A biofuel is any type of fuel that results from the biological fixation of carbon. Technically speaking, fossil fuels qualify under this definition because they result from organic matter and millions of years of decomposition. However, biofuels, or “renewable fuels” as they are sometimes called, can be grown as a crop or produced by converting other biomass into a liquid or gaseous fuel. Let’s look at the most popular biofuel in the US, ethanol, and evaluate some of the questions surrounding its sustainability.

Ethanol is the world’s most produced biofuel by volume. In 2011 the US produced 13.9 billion gallons of ethanol, with the majority of the feedstock coming from corn (maize). Ethanol was originally introduced into the gasoline mix to boost oxygen content and to reduce carbon monoxide emissions from combustion. Today, nearly all gasoline in the US is blended to be 10% ethanol, also known as E10. In 2011 ethanol represented 10.6% of gasoline supplies in the U.S.

One of the biggest benefits for ethanol as a vehicle fuel is the relative ease with which it can replace gasoline. You may have heard of “Flex-Fuel” vehicles. These vehicles have been specifically designed to run on E85, an ethanol-gasoline blend that is 85% ethanol. Flex-fuel vehicle owners can switch back and forth seamlessly between E85 and the standard E10 blend that most pumps offer.

Here are a few facts about ethanol:

• Ethanol has 66% of the energy of gasoline by volume (i.e. a gallon of gasoline contains 33% more energy)
• Average price for gallon of E85: $3.47 (national average, October 2012)
• It takes 3 gallons of water to produce one gallon of corn ethanol, excluding irrigation
• E15 has become the primary fuel for NASCAR
• The original Model T Ford ran on ethanol until 1908

As a replacement for petroleum gasoline, ethanol provides significant benefits including reducing the demand for imported oil, improving vehicle emissions, and integrating with the existing infrastructure. However, there are several concerns with the production and use of corn-based ethanol (currently the most widely produced) including carbon dioxide released from production and land-use change, nutrient runoff, and net energy balance. While each of these issues is an area for further research and debate, perhaps the most popular debate is framed around the polarizing “food versus fuel.” In other words, if we are growing corn, shouldn’t we be using it for food instead of for fuel?

The USDA reports that about 40% of all the corn grown in the US is used to produce ethanol. Other major uses of corn include feed and export, shown by the graph below. Food vs. fuel is not a direct tradeoff, however; in the production process of converting corn to ethanol, valuable co-products are produced called Distiller Dried Grains (DDGS) which can be used as animal feed. For each gallon of ethanol produced, approximately 4lbs of DDGS animal feed with three times the protein content of corn are also produced. Still, DDGS can only be fed to livestock in limited quantities in order to avoid nutritional risks. DDGS – and their limitations – complicate the “food versus fuel” debate because, as it turns out, producing corn ethanol provides a little bit of both. To complicate matters further, government subsidies and growing demand for fuel could cause farmers to replace their food crops with fuel crops, putting further pressure on food prices.

Source: U.S. Department of Agriculture.

Overall, the sustainability of ethanol has shown signs of improvement over the past two decades by reducing the energy required for production, maximizing the use of byproducts, and improving water efficiency. However, despite utilizing 40% of the nation’s most widely produced feed grain, corn ethanol remains a relatively small fraction of overall gasoline consumption. Technological advances, such as producing ethanol from cellulosic material instead of corn, may allow biofuels to overcome many of these sustainability challenges and provide for a more promising renewable fuel future.

The Verdict: After weighing the benefits and drawbacks of corn-based ethanol as a biofuel, it appears to be coming up a bit short. The strain that corn ethanol production places on our agricultural system compared to the relatively small impact it has on fossil fuel use is difficult to justify from an environmental standpoint. Corn-based ethanol may never be a fully sustainable biofuel, but our experience with it provides valuable guidance for developing advanced biofuels that can lead to a more sustainable solution.

John Willard is an alumnus of the University of Washington and the University of Michigan. He currently works as Biosystems Energy Analyst and Project Management Consultant in Ann Arbor, Michigan.

Source: Renewable Energy World.

