First energy independence steps: A Review of Crossing The Energy Divide by Robert and Ed Ayers
The Ayers’s book delivers arguments based upon the science of physics for concreting the first steps on the long and daunting road to a low carbon future. They propose to start ASAP to increase the efficiency of fossil fuel use on a grand scale. The result would be a decrease in the amount of fossil fuels used. The very low “average” exergy1 efficiency of fossil fuel use in the U.S., which they estimate to be 13%, makes this a good target. The benefits of their suggestions for greater energy efficiency include cheaper energy services for consumers and no net increase in CO2 emissions, because the fossil fuels have already been burned and low temperature heat is available without additional greenhouse gas emissions. They provide examples of industrial energy efficiency projects which utilize waste energy from gaseous byproducts and from waste stream heat ( a form of cogeneration) and which have provided up to 100 MW of additional electric power at a single site. The benefit to the industries is cheaper electrical services due to avoided purchases from utilities.
The heart of nearly all their discussion of ways to reduce fossil fuel use is the calculation of Life Cycle Efficiency (LCEC’s ) (my term). These calculations combine the concept of exergy with the life cycle steps in the production, use and distribution of energy – usually by multiplying the percentage of efficiencies at each stage to get one efficiency figure. The results are devastating for most of the larger forms of energy use in modern civilization from contemporary personal transportation to centralized power production.
These examples can be compared with the LCEC’s of smaller, distributed cogeneration projects (CHP) which supply both heat and electricity and are so logical for apartment buildings, commercial buildings and neighborhoods of single family homes. One barrier to greatly increased use of CHP is the existence of laws forbidding the sale of electricity across utility-owned lines by private individuals or businesses. There is a variety of other examples to indicate the large opportunity to create energy generation opportunities at relatively low cost.
When inefficient industries install projects which increase energy efficiency, they free up capital. An additional economic argument for these projects is the recent confirmation of a third very important factor determining the growth of our economy. The availability of energy services at low cost is as important to economic growth as labor and capital. The authors estimate that overall exergy efficiency in the U.S. could be doubled, and that these types of projects can be implemented in a few years rather than a few decades.
It will take decades for this country to achieve a significant renewable energy infrastructure. Increasing the efficiency of our fossil fuel energy system can buy time and add capital to the economy. The authors are proposing to continue using fossil fuel energy sources for the near future, at a much higher level of efficiency. The higher level of efficiency will reduce GHG emissions, and reduce the U.S. dependence on fossil fuel imports while the conversion to zero emissions energy systems is effected as efficiently as possible.
The authors list general options for reducing energy waste from fossil fuel use:
(1)Recycling waste energy streams such as waste low temperature heat from power plants which are located near commercial buildings;
(2) Using local, or distributed, CHP which radically reduces inefficiency by using low heat waste energy and by eliminating transmission losses;
(3) Greater efficiency in industry through modification of industrial processes of all kinds;
(4) Greater consumer end-use efficiency - for example, more efficient light bulbs;
(5) Local small-scale heating sources for houses, rooms, or even cars;
(6) Completely replacing fossil fuels with renewables for local energy services, such as passive solar and micro wind in homes;
(7) Redesigning new buildings and cities to reduce energy waste from transportation and increase use of industrial energy waste streams;
(8) Finding energy efficient improvements for fresh water recovery and distribution, including more efficient pumping, and more efficient purification .
They argue for shifting the product emphasis of fossil fuel companies from their fuels to the services those fuels can provide, and for simplifying the patchwork of existing energy policies.
This book is thorough, tightly reasoned and well worth the time.
There are extensive supporting discussions and citations in the appendix.
1 Exergy describes the quantity of energy AND the temperature of an energy stream. Because high temperature energy can perform tasks that low temperature cannot, exergy is a significantly improved description of energy use. Many of the authors’ examples utilize the low exergy waste energy stream from a high exergy process to gain more work . For example, high exergy energy can be used first to melt steel, and then lower exergy exhaust can heat buildings.