Small nuclear reactors come in several flavors. Many universities have research reactors that aren't intended to produce power, but some somewhat larger reactors have been built to supply power for ships, submarines, remote facilities and commercial power. There are those who suggest newer versions are solutions to cheap and clean power. Looking at the past suggests one has proceed with some caution.
The BAM Group is one the largest Dutch construction companies and it is making good progress in developing an industrial approach to net-zero retrofitting. It built its first prototype of net-zero retrofitting in December 2013. Half a year later the company completed a housing block of six terraced houses. By the end of 2014 the company scaled up its retrofitting approach to 90 houses divided over two different cities in a construction time of just eight weeks. The renovations are an example of a system approach and have various clever innovations that reduce not only the tenant’s energy bill but also the total cost of ownership of the renovated house. Besides that, it is possible to do the retrofit in approximately 10 days per house, without having to move out the residents.
The concentrating Ivanpah solar power station works by aiming thousands of mirrors at a boiling on a central tower. When the grid requirement for power drops during the day the mirrors were aimed above the tower creating a hot spot that famously killed birds. The fix has been to aim the mirrors at different spots in the sky so no area is bright enough to hurt birds. But the initial bad news is probably what people remember ...
Making meat is an inefficient process, but it varies from animal to animal - beef is worse than chicken. Insects have been touted as extremely efficient compared with other animals with crickets cited near the top. It looks like there not as good as once thought and may require high quality food. But if you're into meat don't worry - black soldier flies may thrive on waste from other animals.
Crickets Are Not a Free Lunch: Protein Capture from Scalable Organic Side-Streams via High-Density Populations of Acheta domesticus
Mark E. Lundy1, Michael P. Parrella2
1 University of California Division of Agriculture and Natural Resources, Colusa, CA, United States of America,
2 Department of Entomology and Nematology, University of California Davis, Davis, CA, United States of America
It has been suggested that the ecological impact of crickets as a source of dietary protein is less than conventional forms of livestock due to their comparatively efficient feed conversion and ability to consume organic side-streams. This study measured the biomass output and feed conversion ratios of house crickets (Acheta domesticus) reared on diets that varied in quality, ranging from grain-based to highly cellulosic diets. The measurements were made at a much greater population scale and density than any previously reported in the scientific literature. The biomass accumulation was strongly influenced by the quality of the diet (p<0.001), with the nitrogen (N) content, the ratio of N to acid detergent fiber (ADF) con- tent, and the crude fat (CF) content (y=N/ADF+CF) explaining most of the variability be- tween feed treatments (p = 0.02; R2 = 0.96). In addition, for populations of crickets that were able to survive to a harvestable size, the feed conversion ratios measured were higher (less efficient) than those reported from studies conducted at smaller scales and lower population densities. Compared to the industrial-scale production of chickens, crickets fed a poultry feed diet showed little improvement in protein conversion efficiency, a key metric in determining the ecological footprint of grain-based livestock protein. Crickets fed the solid filtrate from food waste processed at an industrial scale via enzymatic digestion were able to reach a harvestable size and achieve feed and protein efficiencies similar to that of chickens. However, crickets fed minimally-processed, municipal-scale food waste and diets com- posed largely of straw experienced >99% mortality without reaching a harvestable size. Therefore, the potential for A. domesticus to sustainably supplement the global protein supply, beyond what is currently produced via grain-fed chickens, will depend on capturing regionally scalable organic side-streams of relatively high-quality that are not currently being used for livestock production.
Electric airplanes are not in the immediate future, but better batteries a few decades out or hybrid power sources make it likely they'll appear in some manned applications. If you can distribute propellers on the airplane it is possible to build more efficient wings. NASA is building an experimental airplane to test ideas as part of its Leading Edge Asynchronous Propeller Technology (LEAPTech) project. A special wing that will house 18 electric motors will be fitted to a small private airplane to test the concept.
Although the range is limited to about 200 miles with conventional batteries aerodynamic efficiency, propulsion efficiency, emissions, noise, safety, vibration. operation costs and greenhouse emissions are improved - sometimes dramatically.
A doubling of battery energy density (mass) seems likely in the next decade - that would make this type of airplane practical for many applications. It is also possible to imagine a hybrid system with a small fossil fuel engine with a generator supplying power directly the the motors - possibly with a small battery to supply extra power for takeoffs. The improvements allowed by the improved wing result in overall improvements before better batteries are available.