Reducing institutional barriers to solar energy through the use of cooperatively-owned solar energy systems
Despite the conceptual attractiveness of solar energy systems for space-heating applications, the market penetration rate of solar systems remains low. The physical, economic, and institutional barriers to acceptance that cause this disappointing performance are closely related to the present political, social, and economic structure, and so are proving difficult and time-consuming to lower. However, aggregating small solar systems into larger cooperative ventures can avoid many of these barriers altogether. This “product-fit” approach could greatly increase the diffusion rate of solar energy systems into the economy, thereby replacing fossil-fuel uses sooner and to a greater extent than previously expected.
Residential energy use alternatives: 1976 to 2000.
A comprehensive engineering-economic model of residential energy use (developed at ORNL) was used to evaluate the energy impacts of various energy conservation strategies. The model simulates household energy use at the national level for four fuels, six end uses, and three housing types--single family, multifamily buildings, and trailers. Several cases were run with the model to determine the impacts on energy use of each factor, in isolation, and in combination with other determinants of fuel use. Dr. Hirst concludes the following: (1) residential energy use will grow more slowly during the last quarter of the 20th century than it did during the third quarter; (2) a ''high forecast'' developed in the study is not valid because it was assumed that fuel prices will hold constant (1975), that household formation and personal income will increase rapidly, and that the 1960-1970 trend in housing choices (away from single-family) will not continue; (3) implementation of energy conservation programs to raise fuel prices can have significant energy impacts; (4) implementation of a program to increase efficiency of residential equipment by 1980, as specified in the Energy Policy and Conservation Act, can cut energy use in the year 2000 by at least 10 percent; andmore » (5) programs to improve thermal integrity of residential structures can also provide significant energy savings during the next 25 years. (MCW)« less
Engineering bio-inks for 3D bioprinting cell mechanical microenvironment
Three-dimensional (3D) bioprinting has become a promising approach to construct­ing functional biomimetic tissues for tissue engineering and regenerative medicine. In 3D bioprinting, bio-inks are essential for the construction of cell microenviron­ment, thus affecting the biomimetic design and regenerative efficiency. Mechanical properties are one of the essential aspects of microenvironment, which can be char­acterized by matrix stiffness, viscoelasticity, topography, and dynamic mechanical stimulation. With the recent advances in functional biomaterials, various engineered bio-inks have realized the possibility of engineering cell mechanical microenviron­ment in vivo. In this review, we summarize the critical mechanical cues of cell micro­environments, review the engineered bio-inks while focusing on the selection princi­ples for constructing cell mechanical microenvironments, and discuss the challenges facing this field and the possible solutions for them.