Wednesday, August 26, 2020

Efficient at what?

It is common to hear people talk about the efficiency of this-or-that system. Being "efficient" sounds like an unequivocal good, but the question that must be asked is "efficient at what?"

To illustrate this, let's consider "A tale of two heaters" in an average Australian living room.

Heater A is a split system heat-pump. It draws 2 kW of electricity, and outputs 8 kW of heat (it does this by pumping heat from outside the house to the inside of the house). For every 1 kWh of electricity it uses, it puts 4 kWh of hot air into the living room, and has a coefficient-of-performance (COP) of 4.

Heater B is a far-infrared panel (FIR). It is a resistive heater that emits infrared light, and needs to be directed to the occupant to be effective. As a resistive heater, it outputs 1 kWh of directional heat for each 1 kWh of electricity it consumes -- its COP is 1. Let's say it draws 1 kW.

Many people would say that Heater A is "more efficient", and there is some justification for this: for a given electricity consumption, heater A puts more heat into the room than does heater B.

However, because Heater B is targeting its heat directly at the occupant, it doesn't need to put so much heat into the room for the occupant to feel warm. Hence, one can argue that the amount of energy required to provide the service (making the occupant feel warm) is less and hence the FIR is more efficient because it uses less energy to make the person feel warm.

Hopefully, this example shows that when talking about efficiency, it is very important to be clear about exactly what we are doing efficiently. 

Deep problems with efficiency

But the problem goes deeper than this. 

In the 19th century, Britain was worried about running out of coal. At the time, coal was the fuel that drove the factories and war machine that made Britain the world's preeminent power. Some people thought that, as the machines became more efficient, coal consumption would be reduced.

William Jevons argued the opposite -- that an ability to use the resource more efficiently would actually drive increased demand in the resource. He noted that coal consumption rapidly increased after James Watt's more-efficient steam engine, because Watt's new engine made the exploitation of coal much more profitable.

This has become known as Jevon's Paradox, and the Wikipedia article contains much more detail.

We face the same phenomenon today -- improved technology that allows people to climate-control their houses more cheaply has meant that people perform more climate control. Whereas in the early-to-mid 20th century, an internal house temperature of 13 degrees was considered acceptable, it no longer is. Some people even heat their houses to 24 degrees.

Even if you don't do this, consider what you do with the money you save by spending less on fuel -- if you use that money to take more air travel, or to buy more manufactured goods, then you are a living demonstration of Jevon's Paradox.

In a society where 70% of grid electricity comes from coal, as does probably above 90% of the embodied energy in many manufactured goods (such as PV panels), it is simply not good enough to be "efficient".  Efficiency, by itself, will not reduce carbon emissions -- not even in theory.

The only solution is to focus instead on reducing consumption.

Wednesday, June 5, 2019

FAIL: wicking beds that don't last

I have written several articles about building cheap wicking beds using mixed materials and lined with builders plastic to form a reservoir. Unfortunately, these beds simply do not last. The builders plastic develops a leak, roots get in, and the reservoir fails. I am trialling a bed using pond-linear (which is quite a bit thicker), however experiments with a reed-bed made with pond-liner (it leaked!) suggest that this is unlikely to work.

For now, I am transitioning my leaking wicking beds (I think three of four are leaking) to IBCs, which I am hopeful will have better longevity. I will document this more in future.

Monday, March 18, 2019

The cost of travel


This essay examines the carbon cost of travel using different modes of transport, and compares it to other sources of carbon emissions (eg. electricity). It finds that international air travel is a significant source of carbon emissions, especially for people with an efficient house who fly regularly.
Compared to phasing out coal power (a noble goal), phasing out air travel would have a similar impact per-capita for regular flyers.
If middle-class Australians expect coal communities to make personal sacrifices to reduce the emissions intensity of Australia's electricity, I think it is reasonable to ask middle-class Australians to fly less.


In times past, only the wealthy could afford to travel. This was for the simple reason that most people were so poor that moving any significant distance from their home was unaffordable. And, of course, they had to work all the time.

Also energy, or the ability to do work, was so expensive that to travel took a long time (because to travel quickly takes much more energy than to travel slowly). Let's get a perspective on how much energy travel consumes.

