what's new in solar energy research in 2018? - battery energy

What are some new trends in solar R & D in 2018?
Originally appeared in Quora: a place to acquire and share knowledge that allows people to learn from others and better understand the world.
Yogi Goswami, director of the USF clean energy research center, answer on Quora: Before I answer the main question, let me use the stage as the background to understand the trend.
Solar energy is such a huge energy source that can be used for any of our daily needs, including electricity, heating and cooling, water heating, industrial process heating, cooking, transportation, fuel production, and even environmental cleaningup.
It is radiation as pure energy (
No quality related to it)
It is the highest form of energy and can be converted into many other forms for our daily use.
A small part of the solar energy that falls on Earth is enough to meet all the needs on Earth (
For more information, see Chapter 1 of 3rd solar engineering principles. By D.
Yogi Goswami, CRC Press).
However, it is only available during the day, and even during the day, it is not available during cloudy and rainy seasons.
Therefore, it is clear that if we are to rely on solar energy to meet our needs, we must be able to store solar energy efficiently and economically.
By the way, wind, biomass, ocean energy, water power, etc.
It is the indirect form of solar energy, that is, nature converts solar energy into these forms for our benefit.
Even fossil fuels are a form of storage for solar energy. Nature has stored solar energy for us for millions of years in an emergency (
That's our savings account)
Even though we humans have been using them, draining them, and throwing away the upcoming solar energy (our income).
Therefore, the research goal of solar energy has always been and will continue to be: 1.
While reducing costs, improve the efficiency of conversion to other forms. 2.
Store energy more efficiently and reduce costs. 3.
Find new ways to convert solar energy into useful forms.
Since electricity has become the preferred form of energy to meet almost all of our needs, a major focus of the study is to improve the efficiency and reduce costs of converting into electricity.
There are two main ways to convert solar energy into electric energy-Photovoltaic (PV)
Solar thermal power generation (
Commonly referred to as CSP, the first letter of the concentrated solar energy acronym).
The current trend of photovoltaic research is to use earth-rich materials for photovoltaic, because some materials in photovoltaic panels today, such as cadmium, te, ga, indium, selenium, etc.
Not rich, it will also become hazardous waste at the end of panel life.
Of course, silicon is still the main material used in solar cells, and is abundant on Earth.
Solar cells using earth-rich materials are under study, including dye-sensitive solar cells (DSSC)
Polymer solar cells and Perovskite solar cells (PSC).
The research fields of these cells include improving their efficiency and stability over time.
Due to the sharp decline in PV costs over the past 10 years, CSP is unable to compete commercially worldwide.
However, I believe CSP will eventually become competitive.
CSP has two advantages over PV: 1.
It uses the same thermal power conversion as traditional thermal power (
Fossil fuel or nuclear base)
Therefore, it is possible to integrate with existing power infrastructure
Simple structure. 2.
It uses thermal energy storage, about 1 out of 10 of the battery storage cost.
In order to make CSP cost competitive, it is necessary to improve the conversion efficiency and reduce the cost.
As the temperature increases, the thermal power conversion efficiency increases (
Second law of thermodynamics)
The trend of research is to improve the central receiver Tower (power tower)
Technology to raise the conversion temperature to about 700 °c800C.
Since it is not practical to use steam at such a high temperature, the current study is to find a replacement for steam.
Supercritical CO2 (sCO2)
This is a very attractive fluid for this alternative.
The simulation shows that running the sCO2 Breton cycle around 750 °c can achieve more than 50% conversion efficiency, and you can only expect something in a joint cycle factory running above 1100 °c.
Therefore, the current research is mainly to make the sCO2 power conversion technology practical.
For completeness, let me say that there is also a lot of research going on in other solar applications, such as solar desalination, solar refrigeration and cooling, solar catalytic environmental cleaning
Use of lighting and passive solar energy.
I just want to mention a trend (
Prevent this article from being too long)
This is what I started in early 1990.
At that time, I conceptualized a thermodynamic cycle, now called the Goswami cycle, in which you can convert heat energy into power and cool in the same cycle.
This begins the development trend of the joint cycle, where multiple useful outputs, such as electricity and seawater desalination, can be produced;
Power, heating and desalination;
Power, refrigeration, desalination, etc.
In these cycles with multiple outputs, the main innovation is that after the heat conversion success rate, the residual heat in the cycle is used for seawater desalination, heating, cooling, etc.
Instead of rejecting it into the environment.
This not only improves the overall efficiency, but also reduces the environmental heat pollution.
Finally, as I said before, an important part of increasing and fully utilizing solar energy is to store solar energy when it is sunny so that it can be used when there is no sun.
There are many ways to store solar energy, including batteries, thermal energy storage, pumping water, compressed air, etc.
The main research trend is to reduce the cost of battery storage and thermal energy storage (TES).
To date, thermal energy storage is the cheapest way to store energy ($10-
The price for TES is $40/kWhth and $200-
Battery Price $500/kWhe).
However, if you want to store electricity as heat, you need to convert it to heat first and then convert it back to power.
Additional equipment is required to convert heat back to power, with an efficiency of about 30%-
40%, so the $15/kWhth for TES is equivalent to about $45/kWhe, which is still much cheaper than battery storage.
Trends in electro-chemical energy storage (
The battery is stored electrically)
The storage of super capacitors is currently being improved.
The super capacitor can discharge quickly, but the storage capacity is very low.
The purpose of this study is to improve the energy density of the super capacitor and make it close to the energy density of the battery.
Another way to store solar energy is to use it to generate hydrogen from the water, and when you need it, use hydrogen to generate electricity in the fuel cell.
Research in this area is also under way.
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