The surge gains strength

The Brazilian state of São Paulo — the economic and industrial heart of the country — is currently aiming to possess a total of at least 1 GW of solar energy capacity by the year 2020, a goal which is very achievable, according to a solar atlas of the region that was recently released by the state’s energy secretariat. The state of São Paulo possesses twice the maximum global solar irradiation of the solar powerhouse Germany.

SãoPaulo, which in addition to being the economic heart of the country is also the most populous state in Brazil, has a total solar power generation potential of 12 TWh per year in the areas with the absolute highest annual solar radiation, according to the new solar atlas. The areas in question total 732 square kilometers — 0.3% of the state’s total area of 248,209 square kilometers. It’s estimated that these areas could host at least 9,100 MW (9.1 GW) of installed capacity.

São Paulo is already well on its way to achieving its aforementioned goal of possessing 1 GW of solar energy capacity by 2020 — 207 MW of thermal solar capacity are already installed. The rest of the 1 GW target capacity will be split up thusly: a further 592 MW of thermal solar capacity, 50 MW of photovoltaic solar capacity, 50 MW of concentrated solar power, and 100 MW set aside for passive solar energy exploitation in the form of solar architecture projects.

Indian government announced a $7.9 billion investment to double its transmission capacity – designed to increase access to power from wind and solar projects. India’s installed solar energy has jumped from a mere 17 megawatts in 2010, when India’s National Solar Mission was announced, to over 1200 megawatts today. The second phase of JNNSM programme envisages development of cumulative capacity of 1,000 MW for off-grid solar power and targets 15 million sq mt collector area. The targets include improved energy access in remote areas, heating or cooling applications that would encourage employment generation opportunities, replacement of diesel and kerosene as in Telecom Towers, solar cities and solar cookers and steam generating systems.

Not only do these clean energy projects increase India’s energy supply, they also create much needed jobs. As India’s economy grows and develops, its energy consumption likewise is increasing rapidly: it increased 64 percent from 2001-02 to 2011-12 and is projected to grow an additional 72 percent by 2021-22, according to the Indian Planning Commission. To support India’s burgeoning renewable energy ecosystem, NRDC and the Council on Energy, Environment and Water (CEEW) are striving to bolster the case for clean energy by telling this story of job creation and economic benefits.

The surge should pick up likewise in all places that get good sunlight. 

New kid on the solar block

A new type of solar cell, made from a material that is dramatically cheaper to obtain and use than silicon, could generate as much power as today’s commodity solar cells. Solar cells can be made very cheaply but have the downside of being relatively inefficient. Lately, more researchers have focused on developing very high efficiency cells, even if they require more expensive manufacturing techniques. The new material could deliver solar cells that are highly efficient but also cheap to make.

Perovskites have been known for over a century, but no one thought to try them in solar cells until relatively recently. Very good at absorbing light the new solar cells use less than one micrometer of material to capture the same amount of sunlight. The pigment is a semiconductor that is also good at transporting the electric charge created when light hits it.

One group has produced the most efficient perovskite solar cells so far—they convert 15 percent of the energy in sunlight into electricity, far more than other cheap-to-make solar cells. Based on its performance so far, and on its known light-conversion properties, researchers say its efficiency could easily rise as high as 20 to 25 percent, as good as the record efficiencies (typically achieved in labs) of the most common types of solar cells today. Perovskite in solar cells will likely prove to be a “forgiving” material that retains high efficiencies in mass production, since the manufacturing processes are simple.

Perovskites will have difficulty taking on silicon solar cells. The costs of silicon solar cells are falling, and some analysts think they could eventually fall as low as 25 cents per watt, which would eliminate most of the cost advantage of perovskites and lessen the incentive for investing in the new technology. But it might be possible to paint perovskites onto conventional silicon solar cells to improve their efficiency, and so lower the overall cost per watt for solar cells.

Combining solar PV & thermal could be the way

The Advanced Research Projects Agency–Energy in the US is devoting $30 million to several demonstration projects that will attempt to combine photovoltaics with solar thermal. The effort seeks to solve the important problem of intermittency of solar electricity.

Currently, storing electricity from solar panels is either prohibitively expensive or, in some areas, unfeasible. Solar thermal power, which concentrates sunlight to heat water and make steam for turbines, can store energy by keeping heat in insulated containers. But overall, solar thermal power is twice as expensive as power from solar panels.