]]> http://cleantechverdict.com/2013/02/15/changing-perspectives-on-climate-change-in-renewable-energy-world/feed/ 0 cleantechverdict Renewable Energy World logo http://cleantechverdict.com/2013/02/02/secretary-chus-department-of-energy-four-years-later/ http://cleantechverdict.com/2013/02/02/secretary-chus-department-of-energy-four-years-later/#comments Sun, 03 Feb 2013 01:13:24 +0000 cleantechverdict http://cleantechverdict.com/?p=300 ]]> After four years of low-profile ups and high-profile downs, Nobel Prize-winning Secretary of Energy Steven Chu will be stepping down. Coming from a career in research and academia, many critics questioned how he would fair in the politically charged atmosphere inside the Beltway. In a climate where science and data often take a back seat, he certainly faced a new perspective of success. So after his tenure at the helm of the Department of Energy, where do we stand?

Secretary Chu came to the Department of Energy at a unique time, for both the Department and the country. Historically DOE has actually done relatively little with respect to energy; their primary tasks have traditionally been to maintain our arsenal of nuclear weapons and clean up contamination at the government’s nuclear sites. Of the $24.3 billion budget in 2008, the year before Chu took up the post, $15.8 billion was tagged for “atomic energy defense activities,” including nuclear security and environmental cleanups (here and in more detail here). As the country dealt with economic recession, however, the Energy Department faced an economic new order of their own: The 2009 Recovery Act practically overwhelmed the Department with $36 billion in stimulus money, most of which was to be spent over a two-year period. Managing this massive influx of spending directives proved to be one of the great challenges of Chu’s time as Secretary, but also led to some of his most important accomplishments.

Assessing the immediate impact of large and diverse federal agencies is not a straightforward task. With respect to the Department of Energy, whose most promising projects focus on research, developing high risk, high reward technologies, and inducing shifts in the complex and stubborn global energy landscape, doing so is nearly impossible. Since many of their programs have medium- and long-term goals, only deeming successful those that have already started to pay dividends ignores the very nature of these investments. But while giving an assessment of every initiative would be premature, we can evaluate a few central components of Secretary Chu’s term that help paint a picture of his impact.

One DOE program that has had immediate benefits is the Weatherization Assistance Program. Aimed at improving the energy efficiency of lower-income homes, this initiative has been around for over 30 years and has helped weatherize over seven million homes. While the program has certainly had long-term success, over one million of these weatherization projects have occurred since 2009, boosted by the Recover Act. These families save an average of over $400 a year on utility bills. Another program that has taken off under Secretary Chu is the Advanced Research Projects Agency – Energy (ARPA-E). Modeled after the military’s DARPA with the goal of pursuing innovative, game-changing ideas that are too uncertain to attract private investment, ARPA-E was created by Congress in 2007 – but without a budget. It wasn’t until 2009 that the Recovery Act provided $400 million of initial funding. Under Secretary Chu, ARPA-E has funded over 275 “high-potential energy technology projects.” We may not know for decades the payoff of these investments, but DOE’s absorption of the risks will certainly help move some clean technologies beyond their infancy.

Another signature success of the past four years is DOE’s loan guarantee program. While the high-profile bankruptcy of the DOE-backed solar company Solyndra caused a flood of bad press about the program, in reality it has been remarkably successful. The Department distributed about $34 billion in loan guarantees to 33 companies under this program (Solyndra included). While more could fail in the future, so far only three have filed for bankruptcy, an impressively low rate considering that the program was created with the expectation that some companies would fold. And as it turns out, the defaults will almost certainly end up costing less than the amount Congress set aside for failed companies. By and large, the loan guarantee program has been a success, and persistent claims to the contrary seem politically motivated.

But not all of DOE’s recent programs have been successful. A prime example is their $2.4 billion investment in advanced battery facilities in the US. The plants have all been constructed, but many of them aren’t churning out batteries due to lower-than-expected demand for electric vehicles. At this stage, it’s difficult to argue that the investment was a good one, and the program represents the broader problems associated with government investments in a market that isn’t ready. Renewable energy prices depict another questionable success; although the price of wind and solar have dropped dramatically in the last four years, it’s difficult to say how much of this decline is due to DOE. These and other indicators are influenced by a number of outside factors, including Chinese subsidies and global demand. For some, this is an uncomfortable revelation that in the global energy market, Secretary Chu may have been more of a bystander than we would like to think.

