Cities famously tend to suffer from congestion, and the congestion tends to be more extreme the bigger a city gets. Every morning, millions of people squeeze into buses and trains, or climb into cars and in turn squeeze into crowded arterial roads to get from their homes to their place of work. Huge amounts of energy are wasted this way, as well as human hours that could have been spent in leisure, social activity or productive work. The cost of computing bumps up GDP, but it is a net loss to the economy, because most people who do it don't want to do it for its own sake — it is a cost to them. Very few cities seem to be able to control that cost.
The reason is this: it's a product of the natural way that cities tend to grow. Cities usually start as confluences on trade routes — in harbours or at crossroads or near some key resource, such as a goldmine. Traders naturally want to locate as close to the confluence as possible, in order to catch as much passing trade as they can. Thus, they crowd together, and where they congregate, property values rise until those living in the area have to move to its ouskirts. People building transport systems are also attracted to the points of congregation, so they build train stations that stop in the town centre, and roads or railways that radiate outwards from it, accelerating the process of concentration. The level of concentration in a thriving city, if uncontrolled, will always be the maximum that is technically possible. Naturally, therefore, someone had to invent the skyscraper, and concentration exploded further. At the same time, people want peace and quiet, and pleasant open spaces to enjoy in their leisure. This motivates them to locate their homes further and further away from the urban centre as transport systems get better and better, and as the city itself grows. There's a kind of vicious circle: the transport system increases in capacity and speed, so the people spread out more, and the average journey time to work stays the same, or even grows. The only limit to journey time is what people can afford, and that's not determined by what people would like to afford, but by competition for jobs. Therefore, if planning policies don't control the tendency, and the city continues to grow, commuting journey times will grow until either there's no time left outside work and commuting for anything besides sleep, or until the transport system is fully congested and cannot expand further.
When a city is planned from scratch, these problems can be avoided entirely. The solution is to enact zoning policies that compel trade to locate in lots of small centres, or (better still) in long, stretched out ribbons instead of one great big blob. Also, a prohibition on the building of skyscrapers is advisable. If some buildings are much taller than others, the likely outcome is that there will be some areas with much higher density than others, and this will create the kinds of traffic flow that lead to congestion. If a strict policy of even density and ribbon-shaped districts is followed, journey times will tend to be short, and congestion can be zero, no matter how big the city gets.
To illustrate with an example: imagine a city whose sprawl covers 5,000 sq. km. (the size of Atlanta), with the commercial centre being a 1,000 sq. km. blob in the middle. Most people wishing to reach the centre will have a journey of more than 15 km., so they'll have to take some kind of transport, placing high demands on infrastructure. Additionally, those near the centre will have to use the transport system any time they want to visit the countryside. Supposing the city were stretched out into a ribbon just two kilometres wide, with the commercial centre being stretched along that middle. In that case, nearly everyone could live within a ten or fifteen minute walk of the city centre, at the same time as living within walking distance of the countryside. The main cause of congestion is thereby completely eliminated, and for many, the reason to own a car also disappears.
If we can replicate that in the planning of Desertopolis, we can cut down the transport energy requirements to below the level we previously estimated we would need, perhaps a very great deal below.
Saturday, March 04, 2006
Thursday, February 23, 2006
A few more points on water and power
If we use stored water as a means to supply electricity at night, we will need extra water, unless we're able to have our upper reservoirs at least 100 metres higher (equivalent of 30 storeys) than our lower ones. (The amount of power generated is a function of the height of the water and the rate of flow.) Such variations in elevation are not at all rare, but it would be possible if we haven't thought about this, for us to buy a large, flat area of land, and then find ourselves doing an inordinate amount of earthworks or tower building to create the water heights we want for power storage.
Aside from the planned Stirling Engineering Systems installations that I referred to earlier, another project using dishes to concentrate heat from the Sun is under way in Australia. The town of Whyalla has set in train an AUS$80 million project to build a solar thermal plant that will also desalinate water, which has been dubbed the Solar Oasis (story also here). After a pilot, it is planned that the project will use 200 giant dishes (much bigger than the SES ones), that power steam turbines, which in turn power a conventional thermal power station. According to the design, sufficient thermal energy will be generated by the dishes to keep the electricity generation going throughout the night. The design of this system was developed by a team at the Australian National University. (More details of the technology can be had from Wizard Power, who are commercializing it.)
