Over the last decade several attempts have been made to design and build sustainable, zero-carbon, carbon-neutral or self-sufficient cities. The Eden Project in Cornwall aimed to show how a self-contained ecosystem could be created; Dongtan on Chongming Island and Huangbaiyu in Liaoning Province, China, were both intended to demonstrate how to create and run sustainable cities – cities which require minimal inputs of energy, water and food, and produce minimal outputs of heat, waste and pollution. Each of these projects has been established on the back of commendable goals, but they have also, to a certain extent, failed to meet these goals. The Eden Project serves many worthwhile purposes – growing and preserving hundreds of rare plant species, educating schoolchildren and the public about conservation and sustainability, demonstrating the principles behind maintaining a “spaceship Earth” (the theory that the Earth is like a spaceship, with extremely limited resources which must be recycled) – but it has not succeeded in being completely self-sufficient: Water, food and electricity are brought in, and waste is removed. Dongtan and Huangbaiyu have been criticized for failing to adhere to their own construction principles, being delayed, running over budget, and have both been likened to Potemkin villages; dysfunctional developments built to impress and to make a point, rather than to meet their inhabitants’ needs.
But a new star is rising in the east (although it happens to be a little over 2,500km west of Dongtan); the city of Masdar in the United Arab Emirates. Will Masdar have the answers that the critics perhaps don’t want to hear? Will its carbon-neutral goal (downgraded from “zero-carbon”) be achieved? Will wise men be drawn towards its environmentally-friendly light?
Masdar City from the air.
Far be it from me, however, to judge any of these projects: They were all borne out of commendable ambitions, and to unduly criticise them would be akin to criticising a charity that fed a million refugees when it set out to feed two million. It is better to set ambitious targets and fall short than to set facile ones which require little effort.
As models for sustainability these developments may not be relevant in many parts of the world, places where poverty is rife and funding would be impossible, where a vastly different climate demands an antithesis in design principles (to ensure warmth rather than promote cooling), or where overcrowding would not permit the use of acres of desert for solar and wind farms. What these projects can do for us, however, is to test the water, to demonstrate just how much can be done, and to provide a medium upon which to trial and perfect our technology.
Most people will never drive a formula one car, but the technology developed by F1 – to extract the utmost power from an engine of a restricted size, to maximize aerodynamic efficiency, and to ensure the highest safety standards – has trickled down into every day road cars, having a highly positive influence on economy and safety. Similarly, most people could not afford to live in a purpose-built eco-city, but in theory the technology and principles developed for the likes of Masdar will benefit far more people than its projected 40,000 occupants. Principles such as specifying the orientation and width of streets to provide shade and to channel cool breezes could easily be incorporated by any town planner. At the very least, Masdar has raised awareness of such principles.
Artist’s impression of Masdar’s central Plaza.
Furthermore, the project will undoubtedly help in identifying problems with the large scale application of renewable technology, and provide a platform upon which to develop solutions.
What is Masdar?
Masdar, the city, is a 700 hectare development thirty kilometres east of Abu Dhabi, which will have a population of 40,000 (plus workspace for a further 50,000 commuters). Scheduled for completion in 2018, Masdar is designed to be carbon-neutral, entirely powered by renewable energy, to require 60% less water per capita than other settlements in the region, to use significantly less energy per capita, and to recycle all its waste: Reduce, reuse, recycle.
Masdar, the company, is an Abu Dhabi Government initiative to reduce the CO2 emissions of Abu Dhabi as a whole, to accelerate the Emirate’s expansion into renewable energy (no doubt mindful of both peak oil and international pressure to reduce greenhouse gases), and to secure long term income from international renewable energy projects. As the company’s website puts it, Masdar’s aims are to “advance renewable energy and sustainable technologies through education, R&D, investment and commercialization, [to establish Masdar as] a global leader in commercially-viable clean energy and sustainable technologies, and to secure the Emirate’s continued leadership in the evolving global energy market.” Some would argue that Abu Dhabi is merely trying to find a new way of getting rich when the oil runs out, but who would blame them? Having profited immensely from oil, it seems only fair that Abu Dhabi should be one of the countries to lead the way in terms of renewables R&D.