The Verdict: Secretary Chu oversaw a changing role for the Department of Energy. During his tenure, several key programs have had excellent results while others have floundered. The reality is that the outcomes of many long-term investments initiated on his watch will not be clear for several years, or even decades. He was responsible for unprecedented investment in clean energy, however, and shaped the Department’s image as the government’s best-funded effort to address climate change. Without DOE’s support over the past four years, clean energy in the US would certainly not be where it is today.

Image courtesy of: Sailom/freedigitalphotos.net.

Of the four types of CSP systems, the solar power tower is by far the most dramatic. Source: Solarpower.com.

Unlike photovoltaics (PV), CSP systems do not convert sunlight directly into electricity; rather, they convert it into intense heat. Dealing with energy in the form of heat has a number of benefits over direct conversion into electricity. The major advantage when looking to design a grid-scale renewable energy project is the simple fact that our ability to store excess heat is far more advanced than our ability to store excess electricity. CSP plants can employ a technology called Thermal Energy Storage (TES), whereby the sun is used to heat molten salt instead of water. The salt, rather than the sun directly, is then used to heat water, which creates the needed steam. It turns out that salt stays hotter much longer than water, and using molten salt as the middle-man allows the plant to continue generating electricity for over seven hours once the sun sets. Commercial deployment of TES is in its infancy, so the opportunities it already provides are particularly encouraging, all the more because three of the four CSP systems have demonstrated that they’re compatibile with it. Because of TES’s viability on a very large scale, Concentrated Solar Power offers enormous potential for energy storage in ways not even considered for PV (and not yet deployed on a commercial scale for wind, although big plans lie ahead).

NREL’s map of CSP’s potential in the US. Source: NREL.

But CSP is not without its drawbacks, and understanding them is key to determining CSP’s place in the diversified energy landscape of tomorrow. Given its dependence on long hours of intense sun, CSP is most effective in the Southwestern US. (Unlike PV, which is still viable in suboptimal regions, CSP really isn’t worth developing in places with less favorable conditions). Due to the fairly specific geographic range where CSP can be successful, these projects are often sited squarely in the fragile habitat of the threatened desert tortoise. For an industry making great strides on its reputation as environmentally friendly, this is no small hurdle. Already, renewable energy companies have spent tens of millions to protect the prehistoric relics.

In addition to ecological concerns, water issues in this arid region are being aggravated, as well. Current technology is very water intensive and the systems operating in the US today consume between 750 and 1,000 gallons of water per MWh, according to the Department of Energy. They rely on a process known as “wet cooling,” whereby water cools the system and then evaporates in a cooling tower, much like the process used at traditional fossil fuel and nuclear power plants. Since the regions with the greatest potential for CSP are also some of the most water-stressed, this degree of water consumption is a definite red flag. Fortunately, a promising alternative called “dry cooling” uses fans to cool steam pipes with air, completely eliminating the use of water as a coolant. Dry cooling reduces the efficiency of the power plant slightly, and ways to offset these losses are still being developed. This paper by the Congressional Research Service discusses at length CSP’s implications for water supply.

Of course, a major component of CSP’s success ultimately comes down to cost. The cost of electricity from each of the four systems varies, but in 2010 the cost from parabolic troughs (currently the most common system in the US) was between $0.12 and $0.18/kWh. In most cases, this is above grid parity – the point at which it costs the same as grid electricity derived from fossil fuels – but not far off. The Department of Energy’s SunShot Initiative aims to drive down the cost of solar electricity to $0.06/kWh by 2020, a price that is cost competitive in every state. Assuming these projections are on target and less water-intensive cooling technologies emerge, CSP appears poised to experience significant growth in the coming decade.

The Verdict: The future of renewable energy will rely not on a single, “perfect” technology but rather on a set of proven, cost-effective systems that take advantage of the differences in regional resources. CSP is one such system. Its ability to generate large amounts of renewable electricity and the potential to do so long after dark bode well for the industry and for the planet.

The tip of the iceberg. Source: Wikipedia.