This first figure shows the energy output of a human, an ebike, and a horse
Clearly, the ability of a person to do work is tiny compared to a horse -- it takes approximately 10 people to equal the power output of a horse. Horses are pretty powerful! Let's get a bigger perspective:
Suddenly, the horse doesn't look so powerful anymore! Even a small car can produce the power of many horses. The power output of a car is so great that the human output looks like nothing.

Of course, there is a difference -- the power output of both small and large cars is unsustainable (at least for the vast majority of cars which burn fossil fuels), and is causing changes in the Earth's climate that will be paid for by people in the future. Clearly, if we want efficient transport we should avoid cars.
Here we add air travel to the graph. This makes all of the sustainable transport look like it uses no energy at all. Note that for the cars and the plane, I assume that the car has 4 passengers, and the plane is completely full. Also, per-passenger energy consumption of the plane will be larger for business- and first-class passengers (because they take up more space).
Note that it is possible, at least in principle, to electrify car transport. Electrified air travel is currently science fiction. Note also that, currently, more than 60% of Australia's electricity is generated using fossil fuels.

Distance travelled

The figures so far show the energy consumption of different modes of transport, however, clearly people can travel more quickly by air than by foot or bicycle. However, the ability to travel quickly means that people tend to travel more. For example, one would never try to cycle from Sydney to London for a week or two of travel, but with air travel people do precisely this.

The concentration of vast amounts of power to allow air travel is a way for us to cram even more power consumption into our lives.

Let's look at the carbon emissions for different trips to get some perspective:
As before, buses, cars and planes are full and emissions are per-passenger.

Travel vs coal electricity

To reiterate, these numbers are large -- one person flying from Sydney to London produces more than 1.5 tons of emitted carbon. In comparison, in Australia some people (me included) make a fuss about getting rid of coal power because of the environmental impact. The average Australian household uses about 30 kWh per day (this is a huge amount of power), which is just under 11000 kWh per year. The average household has 3 people in it, so that is 3700 kWh/person. Coal power in Australia emits huge quantities of carbon per unit of electricity produced -- it is about 1 kg per 1 kWh. Thus, annual emissions from an average Australian's electricity use is about 3.7 tons.
A one-way flight from Sydney to London produces are much CO2 as 1/3 of annual electricity emissions, if electricity came from 100% coal.

These numbers become even worse if you consider an efficient house (which should be our goal). If you use 8 kWh per day, in a household of three, then one person's annual emissions under a 100% coal scenario are 8 /3 * 365 * 1 = 970 tons/year. A one way flight from Sydney to London is about two years' worth of emissions for this person.

Air travel as a proportion of total carbon emissions

While air travel comprises a relatively small proportion of Australia's total emissions (about 5%), there are hidden costs that are put into other sectors, such as the provision of fuel. Also, the proportion of carbon emissions from air travel is one of the fastest-increasing sectors, and it is also one of the most discretionary -- air travel can be easily reduced. Also, air-travel is a particularly damaging form of carbon emission because of its location in the upper atmosphere.
I have not been able to find statistics, but I suspect that there are a relatively small number of Australians who engage in a relatively large amount of air travel.


There is an increasing push in Australia to phase out coal power and replace it with renewables. This is a good thing. 
However, there is little awareness that carbon emissions from international air travel are similar to the emissions from 100% coal power for average electricity use in Australia. (This is especially true for wealthier Australians that might fly every year).
If middle-class Australians expect coal communities to make personal sacrifices to reduce the emissions intensity of Australia's electricity, I think it is reasonable to ask middle-class Australians to fly less.


Sunday, February 18, 2018

The (potential) problem of distributed energy storage

Over the last 18 months, there have been significant developments in the debate around renewable energy in South Australia. Here are some:
  1. South Australia had a state-wide blackout. It was variously attributed to a storm, wind turbines, renewable energy, the Australian Energy Market Operator, the phase of the moon, and probably other things.
  2. Load shedding (also known as brownouts, or rolling blackouts) was applied to 90000 households in SA on the afternoon of a particularly hot day. This was apparently triple what was requested by the market operator to maintain grid stability, and occurred at a time when a gas-fired power station at Pelican Point (in Adelaide) was idle.
  3. Elon Musk, the CEO of Tesla, told South Australia that Tesla can fix our energy problems in 100 days or it's free -- and has completed the installation of the "big battery" within that 100 day period
  4. The South Australian government released a comprehensive plan calling for grid level battery storage (100 MW), a government owned gas turbine and other energy initiatives
  5. Malcolm Turnbull has proposed an upgrade to the Snowy Mountains hydro facility that will allow it to operate as a pumped hydro plant (effectively a huge battery)
Whew! On top of this, there have been calls to the SA government that, as well as embracing a grid-level battery storage system, they should pursue distributed residential energy storage using a scheme such as Reposit (AGL is also rolling out such a system now, called the virtual battery). The Liberal party, as part of their platform in the upcoming election, are also proposing to subsidise home battery systems in some sort of virtual battery system. This is an internet-coordinated distributed power company that manages home batteries to release energy to the grid during times when the short-term cost (spot price) is high. Households can make money by doing this.

