By Harry T. Roman

With so much energy news in the popular press, people are inundated with information about everything from electric utility deregulation to distributed generation. We engineers in the energy arena should be active in helping folks understand what it all means, and should take the time to write professionally when necessary to address the issues, correct mistakes or misconceptions, and provide a more rigorous forum for debate when warranted.

Over the past 33 years, I've tried to do my part. I have had the pleasure of working with teachers, students, civic and fraternal groups, and professional organizations to discuss and teach the basics of energy. And I've found that a great way to begin is to explain just what engineers mean with our energy measurements.

A good way to visualize a Btu of energy, for instance, is with a matchstick. A lit match will yield approximately 1 Btu of energy.

With that basic unit understood, you can move on to comparing the approximate energy content of various kinds of fuel. A pound of wood can yield 6,800 Btu. Coal is even richer, with 12,000 Btu per pound. A pound of oil or gas yields 20,000 Btu. And if you want to show why, with all its problems, nuclear energy remains an important power source, just explain that one pound of uranium can generate 30 million Btu—by weight, 1,500 times more energy than oil!

Of course, 30 million matchsticks might not make an impression. But people in the Northeast have a feel for what it takes to heat a home for the winter. Back in the days when wood was the fuel of choice, a home would have taken about five cords to make it through the winter. A cord of stacked wood is 8 feet long, 4 feet high, and 4 feet wide, and ideally contains between 20 million and 25 million Btu. To visualize a cord of wood, imagine a nice big oak tree, fully grown, say about 70 feet high. Cut that down, split it and stack it, and you have one cord of wood. Do that five times and you can heat a house. (In the old days, the joke was that wood heated you twice: once when you cut it and once when you burned it.)

While I can't say I remember heating our old family home with wood, I do remember shoveling coal into a voracious old steam boiler. It took something like four or five tons of coal to heat our house for the winter. Had we only had a nuclear plant in the basement, my chores would have gone much faster, since 11 ounces of uranium would produce the energy equivalent of those four tons of coal.

Much of the recent interest in energy comes from people excited about renewables—solar and wind power, especially. Of course, renewable energy isn't as new as some of its promoters would have you believe. Remember that cord of wood? That's just a form of solar energy— solidified sunshine, if you wish to be poetic about it.

But also remember that it took a lot of wood to equal the energy of a modest amount of coal or oil, and that's a drawback to all forms of renewable energy. It just isn't as dense as fossil fuels. We can use renewable energy systems—solar, wind, and biomass—but there will be a trade-off, as we have to devote huge surfaces to collect them. In the past, it was land devoted to forests; in the future, it could be in the form of rooftops covered with photovoltaic cells or coastlines studded with wind turbines.

One way to compare fossil fuels to renewables is in the surface area required to support them. For example, one square mile of land in New Jersey (my home state) can grow enough biomass to generate one megawatt of electricity—enough to supply between 750 and 1,000 homes. Roughly speaking, that means half the state would have to be blanketed with biomass farms to power New Jersey's households.

That same square mile would produce 10 to 15 MW of wind power or 100 to 150 MW of solar power under typical New Jersey conditions.

But conventional power generation is far denser. A square mile devoted to producing electricity from coal, oil, natural gas or nuclear energy would be able to generate between 2,000 and 4,000 MW.

Moving toward renewables or "natural" energy forms, then, means making a trade-off in terms of land devoted to creating power. It's one type of environmental impact versus another, and too many people don't understand this.

Engineers have a role to play in this debate. It is our job to be honest and objective when pointing out the pros and cons of energy-related projects for our clients. Likewise, we need to find the language to explain the issues to the broader public.

Author Harry T. Roman has worked in the energy industry for 33 years and is a founder and chairman of the New Jersey Inventors Hall of Fame.



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