The concept of climate engineering is in some ways deeply appealing. The idea of engineering a way for us to avoid any substantial shifts in our lifestyles speaks to our natural aversion to change. We are also preoccupied by a fascination with technologies that empower us to control nature (we’d rather build levies to hold back the sea than site our communities on higher ground), and a controlled alteration to the climate is on certain levels the ultimate achievement. We like to build our way out of problems and, quite frankly, we’re pretty good at it.

But rather than being the miraculous technical feat we hoped it would be, climate engineering is a reckless attempt to put off the tough choices we must ultimately make. While the sulfate aerosols being considered are chemically identical to those released by volcanic eruptions, the trouble is not the particles’ properties but rather how they are introduced into the atmosphere. The fact that our injections would be inherently artificial is cause for pause. All too often we have been reminded that our understanding of natural systems is far from complete. Intervening (yet again) in one as large and complex as the climate system will surely result in unintended consequences. For a smaller-scale reminder, just look at the story of garlic mustard in the Eastern US. Originally introduced to combat soil erosion, the plant has become enormously widespread. Its pervasiveness destroys forest understory, poisons insects, and threatens the surrounding biodiversity. Similar examples abound, and the lesson is clear: interfering with complex natural system, the intricacies of which we seldom fully understand, is risky, despite good intentions.

Another shortcoming stems from climate engineering’s limited scope. While sulfate aerosols can reflect the sun’s rays back into space, they do nothing to address ocean acidification, a major impact of climate change. Because ocean acidity is directly related to atmospheric concentrations of CO₂ and has nothing to do with surface temperature, any solution that ignores greenhouse gas emissions would be wildly inadequate.

One popular defense of climate engineering is the speed with which it can take effect. Experts are certain that releasing the particles would begin reducing the rate of warming very soon. It turns out that their effects are also relatively short-lived, so a round of injections wouldn’t have a long-term impact. While these facts are undisputed, the broader argument they support is that the technique should be employed to slow climate change while we develop sustainable ways to reduce greenhouse gas emissions. The overwhelming flaw in this approach is that it ignores our predisposition for complacency. A short-term extension is a nice idea, but we’re already taking long enough to develop solutions under increasing agreement about the urgency of climate change. Are we really supposed to believe that taking the pressure off will help? Many experts fear that “buying more time” will simply reduce the incentive to get serious about addressing emissions. And as a bonus, there’s concern that this strategy may impact local weather systems unpredictably.

So the issue with climate engineering is not that the technique won’t work – given enough R&D, there’s a good chance it would. But will it work as planned? Will it slow the rate of warming without changing the weather or acting as a shield for the status quo? Some may say that the continued hope of addressing climate change without climate engineering is wishful thinking. But the real danger lies in distractions such as these, which, although well intended, stand to cripple the pursuit of real solutions.

The Verdict: Climate engineering is an appealing concept that may be technically feasible. Folded into the promises of short-term benefits and time-buying crisis aversion, however, is a concerning set of profound and poorly understood risks. Climate change is an urgent challenge that requires us to think big and pursue our best ideas. While climate engineering is certainly a big idea, it risks more than it offers in an honest pursuit of a more sustainable future.

Chinese High-Speed Train. Source: Treehugger.com.

High-speed rail has been touted by many as the way of the future, providing mass transit for growing populations while countering today’s carbon-intensive transportation. In the United States, high-speed rail is categorized in three groups, determined primarily by speed: Emerging High-Speed Rail (top speeds of 90-110 mph); Regional (110-150 mph); and Express (over 150 mph). Currently, only one line in the country qualifies, Amtrak’s Acela Boston-New York-Washington, DC route. Only a small portion of the route accommodates the train’s top speed of 135 mph, and, including stops, the entire three-point trip averages a pedestrian 68 mph. In contrast, the high-speed line between Seoul and Pusan, South Korea nearly doubles Acela’s speed, achieving an average of 120 mph. Even faster trains than these abound across Europe and Asia, but the question remains: Are they an innovative environmental improvement or simply a costly show of technical savvy?