I think this is a great idea, and it's commendable that such policies have bipartisan support in South Australia. It is good for people in cities to install battery storage systems, as long as they remain connected to the grid. There are a few reasons I think this:
  1. The grid is a sunk cost. It's already built so we should use it
  2. Generally speaking, shared resources are used more efficiently. Let's assume that 5% of houses have a battery installed (in a few years time). We, as a society, will be much better off if those batteries are used to stabilise the grid during times of peak demand, rather than have those households disconnect from the grid. Those households should be paid for the service of course!
  3. Distributed power is a good thing because it lessens the load on the grid and improves resiliance (there is not a central point to fail), it also reduces power transmission losses.

The problem

One of the big benefits of having distributed power supplies is that of resilience. If one (or a few) systems fail or are disconnected it probably doesn't matter for the grid as a whole. It lessens our dependence on the grid as a whole, and so improves resilience.

But... although it decreases reliance on the electricity grid, it greatly increases reliance on the telecommunications grid. The internet is vital to coordinate the distributed "virtual" battery. Without the distributed batteries being able to talk to each other and the central controller, which needs to get data from the grid, it is impossible for them to coordinate their activities and the system ceases to function properly (for example, with no internet, it becomes impossible for the grid to request delivery of power from the distributed storage at a time of need).

Do not believe technical people who tell you a system is secure. It is not secure -- it is only a matter of time until software or hardware vulnerabilities are discovered and exploited.

A mitigation

"Solution" is the wrong word here: it's not possible to remove the consequences of attacks -- we can only reduce their consequence and likelihood of success. The distributed battery system needs to communicate, and that communication is inherently insecure. The system needs to be built so that it is resilient to internet-based attacks at the system level. I am not an expert in internet security, but here are my thoughts:
  • The system should be designed with security in mind. The critical aspect of the system is its ability to respond to legitimate internet instructions (only!) and react accordingly. The designers need to be aware of the inherent risk of exposing such command and control interfaces to the internet. The security team should have oversight across all teams during the development of this system. There needs to be robust testing of the system(s) (at all levels, from low level to high level) to examine the security implications of design and implementation decisions.
  • The system should be heterogenous. There should be many types of devices communicating on an agreed open protocol. Having many types of devices means that, even if some of them are compromised by an attacker, they are unlikely all to fail (they will be based on different hardware and software making it unlikely that a universal security vulnerability exists). This represents security through diversity.
  • The system should fail-safe. The internet should not be the only method of communication between devices. They should second-guess the instructions they receive from the cloud, by performing their own assessments of grid stability. For example, the grid can use frequency modulation to signal whether more generation capacity is needed (eg. if the frequency starts to fall from a nominal 50 Hz to 49 Hz, that is a recognised signal -- this needs to be preserved as a signalling method). In this way, the devices should use the internet as a communications channel where it is available, but not be dependent on it for all aspects of their function.
  • User interface elements should be kept separate from the control systems. User interfaces are almost always less secure than system interface elements. This is because user interfaces have the added constraint of usability, which is often at odds with security requirements. User interfaces should be through a seperate cloud/web portal that has no direct connection to the system interface.

On many occasions, systems have been designed to use internet platforms with the unconscious assumption that the internet is both safe and persistent. The internet is neither of those things. I hope that the designers of distributed storage are mindful of this, so that their system(s) will be resilient in the face of unexpected communications downtime or malicious attacks.

Thursday, December 7, 2017

What's in store for Australia?

We’re a pretty complacent bunch in Australia. Not surprising really — we had a bit of a scare in 1942 when Singapore fell to the Japanese, but we haven’t been invaded in modern history. During world war two, we had the Americans to help us. However, it looks like we can’t rely on American support in the Western Pacific for too much longer.

