All posts by John Shoesmith

About John Shoesmith

I'm an engineer with a strong interest in environmental issues.

Can Nuclear Power help save the Rain Forests?

Energy, Nature, , ,

This is my latest look at what life might be like in 2050. It looks at the use of nuclear power, a topic that I have hesitated to cover because it causes so much division among those who are concerned to protect the planet. However it is an important option for 2050, which is likely to be required unless our energy use falls significantly. I apologise for the sketch, I am taking lessons but progress is slow!

A nuclear station near a rain forest
A nuclear station near a rain forest

A power station comes into view on a tropical coast in 2050. It is one of many nuclear stations of various types and sizes that have been built  over the past 30 years.

There has been a big expansion in nuclear power because the amount of energy required by people on the planet is so large. The poorer countries in the world have all become richer and have energy requirements of their own. Transport is electric, as is all heating, so that electricity demand has soared.

There are of course major renewable installations as well. Large blocks of the Sahara desert, the Australian desert, and the North American deserts are covered in solar panels and solar concentrators for power generation. There are many floating wind turbines at sea. There have been huge strides in cutting energy use, many of which I have covered previously, such as the trend to live in cities and to use community transport rather than individual cars. However, despite these changes, the growing wealth and population of the planet mean that energy demand remains high and that nuclear power is required to meet it.

Back in 2014 there was a strong aversion to nuclear power. Many people were terrified of it. There had been an accident in Japan that contaminated a stretch of land and caused it to be evacuated. That in turn led to decisions by Germany and France to shut perfectly sound nuclear stations. The somewhat idealistic intent was to replace the nuclear stations with renewables but this proved physically impossible. The outcome was therefore an increased burning of coal and the burning of  more and more bio-fuels.

Back then bio-fuel was seen as  a useful way to generate electricity and power cars. It was obtainable from woodlands or from crop wastes so there was little impact on overall food markets. However as it began to be used more these sources reached capacity and bio crops began to be grown on agricultural land – land that was already under pressure from the growing demand for food. To meet the combined demand for food and bio-fuel more and more wild spaces were taken into agricultural use. Some of that land was rain forest. Eventually the demand for bio-fuel was brought under control by building large solar plants in the desert and by building more nuclear plants.

How much land could be saved by nuclear plants? A large plant like this produces the same output as 2/3 of Wales would produce if it was entirely devoted to growing bio-fuel. Rain forest areas can be more productive because they are hotter and wetter, so the area saved is rather smaller, but it is still around a quarter of Wales, three times the area of Greater London or 50 times the area of Manhattan for each large nuclear plant. For an explanation look below, underneath the poll.

Why can’t this happen now? Firstly because many green organisations fiercely oppose nuclear power. More and more people are questioning their position, but as yet there is little sign that they are changing.

Secondly nuclear power ideally needs some intense development. Most of the current investment in nuclear development is devoted to waste reprocessing and to the long term aim of making a nuclear fusion plant. We need Research and Development focused on developing plants that have lower costs, are inherently robust against natural disasters, and are quick to build. .

Explanatory Note

Suppose we compare this typical nuclear station against a bio-fuelled power station of the same output. What area of land would it take to supply the bio-fuelled station?

Assuming that we grow the best crops, process them well and burn them in the best power station, the output we might expect in Europe or North America is around 0.2 Watts for each square metre that is devoted to growing crops, on average around the year. This figure is taken from Ref. 1, which contains a full explanation. It may look small but crops grow quite slowly and the plant material needs to be converted to electricity, a process that is at best around 50% efficient.

Now how much power can the reactor produce? Let us assume that it is similar in size to the reactors planned at Hinkley Point in the UK. The two reactors on that site can produce, on average after allowing for shutdowns, nearly 3000 Megawatts.

Taking the figure of 0.2 Watts/square metre, the output from the nuclear plant therefore equates to the bio-fuel grown on 14,400 square kilometres of land, which is 5,560 square miles. That is an area nine times greater than Greater London, 24 times greater than Singapore, and 165 times greater than Manhattan. It is a square block of land 120 km (74 miles) across. It is equivalent to 2/3rds of Wales saved by this one nuclear station alone. Quite a lot!

What happens if we grow our crops in a hot, wet place? We can get more plant material out, perhaps three times more. That means that this station is worth around three Greater London’s worth of rain forest.

