For years, homeowners who bought solar panels were advised to mount them on the roof facing south. That captures the most solar energy over the course of the day, which benefits the homeowner, but does so at hours that are not so helpful for the utility and the grid as a whole.

Mount them to catch the sunlight from the west in the afternoon, and the panels’ production over all would fall, but it would come at hours when the electricity was more valuable.

But that idea is slow to take hold. A new study of 110,000 California houses with rooftop solar systems confirmed that a vast majority of the panels were pointed south because most of the panel owners were paid by the number of kilowatt-hours the panels produced. Pointing them southward maximizes production over all, but peak production comes at midday, not in late afternoon, when it would be more helpful.

In late afternoon, homeowners are more likely to watch TV, turn on the lights or run the dishwasher. Electricity prices are higher at that period of peak demand.

“The predominance of south-facing panels may reflect a severe misalignment in energy supply and demand,”

said the authors of the study, Barry Fischer and Ben Harack. They work for Opower, a company that provides software that electric companies can use to manage their relationships with their customers.

Houses with solar systems consume less than half as much utility-delivered electricity as ordinary houses, the study found. But from about 4 p.m. through the night, they consume more, and they add to the system’s peak demand, which comes around 5 p.m.

Pointing panels to the west means that in the hour beginning at 5 p.m., they produce 55 percent of their peak output. So a 10-kilowatt system would make 5.5 kilowatts. But point them to the south to maximize total output, and when the electric grid needs it most, they are producing only 15 percent of peak, or 1.5 kilowatts.

Why wouldn’t everyone point the panels west? Some homeowners have their panels face south because that is the direction of the roof. While some solar panel owners are paid time-of-use rates and are compensated by the utility in proportion to prices on the wholesale electric grid, many panel owners cannot take advantage of the higher value of electricity at peak hours because they are paid a flat rate, the energy analysts said. So the payment system creates an incentive for the homeowner to do the wrong thing. The California Energy Commission recently announced a bonus of up to $500 for new installations that point west. A new solar installation is completed every 3.2 minutes, according to the authors of the analysis.

Solar panels do not have to be pointed in just one direction; a homeowner can buy a device called a tracker that will pivot them, over the course of the day, like a sunflower, so they always face the sun. A tracker can raise the output of a panel by 45 percent. But adding trackers can cost hundreds or thousands of dollars, and a cheaper way to get the same number of kilowatt-hours may be simply to buy a few extra panels.

Houses with solar panels are not necessarily efficient; during the hours when the sun is not shining, they use more electricity than houses without solar panels. It may be because the bigger users tend to install the panels in the first place. There may be another reason: People who own electric cars tend to also install solar panels, and their overall electricity consumption is higher. But from an environmental standpoint, it is still better to consume the energy as electricity rather than as gasoline.

Source: New York Times

Energy is not only a battleground between different sources such as nuclear, renewables or fossil fuels. There is also a battle between different means of delivering energy to consumers to provide light, comfort and mobility. Over the last century or more, two energy carriers have effected radical changes on human society and paved the way for a truly global economy. Oil has transformed our ability to move goods and people huge distances over land, sea and air. Electricity has transformed our homes and enabled the transfer of vast quantities of information and virtually instantaneous communication between any two points on the globe.

From a consumer’s perspective, these appear to be two different industries. Oil and gas producers exploit resources upstream and maintain distribution networks that end at the petrol pump. A different set of companies transforms primary energy into electricity and brings it into people’s homes. Two different energy sectors effectively co-exist because their products are so different in character. Liquid fuels have a high energy density and can be stored on-board a vehicle giving it a range of 1,000 kilometres or more. Electricity is difficult and expensive to store, and supply and demand must balance instantaneously. However, electricity is a very high quality form of energy that can be turned to almost any purpose: lighting, heating, motive power and the carriage of information.

