China's new tool for fighting pollution and climate change: kilometre-tall skyscrapers

The concept rendering for the Phoenix Towers, in Wuhan, China. Image: Chetwoods.

Since the emergence of cities during the Agricultural Revolution, humans have struggled not to kill everything they love through bloody-minded exploitation of the environment. We've got two general options for preventing an environmental crisis: stopping doing the thing that's causing the problem, or doing it faster in the hope that we get rich enough that it doesn't matter any more. It's safe to say that the latter option usually wins out.

In China, where problems of air pollution and climate change are combining with the recognisable issues of urbanisation and industrialisation (inequality, poverty, disease) to damage quality of life, the big problems are being met with big solutions. A benefit of urban density is that it allows greater efficiencies in things like energy use, and part of the justification for building Sky City - the ever-delayed "tallest building in the world" in Changsha designed by a company that specialises in air conditioners - is that its offices, home, school, hospital and other amenities will make it something like an arcology from SimCity 2000, and a building that is a city unto itself.

Now, Dezeen reports that British architecture firm Chetwoods has drawn up a proposal for two incredibly huge towers - both of which would be taller than the Burj Khalifa, with the taller tower topping out at a kilometre - for Wuhan, in Central China, which will act as a giant air and water purification system for the city's more than ten million residents. The architects also say that "the use of a pair of towers reflects the dualist elements of Chinese culture in contrast to a more Western monolithic form", but that's just how architects like to talk. The important stuff is in the mechanics of the towers.

Located at the heart of a planned new development on one of Wuhan's lake islands - the city is famed for its numerous lakes - the project takes a Swiss Army Knife approach to environmental problems in China. Name a problem, and Phoenix Towers will deal with it. It has wind turbines and solar panels, biomass generators and vertical farms that can grow crops or insects. The bottom half of each tower will be occupied by the boring stuff of skyscrapers, offices and shops and the like, but the top half is where the party is at.

The towers act as giant solar chimneys, to clean the city's air and the water from the lake while also generating power. Solar chimneys have been around for decades, and while a clever way of turning solar energy into electricity without having to rely on silicon panels or any other direct conversion of light into power, they've not been particularly popular. They usually take the form of a tower surrounded by greenhouses, where the air is heated by sunlight. That warm air rises and slopes along the glass roofs to the tower, where turbines up the entire shaft convert the motion of the air into electricity. While it's an inefficient system compared to other solar power systems (like solar-thermal), it's also cheap in that the land is probably the most expensive component - and you can further economise, maybe by using the greenhouses for growing plants at the same time, or by sticking photovoltaic panels on the outside of the tower.

A prototype built in Manzanares, Spain in 1981 was 194.6m tall and 10m wide, with a circle of greenhouses with a diameter of 244m, and generated 50kW of power, which is roughly similar to the power needs of one of Tesla electric cars. To get a tower with an output of around 200MW - roughly a quarter the output of an average coal power plant, or a tenth the output of the Hoover Dam - there would need to be a tower a kilometre high (so on the scale of the Phoenix Towers) and 120m wide, with a 7km-diameter circle of land taken up by collector greenhouses.

These theoretical towers are assumed to be similar to existing industrial chimneys - this image gives a good idea of just how immense a 200MW one would be - and, in China, there has been a small, 200kW tower in operation in Wuhai City, Inner Mongolia since 2010. Phoenix Towers are slightly different, in that they don't have the greenhouses at the bottom. Instead, sunlight heats up the top of the tower, and as the hotter air at the top moves upwards it draws colder air up from below. The same principle works with water from the lake, and the towers therefore act as massive filters for both air and water. This likely makes them less powerful as generators than they would otherwise be, but the idea is the towers do as much as possible to justify becoming an eco-tourism destination and a centrepiece of a new government-led focus on environmental sustainability.

This is still a concept, and at least three years from any kind of construction getting underway, but it's an encouraging counterweight to much of the other environmental news that has emerged from China recently. Earlier this month it was revealed that, to make space for new towns and suburbs, engineers are literally slice the tops off of mountains and use them to fill the valleys in between. Chinese air pollution is now so bad it has been compared to a nuclear winter, damaging crops and threatening the food supply. If we must accept that large nations prefer to technologically escape the consequences of exploiting the environment, some kilometre-tall towers that act as giant filters are a considerable improvement on what we have already.

 
 
 
 

Why is it acceptable to kill someone? On the mysterious history of Britain’s road death toll

A London speed camera, 2004. Image: Getty.