 

Will Robot Bikes bring home the bacon?

Lifestyle, Transport, , , , , , ,
The robot bikes arrive!
The robot bikes arrive!

This post looks at the rather crazy sounding idea of robot bikes, with no rider. They are however technically feasible given the rate of advance in computing and would have many convenience, cost, and environmental advantages. As usual I’ve tried to liven the technical stuff up with a story.

Chloe has thrown a surprise barbecue. Some friends just called to say that they were in the area and since it is a nice day she suggested a barbecue. She lives in the country, twenty minutes from the nearest butcher. She called the butcher an hour ago and they promised to deliver.

The robot bike has just arrived. She unloads the meat while her partner fires up the barbecue. A second bike arrives with the bread, salad and drinks.

These bikes have no rider and navigate the narrow country lanes at safe speeds. They do not need to go fast because they carry no driver charging time by the hour. They can cope with potholes and if they need to stop they simply put their feet on the ground. They are electrically powered, and because they are so light (the heaviest thing on a bike is normally the rider), they use little energy to get up hills. Their energy consumption is around one tenth of that used by an electric car, which is itself much more energy efficient than a diesel. They are the lowest cost way to deliver goods.

In 2050 they are common. They have transformed some parts of the world, notably Africa, by their ability to deliver drugs, food, and equipment across rough roads using only locally generated solar power to recharge their batteries. There are many cities around the world where the roads are simply too small and crowded for cars and vans, and where these robot bikes  are much easier to accommodate.

Why can’t this happen now? Obviously self-driving cars are becoming available. Robot bikes are a further technical challenge but they can be built. A Chinese company is starting their development and some US companies are looking at them for military applications.

Can Driverless Cars cut journey times?

Future Cities, Transport, , , , ,
A Self Driving City Car
A Self Driving City Car

My last post looked at how driverless cars will benefit the disabled. This post looks their wider benefits.

Driverless cars will be ideally suited to small cities and towns. They will permit a fast low energy transport system without the heavy investment required to build a  subway, a tram system, or new roads.

Most cars will be owned by the local community and will be picked up from parking areas when needed. Electronic personal assistants will show users where the nearest available car is parked. The battery powered cars will be recharged when they are parked via inductive loops in the road. There will be no need for wires to be connected. If a car does not have adequate charge for the requested journey the user will be directed to another. The frequent charging points will mean that a large battery is not required, reducing weight and the resources involved in battery manufacture.

The cars will be activated by voice, keypad, or card. Electronic personal assistants will also be able to direct the cars. Customers will be automatically charged for each journey.

Privately owned cars will also have a self-drive capability by 2050, which will be used when they are in towns.

The cars will travel relatively slowly in town, but nevertheless journey times will be shorter than existing cars because they will talk to a central computer and, for example, select their route and schedule their arrival at junctions so that they do not need to stop. A further speed benefit is that there will be no need to waste time seeking a parking spot.

Once they are underway they will be able to group together to form trains, so that they take less road space in towns and have lower wind resistance, just like road racing cycles. They will be able to do this because they will communicate, telling each other of hazards ahead. Each car will be continually monitored and will be taken out of service at the first warning of any fault.

Accidents will be rare. The sensors on these cars will never tire or be distracted. They will detect cyclists and pedestrians and take action to avoid them if required. The cars will always drive at a safe speed. They will talk to each other to avoid misunderstandings.

Cars will be lightweight with no need for seat belts, airbags, or crumple zones because accidents will be so rare. Engines will be relatively small because the cars rarely need to accelerate and because the lightweight cars will not need much power to climb hills. There will be no need for a steering wheel, dashboard, windscreen wipers and mirrors.

Inside the car arrangements will vary depending on design. I think it would be good if the seats face each other, as shown. Each seat could then be folded up allowing the car to transport wheelchair users, baby buggies, or large items. Parents will be better able to supervise their children if they sit facing them.

Parking in town centres will be much easier because each car will be shorter, and because cars will not be left parked while their owners work or shop. They will be taken by another user, or driven empty out of the town centre to wait and recharge elsewhere.

If new road space is required it can be found by making lanes narrower because these cars will drive very accurately. If necessary additional small flyovers or tunnels could be built  for these cars only. Using these techniques it will be possible to provide faster journey times while increasing the volume of people carried.