Can we take the boundary between these two energy carriers for granted? Although the division appears clear and logical at the moment, history shows that nothing can be taken for granted. When oil was first produced, it was not to fuel the internal combustion engine. It was to provide a fuel for lighting to replace ever scarcer whale oil. Oil fractions that could have been used for transport were discarded as waste. However, through the innovative efforts of Edison and Westinghouse and by virtue of its greater power, flexibility and safety, electricity drove oil and gas from lighting markets. Oil has retreated from other markets too. Against a background of abundance and low cost supplies, Winston Churchill felt able to switch the Royal Navy from coal to oil prior to the First World War. But the high prices and scarcity associated with the 1970s oil crises drove oil from its markets in power stations and industry as companies responded to price signals and governments responded strategically to a deteriorating energy security situation. Lower oil prices in the 1980s and 1990s have not reversed these trends. There is now a prospect that global demand for oil will peak in the next 10-15 years – it may even have peaked already. Meanwhile, global demand for electricity increases at a rate that will lead to a doubling every twenty years.

There are reasons to suppose that the battle of the energy carriers is not over. The International Energy Agency’s latest Energy Technology Perspectives report focuses specifically on harnessing electricity’s potential. The next battleground involving oil and electricity could be in the transport sector. Several factors are involved. Two are environmental. In emerging economies, where car ownership is growing rapidly, transport-related air pollution is a major cause for concern and the attractions of electric vehicles are considerable. Electric vehicles can also help in the fight against climate change by making use, indirectly, of low-carbon energy sources such as renewables or nuclear to fuel the transport sector. Technological change is also playing a role. Energy storage technologies are developing rapidly and the cost and performance of battery technology in particular are improving. This will extend the range of electric vehicles and partly (though certainly not completely) erode the advantage of oil in this respect. Finally, in an uncertain world, it will allow more countries to reduce their reliance on imported transport fuels.

The new battle will not necessarily be clear cut. Improvements in extractive technology and access to new unconventional sources mean that oil will not be physically scarce. As with any major technological transition, it may take decades to work through. And “compromise” technologies such as hybrid and plug-in hybrid vehicles may help to make the best of both worlds, though at a cost.

The “eco-machine” of the future is now up for grabs. It may take a long time before we see an all-electric future for vehicles. But it is certain that the future will be both more electrified and more electrifying.

Source: Huffington Post

Carbon-dioxide emissions have documented negative effects at a planetary level–but could the other gases coming out of vehicle tailpipes be as hazardous to overall public health in total as car accidents are?

In the public discourse to date, the answer has previously seemed to be “no.” Emissions generally aren’t discussed in terms of individual deaths, but rather in the context of climate change or as a contributing factor to specific illnesses.

Now, researcher David Levinson suggests the answer is not that simple. In a post on his blog Transportationist, he argues that the impact of crash-related and emissions-related deaths could be roughly comparable, depending on how you crunch the numbers.

More deaths from air pollution

Levinson cited data from the 2010 Global Burden of Disease Study, which found that 36 deaths per 100,000 were attributable to air pollution, compared to 15 for road and transportation-related injuries–the vast majority of which involve cars.

In this case, air pollution is defined as fine particulate matter and ozone only, but the study does not differentiate between transportation-related emissions and other sources.

However, as Levinson’s colleague Julian Marshall noted in the same post, it’s hard to attribute a death to air pollution.

Pollution doesn’t appear as a cause on death certificates–it’s inferred by looking at higher instances of events like heart attacks in areas with high levels of pollution–and tracking an air pollution-related death to a specific source is even more difficult.

In addition, the 2010 study found that transportation-related injuries were responsible for more years of life lost than air pollution–653 per 100,000 people, compared to 565.

That’s because fatal car crashes tend to involve younger people, so they shorten lives more dramatically.

A matter of perspective

Eric Jaffe at CityLab came to largely the same conclusions–finding a larger apparent number of air-pollution-related deaths under a somewhat non-specific definition, but with car crashes cutting lives shorter.

He said the two problems could be “more on par than we typically treat them.”

Following that argument, automotive emissions should be viewed in the same category as traffic deaths–but the link between cause and effect isn’t as apparent.

Air pollution caused by emissions is already linked to respiratory illnesses.

Recently, a new study from the Columbia Center for Children’s Environmental Health (via Gothamist) found that it may also be linked to ADHD in children.

The study found a higher instance of ADHD-like symptoms in children exposed to polycyclic aromatic hydrocarbons (PAH), a byproduct of burning fossil fuels.

It shows the need to curtail emissions from burning hydrocarbon fuels overall, but it also demonstrates how varied their effects on health and lifespan can be.

That sharply contrasts with the immediate and grimly apparent toll of car crashes.