One of the sayings about getting old is that the age we perceive ourselves to be lags our actual age by about ten years. I think a similar adage applies to world events: Reality tends to outpace our awareness. Consider the collapse of the British Empire: in 1940, most people would have considered Britain a world power, by 1948 they were a very diminished people and had lost most of their colonial possessions. Of course, events such as Indian independence and the fall of Singapore didn’t just happen in 8 years — the seeds for this were sown earlier (though most people didn't notice).

It seems likely to me that we will see similar shifts in fortunes in the first half of this century as American power wanes. Both China and India are expected to have larger economics than the U.S. by 2050.

(This article is not an attempt at scaremongering — I think that an increase in power/wealth for other countries needs to happen and this means a commensurate decrease in power/wealth for Western countries. However, I would like Australia to maintain an independent parliamentary democracy while this happens -- I would rather live in a poor democracy than a wealthy tyranny)

Let’s think about what it will mean when we can’t rely on the U.S protecting Australia’s interests in the Western Pacific.

Australia is a country of 25 million. 2500 km to our North is Indonesia, with a population of 250 million (ten times bigger than Australia) and projected to be the world’s 4th largest economy in 2050 (with a projected GDP 4 times larger than Australia's). The Philippines and Vietnam are expected to be the 19th and 20th biggest economies (both economies larger than Australia). China and India will be number 1 and 2.

In other words, Australia will be a large, wealthy, (relatively) underpopulated country rich in natural resources in a region of heavily populated much larger (and much richer) countries. The world will be greatly resource-constrained by 2050 — our neighbours will need what we have. Note also, that though Australia's economy will be similarly-sized to the Philippines and Vietnam, a lot of Australia's GDP is tied up in unproductive activities such as home renovations and car modifications -- thus, the industrial output of Vietnam and the Philippines is likely to be substantially larger than Australia even if the GDP is similar.

What happened in the past in similar circumstances?

In the 18th and 19th centuries, Britain was the rising world power and wanted natural resources. They established the British East India company (the basis for British colonialism) which basically had license to do anything required to obtain resources. Such “trade” usually occurred at the point of the sword — it really was theft/conquest and nothing more.

For example, the Chinese Emperor banned opium in 1839, so Britain attacked China. In the end, the Chinese were forced to accept a treaty allowing the British to import opium into China. Another example: before British colonialism, India was one of the wealthiest countries in the world. When they became independent they were one of the poorest. Today, a tour of British museums and estates shows gold and jewels from the subcontinent -- the plunder of empire.

Which brings us to today. This year, the Australian government said it would restrict gas exports to maintain domestic supply. This is a policy that makes sense, in much the same way as the Chinese Emperor’s banning of opium. However, the Australian companies that this law affects have long term contracts with Chinese customers, and this law is definitely not in Chinese interests. Basically, it could cause Australian companies to renege on deals with Chinese companies.

If it was the 19th Century, and this was done to the British East India company, I would expect them to sail their warships into Sydney harbour and bombard the city, to teach the impetuous Australians a lesson in humility (pretty much exactly what Britain did to China in the First Opium War). The treaty we would be forced to sign would likely include the appointment of a British Governor who had authority over the Australian government. One does not break contracts with an Imperial power. [1]

Remove U.S. force projection from the Western Pacific, and there is little to stop China, India or Indonesia from doing the same to us.

Which brings us back to population. I am not a proponent of a “Big Australia”, and I think that Australia’s population probably already exceeds its long-term carrying capacity. Having said that, I think that Australia’s population could well hit 100 million this century whether we want it or not. There is simply too much opportunity here. If we try and prevent it, we will likely be invaded by larger, more powerful neighbours (once the U.S. can no longer protect us). It's worth underlining that we are ethnic/cultural outsiders in Asia, and that our ancestors (or people very similar to us) conquered pretty much every Asian country and stole their wealth (I guarantee that no one except Westerners has forgotten this).

Australians need to understand and accept that we are a very small fish in a very big ocean. Our delusions of Australian specialness and superiority will bring us a world of pain. We have a deep belief, based on centuries of cultural/military dominance, that we are superior. That dominance is ending, and with it needs to go our arrogance. The sooner we see our geopolitical neighbours as equals (and show then appropriate respect) the easier our future is likely to be.

How can Australia pull this off?