Masdar, which means “the source” in Arabic, is a subsidiary of Mubadala, the government owned investment arm which clearly states its mandate as “facilitating the diversification of Abu Dhabi’s economy“.
The London Array – one of Masdar’s flagship investments.
You will find on Masdar’s books a 20% stake in The London Array, which at 630MW will be the world’s largest offshore wind farm, the 6MW Seychelles Wind Farm, a 60% stake in SHAMS-1 (Abu Dhabi’s 100MW concentrating solar power station), Masdar City’s own 10MW PV array, and a 40% stake in Torresol. Torresol is a Spanish company which aims to lead the way in concentrating solar power (CSP) technology, and currently operates two 50MW conventional CSP stations as well as the 19MW Gemasolar plant, which uses molten salt heat storage technology to prolong its operating hours. And then there is Masdar City itself. All in all an impressive portfolio, although some would be uncomfortable if their landlord were also their energy, transport and water provider, and quite possibly their employer too, as many of Masdar’s current inhabitants work for the Masdar Institute of Science and Technology. Cosy community or big brother-esque?
The 19MW Gemasolar CSP plant in Spain, funded in part by Masdar.
Ignoring any sociological issues, Masdar as originally planned is highly impressive. A traffic-free city of 40,000 people, utilising a futuristic personal rapid transit (PRT)system, powered entirely by renewable energy, which recycles all its water and waste, emits no carbon on-site, and is built on a seven meter high plinth in the sand. Unfortunately several of Masdar’s ambitious plans, such as the city wide PRT system, have fallen victim to the global recession, but there is still much to celebrate…
Technology and Innovation
Masdar City’s designers dreamed of a city which uses a wide range of renewable and energy saving technologies. Some of these, such as photovoltaic panels and wind turbines are not particularly innovative in themselves, but the combined application of multiple technologies, to attempt to meet the demands of an entire city, is a world-first. Innovations in power curve management, energy saving measures, and installation of these devices on a utility scale are all required.
Solar photovoltaic panels have been in use since the 1940’s, although today’s technology is far more efficient (and cheaper), achieving maximum commercial efficiencies of around 22%[i]. The early devices struggled to reach 1% efficiency[ii]. The technology is based around the Photoelectric Effect, first observed by Heinrich Hertz in 1887: When photons, of which all light is made up, collide with certain types of matter their energy is absorbed and transferred into electrons.
The photoelectric effect.
These electrons are freed from their respective nuclei, and become photoelectrons. Like all electrons, photoelectrons are negatively charged, and will follow a potential gradient; i.e. will move away from negative charges towards positive charges. By using two different types of semiconductor, solar panels establish a potential gradient, such that any photoelectrons released will be induced to move from one type to the other, which constitutes an electric current.
The original vision for Masdar was that the majority of the city’s power would be generated by rooftop and shade-giving solar panels. These would provide enough electricity to run domestic and commercial appliances (including lighting and air conditioning), and the PRT system. Streetlights were to be independent units with built in solar cells and batteries, which would save money on underground cabling. Like most developers, however, Mubadala was not immune to the global recession. Masdar’s budget was cut from $24 billion to$18 billion[iii], and the ambitious plans for seamless integration of solar technology became a casualty. Instead of the majority of Masdar’s above-ground-level surfaces being solar panels, the generation of solar energy has been outsourced to the 10MW PV and 100MW CSP plants outside the city. Installing thousands of solar panels in a single location, in a uniform manner, is far cheaper than integrating them into buildings and cityscapes. Maintenance and repair is also cheaper if the panels are concentrated in a single area. While this reality may be viewed as a failure, the lessons learned from “failed” experiments can be invaluable. I use inverted commas as the experiment was to investigate whether the complete integration of solar power is practicable, in both physical and financial terms. The result that, no, in today’s financial climate it is not practicable, actually means the experiment was a success – it gave us an answer.
Another important lesson to come out of Masdar’s solar story is the importance of dust. There’s plenty of it in the desert, and unfortunately it has a marked effect on the performance of PV panels. So much so that Masdar has had to vastly scale back the PRT system, as the PV panels outside the city are not generating as much power as anticipated, although the budget cuts must share the blame for this disappointing cutback.
