Investment in renewable energy key to securing future of our cities
Google 'future cities' and you'll be met with visions of a science fiction-enhanced urban landscape. In this utopia, we'll have divested entirely from fossil fuels, while investing heavily in renewable energy generation and other technologies. And we'll do so without increasing our spending. This might sound idyllic, but I'd argue that it's a future that is not only much closer than you might think, but one we must urgently move towards, if we are to secure the future of our cities.
We are urbanites
Since 2014, the majority of the world's population, 54pc, have lived in cities, and that proportion is predicted to rise. This will come with numerous challenges - housing, water, energy and transport infrastructure is already at breaking point in many regions. There is also the reality of our changing climate.
A recent paper from scientists at University College London suggested that in order to limit global temperature rises to the 2C set by COP21, four-fifths of our remaining coal, half of our gas, and a third of our oil reserves should remain unused until at least 2050.
While we may be far from achieving that, within the world's cities, decarbonisation of the electricity grid is already happening. Seattle and Oslo source around 98pc of their energy from non-fossil fuel sources (largely hydropower). Paris isn't far behind either, at 91pc, although their grid is dominated by nuclear power.
Irish cities now get, on average, a quarter of their electricity from wind turbines. So, we're not starting from scratch. But there are a number of technologies, that if more widely adopted, could change the city as we know it.
Bristol and Stockholm share a rather smelly secret. Every day, their buses and taxis head to their local sewage treatment plant… to refuel.
They run on a methane-rich gas that's extracted from processed human faeces.
In Bristol, the aptly-named No 2 bus can travel 300km on a full tank of this biogas - equivalent to the annual waste of around five local residents. And the biggest taxi operator in Stockholm uses the same fuel to run its fleet.
Trains in Philadelphia recover excess electricity and either feed it back to a centralised bank of batteries, or sell it to the main power grid.
In Gumi, South Korea, electric buses are recharged by driving along a 10km stretch of inductive roadway, and in India, waste plastic is being used as a road-paving material.
In Oslo, waste heats homes and offices too. The city incinerates thousands of tonnes of rubbish every day. This heats water that is then pumped to communal boilers in the city. Some of the steam produced is also used to drive enormous turbines, producing electricity.
In Sydney, the municipal sewers are 'mined' - extracted wastewater can be treated and reused, and the remaining sludge processed, releasing methane gas for electricity generation.
The new geometric façade on the Manuel Gea González Hospital in Mexico City eats smog, thanks to its outer layer of titanium dioxide. This molecule converts the pollutant nitrogen dioxide into a harmless salt that washes away when it rains.
The same chemistry is being used on paving slabs in Chicago, on billboards in Sheffield and on roof tiles in California. Another way to improve air quality is to plant more trees. Because plants rely on the sun's heat to evaporate water from their leaves, more trees would also make cities cooler, reducing the load on cooling systems.
Rooftops have a role to play too, as shown by a study from Stanford. They found that by utilising more of the available rooftops in California's cities, the entire state (five times the size of Ireland) could be provided with more than three times its electricity and hot water needs.
None of these cases represent a far-flung dream - all are already available on the market. But while their environmental benefits might be clear, we need to talk about the criticism continually laid at the feet of renewable technologies - their cost. Few are cheap to implement, so it's reasonable to wonder if they are worth it.
Money, money, money
A report published by Bloomberg New Energy Finance in late 2015 analysed the overall cost of generating electricity by different means, and calculated it in dollars per megawatt-hour ($/MWh). This cost was calculated over the whole lifetime of the generation method, from digging foundations through to decommissioning, in order to provide a level playing field. And their results were surprising.
In Germany, coal and gas were found to be more expensive than onshore wind - $106 and $118 versus $80/MWh - and the same is true in the UK. In China, coal remains king, coming in at just $44/MWh in 2015. But solar power there was cheaper than gas ($109 versus $113/MWh in 2015), and with China's recent ratification of the Paris Climate Change Agreement, the price of renewables is likely to drop even more.
So, in many countries, renewables already make financial sense, for governments, and an increasingly climate-aware public. But we're also beginning to see another trend. A growing number of individual cities are now actively choosing to withdraw their support of the fossil fuel industry. Earlier this month, Sydney's city council voted unanimously to change their investment policy, from one that has historically leant heavily on coal, oil and gas, to one that champions more sustainable energy projects.
They join a growing list of cities that includes Copenhagen, San Francisco, Münster, Dunedin and Oslo, who have pledged to divest from fossil fuels in the coming years.
And if you're wondering where they could invest their money instead, research from the University of Leeds and the Global Commission on the Economy and Climate analysed the costs and returns of low-carbon investments for cities.
They looked at everything from increasing the rate of recycling, and improving building efficiencies, to electrification of road vehicles, and a wider adoption of solar and wind power. They found that investing in these technologies globally would cost $977bn, but that it would result in a saving of $16.6 trillion. In other words, they'd pay for themselves within 16 years; a fact that led the report's lead author, Professor Andy Gouldson, to say: "Cities around the world can commit to really ambitious carbon reduction targets, safe in the knowledge that economically, they will more than pay back."
So, there you have it. There really is no excuse not to make the 'right' choices for the environment, even within the built-up heart of a city.
The tide is turning for low-carbon technologies, and it's time we starting riding the wave.
Laurie Winkless is the author of 'Science and the City'
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