Aside from the planned Stirling Engineering Systems installations that I referred to earlier, another project using dishes to concentrate heat from the Sun is under way in Australia. The town of Whyalla has set in train an AUS$80 million project to build a solar thermal plant that will also desalinate water, which has been dubbed the Solar Oasis (story also here). After a pilot, it is planned that the project will use 200 giant dishes (much bigger than the SES ones), that power steam turbines, which in turn power a conventional thermal power station. According to the design, sufficient thermal energy will be generated by the dishes to keep the electricity generation going throughout the night. The design of this system was developed by a team at the Australian National University. (More details of the technology can be had from Wizard Power, who are commercializing it.)
Wednesday, February 15, 2006
The Car is the Devil -- perhaps; Mass and Private Transport Options
Cars are a very convenient way to get around, and since we're building a big city, we people are likely to want to move around in it a lot. It seems that people want "face time", and the techical availability of telecommuting does little to diminish most people's desire to move about physically in space. It would seem, therefore, that we must have good, flexible transport links. However, cars currently run on petrol, and we're trying to imagine a post-petroleum city, so we need alternatives. Electric cars and biodiesel could help. Biodiesel would probably all have to be imported, seeing as arable land is hardly abundant in the Sahara, and electric cars frequently need to be charged, which takes a long time, and so is likely to be an inconvenience, especially as spare electricity is likely to be scarce at night in a solar-powered economy. Without something like nuclear power plants producing lots of spare heat that can be used to economically electrolyse water, a hydrogen economy for vehicles doesn't look feasible.
Therefore, the best option seems to be guided transport, that moves around on tracks and gets its power directly from the grid. Then the draw on power would most be during the day, instead of at night, if we had electric cars with their batteries being charged overnight. This could be trams or trains, but I think there's another alternative that has more promise; it's called PRT (Personal Rapid Transit), and uses tracks, but in stead of big heavy trains following a schedule, has little driverless taxis and lots of stops. Because the gap between cabs can be as small as a second or two, a PRT system can move just as many passengers around as a train or tram system, and it's more convenient for passengers.
According to this Telegraph report, a PRT system is to be built in Heathrow, to start testing in 2008. (More details and pictures here.)
Therefore, the best option seems to be guided transport, that moves around on tracks and gets its power directly from the grid. Then the draw on power would most be during the day, instead of at night, if we had electric cars with their batteries being charged overnight. This could be trams or trains, but I think there's another alternative that has more promise; it's called PRT (Personal Rapid Transit), and uses tracks, but in stead of big heavy trains following a schedule, has little driverless taxis and lots of stops. Because the gap between cabs can be as small as a second or two, a PRT system can move just as many passengers around as a train or tram system, and it's more convenient for passengers.
According to this Telegraph report, a PRT system is to be built in Heathrow, to start testing in 2008. (More details and pictures here.)
Water, water, nowhere—how do we get some?
There are no permanent rivers and lakes in the Sahara that can be tapped for our city's water supply. There's groundwater, but nowhere near enough for our city. So we need to find some, deliver it, and store it, before we can start inviting people to live there.
There are two options: desalination, and icebergs. The icebergs idea is a bit sci-fi, but interesting. The amount of ice that breaks off Antarctica every year, only to melt into the sea unused is so vast, it is mind-boggling. Some of the icebergs are as big as small countries, and they happen to be made of some of the purest water on Earth. People have conceived various creative ways of steering an iceberg (far too big for a mere tugboat) to some coastal destination and then getting it onto land, and they've costed their plans plausibly. However, no-one has actually transported an iceberg yet, so really knowing how feasible and expensive or inexpensive such a project would be is impossible for now. There are some good clues on this site, but for the moment, we'll concentrate on desalination, because desalination idea is here-and-now.
