Conceptually, one can define three generations of renewables technologies, reaching back more than 100 years .
First-generation technologies emerged from the industrial revolution at the end of the 19th century and include hydropower, biomass combustion and geothermal power and heat. Some of these technologies are still in widespread use.
Second-generation technologies include solar heating and cooling, wind power, modern forms of bioenergy and solar photovoltaics. These are now entering markets as a result of research, development and demonstration (RD&D) investments since the 1980s. The initial investment was prompted by energy security concerns linked to the oil crises (1973 and 1979) of the 1970s but the continuing appeal of these renewables is due, at least in part, to environmental benefits. Many of the technologies reflect significant advancements in materials.
Third-generation technologies are still under development and include advanced biomass gasification, biorefinery technologies, concentrating solar thermal power, hot dry rock geothermal energy and ocean energy. Advances in nanotechnology may also play a major role.
There are 3 numbers but no signs
Answer:
TRUE
Explanation:
Suspended silt diminishes the entrance of light into the water. This influences angle bolstering and tutoring hones and can lead to decreased survival.
Answer:
The correct answer would be 30 million years.
The molecular clock is a technique used to determine the time when the two species diverged from a common ancestor. It uses the mutation rate to determine the same.
Mutation rate is the rate at which a number of mutations take place in a given unit time.
For example, the mutation rate in a given question is one mutation per 10 million years, that is, one nucleotide is mutated in 10 million years.
If we compare the DNA sequence of the given two species, we would find that three mutations have taken place.
Species A: CTTAAGCTAGTAAGGACC
Species B: CATAAGTTAGTAAGGTCC
Thus, 30 million years would have passed to evolve three mutations.
Hence, they must have shared a common ancestor around 30 million years ago.
