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.

Demand response set to grow

Demand response, or demand side management, one of the biggest potential solutions to manage surging power needs across the grid, is set to double worldwide by 2020.

According to a recent report “Market Data: Demand Response”, demand response (DR) sites will grow from 10.3 million today to 21.9 million in 2020, representing 155,479 megawatts (MW) of potential electrical load curtailment. 

It also predicts automated demand response (ADR) programs where utilities can curtail demand without customer action to grow faster than the market average. Europe’s need to integrate a larger number of renewables will fuel its ADR growth, while Asia-Pacific markets may effectively “leapfrog” over the basic DR programs directly into ADR adoption.

DR is already helping US grid operators keep the lights on during this summer’s heat waves, and it could not only help balance growing demand in developing economies, but also help integrate more renewables onto the grid in North America and the European Union.

Generally speaking, DR is any kind of agreement between an electrical utility and its customer where the customer agrees to reduce power consumption by a pre-determined amount when peak demand hits the grid and power supplies are tightest. The US Energy Information Administration recently projected energy use will increase 56% worldwide by 2040, with most of the growth coming in non-developed countries, and most of the electricity demand being met by fossil fuel generation. As energy needs grow, DR will help global grids get smarter, better able to integrate renewables, and be less dependent upon fossil fuel.

Utilities view these “reserves” as a way to shave electrical demand when they need it most, helping to not only keep the grid stable, but prevent having to dispatch the most expensive power plant options. In return, customers are compensated for their participation, either in the form of bill credits or direct payments.

95% of the more than 1,300 DR programs currently underway across the globe are located in North America, with a potential peak power reduction capacity of 66.4 MW, roughly 9% of US peak demand.

Now the benefits of DR are set to spread rapidly in most other regions of the world, and that could have a major impact on energy access and fuel mix in fast-growing economies. The aforesaid report expects global load curtailment to grow at a compound annual growth rate of 13.5%, mainly fueled by the European and Asia-Pacific regions, with smaller but notable growth in the Middle East and Africa.

Going clean can be tough

As India’s Kudankulam nuclear plant gets set for producing power, doubts still remain on both sides of the nuclear argument. The World Health Organization estimates that preventable deaths from air pollution, meaning soot and smog from burning wood, coal, oil and gasoline, total more than two million per year worldwide. James Hansen, a prominent climate scientist, calculates the positive benefit of nuclear power as having saved about 1.84 million lives by reducing such pollution. Natural gas — methane — which anti-nuclear environmentalists lately seem to be embracing, is a greenhouse gas more than 20 times as potent as carbon dioxide.

Meanwhile, Germany's push to radically remake its energy system by abandoning nuclear and embracing clean energy is threatened by delays in grid investments and, paradoxically, the success of its solar industry. After the nuclear disaster at the Fukushima Daiichi plant in Japan, Germany adopted a policy of phasing out nuclear energy by 2022 and ensuring that 80 percent of the country's electricity supply comes from clean energy by 2050, or more than three times the level of 2010.

Even as the government is cutting back on once-generous subsidies for solar technology, the country is expected to reach a total solar installed capacity of 52,000 MW by 2017 or 2018. That is up from 6,000 MW in 2008, almost a ninefold increase.

The 17 nuclear reactors that were operated in Germany at the time used to produce about a fifth of the country's electricity. One piece of the new system to take their place will be 5,000 wind turbines installed nearly 100 miles out at sea, in water as deep as 130 feet. Another piece will be thousands of megawatts of gleaming rooftop solar panels.
Wind parks, for now mainly located onshore, already represent 17 percent of the country's installed generating capacity. But the expansion of offshore wind has been slowed by grid problems.
Meanwhile, Germany's solar boom is depressing energy prices and hurting the bottom line at the nation's big utilities such as RWE AG and E.ON SE. Germany needs nearly 1,000 miles of new high-voltage power lines in the coming years, according to plans approved by the federal government. Yet less than 155 miles has been built so far. In another blow to the government's plans, E.ON and RWE are reducing spending on renewable energy to cut down debt.

If and when wind and solar capacity double their outputs from current levels, base-load plants, which have to run constantly to ensure grid stability, will start to suffer financially as well and risk becoming uneconomical.
Going clean also comes with its handicaps. But if one can make it work, there are lessons for many in that.

Efficiency standards for US computers

The U.S. Department of Energy has announced that it wants to establish minimum energy efficiency standards for all computers and servers sold in the United States. A new study shows that large server farms can, in fact, cut electricity use and greenhouse gas emissions sharply with off-the-shelf equipment and proven energy management practices.

Most big data centers could slash their greenhouse gas emissions by 88 percent by switching to efficient, off-the-shelf equipment and improving energy management, according to new research.

The carbon emissions generated by a search on Google or a post on Facebook are related mostly to three things: the computing efficiency of IT (information technology) data center equipment, like servers, storage and network switches; the amount of electricity a data center's building uses for things other than computing, primarily cooling; and how much of the center's electricity comes from renewable or low-carbon sources

"Of these three, improving the efficiency of the IT devices is overwhelmingly the most important," said Jonathan Koomey, a co-author of the study, "Characteristics of Low-Carbon Data Centers," published online June 25 in Nature Climate Change.