We need to increase our population and industrial/agricultural output without putting additional strain on the biosphere or economy (a tall order for a country already in overshoot). This means a significant cut in discretionary consumption to free those resources for the needed expansion (see other articles on this blog for suggestions here). I suggest a targeted program of skilled immigration, coupled with large programs to build agricultural, educational, scientific, and industrial capacity. We can't afford so much waste and unproductive capital.
Such cuts in discretionary consumption might seem an undesirable thing to do -- but it's worth remembering that in the past, wealthy societies that have failed this sort of test have been overrun by other societies.

I'm sure most Australians want to avoid that.

[1] Over the years, I have heard many people say things like "China is not expansionist" or "Asian people are less assertive" and therefore Asian people are less likely to seek geopolitical power in the same way that Europeans did. I think this is very naive. For the case in point, see Japan in the early 20th century. They had been inward focused for centuries before their imperial expansion from 1905 to 1945. Asian history is just as bloody as European history. The main reason that Asian people might have seemed submissive or non-aggressive to us is that they were a conquered people. As they gain power, I think it logical to expect they will behave exactly like other people who gain power -- they will become more assertive and, at times, aggressive.

Tuesday, September 19, 2017

What is the right way to save the world?

Myself when young did eagerly frequent
Doctor and Saint, and heard great Argument
About it and about: but evermore
Came out by the same Door as in I went.
      from The Rubaiyat of Omar Khayyam

Many people recognise that we have an ecological problem. Unfortunately for all of us, a lot of those people don’t do much to try to reduce their personal impact, instead limiting their actions to mouthing platitudes.

I have written extensively about this on this blog, and I have commented on the limitations of using economic incentives to encourage people away from engaging in carbon-emitting activities (I see this as a problem, because the most wealthy people, who have already emitted the most carbon, are those least affected by such economic costs). In other words, we need to work hard to ensure that a carbon tax is not a regressive tax. (I think the Australian Labor Party achieved this under Gillard, and that it’s a damn shame their law was repealed).

What I want to focus on here then, is the group of people who know that something needs to be done, and are prepared to make personal changes to help make it happen. I have the most respect for this group of people, because I think taking collective ownership of the problem is the only way to tackle it.

And it is a big problem. Dennis Meadows (one of the original members of the Club of Rome), in a recent interview, said that climate change is not the problem, it is the symptom, and that the problem is over-consumption (too many people, consuming too much). He said that if we can somehow “fix” climate change, but keep everything else the same, and continue growing then we’ll just encounter another symptom (eg. soil loss, ecological collapse, etc). I think this is a compelling argument.

But, as concerned citizens who want to do something active to help reduce our contribution to this problem, what should we do? Clearly over the next century or so, human life will be massively reorganised and entirely new ways of living will need to be invented. But how do we get there?

Should we stay in the city, where we remain largely reliant on industrial food/resource provisioning, where our ability to tap into natural energy flows is limited, where our ability to dispose of wastes is limited by local regulations, where houses and land are more expensive — requiring greater participation in the money economy? The benefits of doing this are that resources and knowledge can be more easily shared, and transport can be more active (less car travel). These are real and large benefits.

Alternatively, should we move to self-sufficient properties and create an independent lifestyle? In doing that we have more space and potentially more money (because land is cheaper in remote locations) so using fuel such as firewood is more feasible, and food production can be much less intensive. There is also less regulation, so more freedom to establish unconventional systems (eg. composting toilets), and opportunities to reestablish native bush. These are clear benefits, but the cost is expensive transport, and provisioning of services, both of which have environmental consequences.

Here are two big choices, but there are successively finer-grained choices all the way down.

Should we pursue a low impact, but low money lifestyle (the frugality approach), value conservation, but not invest particularly in renewable technologies?
Alternatively, should we pursue a high tech approach, investing heavily in renewables and/or batteries?
Should we invest in electric vehicles or try to minimise car use? Should we use taxis? Bicycles? Public transport on diesel buses?
Should we eat meat? Processed food? What about dairy? What about bought alcohol?
Should we buy computers? Phones? Paint? What’s worse — using petrol in an old car or electricity in a new one? Is it better to drive further to buy organic food or to buy non-organic food from the little old lady on the side of the road?

Given the greater efficiencies of collective infrastructure, is it better to focus on improving policy than personal investment (eg. is the embodied energy in rainwater tanks, batteries, cars better put towards shared infrastructure such as dams, grid-batteries or public transport?)