As with so many would-be-silver-bullet technologies, the answer here is “It depends.” One way to compare the environmental impacts of different modes of transportation is to use a metric called passenger miles. This incorporates the number of passengers and the distance over which they are being moved to come up with a single number that applies to all modes. A 2006 study by the Center for Clean Air Policy determined that, for a high-speed train similar to those being considered for use in California, the average emissions of carbon dioxide per passenger mile were half of those from automobiles, and 40 percent of those from airplanes (0.26 lbs of CO₂ for high-speed rail compared to 0.53 lbs for cars and 0.62 lbs for planes). This metric is tricky because it’s dependent upon occupancy – a train only ten percent full, for example, emits far more emissions per passenger mile than an average car (determined by the Department of Transportation to hold 1.6 passengers on average). This study used the DOT number for automobiles and 70 percent occupancy for the high-speed trains, a number that would also ensure financial success for the planned system in California. And although rail is not a primary mode of transportation for many Americans, international examples suggest that ridership can skyrocket once high-speed lines are developed.

A more holistic recent study by engineers at Arizona State University and the University of California, Berkeley concluded that high-speed rail “has the potential to reduce…impacts to people and the environment, but must be deployed” in a way that is consistent with environmental goals. The authors listed ridership and the energy sources relied on by the trains as critical to achieving significant improvements over current modes of transportation. In February 2011, Vice President Biden laid out an ambitious plan to develop high-speed rail in the United States. While the proposal immediately met firm opposition from politicians and transportation lobbies and is currently at a near stand-still (except in California), the proposed routes reflect a goal of replacing long car trips and short- to medium-length flights. These are the distances over which high-speed rail can save the most time and potentially attract the highest ridership. We know that more passengers per train leads to a greater reduction in emissions, particularly since the additional passengers would presumably have driven or flown instead. (By this same logic, carpooling is still a good idea). In addition, high-speed rail is a technology whose environmental impact can be reduced once it has been developed by attracting more riders and, depending on the technology, by increasing renewable energy’s contribution to our electricity grid.

Map of Proposed High-Speed Rail Routes in the US.

To be sure, high-speed rail is still associated with a host of environmental impacts, and while it could lead to significant reductions in greenhouse gas emissions, it is far from a carbon-free technology. Those who boast these claims simply haven’t read – or have chosen to ignore – the facts. Opponents of high-speed rail don’t seem to be turning to the data either. As an entertaining example, one prominent conservative commentator claimed that the “real reason for progressives’ passion for trains is their goal of diminishing Americans’ individualism.” Conspicuously absent from current proposals are the trappings of a conspiracy to eliminate highways and shutdown the auto industry, but this and other criticisms never had more than a distant relationship to logic. It’s clear that high-speed rail has become highly politicized, and, as with many other issues that have suffered this fate, facts and reason (and, ultimately, the pubic interest) have gone by the wayside in favor of shortsightedness and scorekeeping.

The Verdict: High-speed rail is not our answer for eliminating GHG emissions from the transportation sector. Done properly, however, it can significantly offset environmental impacts from passenger cars and air travel. Having a serious discussion about how best to develop high-speed rail is important, but proponents and opponents will both need to stick to the facts.

Derive 75% of all newly installed electricity generation in the US from renewables.

This target may sound unrealistic, and indeed it is lofty. Although the numbers are big, however, they’re quite attainable, and this kind of development is critical if we’re serious about addressing climate change and other energy issues. Through the first 10 months of 2012, renewables accounted for 46% of the 15.1 GW of new generating capacity. We’ve already surpassed the 75% target from renewables over smaller timescales – in September, 100% of newly installed capacity came from wind and solar projects. In 2012, installations of new wind power capacity alone are expected to total over 13 GW. Unfortunately, we’re looking at the possibility of 2013 being the worst year for renewables in a long time, due to the impending expiration of the Production Tax Credit as well as other cuts associated with the “fiscal cliff.”

Continue to provide government support for sensible clean tech projects.

As we discussed briefly in two previous posts (here and here), the Production Tax Credit is one of the government’s greatest gifts to renewable energy. It’s critical to encouraging development, and the current iteration of the PTC expires at the end of the year. The uncertainty about its future has for years scared off investors and threatened the renewable energy industry as a whole, hitting wind energy particularly hard. With the PTC’s renewal as uncertain as ever, renewable energy companies across the country are racing the get their projects online before the ball drops in Times Square (it’s unclear if time zone differences will be taken into account). Rather than scaring the industry into cardiac arrest every few years, we would do well to pass a longer-term deal that delivers reasonable certainty.