The system will permit a higher standard of life for the blind, for people with other disabilities, for the elderly, for those who cannot afford a car, and for those too young to be able to drive. It will also eliminate noise and pollution from town centres, producing health benefits.

They will use less energy than existing cars because they will be lighter, will need to accelerate far less frequently, and will use electrical power rather than a fossil fuelled engine.

Much larger energy savings will come indirectly. Far fewer cars will be needed, cutting down resources used for their manufacture. The system will link well with trains, making public transport much more convenient and increasing its use.

Why can’t this be done now? The basic self driving technology is under development by Google and others.  Advanced batteries already exist that could give these cars an adequate range for use in cities. The ULTRA system, in service in the UK, shows some of these attributes though it operates on a dedicated track.

There are some serious barriers to overcome before the widespread use depicted here is possible. For example cars that lack accident defences cannot easily be used alongside cars or lorries that are under conventional human control. Initial application may need to be in already pedestrianized areas, in dedicated lanes on existing roads, or on new flyovers. Alternatively these vehicles could retain some accident defences initially. Wider use may need to wait until self-driving capability is commonplace, perhaps around 2030.

Insurance is also a key issue – deciding who is at fault if there is an accident. This question is being discussed in the USA at present. Ultimately however these cars should be easier to insure than a human driver because accidents will be rarer.

 

 

 

 

 

Can Driverless Cars help people with disabilities?

Future Cities, Lifestyle, Transport, , , , , ,
How driverless cars can bring a fairer society
How driverless cars can bring a fairer society

Bill is 98. Lots of people are as old as that old in 2050. He is independent, but walks slowly and his eyesight isn’t great. He lives in a city, as most people do in 2050. He fancies a coffee and sets off. When he gets to the nearest road he simply steps off the pavement.

A camera has been set up near his home to watch for this type of incident, which is common because there are many old people and children in the area. It broadcasts a warning. Two cars are approaching, under automatic control. They hear the warning, and slow down slightly so that Bill can get across in front of them.

The first car contains four people who are heading out for a game of wheelchair tennis. The second contains a blind person and her child. She simply got into the car and told it where she wanted to go.

In 2050 the old, the disabled and those unable to drive will have much more satisfying lives. The driverless car will allow them to live normally, no longer imprisoned in their homes or dependent on others to take them where they want to go.

Why can’t this be done now? Well, of course this technology is being developed by Google and others. It is important to allow development to proceed rapidly because these cars will bring a wide range of benefits.

What is an individual’s fair share of the earth’s resources?

Ethics, Lifestyle, ,

This post looks at the role of religious leaders in protecting the planet.

The Archbishop's funeral

Jim looks at his screen. It is the funeral of Archbishop Inuga, who lived from 1970 to 2050. Her coffin lies covered in flowers while the world’s leaders look on. She was a leader in the environmental movement, the person who drove through the new ethics on which so much subsequent political action was based. She insisted that religious leaders should turn their attention away from the past and instead focus on the issues of the 21st century.

Her first great contribution was to state that it is wrong to destroy the planet for our successors. Few people opposed this general statement, but she gave it greater force by consistently restating it. She said that if we produce children we have an absolute moral obligation to ensure that they have the means to live. They have a right to a habitable planet.

Then she took her argument a stage further. She asked how that general obligation should be translated into personal action. What were the moral responsibilities of each individual?

She quoted “Love your neighbour as yourself” and the story of the Good Samaritan which explains that everyone is a neighbour, irrespective of race or religion. She said that it was therefore morally wrong for any individual to take an unsustainable share of the earth’s resources and thus damage the lives of future generations. Her thinking helped to provide a firm ethical foundation for action on climate change.

She angered many people. The rich saw her as a threat to their lifestyles. She pointed out that they were welcome to retain their motor yachts and other toys provided that they were built and powered sustainably. She pointed out that the rich had the money to develop the required technology. Major companies feared the effects on their business. She pointed out that they could adapt (and in due course most of them did). She had powerful enemies but her position provided her with both protection and a platform for her views.

She said that her church members should lead the way by living sustainable lives and provided firm and sensible guidance on what that would involve. She gained the support of rich and powerful church members who used their influence to gather public and political support. Politicians picked up the argument. Other faith groups registered their support. Public opinion swung in favour of action and the lifestyle changes that would be involved.

