Monthly Archives: August 2016

Wood as Fuel

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The capture and control of fire is right up near the top when one considers technology and human evolution. Whether simply warming the hearth, defending a home place from wild animals or cooking food, fire is a most essential ingredient. Estimates are that an ancestral species Homo erectus learned to control fire ½ a million years ago, and some scholars believe as early as 1.7 million years ago.

Wood fueled the production of the various metal ages up to and including the iron age. Wood was still the dominant fuel used in blast furnaces in early 19th century England. In fact it was the shortage of wood for the furnaces that stimulated the development of the use of coal. Forests were gradually cleared farther and farther from the furnaces until transportation costs made hauling the wood impractical.

Wood, straw, dung, etc are still major fuels in the underdeveloped world. Worldwide wood is the fourth largest source of fuel after the fossil fuels – coal, oil, and natural gas. Wood and derived products like charcoal are about one third of all fuel use in Africa and over half in Oceania.

Industrial fuel wood use in the United States is limited. Certain industries that produce significant amounts waste wood can burn it to produce steam for process heat or to drive turbines.

The amount of heat derived from burning wood varies as the density of the wood with hardwoods such as oak and hickory having the highest fuel values. At the other end of the scale are softwoods such as pine. This is only true where the wood is measured by volume such as a cord (a stack of wood 4 feet by 4 feet by 8 feet- 128 cubic feet.)

When measured by mass all wood has about the same fuel value which is the same as the fuel value of carbohydrates like sugar or potatoes. A toothpick and a piece of spaghetti of the same weight will produce the same amount of heat when burned.

In rural areas where available, wood is used for space heat. It may be hard to think about it now in August, but come January or so, there will be nothing like a hot wood stove to back up to on a cold morning. An air tight wood stove can be a useful source of heat, but an open fireplace, regardless of how attractive, will actually remove heat from a room.

Wood can be a renewable energy source but just how “green” is it? Not all that much. There is much waste when wood is harvested for fuel, it’s call the “roots and shoots” issue. The roots below ground and the unused branches and leaves mean that a lot of biomass is wasted.

The biggest drawback about use of wood as fuel is the burning. Any time something burns varying amounts of noxious products are produced. Fine particulates damage respiratory systems and cause asthma, especially in children. Polycyclic Aromatic Hydrocarbons produced by combustion are carcinogenic. Carbon Monoxide production can be deadly. It interferes with oxygen absorption in the blood and result in acute respiratory failure or chronic obstructive pulmonary disease.

It is estimated that over 4 million premature deaths a year can be blamed on cooking and heating with biomass, essentially all in the underdeveloped parts of the world.

Energy from Ocean Currents

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Whether we learn to stop burning fossil fuels as a way to mitigate global warming or we simply use them all up, we will have to find truly sustainable supplies of energy for our future. Nuclear power is always a possibility but seems to be going nowhere as nobody but nobody wants the radioactive wastes.

Solar energy in all its direct and derivative forms is the odds on leader. Solar thermal for powering turbines to generate electricity and Photovoltaic energy production are direct applications of solar power. Important but derivative is wind. Wind is the result of the Coriolis effect (more about this later) and uneven heating of land and water which creates the movement of air from regions of high pressure to low pressure. Wind driven wave action of some coastal areas also can be exploited.

Hydropower is also derived solar power. Solar heating causes water to evaporate from the surface of the earth. The water vapor can then condense and return to the surface as rain. Rainfall can be captured in reservoirs and used to generate power.

Geothermal power, heat from the interior of the earth, can be tapped to generate power where cracks in earth’s mantle make sufficient heat close enough to the surface as to be practically accessed.

Even the moon can provide power. It’s gravitational attraction drives the tides and in prime locations this power source has been tapped. The Bay of Fundy in Nova Scotia has tidal changes as high as 50 feet.

Ocean currents are an as yet untapped source of power. They are driven by several factors. The Coriolis effect is a force exerted by the rotation of the earth. Combine the Coriolis effect with the temperature differential between the equator and the poles and and differences in salinity between the two and you get a gyre.

The north Atlantic gyre is a circulation of water involving the gulf stream flowing north up the east coast of the United States, across the north Atlantic then down the western coast of Europe and back east across the Atlantic. The flow rate if the gulf stream is only about 2 miles an hour. This seems slow compared to wind speeds of about 12 to 15 miles per hour need for practical wind turbine power production.

The much slower movement of water still can provide significant amounts of power as water is about 800 times as dense as air, and power production is directly proportional to fluid density. All that is needed for power production is the placement of turbines anchored in place amid an ocean current.

Another current which could be used to produce power is a similar ocean gyre in the Pacific Ocean. The north Pacific equivalent of the gulf stream is called the Kuroshio current. It flows northward up the east coast of Japan and circulates in a clockwise pattern around the north Pacific.

An abundance of sustainable energy supplies exist around the world. Accessing multiple sources of sustainable supplies can assure all the power we need without using fossil fuels. The energy needs of humanity can be accomplished without utilizing fossil fuels and all the baggage their use entails.

Toxic Beaches

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Beaches in several counties on Florida’s Atlantic Coast are currently closed due to the presence of slimy, malodorous and most importantly toxic algae. The algae growth comes from nutrient laden water being released from Lake Okeechobee to prevent flooding. For the back story read on.

Thomas Malthus was a English cleric who in 1798 published an essay which suggested that human disaster loomed due to over population. He postulated that population grew logarithmically [1,2,4,8,16…] whereas food production only grows arithmetically [1,2,3,4,5…] Malthus predicted famine and starvation were the only possible outcomes without controlling population growth.

The Malthusian Catastrophe of course didn’t come about. Although population is growing logarithmically agricultural practices have been able to sustain burgeoning human populations. Improved tools, irrigation, mechanization, fertilizers, pesticides,plant breeding and ever larger farms averted the catastrophe.

An important agricultural innovation was called the Green Revolution of the 1950s-1960s. Food production was increased by careful selection of plant cultivars which responded favorably to large increases of Nitrogen and Phosphorous fertilizers. Application at rates far above what a crop could actually absorb did result in increased production, but resulted in fertilizer run-off. Increased profits from the crops offset the wasted fertilizer.

But everything goes somewhere. The excess fertilizer washes off the farmland and into adjacent low areas to rivers and lakes, and ultimately into the oceans. Just as the fertilizer increases crop production in farm fields, it increases algal growth in the rivers and lakes.

The Atlantic beaches in South Florida are being fouled with algal blooms from water draining from Lake Okeechobee. The fertilizer laden water is the result of run-off from sugar cane fields which have replaced much of the Everglades.

Besides the inconvenience and costs associated with lost tourism dollars, there is significant secondary environmental damage. After an algae bloom comes an algae crash. As the algae dies off it decomposes aerobically. That means it consumes the Oxygen in the water. The same Oxygen that all the animals require, from the simplest aquatic insects up to and including all the fish.

In certain locales there are “dead zones” with little if any animal life. All the coastal areas of the US, including the Great Lakes, are plagued by dead zones at the mouths of major rivers. They are know scientifically as hypoxic (low-Oxygen) zones and range in size from less than a square mile to over 25,000 square miles. The largest is essentially all of the Baltic Sea. The hypoxic zone at the mouth of the Mississippi is about 7,000 square miles

Around the world there a several hundred of these sterile areas. We have averted the Malthusian Catastrophe for us, but created a catastrophe for the native flora and fauna of the planet.