A decade ago I became fascinated by a graph. This one:

I had been tracking the underlining data for years. The figures were easy to remember. Every year it was 3,500, plus or minus a percentage point or two.

Yet when the 2008 data was released, it had fallen to 2,538. This was 1,000 less than the figure in 2003. I plotted the above graph, and as I said, I became fascinated.

Because this is a really important graph. This is a plot of the number of people killed on Britain’s roads each year.

In Great Britain, collectively, we used to kill nearly 3,500 people on our roads every year. Consistently or, dare I say it, boringly: 3,500 deaths a year, 10 a day. It was accepted, in a, “Well yes it’s bad, but what can you do about it” kind of way. There was no clamour for change. Newspapers weren’t running headlines about the deaths mounting up, as they do with knife crime.

Meanwhile a train crash would be front page news for a week. Take the train that derailed at Hatfield on 17 October 2000, a tragedy in which 4 people died. That led to huge media interest, massive upheaval on the railways, and, ultimately, as the re-nationalisation of Railtrack, whose failings had caused the crash. Yet more than twice as many people will have died on the roads that day. Nothing was written about those deaths. Nothing changed.

In 2000, four people died in train crashes, while 3,409 died on the roads.

Here are those figures again.

1997 – 3,599 people killed on our roads

1998 – 3,422

1999 – 3,423

2000 – 3,409

2001 – 3,450

2002 – 3,431

2003 – 3508

But, in 2004 the figure dropped below 3,400 for the first time, to 3,221. Then in 2005 to 3,201.

2006 – 3,172

2007 – 2,946

Below 3,000! This was change. Significant change: 500 lives a year were not being lost. If you use Britain’s roads, your life may have been one of them.

2008 – 2,538

2009 – 2,222

When the 2010 figures came out I was amazed by the headline figure: 1,857.

That’s still far too high, of course, but it was 1,701 lower than seven years earlier.

This was a major story that deserved a ton of coverage, which it failed to get. Having shown no concern for when we were killing 3,500 people, it wasn’t overly surprising that the fact we were now killing 1,700 fewer wasn’t celebrated.

At any rate, the graph had flat-lined for years, then, in half a dozen years, it halved. Why?

The lack of media coverage resulted in an absence of answers. One commentator, Christian Woolmar, observed that there was no clear answer to why this had happened. But he went on to point out that there had been a fall in the average road speed over this period.

My anticipation of the 2011 figures troubled me, because I expected them to go up. Obviously I didn’t want them to: I desperately want zero deaths on our roads. But something happened in 2010 that I was sure would lead to more fatalities and bring a halt to the falling trend.

I was right. In 2011 we killed 1,901.

Sometimes, being right is shit.

The news was better in 2012. The fatality rate was 1,754. So was the 2011 figure just a blip, due to some significant snowfalls that year? No: the trend was over.

The number of people killed on our roads has remained stuck in the 17 hundreds. 

2013 – 1,713

2014 – 1,775

2015 – 1,732

2016 – 1,792

2017 – 1,793

2018 – 1,782

We have returned to a flatline on the graph – and if anything, I’m more fascinated now than I was before. Road deaths flatlined at 3,500 for years, then fell sharply, then flatlined again at half the rate.

This can’t have happened by accident. I wished I could explain it. I wish we could repeat it. No: I wish the second flatline hadn’t happened, and the fall had continued. If the rate of fall had continued, we’d have reached zero deaths on the road by now. You’d be right to question whether this is possible – but if you can half the number in a few years, why can’t we eradicate them altogether? The railways are an example of what is possible. The last time a passenger died in a train crash on Britain’s railways was in 2007.

It was time to figure out the answers to two questions. Why did the death toll fall? And why did it stop falling?

The obvious reason for a reduction in deaths on the road is the improvement in car safety features. This could create a gradual fall in the death toll as new, safer cars replaced older ones. But I’m not sure it can explain a 40 per cent fall over a 4 year period.

There’s a way to check whether cars on the road became almost twice as safe between 2003 and 2010: you can compare the figures with the rest of the EU. Car safety features are international, and any new feature would have appeared around the same time across the continent.

So I found the EU figures for 2000 to 2017, indexed for 2000 and plotted the graph for multiple countries. It was a busy graph. For clarity the following graph only includes Britain, Germany, France, Spain and Italy along with a straight line drop for comparison.

The good news is that things are improving across Europe – but no country had quite the same trajectory as Britain. They all have a fall much closer to a straight line of the sort you’d expect a general improvement in car safety would produce.

One thing I did notice is that, from 2013, these five countries stop falling. The technology based solutions of recent years, such as automatic emergency braking, don’t appear to be saving lives as of yet.

