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Melbourne building a solar farm for world’s largest tram network

Melbourne building a solar farm for world’s largest tram network Science & Technology World Website


Solar trams are coming to Melbourne and that’s a massive deal for the city, state and country. Melbourne has the largest operating tram network in the world with 250km of track with a staggering 1,763 stops and the trams run more than 20 hours per day. Back in 2013-14 the network serviced 176.9 passenger trips, which in 3 years has certainly grown with the population.

Melbourne’s trains are traditionally powered by overhead cables that draw power from the electricity grid, meaning this mode of public transport is ripe for a transition to a renewable power source like solar, that costs a one off investment, which can then power the trams for years with the free source of the sun.

While I’d hoped they were going to strap solar panels to the top of the trams, given the large surface area and the mostly outdoors routes. I would have loved to see the trams collect and store energy locally using battery technology, but perhaps the power to weight equation may not add up right now. The Government is taking a different approach.

The Government’s Minister for Energy, Environment & Climate Change and Minister for Suburban Development, Lily D’Ambrosio, today announced they’ll build a large scale solar plant to power the network. An Andrews Labor Government will run a tender process to help build a 75MW large scale solar farm to deliver $150 million in new capital investment and 300 new jobs.

Around 35MW of the new solar farms will be linked to Melbourne’s tram network. The Government will voluntarily surrender renewable energy certificates matching the amount of electricity used by all of Melbourne’s trams. This will result in a reduction of more than 80,000 tonnes of greenhouse gas emissions every year.

An open tender will be run in the first half of this year, with a completion date of the end of 2018.

It seems the minister is fond of electric vehicles, back in May 2015, she attended the launch of Telsa’s Melbourne store, if only more of our politicians felt the same.


Milestone in solar cell efficiency by UNSW engineers

Melbourne building a solar farm for world’s largest tram network Science & Technology World Website


A new solar cell configuration developed by engineers at the University of New South Wales has pushed sunlight-to-electricity conversion efficiency to 34.5% – establishing a new world record for unfocused sunlight and nudging closer to the theoretical limits for such a device.

The record was set by Dr Mark Keevers and Professor Martin Green, Senior Research Fellow and Director, respectively, of UNSW’s Australian Centre for Advanced Photovoltaics, using a 28-cm2 four-junction mini-module – embedded in a prism – that extracts the maximum energy from sunlight. It does this by splitting the incoming rays into four bands, using a hybrid four-junction receiver to squeeze even more electricity from each beam of sunlight.

The new UNSW result, confirmed by the US National Renewable Energy Laboratory, is almost 44% better than the previous record – made by Alta Devices of the USA, which reached 24% efficiency, but over a larger surface area of 800-cm2.

“This encouraging result shows that there are still advances to come in photovoltaics research to make solar cells even more efficient,” said Keevers. “Extracting more energy from every beam of sunlight is critical to reducing the cost of electricity generated by solar cells as it lowers the investment needed, and delivering payback faster.”

The result was obtained by the same UNSW team that set a world record in 2014, achieving an electricity conversion rate of over 40% by using mirrors to concentrate the light – a technique known as CPV (concentrator photovoltaics) – and then similarly splitting out various wavelengths. The new result, however, was achieved using normal sunlight with no concentrators.

Dr Mark Keevers and Professor Martin Green of UNSW's Australian Centre for Advanced Photovoltaics.

“What’s remarkable is that this level of efficiency had not been expected for many years,” said Green, a pioneer who has led the field for much of his 40 years at UNSW. “A recent study by Germany’s Agora Energiewende think tank set an aggressive target of 35% efficiency by 2050 for a module that uses unconcentrated sunlight, such as the standard ones on family homes.

“So things are moving faster in solar cell efficiency than many experts expected, and that’s good news for solar energy,” he added. “But we must maintain the pace of photovoltaic research in Australia to ensure that we not only build on such tremendous results, but continue to bring benefits back to Australia.”

Australia’s research in photovoltaics has already generated flow-on benefits of more than $8 billion to the country, Green said. Gains in efficiency alone, made possible by UNSW’s PERC cells, are forecast to save $750 million in domestic electricity generation in the next decade. PERC cells were invented at UNSW and are now becoming the commercial standard globally.

The record-setting UNSW mini-module combines a silicon cell on one face of a glass prism, with a triple-junction solar cell on the other.