Jim joined millions of others, of all religions and none, in signifying his respect by contributing to her chosen charity. He recognised that without her, and the many others who had supported her and taken her ideas further, the earth would be a far less hopeful place in 2050.

Why can’t this happen? Obviously it can. I illustrated this with a fictitious Christian leader, but it could equally have been led by another faith, an international politician, an academic, or a celebrity. What I am sure of is that there is a need for moral leadership to come from somewhere.

Can Bikes be cool?

Transport, ,

This post is about electric bikes. They work by helping with the effort of pedalling. Hills are no longer a problem because little effort is required. They can play a big part in a green future. I apologise for the picture. It seems very hard to draw a bike and rider, and I don’t think I’ve found the best way of colouring it using PAINT.net. Any advice is welcome.

Cycling from the shops
Cycling from the shops

It is 2050. Pete is a young professional who lives at the top of a hill. The local town, including the shops, the railway, and the restaurants are at the bottom. After shopping in the town he loads his beer into the panniers, and cycles easily home up the hill. When he gets home he isn’t even sweating.

He isn’t sweating because the electric bike helped him up the hill, but it didn’t need much energy to do that. The energy used to go uphill depends on the weight of a vehicle. His body, bike and groceries weigh under 100 kg. A car weighs over 10 times as much. His round trip therefore consumed less than a tenth of the energy used by a car, and since that small amount of energy can be easily obtained from carbon free sources his carbon emissions are effectively zero.

Pete knows all this and so do his friends. He cycles because they would look down on him if he didn’t.  It is uncool to emit carbon without good reason.  He loves being seen around on his bike.

Pete also uses the bike because it is quicker. He lives a mile (1.6 kilometres) from the shops. His bike will do that distance in around 5 minutes. A car would do the actual journey a little quicker, but he would have to mess around finding a car parking space and might have to park away from the shops.

Isn’t it cool to bike now? Only with the right gear and with a carbon fibre bike. That sort of thing is fine as recreation but not if you are cycling with a purpose – to go to the shops, to the pub, or the gym. The time required to put the kit on is too great, the kit looks odd in a supermarket, and the  bike is too costly to leave around.

We need to make it cool to just get on a simple bike and go, wearing normal clothes.  The bike needs space to carry stuff. The gear needs to be practical. It shouldn’t be necessary to have a shower when you get home. The coolness needs to attach to the fact that such a journey protects the planet and is less hazardous to others than a car.

There are some other factors to overcome if bike use is to spread, notably fear of traffic. Councils can therefore help. 20 mph limits are bike friendly because cars overtake less often and more slowly. Junctions need to be designed to be safe for bikes. Road layouts need to ensure that drivers, cyclists and pedestrians can exist in harmony.

Most of all maybe we need a publicity campaign. Celebrities need to be seen cycling on ordinary bikes in everyday clothes. Adverts need to show people how to use an everyday bike – how to carry shopping, how to make sure the bike isn’t stolen. Most of all we need people to understand how much carbon is emitted by cars, and that it is socially unacceptable for a healthy person to use a car when there are low energy alternatives.

 

Will Future Cities be Linear (Issue 2)

Future Cities, , , ,

Some time ago I produced some pictures of a linear city. It looked rather like a huge greenhouse and attracted some criticism. These pictures show a modified city with separate buildings, town centres and rather more variety. I hope they are self-explanatory.

Just like the earlier version this city copies Manhattan. It is only 2 miles wide but it is as long as required.

The aim is to house millions of people but ensure that none are more than a mile from open countryside. Public transport is provided in the form of trams and trains. Cycleways are built into the city from the outset. Housing density is high so that distances are short. Energy consumption on travel and home heating will be less than 20% of current UK average levels. At that level renewable energy could meet the need, making the city effectively zero carbon.

The Central Street
The Central Street

 

City Plan
City Plan
City Plan showing Tram stops and local towns
City Plan showing Tram stops and local towns
How roads would be organised
How roads would be organised

 

 

The Edge of the City
The Edge of the City
The Centre of a Local Town
The Centre of a Local Town

Can the Deserts power us?

Energy, , ,
The African Coast in 2050
The African Coast in 2050

The picture is on the North-West coast of Africa in 2050. Large ships are loading fuels for export across the world. In the distance smaller ships are loading specialist chemicals and bringing feedstock for processes.