So what can other nations and councils take out of this? Solar panels are too expensive? Put all your solar panels in one basket? Well, as is so often the case, the answer is “it depends”. Masdar had a budget which was significantly reduced, and the planners therefore needed to save money. They had the option of installing all the solar panels in the desert, instead of rooftops, which was cheaper. Many towns don’t have the space to build large solar farms on their doorstep (Masdar’s 10MW array occupies 55 acres[iv]). On a utility scale the savings afforded by making such a change will be significant, but on a domestic scale, where the cost is spread among thousands of householders, the cost of rooftop installs can easily be absorbed. This has been proved in many developed countries, where, with appropriate incentive schemes in place, householders are installing their own solar panels. In developing nations, however, it may be more appropriate for the government to minimise costs and follow Masdar’s strategy. In the end, money always talks, and developers/policymakers will need to listen.
It is worth briefly noting that as Masdar is more concerned with keeping cool than staying warm, no significant use has been made of solar thermal panels.
Unlike solar PV, there is no option but to locate a concentrating solar power station outside the city, requiring as they do a large, flat expanse. CSP plants can either be of the “tower” variety, using hundreds of mirrors to focus the sun’s energy onto a central point, or the “trough” variety, which use parabolic troughs to target a pipe running along the trough’s focal axis. Masdar’s plant, known as SHAMS-1, is of the latter design, and will use 786 mirrors spread across 2.5 square kilometres. The network of pipes running through each trough’s focal point contains synthetic oil, which is heated to over 300oC[v]. This oil transfers the sun’s energy to a central water tank, where steam is generated. Natural gas is then used to superheat this steam, before passing it through a conventional steam turbine. This hybrid approach is a far more efficient use of natural gas, and also allows the generating equipment to run at night, which is financially more efficient than having separate CSP and gas power plants.
Masdar’s 100MW concentrating solar power plant.
SHAMS-1 is on course for completion in the early stages of 2013, and is projected to generate 210 gigawatt-hours per year; enough for 20,000 homes. In terms of carbon reductions, that is equivalent to planting 1.5 million trees or taking 30,000 cars off the road[vi]. Shams 2 and 3 are also in the pipeline, although given the rapid reduction in the price of photovoltaic technology, it is uncertain whether these will be CSP or PV plants.
Like the PV panels, Shams 1 is also experiencing dust-related performance issues. The developers did foresee this problem, although perhaps not the extent of it, and decided to locate the plant well away from the city (120km southwest of Abu Dhabi and neighbouring Masdar) where airborne pollution should be less intense. Despite its location, significant dust deposits have been observed during construction. These may be due in part to the ongoing construction activity, and it remains to be seen just how severely the plant’s performance will be affected on an ongoing basis. Cleaning the mirrors will not be easy in an area where water is an extremely valuable commodity.
Concentrated solar power is an established technology, and as such there are limited lessons that the rest of the world can take from SHAMS. What will be interesting is the financial performance of the plant, given its dual-fuel approach, the dust issue, and the fact that the cost of photovoltaic technology has fallen dramatically since SHAMS was commissioned. Any financial figures published will be only be relevant to this part of the world, however, where gas is cheap, insolation (a measure of the amount of solar energy a particular area is exposed to) is high, dust is omnipresent, and water is extremely scarce. If the plant is proven to be profitable, operating without subsidies and paying back its capital costs at a commercial rate of interest, then it will be lauded as a major success for Masdar, and others may be tempted to follow suit. If the plant is not profitable, then it is likely that PV technology will be favoured over CSP by future developers. Either way, developers in the Middle East should thank Masdar for funding this guinea-pig project.
Wind power is not a major player in Masdar’s energy mix. The gulf is not a windy region, and it is arguably more sensible to allocate investment to solar energy, as Masdar has done. However, Masdar is keen to be seen to embrace all forms of renewable energy. In addition to investing in major wind projects overseas (e.g. The London Array), the company is developing a wind farm on Sir Bani Yas island in the UAE. With an expected capacity of around 30MW, this will be small by international standards (the London Array is 630MW and may be increased to over 1000MW), but would still represent by far the largest windfarm in the area.
Also at the planning stage is a $200 million[vii] onshore windfarm in the UAE, close to the Saudi Arabian border, although this project is not certain to go ahead. In a similar vein to the SHAMS CSP project, Masdar’s Middle Eastern wind power projects will demonstrate the financial viability of wind power in this dusty and relatively wind-less region.