Tied up in the “fiscal cliff” debate is the future of funding for research and development in a range of clean tech sectors. Beyond simply avoiding cuts to existing programs, however, we need to ensure a deeper commitment to investing in promising ideas that aren’t ripe for private investment. (Military-driven) government support is how GPS and the Internet came to be, and public funding has already been integral to making numerous “clean” technologies competitive.

Restore science and reason to their rightful place above passions and politics.

Comparing climate scientists to terrorists doesn’t help anyone, and neither does the incessant vilification of “the other guys.” It took over 1,000 years for people worldwide to accept that the earth was spherical, but unfortunately the challenges we face today don’t allow that kind of time. The scientific method has taken us to incredible places since “flat earthers” became a minority, but it seems that we have forgotten its virtues.  Scientific facts aren’t dependent upon our acceptance of them – the ways we respond to these realities, however, are. So let’s pledge to make decisions based on facts and to debate how to solve our problems, not whether to address them at all.

Focus less on winning and more on achieving.

This one applies across the board. With respect to clean tech, our obsession with competition is hindering our ability to have honest discussions about the issues that threaten our future and to take advantage of solutions that offer a different course. Those who would rather tear something down than build something great have for too long put artificial limits on our efforts to ensure a healthy planet for our children. The world won’t long remember the fleeting nature of these senseless roadblocks, but it will reflect the impacts of inaction long after today’s “winners” are forgotten.

Happy New Year! Source: Wikipedia.

With enough patience and motivation (and, of course, the right app), consumers today can find organic or “green” alternatives to almost anything. One enticing option that’s been popping up across urban America is the organic dry cleaners. We’ve assumed for years that the chemicals that miraculously clean ketchup stains and skunk odors without a drop of moisture can’t be good for us (or – worse – for those who work with them), and it doesn’t take much imagination to conclude that they harm the environment, as well. But what of the alternatives marketed to us as “green”? Do they really rely on benign concoctions to dissolve schmutz or are you and your clothes simply being greenwashed?

Source: classiccleaners.net

The most common method used in conventional dry cleaners today uses a chemical called perchloroethylene, known as perc for short. Although perc effectively removes dirt and stains from delicate clothing, it inevitably enters rivers and lakes and is “reasonably anticipated to be a human carcinogen” by the National Institutes of Health. In fact, the EPA has established rules that will eliminate the use of perc in residential buildings starting in 2020; it’s not clear if they will ever ban the chemical entirely, but all signs suggest that a search for better options isn’t frivolous. In response, a host of alternatives has emerged, and many cleaners are taking advantage of this shift to label themselves “green” or even “organic”. Four processes dominate the market for perc-free cleaning, and they are all less harmful than perc. But here’s a wrinkle that shouldn’t go unnoticed – unlike the Department of Agriculture’s strict controls on use of the term “organic” for foods, no such restrictions exist on its use in dry cleaning. A cleaners can be deemed organic as long as the cleaning process uses chemicals containing carbon. This molecular definition, through luck or misfortune, includes perc.

One popular alternative to perc is called hydrocarbon cleaning. The chemical used here is petroleum-based, however, and is a volatile organic compound (there’s that word again). This method has been found to be less toxic than using perc, but if you’re looking for good alternatives, don’t stop here. Another method that appears to be gaining favor in the dry cleaning world is CO₂-based. This process involves mixing the clothes with gaseous and liquid carbon dioxide, which apparently dissolves away dirt and grime (but some facilities also add detergents). Those concerned about the CO₂’s impact on the climate need not worry – most of the CO₂ used for cleaning is captured from industrial processes and reused, so it’s simply being passed through your clothes on its way to the atmosphere. Unfortunately, CO₂ cleaning happens to be the most expensive technology.