There are numerous desalination plants around the world, and it is not hugely expensive to desalinate water. The standard ways are distillation and reverse osmosis (filtering, basically). Reverse osmosis has become very popular of late, because it is usually more energy efficient. However, as we're in a hot desert, we might let the sun do our distilling for us. Solar stills can distill 5-6 litres per sq m day (less in less sunny climes), using free energy. A square kilometer will provide 5-6,000,000 litres.
Our city will be growing by 2,000,000 people a year (as we aim that it should reach a population of 100 million in 50 years), and we want to get their water to the new residents before they arrive. So, every year we need to desalinate (or melt) enough water for 2,000,000 people, at least.
How much is enough? World bank data offer the following figures for the US in 2000:
According to the World Bank, the US made use of the following quantities of water in the year 2000:
We could use these as a guide. Because the Sahara is drier than the US, we'll choose a slightly higher number -- 1.5 kilolitres per capita per day, which translates into 3,000,000 kilolitres in total per day. Solar desalination would require about a thousand square kilometers, though clever stacking of the solar stills could reduce the amount of land required perhaps a quarter or a fifth of that, so it is a possibility. However, there's the question of what to do with the salt. If the distillation occurs inland (where we already have lots of land), we'll need some way of disposing of the salt (perhaps by burial). If the distillation is to occur on the coast, so that the salt can be returned to the sea, we don't have a lot of land there, and we're relucant to acquire so much.
If we resort to using reverse osmosis, the energy cost of seawater desalination would be about 3 kWh/kL. We'd need the capacity to produce 9 GWh per day. That would require 180,000 solar dishes and 362 sq. km. of land. Just as bad, really.
Whether we desalinate our water or get it from Antarctic icebergs, we need to get it from the coast to our inland city, and this will require a pipeline. The energy cost of doing so will be affected by the distance inland and the height above sea level of our city's reservoirs. Assuming the cost of a water pipeline would be similar to that of an oil pipeline, I looked at some pipelines, such as the Baku-Tbilisi-Ceyhan pipeline so see how much power they used for pumping. From there, I worked out that to pump three million kilolitres a day one thousand kilometres inland would require 43 GWh of power per day, achievable with 2-5 GW of installed capacity (depending on is used). The power would probably be delivered at four pumping stations, 250 km distances apart. Four GW of Stirling engine solar dishes would need 160,000 dishes and 36 sq. km. of land (1GW at each pumping station). It would cost perhaps $12 billion.
Such a project would not be exceptionally large by global standards, but it would be tremendous by regional standards. Indeed, 4 GW is greater than the total installed generating capacity of the entire Sahel region. If, as this city grew, it donated just a small part of its electricity and water to the rest of the region, it could end poverty in that region for ever. In relation to our central point, our city could indeed be supplied with enough water and power for everyone, without having to rely on any petroleum.
After the city was built, we would still have to keep desalinating water, because even with a carefully designed system that recycled as much water as possible, a certain amount would be lost through evaporation. We might even need to increase the flow somewhat, to compensate for losses. There'd be no danger of the sea running dry as a result of this process, even if it continued for millions of years, as the water that escaped from the city would enter the hydrologic cycle and eventually wind up back in the sea.
There are two options: desalination, and icebergs. The icebergs idea is a bit sci-fi, but interesting. The amount of ice that breaks off Antarctica every year, only to melt into the sea unused is so vast, it is mind-boggling. Some of the icebergs are as big as small countries, and they happen to be made of some of the purest water on Earth. People have conceived various creative ways of steering an iceberg (far too big for a mere tugboat) to some coastal destination and then getting it onto land, and they've costed their plans plausibly. However, no-one has actually transported an iceberg yet, so really knowing how feasible and expensive or inexpensive such a project would be is impossible for now. There are some good clues on this site, but for the moment, we'll concentrate on desalination, because desalination idea is here-and-now.