Energy from Waste
US firm Enertech Environmental has signed an agreement with Masdar to install a demonstration energy-from-waste facility. By pressurising and heating sewage slurry without oxygen – a process known as pyrolysis – the hydrocarbons are extracted, resulting in a product that Enertech calls “efuel”. This fuel is a mixture of gases and solids, which can be burnt like natural gas or coal to raise steam and power a turbine. Other benefits of treating human waste in this way are the by-products of fertiliser and water, both of which can be used to improve the region’s agricultural output. Details concerning the scale of this project have not been published.
As one of the hottest regions on Earth, the Middle East uses a huge amount of energy to keep cool. The UAE’s summertime peak electricity demand per person is more than three times that of Spain[viii], which is primarily attributed to the extensive use of air conditioning. The recent surge in its use has led to summertime blackouts as power stations struggle to meet demand, and according to the oil minister, Mohammad Bin Dha’en Al Hameli, the nation is now likely to become a net importer of natural gas[ix]. Mindful of this situation, Masdar’s architects have tried to minimize the city’s cooling requirements. This has been achieved through various means, including aligning the city’s streets with the prevailing wind, making them narrow so as to channel the wind more efficiently, designing building facades that are able to minimize solar glare[x] (not unlike a stealth jet reducing its radar footprint), and using thermally efficient construction materials that provide insulation without locking in oodles of energy. Global chemical company BASF will be manufacturing the majority of Masdar’s insulation foam out of recycled polystyrene and polyurethane[xi], in accordance with Masdar’s zero-carbon policy (which is more of an ideal that a reality). Finally, in terms of passive cooling, Masdar will make excellent use of an ancient technology knows as the wind catcher, or wind tower…
Evidence of wind towers dates back over 3000 years, with ancient Egypt being credited with their invention[xii]. However, with the expansion of cities around the world, and the resultant demand for rapid construction in confined areas, not to mention the abundance of cheap energy and the invention of air conditioning, their use fell out of fashion, and it’s only recently that architects have learnt to appreciate their energy saving powers again.
Wind towers work in one of three ways:
- Physically directing airflow downwards.
- Directing airflow upwards using a wind assisted temperature gradient.
- Directing airflow upwards using a solar-assisted temperature gradient.
Masdar City’s wind tower works on either the first or third of these principles: On calm days the wind tower, which is situated in the city’s main square, heats up and hot air starts to flow upwards through the tower. This establishes a street level breeze towards the base of the tower, and cools the surrounding area by a perceived 5oC[xiii]. Alternatively, when it’s windy the tower’s louvres (flaps) can be adjusted to allow the wind to enter the top of the tower and to direct it downwards, injecting a cool breeze into the ground level streets…in theory. These narrow streets are designed to efficiently channel the breezes away from the base of the tower, maximising the cooling effect.
Masdar’s 43m high wind tower.
The effectiveness of this wind tower remains to be seen. At the design phase, Masdar’s officials predicted that the cooling effect in the plaza may be as much as 20oC[xiv], but whether the effect will be noticeable at all is now in question: As the streets fill up and the air’s fluidity characteristics are altered, the strength of these breezes will reduce. However, as Gerard Evenden, senior consultant with Masdar’s designers Foster & Partners, points out: “We want to make the structure itself a laboratory and get people talking about other possibilities, and hopefully get that to influence the next phase. We see it as an ongoing learning process.”[xv]
Possible improvements include painting the tower black to increase its thermal absorption, and consequently the temperature gradient within the tower. This would lead to stronger airflows, providing greater cooling, and the potential to install small wind turbines within the tower. The wind tower project is another example of Abu Dhabi putting up its oil money to test and refine new energy saving techniques.
Moving from passive to active cooling, Masdar is also pioneering the use of a large scale solar absorption refrigerator for district cooling. This project consists of a solar concentrating array (i.e. mirrors) outside the city, which are used to heat a transfer fluid. This fluid then drives the absorption refrigerator and generates cold water. For an explanation of how absorption refrigerators use heat to produce a cooling effect, see wikipedia. The cold water is piped to several buildings, where it accepts heat and transports it back to the refrigeration plant.
