Thursday, March 27, 2008

The Road to Grid Parity may be through Route 1366

1366 Technologies (what's in a name?), a spin-off company of MIT, has received $12.4 million in seed money. The company is co-founded by Ely Sachs, the father of the string ribbon solar manufacturing process that has been the hallmark of Evergreen Solar.

1366 aims to be bring the costs of solar power down to $1 a watt (the price which many agree will make solar competitive with fossil fuel energy) by employing its light ribbon technology. The beauty of the technology is that it does so not by tinkering with the solar wafer itself, but but replacing the interconnect wire between solar panels with a grooved light-capturing ribbon strip, which as the schematic below illustrates, reflects incoming light back onto the surface of the solar cell.Apart from the light ribbon technology, 1366 is also developing "new [solar]cell architecture that uses innovative, low-cost fabrication methods"that can increase the polycrystalline efficiency by 25%. According to MIT Technology Review, 1366's design includes two other key innovations in addition to its light-capture ribbons:
The first is a method for adding texture to the surface of the cells that allows the silicon to absorb more light, a trick that's been used before with single-crystalline devices but has been difficult to implement with multicrystalline silicon. The rough surface causes light to bend as it enters the cell so that when it encounters the back of the cell, it doesn't reflect right back out; rather, it bounces off at a low angle and remains inside the slab of silicon. The longer the light remains within the silicon, the greater the chance that it will be absorbed and converted into electricity.

The second innovation involves the silver wires that harvest electrical current generated by the silicon. Sachs has developed a method for making these wires as small as one-fifth the width of the wires that are typically used, while improving their conductivity. The thinner wires use less silver, which cuts down costs. Also, because the wires are thinner, they can be spaced closer together and still block less light than ordinary wires can. The closer spacing makes the wires more efficient at collecting electrical current generated in the silicon.
The company plans to build its pilot solar cell manufacturing facility in Lexington, Massachusetts. .

Wednesday, March 26, 2008

AES and Riverstone also go Big on Solar

Yet another wealth fund and energy company are pairing up to build utility-scale solar power plants. A hint of deja vu (see earlier post on the Torresol joint-venture)? Global diversified energy giant and Virginia-based AES and New York private equity firm Riverstone, an affiliate of the Carlyle Group are forming a joint venture in the name of AES Solar. AES and Riverstone will each "provide up to $500 million of capital over five years to invest in PV solar projects around the world, ranging from fewer than two to more than 50 megawatts in size."

In my view, this is a significant announcement. What sets this venture apart from the Torresol venture is that AES and Carlyle are both powerhouses in their respective industries of energy (although much has been made of AES' sustainability push, they have traditionally been, and still are, very much vested in fossil fuels) and private equity and very much represent the status quo. As this Washington Post article notes, this investment represents AES's first venture into solar. For the two giants to come together and make a billion dollar bet on big solar is a major validation on the outlook of the role utility-scale solar will play in our global energy mix.

Wednesday, March 19, 2008

Torresol: The New Kid on the CSP Block

Credit to the Green Wombat for first covering this company, and for the graphic below.

Torresol Energy, a 60-40 joint venture between Masdar, Abu Dhabi's $15 billion renewable energy initiative, and Sener, a Spanish engineering company, aims to build a series of utility-scale power plants using concentrated solar power (CSP) technologies, starting with projects in Spain and Abu Dhabi.

Torresol aims to build two solar plants a year in order to reach 320 MW in total capacity by 2010, and 1,000 MW by 2018. Their target geographic areas consist of Southern Europe (especially Spain), Northern Africa, the Middle East and eventually, southeastern USA, constituting a de facto "global sunbelt". I for one would be thrilled if the likes of China and other Asian markets are eventually included.

I'd like to take a closer look at Torresol’s technologies:

The prototypical Torresol solar plant structure consists of multiple rows of heliostats circling a central receiving tower filled with molten salt. The heliostats consist of parabolic troughs that pivot around an axis to track the changing position of the sun through the day. The heliostats concentrate and reflect the sunlight onto the central receiving tower filled with molten salt, which acts as an energy storage conduit. Though the technology was conceived in the 1970s, the company claims to be the first company in the world to apply this molten salt energy storage technology in a commercial plant.

According to the Sandia National Laboratory National Solar Thermal Test Facility, the molten salt, also known as saltpeter, is a mixture of 60% sodium nitrate and 40% potassium-nitrate. Sodium has a high heat capacity and hence, saltpeter serves as an effective medium to store the solar power in the form of heat. Heated saltpeter is channeled into insulated storage tanks where they can be released into a conventional steam-generating system to boil water to generate steam to cycle through turbines to produce electricity.