The triple-junction cell targets discrete bands of the incoming sunlight, using a combination of three layers: indium-gallium-phosphide; indium-gallium-arsenide; and germanium. As sunlight passes through each layer, energy is extracted by each junction at its most efficient wavelength, while the unused part of the light passes through to the next layer, and so on.

A diagram of the spectrum-splitting, four-junction mini-module developed at UNSW.

Some of the infrared band of incoming sunlight, unused by the triple-junction cell, is filtered out and bounced onto the silicon cell, thereby extracting just about all of the energy from each beam of sunlight hitting the mini-module.

The 34.5% result with the 28 cm2 mini-module is already a world record, but scaling it up to a larger 800-cm2 – thereby leaping beyond Alta Devices’ 24% – is well within reach. “There’ll be some marginal loss from interconnection in the scale-up, but we are so far ahead that it’s entirely feasible,” Keevers said. The theoretical limit for such a four-junction device is thought to be 53%, which puts the UNSW result two-thirds of the way there.

Multi-junction solar cells of this type are unlikely to find their way onto the rooftops of homes and offices soon, as they require more effort to manufacture and therefore cost more than standard crystalline silicon cells with a single junction. But the UNSW team is working on new techniques to reduce the manufacturing complexity, and create cheaper multi-junction cells.

However, the spectrum-splitting approach is perfect for solar towers, like those being developed by Australia’s RayGen Resources, which use mirrors to concentrate sunlight which is then converted directly into electricity.

The research is supported by $1.4 million grant funding from the Australian Renewable Energy Agency (ARENA), whose CEO Ivor Frischknecht said the achievement demonstrated the importance of supporting early stage renewable energy technologies.

“Australia already punches above its weight in solar R&D and is recognised as a world leader in solar innovation,” Frischknecht said. “These early stage foundations are increasingly making it possible for Australia to return solar dividends here at home and in export markets – and there’s no reason to believe the same results can’t be achieved with this record-breaking technology.”

He noted that the UNSW team is working with another ARENA-supported company, RayGen, to explore how the advanced receiver could be rolled out at concentrated solar PV power plants.

“With the right support, Australia’s world leading R&D is well placed to translate into efficiency wins for households through the ongoing roll out of rooftop solar and utility-scale solar projects such as those being advanced by ARENA through its current $100 million large-scale solar round, he added. “Over the longer term, these innovative technologies are also likely to take up less space on our rooftops and in our fields.”

Other research partners working with UNSW include Trina Solar, a PV module manufacturer and the U.S. National Renewable Energy Laboratory.


New Zealanders warming to solar power: report

Melbourne building a solar farm for world’s largest tram network Science & Technology World Website


Dr Rebecca Ford, a lecturer at Victoria University of Wellington's School of Engineering and Computer Science, is the lead researcher on the report which looks into the uptake of Photovoltaic (PV) to generate electricity in New Zealand.

Dr Ford says the report showed that of the participants surveyed only 30 percent were happy with getting electricity from their power company, and almost 60 percent would like to generate some or all of their own electricity and would be willing to purchase PV in the future.

It also identifies that greater numbers of Kiwi's are already putting their money where their mouth is and investing in PV, with the number of grid-connected small-scale systems having grown by 330 percent in the last two years.

Dr Ford says while the numbers are still relatively low compared to other countries, the growth trend has potential to have a substantial impact in the future.

The report is part of the GREEN Grid project, funded by the Ministry of Business, Innovation and Employment which Dr Ford is working on along with researchers from Otago, Canterbury and Auckland universities.

The project is a wide-ranging investigation into how New Zealanders use power, how the demand can best be met using renewable sources, and how the national grid can be made smarter and more efficient.

The report also investigates what is stopping more New Zealanders getting on board with solar power in their homes and businesses.

"The biggest barrier for people," Dr Ford says, "seems to be the upfront cost. While there are substantial benefits to installing a Photovoltaic system in your home it's the high start-up costs and the lack of current financial incentives that put people off."

Currently there is no support from the Government to encourage a greater uptake but, the report says, there are new types of business models being trialled by companies such as Vector.

Vector's model allows customers to lease a PV system, making it possible for people to choose solar energy generation even if they don't have the money to invest in a system or do not own their own home.

"It's early days," says Dr Ford, "but the results of our surveys were very promising. It showed us that New Zealanders do want to take personal responsibility for producing clean energy—we just need to find achievable ways to help make that happen."

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