© Screenshot: http://sf.solarmap.org/
A map of solar facilities in San Francisco
At the time of the first Rio Earth Summit in 1992, 5.4 billion humans lived on Earth. In November 2011, the world’s seven billionth citizen took his or her) first breath. On the same day, more than 140,000 people moved into a city. That’s one million people per week or the equivalent of seven New York Cities every year. This projected growth means that 70 % of an estimated nine billion people will live in cities by 2050, compared to just 13 % in the year 1900. Of this growth, according to UN data, 93 % will occur in developing nations, with 80 % of urban growth occurring in Asia and Africa.
On a planet with finite resources, such numbers push the limits of the term “sustainable”. Yet the hard truth is that governments, business and industry will need to find food, shelter and transport for the increasing number of people. How this happens can either become a burgeoning social, economic and environmental crisis, or an opportunity to create a truly green economy.
In any scenario for this growth, energy is a key factor, and cities will need an enormous amount – plus the infrastructure to deliver it. In the past decade, coal met nearly 50 % of new electricity demand globally. Oil currently accounts for 94 % of energy supply in the transport sector. The International Energy Agency (IEA) forecasts that $ 38 trillion of investment – mostly in fossil fuels – is required to meet projected energy demand through to 2035.
The science of climate change and global warming, however, is clear – a future derived from business-as-usual investment today will exacerbate many of the current challenges from an economy-wide dependence on fossil fuels. The Intergovernmental Panel on Climate Change (IPCC), the United Nations Environment Programme (UNEP) and the IEA have all warned that the time for substantially reducing greenhouse gas emissions is quickly running out. In less than a decade, the world must take significant action to keep global surface temperatures from rising by more than two degrees Celsius, a point at which dangerous climate change becomes a much greater probability.
But can massive energy efficiency combined with renewable energy really replace fossil fuels? If technical issues were the only constraint, the answer is an unqualified yes. The clean energy genie has left the bottle. Zero and even negative emission technologies (that absorb carbon) are available in the commercial market. Their expanded use, however, depends on a range of economic, social and political issues.
Even so, renewable energy sources supplied an estimated 16 % of global final energy consumption in 2010, according to the Global Status Report that was recently published by REN21, the Renewable Energy Research and Policy Network for the 21st Century. Renewable energy accounted for approximately half of the estimated 194 GW of new electric capacity added globally in 2010. Renewable energy delivered close to 20 % of global electricity supply that year, and continues to grow strongly in all end-use sectors of power, heat and transport.
Cities of today vary greatly in both the magnitude of energy use and sources of energy. In the wealthier cities in the industrialised world, more than half of the energy is used to heat and light residential and commercial buildings, while transport and industry follow as the second and third greatest consumers of energy. This is true in cities such as London, Bologna and Tokyo, while the transport sector consumes between 25 and 38 % of energy. Industry consumes less than 10 % of energy in cities such as Berlin and Tokyo because services have replaced manufacturing as the dominant economic activity.
All cities rely on electricity as a key energy carrier. In the past, however, electricity was brought into cities from a few large power plants that mostly relied on fossil fuels or nuclear technology. Today’s power grids were developed at a time when power was cheap, the environment wasn’t an issue and the consumer wasn’t part of the equation. In essence, electricity was all one way – the electricity company sent you the power and then they sent you a bill.
In the 1980s however, several forces began to converge. The cost of energy from renewable energy sources started to decline fast as smaller power plants were integrated into the power grid, closer to the points of electricity demand. Many new facilities rely on renewable resources like wind, solar light, geothermal heat and small hydropower schemes. Combined with the birth of the internet, which was perhaps the greatest game changing innovation of the 20th century, and rapidly declining computing costs, communication networks evolved rapidly. This trend is transforming energy utilities.
In the same way that today’s information technologies allow businesses to connect thousands of desktop computers, creating far more distributed computing power than even the most powerful centralised computers command, millions of local producers of renewable energy can potentially produce far more distributed power than the older centralised forms of fossil fuel energy.
Socially, the marriage of distributed communication technologies and distributed renewable energies through an open access, intelligent power grid – often called the “smart grid” – lays the foundation for a true democracy for power options and citizens. Today’s youth grow up in a less hierarchical and more networked world. To them, the ability to produce and share energy in an open access intergrid will seem just as natural and commonplace as producing and sharing information on the internet.
One of the keys to a sustainable energy system is the infrastructure it is designed to serve. In the next 20 years, millions of buildings – homes, offices, shopping malls, industrial and technology parks – will be renovated and constructed with much greater energy efficiency. Such efficiency will be boosted by smart appliances, connected and controlled by a smart grid. These buildings will have solar cells integrated into walls and roofs and thus serve as power plants capable of exporting power into the local smart grid.
The German city of Munich aims to produce 100 % of its projected 7.5 billion kilowatt hours of electricity from renewable energy by 2025, becoming the first city in the world with over a million inhabitants to reach this target. Using a diversified mix of local and regional projects, the city is on track to meet the target, with 50 % of energy coming from renewable sources in 2010.
Because most renewable energy sources are intermittent, a critical element of a distributed sustainable energy system is the capacity to store energy when it is generated but not needed. Advanced batteries, fuel cells, super capacitors and compressed air are all interesting candidates for energy storage. They are at different stages of development. The transport sector will prove a key element to both the development of energy storage and the effective operation of a distributed network. Plug-in electric and hybrid vehicles offer the abilities to supply energy to the grid and to get electricity from it.
What about cities in the developing world where infrastructure, particularly electricity distribution, is well below the standard for cities in the advanced world? Well, they may actually have an advantage because they are not saddled with an aging electrical grid, so they can potentially leapfrog into a sustainable energy future. It makes sense to build new infrastructures that rely on widely accessible renewable sources.
In much the same way they let mobile phones leapfrog fixed line telephones, developing countries can reduce the time and expenses for moving on to an era of sustainable energy by building new, distributed electricity systems from scratch, rather than continuing to patch up old and outworn grids. New distributed energy systems can evolve with little risk, spanning localities first, regions later and eventually inter-connecting them with other nodes across nations.
Of course, the move to a 100 % sustainable energy economy for cities requires more than just technology. Changes are needed in the way people think about and use energy. Planning must be geared to this goal. Energy prices must tell the full environmental truth (see box).
Continuously boosting energy efficiency will help to drive the transition, including many efforts to substitute energy carriers, such as electricity to power cars instead of liquid fuels. Public transport and non-motorised modes of transport are extremely important for cities. The Vélib’ public bicycle system, for example, has drastically changed the way people move about in Paris.
The UN has designated 2012 as the International Year of Sustainable Energy for All. Goals include doubling energy efficiency and the use of renewable energy in the next two decades. Cities have an inherent advantage for such change, with concentrations of people and infrastructure that is constantly being renewed. The complete toolbox for cities to make the transition to a 100 % sustainable energy target is huge. It is beyond the scope of this article to indicate all instruments, but they include regulation, incentives and clever use of purchasing power. REN21 gives a good overview. UNEP’s Green Economy Report similarly discusses relevant measures.
What could be most surprising is just how fast the transition happens to clean, sustainable energy. It took about two decades before computers and printers made the typewriter a relic. Music and media companies in the first part of the 21st Century didn’t understand distributed file sharing, and these industries are undergoing almost total transformation in less than a decade.
As the seven billionth human on Earth reaches his or her 20th birthday, two decades of advanced computer and communications technologies will make the traditional top-down energy utility a relic of the past, like a typewriter. Whether he or she powers their urban home with their own renewable energy or buys it from somewhere else, the odds are that a choice will be available.