The processors in most server farms perform computations at just 3 percent to 5 percent of their maximum capacity. Server virtualization, consolidation and better software can increase utilization to greater than 30 percent, and in some cases to be as high as 80 percent.

Big, outward-facing companies whose business primarily is cloud computing have solved the sustainability problem for data centers. eBay even discloses its data center efficiency publicly at dse.ebay.com.

After IT equipment, the second major way to reduce greenhouse gas emissions associated with data centers is to improve the efficiency of the buildings that support them. A key measurement of efficiency is the ratio of electricity used to perform computations to the amount of power consumed for secondary support, like cooling and monitoring systems. Typically that ratio is about 1 kilowatt-hour for computing to 0.8 kWh for the facility. State-of-the-art data centers have reduced the ratio to about 1 to 0.1 kWh, said study co-author Arman Shehabi of Lawrence Berkeley National Laboratory's Environmental Energy Technologies Division. "They locate server farms in cool climates like the U.S. Northwest, Sweden and Iceland. They purchase processors that are less sensitive to heat. And they use efficient cooling equipment and air-flow management."

Of the potential 88 percent reduction in greenhouse gas emissions, though, IT device efficiency accounts for about 80 percent and facility energy management for only about 8 percent. Once those two areas are maximized, sourcing electricity from renewables like wind and solar power, plus green handling of retired equipment, can get a typical data center's emissions down 98 percent.

Produce what you consume!

The Internet of Things is the imagined network of data links that will emerge when everyday objects are fitted with tiny identifying devices. The idea is that every parcel in a post office would transmit its position, origin and destination so that it can be tracked and routed more efficiently, that every product on a supermarket shelf would transmit its contents, price, shelf life and so on, that your smartphone would interrogate the contents of your fridge and cupboards every time you walk into the kitchen to warn you when the milk is running low. And so on.

Each of these things will enhance our businesses and lifestyles in a small way. But there’s a problem: these tiny identifying devices require a power source. Batteries are expensive and impractical so computer scientists are hoping to harvest the necessary energy from the environment, in particular from lights and from human motion.

Maria Gorlatova and pals at Columbia University in New York measured the inertial energy available from the activity of 40 individuals over periods up to 9 days. To do this they attached to each person inertial energy harvesting devices, essentially a mass attached a spring, that recorded their motion.

They also measured the power available from the movement of objects such as doors, drawers and pencils to see how much might be harvested here.

Here’s a list of their main findings: Periodic motion is energy rich. So writing with a pencil generates more power (10-15 microwatts) than the acceleration associated with a 3-hour flight flight including take off! Humans are passive most of the time. About 95 per cent of the total harvestable energy they produce is generated during less than 7 per cent of the day. Most people generate enough power to continuously transmit data at the rate of about 1 Kb/s (more than 5 microwatts). Why not tap all that wasted energy for little applications?

Air pollution shortens lives: MIT study

A study released earlier this week indicates that airborne pollution in China may have shortened the lives of 500 million Chinese by 2.5 billion years. The paper, published in PNAS on Monday, examined pollution data and death records to see whether coal burning, long a source of air pollution, could have damaged public health across northern China in the 1990s. It does. The findings raise concern for developing countries.

The nose, mucus in the esophagus and cells in the lungs all filter foreign substances to facilitate clean breathing. But some pollutant particles can overwhelm the body’s natural defense systems, however, causing inflammation in the lungs. This inflammation could result in breathing difficulties, exacerbate preexisting conditions and, in extreme cases, cause death.

Michael Greenstone, an economist at Massachusetts Institute of Technology and a primary author of the study, says finding answers has been extremely difficult, because simply comparing pollution levels and health in different locales can be misleading. For one thing, people often move from place to place and experience varying levels of pollution, so it is not safe to assume that all have had the same exposure.

From 1950 to 1980 the Chinese government was in a period of socialist transformation. During this time the “Huai River policy” provided free coal for heating homes and offices north of the Huai River, which runs west to east across eastern China. Meanwhile budget constraints kept free coal from being provided south of the river. At the same time, government rules restricted a family's ability to move, so that many lived in one location for decades.

By examining rates of mortality and respiratory-related illnesses on both sides of the river, Greenstone’s team identified a difference: life expectancies are lower and pollution concentrations are higher north of the Huai, where coal burning was widespread.

To make these connections, Greenstone and his team examined pollution data from sites across the country for the years 1981 to 2000. They then collected mortality data from China's Disease Surveillance Points, 145 sites chosen by the government to accurately represent the wealth and geographic dispersion of the populace.

The results estimate that lifelong exposure to 100 micrograms of “total suspended particulates,” or TSPs, (minuscule solid particles floating in the air, such as pollutants) per meter of air cubed will shorten a person’s life by three years, on average.

As more countries in Asia and Africa power toward industrialization, air pollution becomes an increasing concern. Developing countries are really trying to strike the right balance between economic growth to confront poverty and environmental quality and public health,” Greenstone says. “I think this study will help them—it shows a relationship between pollution and health.”