Tuesday, April 19, 2016

A moment of Zen

From "Bird and Moon Comics."

Click to enlarge.

GL 4003 Practice Exam


Biomass energy field trip

Students in PS3003 Sustainable Energy, including famous SEM students Michelle, Mac, Steven, Jared, and Sly, all visited former US Navy Commander Rick Holt's seven hundred acre working forest in Dixmont Maine, where we learned about forest management, with an emphasis on how biomass extraction for firewood, pellet, and chip is used as an adjunct to tree stand improvement practices.

Ricky first demonstrated the used of the "Biltmore" stick to estimate board feet content of a sawlog.

We then took about a mile and a half walking tour of the forest, inspecting tree stands in various stages of management. This is an area where future maple sawlogs and veneer logs are being encouraged by selective cutting of lower value, damaged, diseased, and otherwise competing trees, which are then used for firewood. Ricky explained that it helps when making a veneer log to increase the light availability of the target tree only slowly, or sprouts will appear on the trunk, leading to knots, which reduce the value.

This was a tree cut to stop the spread of the sugar maple borer, a pest of maple trees. The road in the background is one of several Rick has built over the years to facilitate forest management and timber extraction. Rick was able to show us very clearly how the new roads, with proper culverts and water-splashes or "rock fords" are a great improvement on the old skid roads and trails. Eroded skid trails from former harvest areas are easy to see on the landscape, even though it's been forty-five years since the harvesting was done.

Here's the view from the dam on Ricky's pond.

The landscape we see here is quite new, since the whole area was logged off and used for extensive sheep farming in the 1800s. Ricky has a map showing the names of some of the settlers. Most of the names are north British, which is not surprising, considering that extensive sheep farming of very similar upland ranges was developed in Britain. The settlers would have known how to manage the landscape and climate for sheep. Americans used more woolen clothing and ate more lamb and mutton back then, so there would have been a better market for the products than there is now.

Many thanks to Ricky for being willing to share his knowledge and his land with our students. Ricky is a great forester, but he's also a very good teacher, so the field trip was especially worthwhile.

Sunday, April 10, 2016

Intergenerational design criteria

Proposed by sustainability economics author and commentator Andrew Simms, published today in The Guardian (here):

  • Employment and broader economic return on investment - how much value to the broader economy does investment in different technologies bring; in other words, what is its economic multiplier effect?
  • Environmental return on investment - how efficiently does an investment lower carbon emissions and minimise other toxic pollutants and contribute to a healthy environment?
  • Energy return on investment - how much energy is generated for the amount of money invested to produce that energy?
  • Security return on investment - how much does the technology contribute to domestic energy security and what other security risks does it carry?
  • Transition return on investment - how does it contribute, comparatively to the speed and scale of deployment of low carbon energy generating capacity?
  • Conviviality return on investment - the degree to which a technology can be responsive to and supportive of a society’s or a community’s own vision and pathway for its development, and that of future generations.

Tuesday, April 5, 2016

Sustainable Energy second midterm

Sustainable Energy
Midterm Exam

Professor Womersley

Due Monday April 25th in class

This is a take-home exam. Answer all questions, showing work where necessary to demonstrate skills or learning, diagrams if asked or if it helps. If you don’t know or can’t work out an answer, put down what you do know. You may research answers.  You may discuss them with the instructor. You may not confer with other students. Submit electronically, multiple files allowed including statistical files in JMP, Excel, or Smith’s. Use PowerPoint for posters unless alternately agreed with the instructor.

Exam is 20% of grade for class, 10% given for each problem below

Only one problem:

Create a cost analysis for an industrial wind farm for an appropriate Maine site. Specify make, model and installed cost of equipment, wind speed estimates (from wind maps), rated and actual power produced. Use a Weibull model. Provide simple payback and amortized (levelized) cost effectiveness calculations, including economic profits and levelized cost per watt. (Use an annuity model for amortized/levelized costs.)

(See me for help if you didn’t get enough practice doing all this in class or lab.)

Your blank Weibull model spreadsheet is available at

PETM video, for GL 4003