Clearly, when asking these questions, we need to look not only at the now, but how things might evolve as time passes. What effects will technology have? How will politics change? What about economic or demographic factors?

None of these questions have simple answers, and I believe that there is that there is no correct approach. There is no unified “green movement”, but I’m concerned that greenies are becoming divided into subgroups, each of which is firming its orthodoxy into, in some cases, dogma. This makes it harder for separate groups to work together, but it also makes it harder for individuals to explore new ideas and approaches to doing things.

We are likely to have more success, as a disparate group of people whose goal is to achieve something about ecological overshoot, if we are tolerant of different approaches and philosophies. We will work more cohesively as a group, but we will also be able to explore more ideas.

Western countries in 2117 will look very different to today. Many aspects of society will need to be reinvented to cope with ecological overshoot and resource scarcity (not to mention technological, geopolitical, economic and demographic change). We will need all the ideas we can get if we are to achieve this, and we can’t afford to dismiss any without consideration.

Monday, June 26, 2017

Council deputation

Below is a deputation I made to Unley Council on Monday, 26 June

Good evening Councillors,

I am Dr Angus Wallace, and I am here as a representative of the Unley Bicycle Users Group. I wish to speak briefly to you, regarding the Rugby/Porter bikeway, given the report in the Eastern Courier about the priority for cycle commuters being reconsidered.

Cycling has many benefits. The chief benefit is health. Cycle-commuters are 46% less likely to die of any cause than otherwise-similar people who do not cycle-commute. That is an incredible statistic, and shows the power of “incidental exercise” to make our population healthier. The other clear benefit is, or course, cost. Cycling is at least an order of magnitude cheap that car travel -- money that can be spent in the local economy. Cycling is also more convenient -- the increased density that bicycles afford means that even narrow paths can carry many people. Also, cycling is often pleasant and fun, social, communitarian and spontaneous in a way that driving in a car never can be.

Unley Council has been one of Adelaide’s far-sighted councils in encouraging cycling. Truely, you have made great strides in the last decade, and the City of Unley has reaped the rewards — quieter suburban streets, more usable spaces for children, more money being spent locally, better health of the population. And of course, the tourism that events like the Tour Down Under brings.

But we can go much further.

There is much untapped potential, and it is excellent that Unley Council recognises this. The decision to build the Rugby/Porter bikeway will be seen, in years to come, as a watershed moment, though not the only one. Right now, 500 people commute along the Rugby/Porter bikeway at each end of the day. Unley Road carries 30000, making that 500 people sound like not much. But, it is important to remember that traffic congestion is non-linear. A few extra cars make a very big difference. Who notices how much worse their driving commute is on a rainy day, when some cyclists drive instead? It is significant. But, if the Porter St bikeway was a genuine arterial cycleway, we could, in a few years, take 1000 cars OFF Unley Road, getting those motorists on their bikes instead. Imagine the effect that would have on commuting times.
For example, reflect on the proposed Adelaide Botanic High School. The school will be serviced by the Frome St bikeway, which connects to the Rugby/Porter bikeway. Empowering students to cycle to this new school frees their parents from the burden of driving them. This decreases traffic congestion and increases our productivity. I believe there is broad community support for such works.

But, for this to happen, it is imperative that an arterial cycleway has priority. It needs priority like Fisher St has over its side streets. No one would dream of giving a small cul-de-sac priority over Fisher St. This is not about safety — it is a simple, utilitarian question of the greater good. Roads with more traffic have priority over roads with less – whether the vehicles are cars or bicycles. Also, we must remember that the status quo is inherently dangerous. Commuter cyclists on Unley Rd are sharing a contested space: there are obstacles to navigate, buses and trucks. Every car passing a cyclist will be slowed by the cyclist, and every such passing is an opportunity for error. Providing a dedicated, connected, arterial cycleway is the only way to increase the safety of these cyclists, and to increase the uptake of cycling..

Unley Council’s leadership in the promotion of cycling has had great benefits already. We are on the cusp of realising yet more benefits. All that is needed is to provide the space, and the cyclists will come — decreasing demand on our over-crowded roads — increasing safety, health, our sense of community and the local economy. To allow this, dedicated arterial cycleways are needed, and they need to have appropriate priority over side streets.
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