RSS Entries ATOM Entries

Posts Tagged ‘sea level rise’

Seawater Agriculture: High-tech and Low-tech paths

Posted in Movements, Research by Kate Archdeacon on December 3rd, 2012

Source: guardian.co.uk


Image from Seawater Greenhouse

In the Guardian this week, there’s an article by Jonathan Margolis about the commercialisation of a technology that uses seawater as the main element of agriculturally productive greenhouses.  Much of the article focuses on the way the technology, developed by British theatre lighting engineer Charlie Paton, has been scaled up and combined with extra technology to provide consistent, commercial-quality crops from the Sundrop Farms greenhouse in the desert outside Port Augusta, in South Australia.  On it’s own, that’s pretty exciting and well worth a read.

A 75m line of motorised parabolic mirrors that follow the sun all day focuses its heat on a pipe containing a sealed-in supply of oil. The hot oil in turn heats nearby tanks of seawater pumped up from a few metres below ground – the shore is only 100m away. The oil brings the seawater up to 160C and steam from this drives turbines providing electricity. Some of the hot water from the process heats the greenhouse through the cold desert nights, while the rest is fed into a desalination plant that produces the 10,000 litres of fresh water a day needed to keep the plants happy. The water the grower gets is pure and ready for the perfect mix of nutrients to be added. The air in the greenhouse is kept humid and cool by trickling water over a wall of honeycombed cardboard evaporative pads through which air is driven by wind and fans. The system is hi-tech all the way; the greenhouse is in a remote spot, but the grower, a hyper-enthusiastic 27-year-old Canadian, Dave Pratt, can rather delightfully control all the growing conditions for his tonnes of crops from an iPhone app if he’s out on the town – or even home in Ontario.

The remainder of the article touches on the divergence of philosophy between Paton’s Seawater Greenhouse, and SunDrop.

The Seawater Greenhouse method, which they are still promoting actively, involves no desalination plant, no gleaming solar mirrors and little by way of anything electronic. Everything in the Seawater Greenhouse vision is low-tech, cheap to start up and reliant on the subtle, gentle interaction of evaporation and condensation of seawater with wind, both natural and artificial, blown by fans powered by solar panels. If things go wrong and production is disrupted by a glitch in this model, you just persuade people to eat perfectly good but odd-looking produce – or harvest less and stand firm by your sustainable principles.

For those of us interested in the gap between local, low-tech production designed to shift society away from BAU, and the changes that occur when those systems scale up to cater to the existing market, this article may also provide a few points of contention.

Read the full article by Jonathan Margolis for the Guardian.


Transforming Tokelau: Heading for 100% solar by the end of 2012

Posted in Models, Movements by Jessica Bird on August 27th, 2012

Source: New Zealand Ministry of Foreign Affairs and Trade Aid Programme

From “Tokelau: A Leading Light in Renewable Energy

 

An innovative renewable energy project is set to transform Tokelau and lead the world in transitioning from dependence on fossil-fuels to renewable energy.  

With global attention focused on the effects of climate change and the international price of oil, it may come as a surprise that the tiny nation of Tokelau, comprising three remote atolls midway between New Zealand and Hawai’i, is moving to the forefront of the debate by installing renewable energy systems that will dramatically slash its reliance on imported fossil fuels. Undertaking a project of this scale on all three atolls is no mean feat. The closest atoll is around 500km north of Samoa; there are no airstrips or wharves, and the only access is a long boat trip from Samoa that ends outside the reefs, where a landing barge takes passengers and equipment to shore. Offloading goods in the swell is challenging. However, soon the job will become easier since almost 2,000 barrels of diesel a year will no longer be required to generate electricity.

Developing renewable energy projects in the Pacific brings unique challenges. Systems and components must be designed to withstand harsh tropical and marine environments, strong winds, high temperatures, and a corrosive salt-laden atmosphere. Unlike in New Zealand, where if a part breaks or needs replacing it is possible to replace easily, in Tokelau the systems and components must be designed to promote robustness and longevity, because transport is infrequent and challenging. And yet by the end of 2012 Tokelau expects to switch off its generators and begin to use an indigenous resource it has plenty of – sunlight.

Tokelau’s 1,411 residents are New Zealand citizens, and New Zealand is advancing $7 million to the Government of Tokelau to install the renewable energy systems that will help achieve its long-term goals of energy independence and reducing reliance on expensive imported diesel, which will put Tokelau at the forefront of global climate change mitigation efforts.

The energy crisis in the Pacific is not confined to Tokelau. Most Pacific Island nations are highly dependent on imported fossil fuels to meet energy needs, and are vulnerable to international price fluctuations and escalating fuel costs. Almost every aspect of Pacific economies is underpinned by imported fossil fuels, and the increasing cost of diesel results in extremely high costs of electricity for households and businesses. In many cases, the cost of importing fuel is many times higher than all export earnings combined, so Tokelau’s, and the Pacific’s, dependence on diesel is bad for the economy as well as the environment. […]

“This project is unique and has the potential to demonstrate what can be achieved through the perseverance and hard work by the Government of Tokelau,” adds Joseph Mayhew, Development Manager Energy in the New Zealand Aid Programme. “Photovoltaics are a mature, reliable off-the-shelf technology that has been proven for years. Given the high cost of diesel, renewable energy should not be seen as an ‘alternative’ source of energy, but rather an essential key to unlocking the Pacific’s potential.”

Read the full article from the New Zealand Ministry of Foreign Affairs and Trade