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How much are you willing to pay for residential solar power? Would you rather pay an upfront cost or monthly heating bills?
A square yard of sunlight delivers about a kilowatt when it hits the ground, the same as the average electric power used by a U.S. household
— Physics for Future Presidents, by Richard A. Muller
President Obama has mandated a new energy plan that requires 10% of electricity consumed in the U.S. come from renewable energy sources, such as solar power, by the year 2012. Can we make that goal? Should we with the current technologies?
Just about everyone likes the idea of using solar power to heat and cool their homes. The sun is a potentially clean, free source of energy. What’s not to like about that? We even already have working residential solar power systems on the market. So why isn’t everyone doing it already? Why is only 0.01% of the United State’s electricity generated from solar power? The answer, of course, gets down to cost.
The basic problem is that standard solar cells are expensive and not very efficient. Solar cells are typically 15% efficient. However, the sun is not always out and it is directly overhead only rarely. If you take into account these factors, the average solar cell efficiency is only a few percent. That means that the average solar cell will deliver about 4% of a kilowatt of electric power, if it has an area of 1 square yard. The average household in the U.S. uses about 1 kilowatt of electric power (or 24 kilowatt-hrs per day of energy), which is the equivalent of having 10 100-watt light bulbs turned on. So the average household would need about 25 square yards of solar cells (i.e., 25 sq yds x 0.04 kilowatt/sq yd = 1 kilowatt). Placing this many solar cells on the roof is feasible for many homes, so some people are doing it. It is environmentally clean and politically “green.” Sounds great, right? The problem for most people is the up-front and overall cost.
The price of residential solar power is variable, of course. For the sake of discussion though, I’ll use some 2008 numbers based on California usage (without worrying about issues like tax savings). For a home that uses 1 kilowatt, it costs about $14,000 to have a sufficient residential solar system installed. That means that if you invest $14,000 up-front, you don’t have to pay monthly bills for electricity (except possibly some minor fees for maintenance, but lets ignore those). The amount that an electric power company would charge you for that energy varies, but it averages about 10 cents for 1 kilowatt for 1 hour which translates into $876 per year. If you never have to replace your solar cells, that would mean that you are getting a 6.2% average on your $14,000 investment. Pretty good. The problem is that the solar cells don’t really last forever. To break even, an actuarial calculation shows that the cells would have to last 22 years. If they require repair or replacement sooner than 22 years, which is likely, then you’re actually losing money.
There is some good news though. Currently turning solar power into electricity is expensive, but using the heat directly can be highly efficient without requiring expensive solar cells. As a result, solar-powered water heaters or swimming pool heaters are more popular and economically viable. So you might want to consider those alternatives, if you want to lower your carbon footprint.
Hopefully residential solar heating and cooling will become more attractive in the future, when significantly less expensive and more efficient solar cells have been developed and mass-produced. Stay tuned for future blogs on the science of solar power, since there is a lot of interesting research currently underway.
Nothing in science has any value to society if it is not communicated, and scientists are beginning to learn their social obligations.
— Anne Roe, The Making of a Scientist (1953)
The famous philosophical riddle asks, “If a tree falls in a forest and no one is around to hear it, does it make a sound?” Similarly I pose the riddle, “If a scientist speaks and no one hears, has he said anything?”
Scientists like to focus on what they do best, which is generally doing science. Most scientists are forced to do other things of course, like writing grants to get funding or presenting their research results at professional conferences, and they can live with that. But most scientists that I know do not want to hassle with “marketing” their science. Some have the perhaps naive belief that remarkable science will sell itself, and others feel that this is best left to the marketing experts. Although both beliefs certainly have validity, I think scientists still need to have basic Web 2.0 skills so they can directly communicate their science to the world.
But who has the time? If you are like many scientists, then you probably have a personal Facebook account that you use regularly, as well as a professional Linked In account that you rarely update. That is about it. If you think that probably isn’t enough, then I have a book recommendation for you. Your probably thinking, “Read a marketing book? Are you serious?” But really, trust me, you don’t have to invest a lot of time and it won’t even put you to sleep.
