Sunday, March 13, 2011

How to Overly Complicate a Simple Problem

In the United States, energy is at the core of a variety of real and perceived problems, both now and projected into the future. Due to an amazingly wide array of political and technological limitations, a clear path to energy related solutions is obscured in noise generated by agenda driven groups. Honest risk assessment is key to resolving this overly complicated issue.

1. Reduced dependence on potentially unstable sources of energy is in the best interest of our nation. It is impossible to make a case were reduction in the supply of foreign sources of energy will not have an adverse impact on America.

2. Every source of energy has risk and rewards. Honest evaluation of the "real" risks related to health, welfare, environmental and financial concerns, is improperly communicated. All of these risks are known. Even the "unknown" events can be quantified in terms of risk. Understanding of the "real" risks is inadequate for the general population to agree on appropriate action.

3. Sustainable energy sources are defined by both availability and cumulative negative impacts. Sustainable should not be interpreted as infinite. Technological advances and scientific evaluation of impact progresses as the "unknowns" are identified. This requires flexibility and diversity of energy choices to limit negative impacts.

Based on the three facts stated above each energy source should be evaluated.

Oil - Oil is primarily used as a transportation fuel. The methods used to convert any form of oil into energy are limited by the efficiency of the process used. Internal combustion engines are approaching a plateau of maximum efficiency. Efficiency limits the reduction of negative impacts possible with mass use of oil. For example; lower efficiency leads to more rapid depletion, increased of waste products and increase probability of "unknown" impacts.

Coal - As with oil, efficiency is a major consideration. Unlike oil, average efficiency as used, is much lower than the maximum limit of current technology and the theoretical limit of efficiency. Current technology limits efficiency to 80% versus a current industry standard efficiency of 40% (See efficiency options). Environmental concerns with coal production and use are real, but have a high degree of variability. Increased efficiency in conversion will reduce many of the risks, but methods of extraction and transport must be evaluated to address to minimization of negative impacts.

Natural Gas - Natural gas can be used for fuel a variety of processes. Efficiency considerations vary with use. A utility scale power plant application is were highest efficiency operation is required (See efficiency options). Environmental concerns of natural gas are fairly well known.

Efficiency options: Theoretical maximum efficiency is 95% for utility scale fossil fuel power plants. While maximum efficiency is desired in most cases there are limits and exceptions. Co-generation efficiencies of 80% are obtainable where waste heat (which can produce chilled water or ice) can be use for heat related processes including building heating and cooling. In applications where waste products are included as a percentage of fuel, lower efficiencies may be desired.

Nuclear - Efficiency of conversion to energy has to be considered differently in the case of nuclear. Lower efficiency in many designs increases safety. Wide spread use of nuclear energy requires lower efficiency reactor designs for greater geographical coverage with centralized high efficiency reactors to process fuel from the lower efficiency reactors in a more secure environment. As technology is proven, a variety of passively safe designs will provide one or more alternatives for current technology. Clearly communicating "real" risks associated with nuclear technology is much more problematic than most energy sources. False perceptions of risk have been instilled in society through generations of science fiction and action entertainment productions that greatly overstate real and create unreal scenarios of mass destruction. Despite real and grotesquely portrayed unreal risks, environmental and financial benefits of responsible use of nuclear energy are much greater than many other alternatives.

Wind - Efficiency of conversion has primarily financial and environmental impacts. Environmental impacts are less likely to be completely understood because of the limited time the impacts have been studied. Some impact bird and bats has been noted. Sound and light pollution (pulsating shadows of the moving blades) impact has been noted. The degree of impact of these issues are not well understood. There are also instances where designs are failing prematurely, blade icing posing problems, grid capacity limitations and requirements for other energy sources to compensate for intermittent availability. Real costs have been artificially deflated with subsidies while long term cost cannot be accurately determined. Wind energy is currently limited to no more than 20% of total production due to the nature of its intermittent source.

Solar - Efficiency plays a huge role in its viability both in terms of conversion of energy and cost of production. While technological advancement is slowing, the proper balance between product efficiency and production efficiency has not been resolved. Reduction in over all cost continues which reduces the wisdom of major expansion faced with a falling market. Environmental impacts appear to be low, but wide scale implementation may produce unanticipated negative impacts related to disposal, manufacturing waste and land use.