Inland, across the 5000 kilometre wide Sahara desert, huge solar power stations are in action. Some use solar cells, others store heat and use it to make power for 24 hours a day, others generate hydrogen. Near the Atlantic coast, where access is available for large ships, industrial plants use that hydrogen and electricity. The output is chemicals of various types and transport fuels for cars, ships and planes.

Mauritania, which is on this coast, is now one of the most prosperous countries in the world. Its development from one of the world’s poorest countries was as sudden as the oil boom that transformed the Persian Gulf in the twentieth century. It boasts cities built by the best architects. Its citizens own the top soccer teams.  Its population has grown as it has attracted people from across Africa and the brightest and best from across the planet.

The abundance of electricity has attracted other industries both to Mauritania and to its neighbours. Nigeria is now a top manufacturing country and has remained prosperous even though there is little demand for its oil.

This is not the only such industrial site in the world. There are others in Australia, the Southern USA, Mexico, Namibia, the Middle East, India and China.

The North African countries that face the Mediterranean also generate electricity and hydrogen but their prime market is direct sales to Europe. Half of Europe’s electricity supply comes from North Africa.

Why can’t this happen now? Fuels produced this way are more costly than fossil fuels. Opinions differ on when the cost of energy from renewable sources will fall far enough to make them competitive. My view is that renewables may be more costly than fossil fuels for many years. The cost of renewables is falling, but not quickly enough. There is more than enough fossil fuel available to destroy the planet.

Isn’t solar electricity becoming competitive now? Well I keep reading that it is, but I suspect that doesn’t include the costs of the kit required to turn an intermittent supply during the middle part of the day into a 24 hour supply wherever it is needed. I’d be very pleased to be proved wrong.

Can’t we increase the price of fossil fuels to deter their use? Taxes on fossil fuel, or charges on fuel producers will always be politically unpopular. They make fuel expensive. They leave the poor unable to heat their homes or travel to work while the rich can still afford tons of fossil fuel for their super-yachts.

The most important issue in bringing about a sustainable economy is to find an acceptable financial mechanism to drive it. The Qtax is one option. It directly measures the environmental degradation caused by each individual. It does not prevent the rich from owning super-yachts, but it punishes them financially if they use fossil fuels to build or propel them. The rich will therefore drive development of sustainable technologies.

Why make fuels? Won’t everything be electric in 2050? Many things will be electric, because it is efficient to use electricity directly, but liquid fuels like petrol are much more energy dense than even the best battery. Hydrogen gas is another potential fuel. It can be used directly as a fuel but it tends to work out heavier than a liquid fuel because of the heavy containers needed to store it. There are therefore many applications where range, weight and power requirements will dictate the use of a liquid fuel.

Why not make liquid fuels from plant materials? That is done at present but the amount that can be made is limited by the space available to grow plants and the fact that we need plants for food. In theory much more could be produced using solar power in deserts.

Is it possible to make liquid fuels this way? See Wikipedia for the state of development of these processes. The cost and efficiency of these conversion processes will be crucial factors in deciding whether they are widely used.

Isn’t it environmentally destructive to industrialise the desert? Yes, to an extent it is. Humans have to make judgements about which parts of the planet they want to sacrifice in the interests of protecting the remainder. The Qtax gives a mechanism to drive the least damaging forms of planetary degradation. Desert power production to meet all of the world’s energy requirements would use much less than half of the available desert, There will still be vast tracts left empty. See SEWTHA for details of how much energy can be produced in this way.

Is desert solar the obvious answer to all our problems? It looks very promising, and will probably be a big part of the future. There are however potential political questions that could affect the reliability of supply. The cost of this energy will be higher than fossil fuels, and if it is too high only the wealthy will be able to afford it. It is worth developing other energy options until those questions are answered.

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Can we find a better Work-Life Balance?

Lifestyle, , , , , ,
Asha sorts things out.
Asha sorts things out.

Asha works for a software company. It is a fast moving business where competition is fierce. She is a project manager, a demanding job. She has two children, one aged 4, the other 7.

Her company produces personal software that measures food intake by continuously analysing images taken by the wearer’s spectacles. It isn’t too hard to measure piles of potatoes and meat, or to understand the contents of processed food since that is available from the producers. However one of the weak areas of all food intake software is added salt. People shake salt pots onto their food, and it is very hard to know exactly how much has been added. Likewise cooks casually toss salt into home cooked food.