According to ARPA-E, there are several ways the two types of solar power might be combined. Some solar power systems involve concentrating sunlight on tiny, super-efficient solar cells. As they’re currently configured, the heat from the concentrated sunlight is quickly extracted and allowed to dissipate into the atmosphere. If it could be collected instead, it could be stored and used to generate electricity later. The challenge is that this approach would require operating solar cells at much higher temperatures than is normal, and this can damage them. Researchers are looking at ways to make solar cells more resistant to high temperatures.

Another possibility is to split up the solar spectrum. Solar cells are very good at converting certain wavelengths of light into electricity—but not others. It may be possible to redirect wavelengths that can’t be used efficiently, and to use these to heat up water and produce steam.

Yet another approach is being developed by Todd Otanicar, a professor of mechanical engineering at the University of Tulsa. He uses nanoparticles suspended in a translucent fluid to absorb certain wavelengths but allow others to pass through to a solar cell. As the nanoparticles absorb sunlight, they heat up, and the fluid can be used to generate steam.

ARPA-E is also considering funding novel energy storage technologies that use both heat and electricity. Adding heat to electrolysis, for example, might improve the economics of splitting water to produce hydrogen. The hydrogen could then be run through a fuel cell to generate electricity. Heat could also aid other electrochemical reactions, such as those that can be used to make liquid fuels for vehicles.

Positives of fracking

"Geothermal is homegrown, reliable and clean," says Rohit Khanna, program manager at the World Bank for its Energy Sector Management Assistance Program. That is a big part of the reason it is being pursued in developing countries such as Chile, Indonesia, Kenya and the Philippines.

Australia's first enhanced geothermal system, spicily named Habanero, began producing power in May, and Europe has brought three such power plants online. A geothermal power plant in Larderello, Italy, has churned out electricity this way in Tuscany for more than a century, and big power plants can be built this way.

By some estimates, the U.S. could tap as much as 2,000 times the nation’s current annual energy use of roughly 100 exajoules (an exajoule equals a quintillion, or 10¹⁸ joules) via enhanced geothermal technologies. With respect to electricity, the DoE concludes at least 500 gigawatts of electric capacity could be harvested from such EGS systems. Even better, hot rocks underlie every part of the country and the rest of the world. The Geysers in California can produce 850 megawatts of electricity alone.

The idea is simple: pump water or other fluids down to the hot rocks beneath the surface. Heat from the rocks turns the water to steam. The steam rises and turns a turbine that spins a magnet to make electricity.

Some places have the natural bounty of hot rocks and cracks in them. But such sites are not plenty.  That's where fracking, the controversial practice of pumping fluid underground to shatter shale and release oil or gas, can help. Fracking “enhances” geothermal by making cracks in hot rocks where none existed, allowing heat to be harvested from Earth’s interior practically anywhere, although this reduces the total power produced because of the need to pump water through the system.

Yet, geothermal’s abundant, renewable, clean potential for making electricity largely languishes, producing "less than 1 percent of global energy," according to a recent perspective in Science. Indeed, only 6 percent of naturally occurring geothermal resources have been tapped to date, according to Bloomberg New Energy Finance (BNEF).

The reason is simple: money. In addition to the $6-million to $8-million risk of drilling a dry hole or a well that does not produce steam as it should there is the multimillion-dollar expense of building a power plant on top of those wells that do produce steam as they should. That adds up to a total cost for a geothermal power plant of roughly $90 per megawatt-hour,

Gradient holes have to be drilled to explore a particular area. Explosions need to be set off at the surface to send seismic waves through the rock that allow for surveying the underground landscape—a technique familiar from the oil and gas industry. It can take years and millions of dollars to do this exploration with the prospect of earning that money back slowly via electricity sales—or all those funds could be lost.

 BNEF puts the odds of successfully completing a geothermal well at 67 percent, which means one third of all geothermal projects fail. The analyst outfit has called for a "global geothermal exploration drilling fund" of some $500 million provided by investment agencies like the World Bank.

Another problem: some EGS projects have been associated with small earthquakes, much like oil and gas drilling and wastewater disposal. That has caused some projects to be abandoned.