There are numerous desalination plants around the world, and it is not hugely expensive to desalinate water. The standard ways are distillation and reverse osmosis (filtering, basically). Reverse osmosis has become very popular of late, because it is usually more energy efficient. However, as we're in a hot desert, we might let the sun do our distilling for us. Solar stills can distill 5-6 litres per sq m day (less in less sunny climes), using free energy. A square kilometer will provide 5-6,000,000 litres.
Our city will be growing by 2,000,000 people a year (as we aim that it should reach a population of 100 million in 50 years), and we want to get their water to the new residents before they arrive. So, every year we need to desalinate (or melt) enough water for 2,000,000 people, at least.
How much is enough? World bank data offer the following figures for the US in 2000:
According to the World Bank, the US made use of the following quantities of water in the year 2000:
| type of use | billion kilolitres | per capita, kilolitres | per capita per day, litres |
|---|---|---|---|
| Industrial | 291.0 | 896 | 2,448 |
| Domestic | 35.8 | 121 | 331 |
| Agricultural | 120.9 | 410 | 1,120 |
| All uses | 447.7 | 1518 | 1,223 |
We could use these as a guide. Because the Sahara is drier than the US, we'll choose a slightly higher number -- 1.5 kilolitres per capita per day, which translates into 3,000,000 kilolitres in total per day. Solar desalination would require about a thousand square kilometers, though clever stacking of the solar stills could reduce the amount of land required perhaps a quarter or a fifth of that, so it is a possibility. However, there's the question of what to do with the salt. If the distillation occurs inland (where we already have lots of land), we'll need some way of disposing of the salt (perhaps by burial). If the distillation is to occur on the coast, so that the salt can be returned to the sea, we don't have a lot of land there, and we're relucant to acquire so much.
If we resort to using reverse osmosis, the energy cost of seawater desalination would be about 3 kWh/kL. We'd need the capacity to produce 9 GWh per day. That would require 180,000 solar dishes and 362 sq. km. of land. Just as bad, really.
Whether we desalinate our water or get it from Antarctic icebergs, we need to get it from the coast to our inland city, and this will require a pipeline. The energy cost of doing so will be affected by the distance inland and the height above sea level of our city's reservoirs. Assuming the cost of a water pipeline would be similar to that of an oil pipeline, I looked at some pipelines, such as the Baku-Tbilisi-Ceyhan pipeline so see how much power they used for pumping. From there, I worked out that to pump three million kilolitres a day one thousand kilometres inland would require 43 GWh of power per day, achievable with 2-5 GW of installed capacity (depending on is used). The power would probably be delivered at four pumping stations, 250 km distances apart. Four GW of Stirling engine solar dishes would need 160,000 dishes and 36 sq. km. of land (1GW at each pumping station). It would cost perhaps $12 billion.
Such a project would not be exceptionally large by global standards, but it would be tremendous by regional standards. Indeed, 4 GW is greater than the total installed generating capacity of the entire Sahel region. If, as this city grew, it donated just a small part of its electricity and water to the rest of the region, it could end poverty in that region for ever. In relation to our central point, our city could indeed be supplied with enough water and power for everyone, without having to rely on any petroleum.
After the city was built, we would still have to keep desalinating water, because even with a carefully designed system that recycled as much water as possible, a certain amount would be lost through evaporation. We might even need to increase the flow somewhat, to compensate for losses. There'd be no danger of the sea running dry as a result of this process, even if it continued for millions of years, as the water that escaped from the city would enter the hydrologic cycle and eventually wind up back in the sea.
Power at night in the city of solar light
When the Sun goes down, the solar dishes stop generating power (photovoltaic systems stop working immediately, but solar thermal systems may continue working for some time after the sunlight has gone, because of the heat stored up). That presents the problem of storing the electricity generated during the day so that it can be used at night. It's especially important if people are likely to have plug-in battery electric vehicles that they charge overnight, for commuting by day.
Several well-tried solutions exist, one being pumped-storage hydroelectricity. Water would be pumped from a low reservoir to a high reservoir during the day, and then allowed to fall back into the low reservoir at night, driving turbines as it went. We haven't worked out where our water's going to come from yet, but we will have some, that much is certain. 80% of the electricity used to pump the water is recovered via the turbine.