They have been working with a University in Nairobi to solve this problem. The software analyses images in very fast time to assess the number and size of the grains of salt.  They are having problems. She needs the software to be in use by October 2050 to combat other organisations that are beginning to take their customers.

Asha gathers her team around a conference board. The Professor and Researcher in Nairobi explain how work is going. Her own team look for answers. The conference board listens and displays relevant information and its own ideas and questions. It searches the internet for relevant research and announcements. People move ideas around in 3 dimensions on the board. Costs and timescales of various options are generated and compared. Asha can look her team members in the eye to assess their level of assurance and commitment. Eventually they agree a way ahead.

At 3.15  Asha and her entire team go home, because an adult education group has booked the office. Their working day follows a pattern which is quite common in 2050.  They start the day by working at home. They go to the office from 9.15 until 3.15. They work again from home at some point during most evenings. It is a working day that leaves time for the family. The early morning and late evening sessions allow conversations with those in other time-zones. They also allow time for continuing professional development which is key to business success in 2050.

Asha lives in one of the new linear cities. Her commute to work is only 10 minutes by bike. The children go to a nearby school so it is easy to collect them. Her partner works similar hours in another company. If they worked in an 8 ’til 6 company they would be disadvantaged because they would be considered to be part-time. Organisations in 2050 offer varied working patterns to attract the best staff. Her company attracts people in their thirties and forties with growing families, a rich pool of talent.

Why can’t this happen now? To an extent, it is. However change will occur much more rapidly in future, driven by the fact that the world will become more complex and talent like Asha’s will be able to dictate employment terms.

p.s. I’m sorry about the picture, it is harder than I thought to sketch people!

 

Can we Employ Everyone in a Low Carbon Economy?

Lifestyle, ,
Jim talks about decorating a lounge
Jim talks about decorating a lounge

Jim visits his friend Arnav in the nearby city. Arnav has just moved to a new flat with great views over the surrounding countryside towards the coast. He shows Jim the lounge and asks for his views on the décor. Jim thinks that the room is great but isn’t too keen on the decoration.

Jim suggests a few people who may be able to help Arnav.  Jim’s interior designer would be a good start. He could maybe suggest some better colours and revise the room layout. He knows a business that will renovate the furniture. He knows of several good sculptors if Arnav wants to recast the existing sculpture. The wall screens show broadcasts when Arnav is alone, and are his interface with work colleagues, but can be set to be part of the decoration when Arnav has company. Jim  knows a company that specialises in creative options for those screens. Arnav will probably also need a decorator, an electrician, a plasterer, a cleaner, and a project manager.

In 2050 service industries have expanded. Few people would think of trying to decorate a room without professional assistance to create the vision and to implement it. The quality of decoration is one of the factors that defines the status of a person. People visit each other’s homes much more often than in 2014, because public transport is so easy. Many people, especially mothers, use IT to allow them to work from home. Colleagues and clients often see the interior of homes, either during face to face meetings or in the background during video conferences. Room décor is important.

The service industries associated with decoration are just the start. Others deal with clothing, fitness, food, holidays, education, IT, and many other topics.

This expansion of service industries brings environmental benefits because the planetary impact of service industries is generally much lower than for manufacturing industries.

It also means that we can employ everyone in a low carbon economy. There is no direct link between carbon use and employment. It will be possible to create a thriving and sustainable economy in future without changing the basic human need for status and a good lifestyle.

Can’t we do this now? We already are to some extent. Service industries in western economies are expanding at the expense of manufacturing, though at present this is because of manufacturing automation and cheap foreign labour rather than because of environmental concerns.

The trend towards brand names is also encouraging. People will readily pay considerably more for a fashionable brand name. They would sooner buy one item with a good name than 10 generic items. The effect is to reduce the number of items made and bought, reducing environmental impact. The advertising for these high status items is increasingly claiming environmental benefit as one of the main reasons to buy the product.

By 2050 public opinion will have swung much further and it will be regarded as vulgar to indulge in excessive consumption. Status will be defined by image, quality and style rather than by the number, size or power of personal possessions.

The Q tax will help to drive this trend. It will ensure that advertised claims of environmental benefit have a basis in reality. It will also drive behaviour by making excessive consumption costly in financial terms.