In order to help expand my social media skills, I recently read the book“Inbound Marketing: Get Found Using Google, Social Media, and Blogs” by Brian Halligan and Dharmesh Shah. The book is written as a basic primer for clueless small businessmen to learn how to connect to today’s buyers online. As you read each short chapter, the authors take you through each concept with a practical hands-on style using examples of small businesses that have successfully applied these inbound marketing tools. The most remarkable thing about the book is that it is easy to read. The conversational writing style makes it seem like your best friend is a Web 2.0 expert, and he is chatting with you over your laptop as you sip a glass of wine in the dining room.
My brother-in-law was seemingly the healthiest person we knew. He hikes up and down steep hills as part of his daily work. He kayaks intense oceans as part of his weekend play. He never even gets a cold. So he rarely sees a doctor. Luckily he did finally go for a general checkup when he turned 50, and those simple blood tests saved his life. Turned out, he had aggressive prostate cancer. Standard screening, to find prostate cancer in people who do not have symptoms, allowed him to be treated in time.
Against a backdrop of uncertainty and controversy, the American Cancer Society recently updated their prostate screening guidelines for the first time in almost a decade. This was largely in response to the findings of a massive federal study that was published in the New England Journal of Medicine last year. This study evaluated the usefulness of a popular prostate screening test that measures the amount of prostate-specific antigen (PSA) in your blood. Basically, PSA is a protein produced by the prostate gland. PSA is present in small quantities for normal men, but it is generally elevated for men with prostate cancer or other prostate disorders.
Some recent news coverage sensationalized the results of this federal study, so here are the basics of the report. The research findings are based on 10 years of follow-up of nearly 77,000 men (ages 55-74). Half of the men received annual PSA tests for six years, and the other half received “usual care” from their own doctors (physicals that in some cases included PSA tests). After 10 years, the men that received annual screening were diagnosed with prostate cancer 17 percent more than those in the “usual care” group. However, the screening didn’t reduce the rate of death from the disease. (Various possible and plausible explanations are discussed in the report, but I’m not going to get into the gory details here.) This brings into question whether the PSA test should be used for general screening, because prostate cancer over-diagnosis leads to unnecessary treatment and potential lasting side effects such as impotence and incontinence.
So, what is a man to do? Since I work in the area of prostate cancer research, friends and family members have been asking my opinion on whether or not they should be regularly checked for prostate cancer.
To me, it seems like these new screening guidelines assume that ignorance is less stressful than having faith in your doctor. Namely, it is better to not even perform a simple PSA blood test, because patients with low PSA levels are often over-treated. I understand the issues that they are addressing, but I think the reasoning is somewhat flawed. Why not instead just change how you treat patients with low PSA levels? Such PSA test results would indicate that you probably have some non-aggressive cancer cells in your prostate but they are unlikely to harm you. Scary yes, but so are impotence and incontinence treatment side effects. So why not just repeat the blood test in 6 months or a year to see if PSA levels have risen? Is this common practice of “watchful waiting” by your doctor really more stressful than not having the blood test at all? Because, for some, that simple blood test could also indicate that you have aggressive prostate cancer that needs immediate treatment.
Based on my personal and professional experience, I recommend that men get at least one initial PSA test when they are in their early 40’s. Doctors can use this as an important baseline in the future. This agrees with the American Urological Association’s guidelines. However, I am not a medical physician and some men have higher risk for prostate cancer, so it is important to speak about your health and concerns with your physician
Scientists often talk about their work only with other scientists within their specialized research field. As a result, they spend years learning to speak in a technical dialect full of acronyms and jargon that is difficult for others to understand.
If the person off the street can’t understand you, is that a sign that you’re incredibly smart and well educated? Actually, in my opinion it means the opposite. If you really understand something, then you should be able to explain it to anyone. You shouldn’t have to rely on jargon or math. And you should also be able to explain why the concept is relevant to “real” life.
So, my challenge for this science blog is to be able to communicate about science using every day language. I spend much of my time at work writing dry technical publications, reports and grants. This is my attempt to talk in a more conversational way about science news and what it is like to be a woman scientist.