If large numbers of people are charging battery-powered vehicles at night, we'll be cutting it a bit fine on the energy-for-transport front, so we'd want to avoid that situation. One way is to charge more for electricity at night -- the opposite of what obtains in most cities -- so that people are encouraged to draw from the grid during the day time rather than at night, whenever possible.
Other strategies involve types of transport systems and infrastructure, and planning that minimises commuting. These, though, are for another day.
Several well-tried solutions exist, one being pumped-storage hydroelectricity. Water would be pumped from a low reservoir to a high reservoir during the day, and then allowed to fall back into the low reservoir at night, driving turbines as it went. We haven't worked out where our water's going to come from yet, but we will have some, that much is certain. 80% of the electricity used to pump the water is recovered via the turbine.
If large numbers of people are charging battery-powered vehicles at night, we'll be cutting it a bit fine on the energy-for-transport front, so we'd want to avoid that situation. One way is to charge more for electricity at night -- the opposite of what obtains in most cities -- so that people are encouraged to draw from the grid during the day time rather than at night, whenever possible.
Other strategies involve types of transport systems and infrastructure, and planning that minimises commuting. These, though, are for another day.
Where will the energy come from?
Fossil fuels are running out (that's a founding assumption), so they're out of the question. There's no hydro potential in the Malian desert, and geothermal doesn't seem to hold much promise, either. Bootstrapping with biomass in a desert is a non-starter. Wind is abundant on the West coast of the Sahara, but much less so inland. Therefore, the obvious, and perhaps only, options are solar and nuclear. (Niger, next door, is a well-known source of "yellow cake", as raw uranium from the Earth is known.)
The City Corporation that has been established to develop this project has only a few billion budgeted to kick-start the city, and it is naturally reluctant to spend the whole sum on a nuclear power station. Therefore, solar is all that's left. The alternatives are between solar thermal and solar photovoltaics.
At the moment, photovoltaics are much more expensive and use much more land than solar thermal. Regardless of whether we choose photovoltaics or solar thermal, land could be saved by building high scaffolds and suspending either thermal concentrators or photovoltaic panels off them (taking care to arrange the panels or dishes so they cast little or no shadow on each other). Towers containing dishes or panels arranged radially or spirally like leaves on a stem could reduce the amount of land needed for a given amount of power by as much as 90%. It's a question of trading land costs for infrastructure costs. If we grow desperate for land, we'll build those towers. For now, though, we'll just arrange our panels or concentrators on the ground in the conventional manner.
Based on an installation in Brockton, Massachusetts, in which 500kW are generated on a 27 acre plot, I calculate that a photovoltaic array will yield 4.576 MW per sq. km. Meanwhile, from news of a big project in California, we can get 27.45 MW per sq. km. if we employ thermal concentrators and convert the heat to electricity using Stirling engines. The dishes used in the California project each have a capacity of 25kW.
If we assume they work at full capacity for eight hours a day, 365 days a year, each will generate 73MWh per year. (Actually, they'll probably work for more like 11 hours a day at full capacity in the Sahara, and while a photovoltaic system will stop generating as soon as the light drops below a certain level, a thermal system will continue working for a while after it gets dark, because of the heat stored in the system.)
The city needs 1100 TWh plus a further 800 TWh of electricity to replace the use of petrol-driven vehicles -- 1,900 TWh in all.
To generate 1,900 TWh in a year -- the sum needed by 100 million people to enjoy the high standard of living they feel they deserve, we'll need 26 million dishes, giving a total capacity of 650 gigawatts. The California project indicates that we can fit 1100 such dishes in one square kilometre. Therefore, we need to cover 23,700 sq. km. (9,266 sq. miles) in order to produce the power we need. If the dishes are all organized into one big, square field, it will be 153 km (94 miles) on each side.
Since Desertopolis is 40,000 sq. km., if we reserve the land exclusively for the solar collectors, we'll lose 40% of our land to solar dishes, and have just 26,300 sq. km left, unless we put the dishes on the roofs of buildings, or put other useful things in the ground under them. In that case, we'd lose almost no land. Either way, we've seen that there's enough land available to generate all the power desired.