Uniquely, the plant uses two types of solar concentrator: First of all, parabolic troughs similar to those used in Masdar’s CSP electricity plant are used to heat thermal oil. The energy is then transferred through a heat exchanger from the oil into a pressurised water circuit, which further heats the water through the use of Fresnel reflectors[xvi]. Without going into detail, Fresnel reflectors are similar to parabolic troughs in that they focus the sun’s energy onto a single axis, but differ in the fact that they use flat reflector surfaces, which are cheaper to produce, and through intelligent design their focal axis can be rendered stationary. The latter point is crucial, as stationary pipes can contain a higher pressure fluid than those requiring moveable joints. This means it isn’t a problem if the fluid boils and becomes steam. Steam can achieve higher temperatures than liquid oil, which means a greater cooling effect can be generated at the central refrigeration plant. By initially using thermal oil and parabolic trough reflectors, before passing the accumulated heat into water and using Fresnel reflectors, Masdar’s absorption refrigeration plant is able to minimise the volume of water it requires (a highly scarce resource in the desert), and to maximise the temperatures achieved, and subsequently its performance.
Parabolic troughs use the sun’s energy to cool Masdar’s buildings, via absorptive refrigeration.
This pilot project produces enough cold water to cool 1,700m2 of office space, replacing around 80 conventional air conditioning units and reducing CO2 emissions by about 70,000 kg per annum. Already a success in terms of its operation, the plant’s operating costs are currently being assessed for standalone commercial viability. Dust on the solar collectors and the associated cleaning costs are a recurring issue.
There isn’t space in one article to cover all that Masdar City is doing to minimize its carbon footprint. The personal rapid transport system, for example, would require several square feet of web space to analyse its successes and failures, and the reasons for these; a discussion of the effectiveness of smart electricity meters and low flow showers may best be left to those with a specific interest; and the ingenious materials and construction techniques used in the making of Masdar City could occupy an entire manual. Throw “Masdar” and “PRT” or any other of these technologies into Google and you will find lots more information.
Masdar City is a living, breathing experiment. With the backing of a wealthy and determined government, proximity to a major international airport, and an attractive financial and political climate for investors, few observers doubt that the city will be successful at least as a place of learning and business. But how successful will it be in terms of carbon neutrality, and is this really the best way to measure its success?
Masdar’s decision to scale back the amount of rooftop PV is particularly noteworthy, and may well serve as a lesson to others, to at least compare this strategy with that of building an extra-urban PV plant. It does seem that large scale installations outside cities are the future: Huge wind farms in the temperate regions and huge solar farms in the tropics are the current trend. In my opinion, it is actually pretty irrelevant if Masdar City is energy self-sufficient or not. If it isn’t, more solar or wind farms can be built. If it is, others may say that Masdar had an unfair advantage with so much space and money to invest. Most developed countries are investing heavily in renewable electricity, and in that respect, Abu Dhabi can’t really claim to be any different: They are using various renewable power stations around the country, measuring how much energy these are producing, and offsetting the demands of one city against this total. If the UK did that we could say that in terms of electricity, Greater London, with a population of over eight million people, was almost self-sufficient (in 2011 the UK generated almost 35,000 GWh[xvii] of renewable electricity, which is 87%[xviii] of Greater London’s demand).
But I’m being facetious. Masdar’s goal of being carbon neutral is undeniably accelerating the deployment of renewable power in the UAE, which is clearly a positive result. Because, however, the rest of the developed world is also installing as many solar and wind farms as it can afford (in terms of both space and money), the real lessons that Masdar can teach us are about sustainable living: Will the city’s waste be negligible, her streets be pollution free, her population’s water demand minimal, and her energy demand per capita significantly reduced? In my opinion Masdar will be significantly ahead of other cities with respect to all of these criteria, and the international media spotlight will help disseminate the design principles used to achieve these goals, so that architects and planners elsewhere are more likely to incorporate them; a fantastic result if it happens.
But one particular question lingers…
Will the people feel good about it, or, each time big brother switches off their showers after a few minutes, or they can’t see the sunset because their house is designed to look the other way, will they gradually become inclined to move elsewhere? Perhaps I’m being too sceptical – I’ll reserve judgement until someone buys me a ticket to the UAE (and offsets its carbon footprint).