Renewable Energy
By Angela Tam
The burning of fossil fuels, rearing of livestock and other human activities have resulted in a climate change crisis. At the same time, we have a related health crisis: excessive consumption of meat and junk food and a sedentary lifestyle with too much travelling by car have led to rising obesity rates in the developed world, which will prove costly in health care terms as more and more people require treatment for diabetes, hypertension, certain types of cancer and other conditions.
Now, could there be a solution to both problems, or is it just wishful thinking? Consider this: suppose a teenager who wants to play computer games has to sweat for an hour on a stationary bike first to produce enough electricity to power the computer and games console. He will become fitter and perhaps less addicted to computer games; what’s more, he will have produced power from renewable energy.
This may sound like a fancy scenario, but it isn’t. In Portland, Oregon, the US, there is a fitness centre called simply the Green Gym, where all the electricity is derived from a combination of solar and human power. Two years ago California Fitness became the local pioneer when it launched the “Powered by You” concept at its Central branch, where cycling machines, steppers and cross-trainers were hooked up to batteries that store the electrical energy converted from the heat generated by users.
According to Steve Clinefelter, president of California Fitness at the time the initiative was launched in 2007, a person exercising at a moderate pace can generate about 50 W of electricity per hour on a machine. He estimated that someone who ran on a treadmill for one hour everyday could generate 18.2 KW of electricity and prevent 4.38 cu m of carbon dioxide (CO2) from entering the atmosphere per year.
Imagine the carbon emission reduction we would achieve if every household had an exercise machine installed to power entertainment devices such as the television and games consoles. With parents and children taking turns on the machine and all light fittings replaced with LED options, we could conceivably become much healthier and greener at the same time.
Of course, what with the need for air-conditioning and electricity to power appliances such as washing machines and refrigerators, human power alone is not likely to be sufficient to meet all our electricity needs, however useful it may be in training us to become fitter.
Alternatives
This is where other forms of renewable energy comes in. Solar power, wind turbines, geothermal energy, hydroelectric power … there is a large number of alternatives to fossil fuels in today’s world, depending on one’s location. Even Hong Kong, which may not at first glance appear a prime candidate for geothermal energy, has managed to tap this greener way of cooling a building – at the Wetland Park Visitor’s Centre, where 450 pipes of 32 mm diameter were drilled to a depth of 50 m for heat exchange. Although the system’s capital cost was considerably higher than a typical system using air-cooled or water-cooled chillers, its operating cost is lower because it is more energy-efficient.
In a study carried out by the Electrical & Mechanical Services Department (EMSD), it was determined that, given “current technological trends and applications, and taking into account Hong Kong’s local characteristics,” the main kinds of renewable energy suitable for local application are solar power, wind power and energy from waste. Other forms of renewable energy, namely, biomass energy, geothermal energy, hydro power and tidal and wave power are considered to have limited potential for development in Hong Kong.
Industry opinion differs, however. Solar power, for example, is not likely to provide more than a token portion of renewable energy in Hong Kong. The reason, according to Widex Technology Development Ltd project manager Mike Mai, is the fact that this is such a densely built city, which means limited roof space for photovoltaic (PV) installations relative to the number of households to be supplied.
There is no shortage of sunlight in Hong Kong, to be sure, but only a few low-rise, townhouse-type developments offer the possibility of solar power on any practical scale. PV modules can be installed on the facades of high-rise commercial or residential buildings, but since the efficiency of the PV cells can drop dramatically if they are not installed at an optimum angle to absorb solar radiation, the amount of electricity generated by those installed on vertical facades will be small. As a consequence, the payback period will be long and unattractive.
Solar water heaters are more feasible, according to Mr Mai, both because the payback period – about five years compared to ten for PV panels – is shorter and because of their high efficiency. They are also cost-effective to maintain. However, existing legislation has proved to be an obstacle to their wider adoption as building owners are concerned that they will be considered illegal structures under existing regulations.
Given the limited availability of remote sites with the right wind potential, Hong Kong does not appear to be suitable for much more than token amounts of wind power either. However, that is only the case if we think in terms of large, conventional wind turbines.
Mini-wind turbines capable of generating electricity at low wind speeds are much more suitable for the city and, in fact, are already growing in popularity since the renewable energy company Motorwave Ltd announcd the development of its first generation of mini-wind turbines in collaboration with the University of Hong Kong’s Department of Mechanical Engineering in March 2007.
Measuring just 26 cm in diameter, the first generation of mini-wind turbines can be arranged into arrays of varying sizes to generate power where even conventional small wind turbines cannot. It is estimated that they can operate 80% of the time, at locations where the latter would work 20-40% of the time. According to Motorwave president Lucien Gambarota, they can generate electricity at a wind speed as low as 2m/sec. With one mini-wind turbine capable of generating 1 W of electricity at wind speed of 5 m/sec, 100 million of them will yield 100 MW of electricity. That may seem a large number, but given their size, large panels of them may be put up anywhere.
Already, from an experimental installation at the Hong Kong Sea School two years ago, the company has gone on to install 10,000 mini-wind turbines across Hong Kong. Some architects are also beginning to incorporate them into designs for new buildings. Since they come in a variety of colours, desingers are even playing with them, to spell out words or simply for aesthetic effect.
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Incentives
To date, the adoption of renewable energy has been largely limited to trial installations by the two power companies, PV arrays on government buildings and mini-wind turbines on site offices and schools. What is the likelihood of Hong kong being able to exceed its conservative target of 1% of electricity from renewable sources by 2012, 2% by 2017 and 3% by 2022. (with 1999 as the base year)? By contrast, Sheikh Mohammed bin Zayed Al Nahyan, the crown prince of Abu Dhabi, pledged at the World Future Energy Summit in January that the oil-producing state would derive 7% of its power from green energy sources by 2020.
Given the right incentives, like the subsidy being offered to building owners to conduct energy audits and implement energy efficiency projects, there is no reason why users cannot be persuaded to go green with their energy use.
“In Europe many countries subsidise people for using solar energy at four times what they would have to pay for conventional electricity and there are banks offering special financing to cover the initial cost of installation,” Mr Mai said. “Some elderly people install them as an investment because, say the panels last 25 years and the payback period is five years, then after the first five years they’ll be earning a kind of interest because the government is paying them for using renewable energy and they don’t have to pay the electricity company anything.”
“There are even people who don’t have their own roof, who’d rent somebody else’s roof so they can benefit from the subsidy, and there are agents who specialise in this kind of roof leasing. There are lots of side businesses that make for a green economy.”
Adapt the idea to local conditions, and we could be looking at a much cleaner, more climate-friendly Hong Kong.