How much will it cost? Stirling Engineering systems say that if their solar dishes are mass produced, they can make them for $80,000, "or possibly $50,000", apiece. If we assume $70,000 as a compromise, we need $1,820 billion to acquire the 11 million dishes needed to power the city. However, we don't have to get them all at once. If we buy 520,000 units (6.25 GW capacity) a year, at a cost of $36.4 billion, as we grow the city, we'll have it all done in fifty years.
Expensive, but doable, if you have the budget of a fairly large country, which you have to have, if you're planning to equip the population of a fairly large country with all its energy needs.
Are there enough materials in the world to make so many solar dishes? Certainly, yes. They're not made from any exotic materials -- just boring stuff like steel and aluminium, and each uses about as much material as a couple of motor cars, or perhaps one large car. All we need is metal equivalent to 52 million cars -- about a third the number of cars there are in the USA.
It looks as if we may have the energy supply cracked, apart from one small problem, namely that solar energy doesn't work at night. We'll have to look into that. Meanwhile, there's still the food and water supply to deal with.
The City Corporation that has been established to develop this project has only a few billion budgeted to kick-start the city, and it is naturally reluctant to spend the whole sum on a nuclear power station. Therefore, solar is all that's left. The alternatives are between solar thermal and solar photovoltaics.
At the moment, photovoltaics are much more expensive and use much more land than solar thermal. Regardless of whether we choose photovoltaics or solar thermal, land could be saved by building high scaffolds and suspending either thermal concentrators or photovoltaic panels off them (taking care to arrange the panels or dishes so they cast little or no shadow on each other). Towers containing dishes or panels arranged radially or spirally like leaves on a stem could reduce the amount of land needed for a given amount of power by as much as 90%. It's a question of trading land costs for infrastructure costs. If we grow desperate for land, we'll build those towers. For now, though, we'll just arrange our panels or concentrators on the ground in the conventional manner.
Based on an installation in Brockton, Massachusetts, in which 500kW are generated on a 27 acre plot, I calculate that a photovoltaic array will yield 4.576 MW per sq. km. Meanwhile, from news of a big project in California, we can get 27.45 MW per sq. km. if we employ thermal concentrators and convert the heat to electricity using Stirling engines. The dishes used in the California project each have a capacity of 25kW.
If we assume they work at full capacity for eight hours a day, 365 days a year, each will generate 73MWh per year. (Actually, they'll probably work for more like 11 hours a day at full capacity in the Sahara, and while a photovoltaic system will stop generating as soon as the light drops below a certain level, a thermal system will continue working for a while after it gets dark, because of the heat stored in the system.)
Solar thermal concentrator facing the sun — Image from Sterling Energy Systems
The city needs 1100 TWh plus a further 800 TWh of electricity to replace the use of petrol-driven vehicles -- 1,900 TWh in all.
To generate 1,900 TWh in a year -- the sum needed by 100 million people to enjoy the high standard of living they feel they deserve, we'll need 26 million dishes, giving a total capacity of 650 gigawatts. The California project indicates that we can fit 1100 such dishes in one square kilometre. Therefore, we need to cover 23,700 sq. km. (9,266 sq. miles) in order to produce the power we need. If the dishes are all organized into one big, square field, it will be 153 km (94 miles) on each side.
Since Desertopolis is 40,000 sq. km., if we reserve the land exclusively for the solar collectors, we'll lose 40% of our land to solar dishes, and have just 26,300 sq. km left, unless we put the dishes on the roofs of buildings, or put other useful things in the ground under them. In that case, we'd lose almost no land. Either way, we've seen that there's enough land available to generate all the power desired.
How much will it cost? Stirling Engineering systems say that if their solar dishes are mass produced, they can make them for $80,000, "or possibly $50,000", apiece. If we assume $70,000 as a compromise, we need $1,820 billion to acquire the 11 million dishes needed to power the city. However, we don't have to get them all at once. If we buy 520,000 units (6.25 GW capacity) a year, at a cost of $36.4 billion, as we grow the city, we'll have it all done in fifty years.
