having a longer gap and an ignition system which would deliver a longer duration spark. That could all be done quite easily.
Dimethyl ether (C2H6O) has also been proposed as a fuel. It has been suggested that the carbon could be obtained from atmospheric CO2. How practical that would be I don’t know but surely it would be worth looking into. Engines can run well on dimethyl ether.
It has yet to be determined whether it would be best to use battery electric vehicles or vehicles running on an artificial fuel manufactured by methods that are CO2 free. I suspect that battery EVs will win except for air travel.
Making hydrocarbons from point sources of CO2, e.g., concrete plants, is potentially viable, but doing the same from atmospheric CO2 (400 PPM) isn’t.