Biomass - Efficiency in terms of production, land use and end use, poses a complex blend of real and potential issues. Use of commodities such as corn, soybeans and sugar subject prices to radical fluctuation common to the commodities markets. Diversion of acreage suitable to food production, to fuel production, decreases the real sustainability of biomass as an energy source. Biomass using non-arable acreage shows promise though current production is too low for complete analysis. Environmental impact varies greatly depending on acreage used, methods used, resources used and percentage of total energy produced.

Standard Hydroelectric - Management of water resources and flood control are the major considerations. Environmental impacts are well known and have to be weighed against the water resource and flood control needs. Energy only expansion is unlikely to be significant. Efficiency is not an issue.

Non-Standard Hydroelectric - This is a potentially huge area that has limited current applications installed for proper evaluation. Waves, currents, tides and ocean temperature differentials can be used to produce energy. Transmission distance is a current limiting factor that may be reduced by energy storage. Environmental impact has to be determined by design and method of transmission and/or storage. Efficiency, as it relates to cost, is an issue that can be simplified to comparative cost of usable energy output.

Geo-Thermal - This area also has a wide variety of applications. Currently, environmental impacts and scale of produced usable energy are limiting factors. Smaller scale hybrid geo-thermal applications for heating and cooling are promising. Large scale electrical production is limited by geographical and technological constraints.

Other - Undiscovered energy production potential and hybridization of various technologies to better exploit waste are interesting and often over looked potential energy sources. Normally lumped in with other energy categories, it deserves a place of its own. Everything from landfill mining, sterling engines, super-conductive technology, hydrogen production and methane production from waste can be exciting additions to our energy portfolio.

Energy from trash (waste) combines disposal of certain types of problematic waste, petroleum coke, used tires and combustible, recyclable waste. The quality of the waste as a combustion fuel dictates the type of process used. Liquifecation of waste under heat and pressure allows for easier separation of non-combustible material such as metal tire reenforcement wires, then the liquid waste fuel can be used for a variety of purposes. When waste is used as a fuel mix in coal or natural gas fired plants, the plant design must allow for removal of non-combustibles after firing. Lower thermal efficiency is offset by benefit of waste disposal. Environmental impact of the raw waste and the combustion waste must be compared when evaluating these systems.

I will try to expand the detail and add links to promising new designs in the future.

Health risks - Coal, nuclear and combustible waste have the greater health risks of the energy sources. Each require special considerations to reduce introduction of harmful pollutants that can cause health problems. Ionizing radiation is a harmful by-product of all three. In nuclear applications containment and reactor design are used to minimize release of harmful radiation. With coal and waste fuels, dispersion minimizes health impact. Non-radioactive pollutants are more prevalent. Pre-combustion additives can be used to chemically react with certain elements during the combustion process. Post combustion, neutralizing chemical scrubbers, electrostatic precipitation and filtration can be used in combination to capture harmful pollutants. 100% capture is not economically feasible with current direct combustion technology. The Environmental Protection Agency (EPA) has minimum standards for all known pollutants for coal fired plants. Waste fueled (incinerators) and combined waste fueled power plants have a greater potential for unknown pollutants. Current EPA requirements appear to be more than adequate for public health protection.

CO2 - Carbon dioxide has been recently added to the EPA pollutant list. CO2 is not considered a pollutant in terms of human health. It may lead to harmful climate disruption and ocean PH reduction in sufficiently high concentrations. Fossil fuels, oil, coal and natural gas produce CO2 which are considered positive carbon contributors. The percentage of carbon dioxide per unit energy is a consideration needed for all fossil fuel applications. At equal thermal efficiency, coal produces the most, followed by oil then natural gas. A coal plant that is 60% more efficient than natural gas plant will produce roughly the same CO2 as the natural gas plant. Integrated Gasification Combined Cycle and other experimental combustion cycles can capture carbon dioxide. If the CO2 is used for practical purposes or sequestered, the process can approach carbon neutral. CO2 scrubbing is an experimental process using salt water and lime to react with flue gas to capture CO2. Algae can also be used to scrub CO2 producing bio-mass as a by-product.

Biomass also produces carbon dioxide, but is considered carbon neutral. All biomass is not carbon neutral. Only biomass derived from annual bio-crops is carbon neutral. Peat and mature trees are carbon positive. If the age of the bio-mass is equal to the atmospheric residence time of carbon dioxide it should be considered a fossil fuel. Time to harvest is a major consideration for bio-crops.


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