Expensive, but doable, if you have the budget of a fairly large country, which you have to have, if you're planning to equip the population of a fairly large country with all its energy needs.
Are there enough materials in the world to make so many solar dishes? Certainly, yes. They're not made from any exotic materials -- just boring stuff like steel and aluminium, and each uses about as much material as a couple of motor cars, or perhaps one large car. All we need is metal equivalent to 52 million cars -- about a third the number of cars there are in the USA.
It looks as if we may have the energy supply cracked, apart from one small problem, namely that solar energy doesn't work at night. We'll have to look into that. Meanwhile, there's still the food and water supply to deal with.
Energy targets for Desertopolis
Bill Dutopia has read that according to surveys, the people of Denmark are the happiest in the world. Therefore, he supposes, if his city can provide physical amenities at least equivalent to those available in Danish cities, it will have all the physical resources needed to ensure a happy population.
According to the CIA World Factbook, Denmark has a population of 5,432,335 (July 2005 estimate), and a per capita GDP of $33,000. Its energy and water needs are as follows:
Electricity consumption: 31.68 billion kWh, which amounts to 5832 kWh per capita.
Oil consumption: 188,300 bbl/day (2003 est.), which amounts to 2012 litres per capita per year.
Natural gas consumption: 5.28 billion cu m (2001 est.) , which amounts to 972 cu m per capita.
Coal isn't mentioned, but presumably nearly all coal, if used at all, is used to generate electricity. A lot of the natural gas is presumably used to provide electricity, too. Let's assume half the natural gas is used for that purpose, and the rest is for heating and cooking. We'll assume that 90% of oil is used for transport, and the rest is used as a raw material for manufacture of, e.g., plastics.
One cubic metre of natural gas translates into 10.6 kWh of electricity. The proportion of natural gas that isn't used for electricity generation (we're assuming half) needs to be converted into kWh, and added to our energy total. It amounts to 5.28/2 * 10.6 kWh = 27.964 billion kWh, or 5151 kWh per capita.
One litre of petrol is equivalent to 9 kWh of electricity (if converted with 100% efficiency). In driving a petrol-engined car, it is converted into motion with about 25% efficiency. Electric vehicles are twice as efficient as petrol, and since there will be no petrol in Desertopolis, we're going to assume we need half as much energy to get people around in our electric buses/cars/whatever as we would have done in petrol-driven vehicles. Currently, Danes use up 16297.2 kWh per capita travelling around in petrol-driven vehicles (if our assumptions are right). Therefore, in our zero-petrol city, the denizens will spend 8,148.6 kWh travelling around in the equivalent electric vehicles, if they move about just as much.
The energy requirements per annum for Desertopolis are as follows, then:
Quite hefty, really.
There's also a need for 201 litres of hydrocarbons per capita per year as a raw material for manufacturing. or 20.1 billion litres for the city as a whole. These will have to be obtained through some chemical or biological process, as there's no petroleum.
According to the CIA World Factbook, Denmark has a population of 5,432,335 (July 2005 estimate), and a per capita GDP of $33,000. Its energy and water needs are as follows:
Electricity consumption: 31.68 billion kWh, which amounts to 5832 kWh per capita.
Oil consumption: 188,300 bbl/day (2003 est.), which amounts to 2012 litres per capita per year.
Natural gas consumption: 5.28 billion cu m (2001 est.) , which amounts to 972 cu m per capita.
Coal isn't mentioned, but presumably nearly all coal, if used at all, is used to generate electricity. A lot of the natural gas is presumably used to provide electricity, too. Let's assume half the natural gas is used for that purpose, and the rest is for heating and cooking. We'll assume that 90% of oil is used for transport, and the rest is used as a raw material for manufacture of, e.g., plastics.
One cubic metre of natural gas translates into 10.6 kWh of electricity. The proportion of natural gas that isn't used for electricity generation (we're assuming half) needs to be converted into kWh, and added to our energy total. It amounts to 5.28/2 * 10.6 kWh = 27.964 billion kWh, or 5151 kWh per capita.