The third alternative is a patented process called Green Earth Cleaning. Particularly popular in California, Green Earth Cleaning uses a non-toxic solvent that decomposes in a matter of days. Some say they’re certain it’s great, and others say they think it is. Interestingly, the fourth option is actually called wet cleaning. Lauded by environmental groups as the best method for cleaning delicate garments, professional wet cleaning involves mixing your clothes with biodegradable detergents and water at carefully controlled temperatures. Though there’s nothing dry about it, this can safely remove dirt and stains from almost any piece of fragile clothing.

Who knew that dry cleaning could be so convoluted? Next time you misfire the ketchup or spill your double latte, consider what’s behind the flashing neon sign. We have a real opportunity to take advantage of good alternatives – but if we aren’t informed, we may simply be drowning ourselves in a vat of good intentions.

The Verdict: An entire world exists behind the drop-it-and-forget-it banner of revolving hangers. Cleaner, safer alternatives to perc are a reality – but the “green” or “organic” labels at many cleaners do little to ensure they’re really being used. Wet cleaning and the patented Green Earth Cleaning seem to be the best options for cleaning your clothes and avoiding cancer simultaneously. The only way to know what you’re getting is to ask what method a specific cleaners uses – the good news is that if your first stop isn’t satisfactory, there is sure to be a cleaners near by that is.

The International Space Station. Source: PBS-NOVA

As a bit of review, PV panels comprise multiple cells made from specific semiconductors whose electrons become excited by contact with light. The resulting energy is in the form of an electric current, allowing us to convert sunlight directly into electricity. This technology was first patented in 1946, and entered the public view in a big way in 1958 with the launch of the Vanguard 1 satellite, the first to be powered by photovoltaics. Today, the iconic image of the International Space Station soaking up the sun represents one sector for which PV has proven revolutionary.

But many earthly uses exist, as well, and in 2011 PV accounted for 67 gigawatts (GW) of global electricity generating capacity, compared to only 1.5 GW in 2000 (that’s an increase of over 4,300%). Still, this only meets a tiny portion of electricity demand – in the US, PV generation has grown rapidly, and its capacity stood at 3.5 GW in 2011, but this only made up about 0.03% of total generation. Even at these growth rates, PV will remain a relatively small contributor for some time.

And yet, we continue to hear about PV and its potential to provide renewable energy. In fact, solar panels have become a symbol of environmental friendliness, the emblem of sustainable energy. Given its small contribution to energy production, PV’s popularity may seem out of place, or at least premature. While those who have visions of a PV-powered world may aspire to an unrealistic dream, however, the technology’s significance – and its potential – should not be overlooked. For starters, the cost (historically, the biggest barrier to its widespread adoption) has come down significantly over the past few years. The average price of installed modules has plummeted by 50% since 2008 alone. At this pace, PV is quickly approaching grid parity, the point at which electricity from PV is equal to the average cost of electricity from the grid. Grid parity is widely viewed as a critical turning point for the competitiveness of PV – so much so, that the Department of Energy launched the SunShot Initiative, which aims to help achieve this goal by 2020. Many experts predict explosive growth as we approach and then surpass grid parity, and the Department of Energy expects this to allow PV’s contribution to national electricity generation to grow to 11% by 2030.

NREL’s map of PV potential in the US.

Like most renewable energy technologies, PV offers different opportunities in different regions. While it may never be the world’s predominant energy technology, PV can provide a large portion of electricity in certain areas. As we mentioned in our earlier post about solar energy, the amount of electricity produced by photovoltaic cells depends on the amount of available sunlight, but they actually operate less efficiently at extreme temperatures. As you can see on the map above, the Southwest is the US region that receives the greatest intensity of solar energy. Temperatures in that part of the country, however, generally exceed the optimal operating temperature for most PV panels – in the Southwest, a technology called Concentrating Solar Power actually tends to be the best bet for large-scale solar energy development. Although the sun is a bit less intense in Miami than in Albuquerque, PV panels will have a longer operating life in Florida (due to milder temperatures), and will ultimately generate more electricity as a result. That’s not to say that PV can’t harness large amounts of renewable energy in places like New Mexico and Southern California (it already does). It’s just to demonstrate that, while the Southwest and Southeast are both hot, sunny places, from the standpoint of solar energy potential, they have important differences. But all across the country, PV offers opportunities for residential or commercial on-site renewable energy generation, often reducing reliance on the grid. This allows homeowners or companies to generate their own electricity when the sun is shining, something that deserves our renewed attention in the aftermath of Hurricane Sandy.