The upshot of thermal storage is that the ability of the solar plant is no longer subject to the intermittency of solar irradiation—surplus solar energy collected on the sunny days can be stored in the molten salt for discharge on cloudy days or at night. According to Torresol’s website, molten salt storage allows for 15 hours of independent electricity generation without sun irradiation, resulting in electricity production during 6,500 hours a year, 2.5 to 3 times more than other renewable energies such as wind or photovoltaic energy.

Friday, March 14, 2008

More Singapore solar milestones

A few more solar milestones for Singapore's burgeoning solar industry have been achieved (see previous posts on Singapore's solar scene here and here):

Norwegian solar wafer manufacturer, NorSun, is the latest major solar company to announce plans to set up shop in Singapore. Norsun plans to build a US$300 million mono-crystalline solar wafer manufacturing facility, which will be NorSun's largest production centre in the world. The facility is expected to produce at least 120 million mono-crystalline wafers every year and will account for 60% of NorSun's global output, making it its biggest facility. The first phase of the new plant in Singapore is scheduled to be completed in the third quarter of 2010 and is expected to require 300 new hires.

The Norsun news comes close on the heels of last month's announcement that a National Research Institute on Solar Energy. More importantly, Singapore lured world renown solar expert
Professor Joachim Luther, former director of the renown Fraunhofer Institute for Solar Energy Systems - Europe's largest solar energy R&D institute - to head NRISE for an initial two-year tenure. This research and educational component is an important ingredient in the solar ecology that the tiny island-city hopes to build up.

Wednesday, March 12, 2008

The Dark Side of Solar

As if to rebut my last blog post on the positive environmental performance of PV generated electricity vis-a-vis fossil fuel derived power, the Washing Post has run an excellent expose on the collateral damage of polysilicon (a raw ingredient to crystalline-based PV solar cells) production in China. Silicon tetrachloride, a highly toxic byproduct of polysilicon processing, is being dumped by Chinese polysilicon factories into the soil rather than being reprocessed, so as to cut investment costs and time.

The result? The global solar boom in the likes of Germany and the US is creating a toxic legacy of silicon tetrachloride dumping by Chinese polysilicon factories.

Ironic and depressing. Kinda like this story in the New York Times about glycerol dumping by biofuel plant operators, or this piece in an old blog I used to maintain on tropical rainforest deforestation in Indonesia for the sake of planting oil palm for biodiesel.

All this means that we'll soon be needing certification systems for the audit of the supply chain of our clean energy.

Sunday, March 9, 2008

Life-Cycle Assessment results in thumbs up for solar!

A new study that measures the life-cycle greenhouse-gas, pollutant and heavy metal emissions of four types of photovoltaic (PV) technologies--multicrystalline silicon, monocrystalline silicon, ribbon silicon, and thin-film cadmium telluride (CdTe)--reveals certain findings that are predictable and others that are surprising.

Simplified process-flow diagrams from mining to system manufacturing stages, namely
cradle-to-gate for (a) mono-, ribbon-, and multi-Si PVs, and (b) thinfilm CdTe PVs. Source: Study

Predictably, the authors of the study concluded that "all PV technologies generate far less life-cycle air emissions per GWh than conventional fossil-fuel-based electricity generation technologies." Despite concerns that the manufacture process of PV panels may be energy intensive, PV technologies harness a clean and ubiquitous source of energy, whereas fossil-fuel or nuclear generate electricity requires capital-intensive (i.e. energy and emissions intensive) plant infrastructure and significant transportation of fuel from its source to the location it is used.

The authors go on to say that at least 89% of emissions can be reduced if electricty from "central PV systems" replaces those from the grid, and that even more emissions can be reduces with decentralized PV systems due to the reduction in energy loss as the need for electricity transmission is reduced.

In an article in Scientific American reviewing this same study, it is suggested that if solar power can be used to start powering the production of PV cells--a so-called "PV breeder cycle"--then the emissions reductions will be even more dramatic.

Among the four PV technologies, CdTe came out tops, against conventional concerns of the toxicity of cadmium (cadmium in its metallic form is a toxic substance that has the tendency to accumulate in ecological food chains). CdTe thin-film PV technologies outperforms silicon-based PV technologies because less energy is required in the manufacture of the former (indeed, the purification of solar-grade silicon is a energy-intensive process), resulting in lower emissions of GHG, criteria pollutants and heavy metals.

Click here if you are interested in other comparative life-cycle studies of PV technologies. by the Columbia University Center for Life Cycle Analysis.