One litre of petrol is equivalent to 9 kWh of electricity (if converted with 100% efficiency). In driving a petrol-engined car, it is converted into motion with about 25% efficiency. Electric vehicles are twice as efficient as petrol, and since there will be no petrol in Desertopolis, we're going to assume we need half as much energy to get people around in our electric buses/cars/whatever as we would have done in petrol-driven vehicles. Currently, Danes use up 16297.2 kWh per capita travelling around in petrol-driven vehicles (if our assumptions are right). Therefore, in our zero-petrol city, the denizens will spend 8,148.6 kWh travelling around in the equivalent electric vehicles, if they move about just as much.
The energy requirements per annum for Desertopolis are as follows, then:
| resource | per capita | total | rounded up |
|---|---|---|---|
| energy for replacement of petroleum in transport | 8,148.6 kWh | 814,860 GWh | 820 TWh |
| energy for other uses | (5832 + 5151) = 10,983 kWh | 1,098,300 GWh | 1,100 TWh |
Quite hefty, really.
There's also a need for 201 litres of hydrocarbons per capita per year as a raw material for manufacturing. or 20.1 billion litres for the city as a whole. These will have to be obtained through some chemical or biological process, as there's no petroleum.
Bill Dutopia's fabulous dream
I wondered, in the climate of all the current talk of "peak oil" and its consequences (some fear the end of civilisation, some think civilisation will survive, but a huge proportion of the world's population will die in a catastrophic famine), can it be demonstrated that large populations can enjoy a high standard of living without petroleum?
This led me to imagine the following scenario:
An eccentric billionaire (we'll call him Bill Dutopia) has acquired a large tract of land dirt cheap in Mali, smack dab in the middle of the Sahara Desert. It is a long rectangle, 100 by 400 km in size (one thirtieth of Mali, one tenth the size of California, one sixth the size of the UK, and slightly smaller than Denmark), and he has set himself the ambition of building on it the biggest city in the world. It will house a hundred million people. Bill Dutopia sees himself as a latter day Baron Hausmann, or Christopher Wren, so, naturally, he intends that his city will be a utopia, with beautiful architecture and excellent amenities for everyone. He also wants to offer a developed-world standard of living. Last, but not least, he wants the city to be self-sustaining without petroleum.
The city will therefore have to be a miracle city, because at the moment, all he's got on his plot of land are a lot of sunlight, fresh air, and sand. Can he build his city?
If he can, then ninety such cities built in desert sites around the world would be sufficient to accommodate the nine billion population that the UN says are likely to populate the Earth come 2050, and keep them living well in perpetuity. If Bill's city can be built and sustained, then there's no reason to be gloomy about peak oil.
Let's Christen the city Desertopolis.
This led me to imagine the following scenario:
An eccentric billionaire (we'll call him Bill Dutopia) has acquired a large tract of land dirt cheap in Mali, smack dab in the middle of the Sahara Desert. It is a long rectangle, 100 by 400 km in size (one thirtieth of Mali, one tenth the size of California, one sixth the size of the UK, and slightly smaller than Denmark), and he has set himself the ambition of building on it the biggest city in the world. It will house a hundred million people. Bill Dutopia sees himself as a latter day Baron Hausmann, or Christopher Wren, so, naturally, he intends that his city will be a utopia, with beautiful architecture and excellent amenities for everyone. He also wants to offer a developed-world standard of living. Last, but not least, he wants the city to be self-sustaining without petroleum.
The city will therefore have to be a miracle city, because at the moment, all he's got on his plot of land are a lot of sunlight, fresh air, and sand. Can he build his city?
If he can, then ninety such cities built in desert sites around the world would be sufficient to accommodate the nine billion population that the UN says are likely to populate the Earth come 2050, and keep them living well in perpetuity. If Bill's city can be built and sustained, then there's no reason to be gloomy about peak oil.
Let's Christen the city Desertopolis.
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