The Verdict: PV is a promising technology that stands to play an increasingly prominent role as we move toward greater reliance on renewable energy. With prices coming down and efficiency improving every year, PV is becoming more attractive to homeowners, investors and utilities. This renewable energy option has been growing at breakneck speed and all signs point to even faster growth ahead. While it may never power the world, PV can certainly be a significant contributor to our energy future.

The term clean coal actually refers to a range of technologies that can reduce the environmental impact of coal combustion. Overwhelmingly, the technology that people refer to when talking about clean coal is Carbon Capture and Sequestration (CCS). While CCS is just one of the relevant technologies, it’s the one that gets (and arguably deserves) the most attention. CCS is the process of capturing carbon dioxide (CO₂) as it’s emitted from a fossil fuel-burning facility and storing it at a long-term storage site, generally impermeable geologic formations. By preventing the CO₂ from entering the atmosphere, CCS offers a way to nearly eliminate the greenhouse gas emissions from large point sources, such as coal-fired power plants (hence the term “clean coal”). From the viewpoint of short-term emissions reductions, CCS seems to have potential. But looking deeper, we can see that it’s riddled with risk and may actually perpetuate other pressing environmental issues.

Carbon Capture and Sequestration. Source: World Resources Institute.

The first step in CCS is to “capture” the CO₂ emissions before they are released into the atmosphere. This can be done on-site (at the power plant) by a number of systems, separating and purifying the gas either before, during or after combustion. Next, the CO₂ is transported to the storage site, most commonly by pipeline. Geologic structures, such as depleted oil and gas wells, are receiving the most attention for long-term storage. Once at the storage site, the CO₂ is injected underground at extremely high pressure. In many cases, CO₂ is already being pumped into partially depleted oil wells to force out the remaining petroleum, a process known as Enhanced Oil Recovery. If a coal-fired power plant’s emissions can be successfully captured, transported and stored, then its contribution to climate change can be dramatically reduced.

But CCS is plagued by uncertainty, and the implications of a potential failure are cause for reconsideration. One major concern with geologic storage is the possibility of leakage. If a leak occurs at a storage site containing several years of CO₂, for example, the result could be equivalent to emitting years’ worth of CO₂ into the atmosphere over a much shorter time period. Even now, when the vast majority of existing CCS projects are only pilot scale, we’re already seeing anecdotal evidence of leaks. While such leaks might be kept to a minimum with the appropriate technology, even rare occurrences would be likely to mitigate many of the benefits to the climate. And in addition to reentering the atmosphere, the impact of leaked CO₂ on drinking water has been well documented.

Mountain top removal. Source: Explore.org.

Another critique of CCS has to do with its limited scope. While storing the gas underground could theoretically reduce the impact of coal combustion on the climate system, it does nothing to address a number of other environmental issues associated with coal extraction and use. Coal mining ravages large swaths of land, most dramatically when employing mountain top removal. Once the mines are open, acidic water often flows out, polluting nearby surface water. And the exhaust from coal-fired power plants has consistently been linked to poor public health and respiratory ailments. A technology that allows these and other impacts to persist while encouraging increased use of coal doesn’t fit any reasonable definition of “clean”.

It turns out that the process of capturing CO₂ on-site at power plants is also a substantial parasitic load – this means that it consumes a significant amount of the electricity generated by the facility, requiring even more production to meet normal demand. Current CCS technology is estimated to require 15-30% of a power plant’s output. Not only does this increase the amount of CO₂ to be sequestered, it also requires more coal, perpetuating the impacts associated with extraction. All in all, CCS seems to have the potential to address one problem alongside the certainty of exacerbating a number of others.

The Verdict: The main technology relied on by clean coal, CCS, is plagued by risk and uncertainty, and only deals with a portion of the impacts that make current coal use dirty. Although the effectiveness of burying the emissions from coal combustion is still debatable, evidence of coal’s effects on water, air and human health is rock solid. Even if CCS were a proven technology, the concept of clean coal would remain a fantasy.