So, yes, cars are safer – but that doesn’t seem to explain why British roads suddenly became 40 per cent safer between 2006 and 2010.


In 1999, the New Labour government announced that it was going to reduce deaths on our roads. The target was a 50 per cent reduction by 2010. As you now know, it succeeded. This was a major achievement for a government. The kind of thing you would bang on about all the time. “Deaths on our roads halved by Labour!” But the party wasn’t in government when the 2010 figures were released – and it’s hard to take credit for your achievements from the opposition benches.

That it was government policy is not a full explanation, and how this happened is a little opaque. From what I can gather there was a wide ranging approach. The fire and rescue service changed their practices: because they recognised that survival rates were directly dependent on how quickly people got to hospital, this became the priority. Disturbing a police crime scene was allowed if it saved a life. Accident black spots were located, highlighted and safety measures implemented. Throughout that period road safety campaigns focused on speed, with “Speed Kills” being the dominate message for that decade. The government also changed the laws on speed cameras.

RoSPA, the Royal Society for the Prevention of Accidents, has a lot to say about speeding and speed cameras. Its “Speed Camera Factsheet” states that, “Cameras are a very effective way of persuading drivers not to speed, and thereby reducing the number of people killed and seriously injured.” It reports that an independent review published by the Department for Transport (DfT) in 2005 said that “cameras significantly reduce speeding and collisions, and cut deaths and serious injuries at camera sites”, adding that cameras sites were delivering 100 fewer deaths per year.

Cameras first appeared in 1991, and revenue from court fines and fixed penalties went to the Exchequer. However in 2000 a trial scheme saw local councils keep the fines to pay for the cost of speed and red-light cameras. The pilot was so successful that, in 2001, legislation enabled this to happen across the country. The cost of providing and operating cameras moved from the local authority to the law breaking motorist.

The golden age of the speed camera had begun.

There was a tweak to this legislation in 2007. Fines reverted back to the Exchequer’s piggy bank. The DfT switched to funding cameras through a road safety grant. The intention was to create a greater mix of road safety measures agreed between local authorities and the police.

The number of people killed on British roads in 2007: 2,946

The number of people killed on British roads in 2010: 1,857

So perhaps the creation of the Road Safety Grant had a significant impact.

The second question: why did the death toll stop falling?

In 2010 I was unaware of Labour’s target to halve deaths on the roads. But, the change in government was enough for me to predict that the fall was over.

When the Tory/Lib Dem government negotiated its way into power in May 2010, the press declared that it was the end of the horrible nanny state – a return to personal freedom, liberty and the rule of common sense.

The way that this was to play out in real practical terms was on our roads. The evil speed camera was in the firing line. The narrative was that these cameras were just there so councils could extract cash from the poor public. Completely ignored were the facts that the fines were only handed down to dangerous, law-breaking drivers, and that councils no longer got the cash from fines.

Soon after the election the coalition government said that “Labour's 13-year war on the motorist is over” and pledged to scrap public funding for speed cameras. The Road Safety Grant to local authorities was cut from £95m to £57m. This meant that the government was now receiving an estimated £40m more raised in fines than it was spending on road safety. The cut to the grant reduced the camera maintenance budget by 27 per cent. It removed all the funding for new cameras, speed humps and other safety measures.

And the golden age ended.

Councils across the country announced their change of policy. Oxfordshire County Council switched off its speed cameras on 1 August 2010. Money was saved; lives were lost.

Eight months later, on 1 April, Oxfordshire’s cameras snapped back into life when the council reversed its decision because deaths on the county’s roads had immediately increased.

Turning off speed cameras sent out the message that we were no longer taking speeding seriously. The road safety campaigns changed their focus. The message that Speed Kills fell away and was replaced by drink- and drug-driving messages. It’s easy to miss that these campaigns move from encompassing virtually every driver to targeting a minority. A switch from confronting a socially acceptable behaviour to re-enforcing something already unacceptable. The state is no longer challenging everyone to be safe – only the small minority of bad people.

Yet speed still kills. The World Health Organisation states that an increase in average speed of 1 km[h typically results in a 3 per cent higher risk of a crash involving injury, with a 4–5 per cent increase for crashes that result in fatalities.
The majority of safety measures installed before 2010 remain in place and are saving lives. But with the funding gone councils are no longer installing new measures and the death toll is no longer falling.

So you can make a strong case that the pattern of road deaths was the result of government policy.

Which begs the question of our government: why has it accepted that it’s OK to kill, or be killed, on our roads?