What is the prospect of "energy storage" technology that dramatically reduces electricity bills and can greatly change the future life?

ByGerman Aerospace Center DLR

"Energy storage"A technology to store energy so that it can be drawn out in a form that can be used later," battery "which stores electric energy is a typical energy storage medium. While technological development is going to make a big progress by the substantial evolution of lithium battery etc., generalSecondary batteryIt is expected that the energy situation of the world will change greatly by the technology of energy storage medium of a different form.

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It is widely known that there is evolution of large capacity lithium ion batteries as a factor that widespread use of notebook PCs, smart phones, electric vehicles and the like. Evolution of lithium-ion battery is not only improvement of output and durability, but also a big point that prices have declined year by year. The price of lithium-ion batteries declined to 1/10 of the price in the 15 years from 1990 to 2005, which has greatly contributed to the subsequent popularization of mobile devices.

ByIntel Free Press

However, most of the secondary batteries, typified by lithium-ion batteries, are expensive enough to be compared with power plants, which are the power sources for power generation, in terms of unit cost of power and unit cost of output power, and lithium battery Although it is suitable as an energy storage medium for carrying mainly, it is thought that it is disadvantageous in terms of cost as a permanent device which preserves the electric energy of a larger capacity. On the other hand, although the weight increase and the volume increase are more than the lithium ion battery, as a device capable of storing a large amount of electric power,Redox flow battery) "And" compressed air storage battery "have received much attention in recent years.

· Fluid battery
In general secondary batteries such as lithium ion batteries, the solid electrodes themselves change due to oxidation-reduction reactions, whereas in flowing batteries there is no chemical change of the electrodes because ions in the solution undergo oxidation-reduction reactions, so they are structurally It has a feature that there is almost no degradation. In addition, the biggest merit of the fluid battery is the ability to increase the amount of electricity that can be stored by increasing the volume of solution. In other words, if you want to increase the capacity, you can increase the capacity of the tank itself to contain the battery solution, which means that it is much easier and more cost-effective to store a large amount of electricity than a general rechargeable battery .


Compressed air storage battery
A compressed air storage battery is a device that stores heat generated when compressing air as electric energy, and although the basic idea itself has been known for a long time, the ratio of the amount of energy that can be extracted to the amount of stored energy It is a technology that has not been put into practical use due to the low power generation efficiency shown. However, a genius scientist who went to Princeton University graduate school at the age of 17Daniel · vonStarted businessLightSail Energy, The practical application of compressed air storage batteries is becoming real.


Lithium ion batteries, flow batteries, compressed air storage batteries, etc. Either type of energy storage medium can be used, once it enters a cycle of virtuous cycle, it has the feature that it spreads at a stretch. This is because the cycle of "low battery price" → "birth of new market" → "increase in battery demand" → "low battery price" caused by mass production is accelerated. Next-generation energy storage technology that can store large capacity electric power such as flow battery, compressed air storage battery, etc. will be able to get on this cycle of this virtuous circle and spread at a stretch in the future.


◆ What is the effect of energy storage technology?
· Decline in electricity bill
"Reduction in electricity cost" is mentioned as an advantage obtained by dissemination of next generation type energy storage technology which can store large capacity electric power such as flow battery and compressed air storage battery. Currently, electricity bills in each country have adopted a mechanism in which the electricity bill fluctuates according to the electricity usage time. The figure below graphs California state electricity charges by time. At the peak from 1:00 pm to 7:00 pm where electricity is used, the electricity cost is 34.6 cents per kWh (about 41.4 yen), whereas after 9 pm it is 15.4 cents per kWh (about 18.4 yen) at the peak time We have adopted a metered-rate system that is less than half of the standard.


The simple reason that "Why is the high electricity usage time period high?" Can be explained from the power generation cost of electric power companies. Electric power companies are required to constantly supply electricity 24 hours a day, 365 days a year, and we are maintaining power plants that do not usually generate power at full power so that we can cope with peak times. The power plants that are active to compensate for the power shortage during peak hours use clean energy that has relatively high power generation cost compared to the power plants that are constantly generating electricity, so the power generation cost at the peak is also high As a result, it becomes a simple mechanism that the electricity bill becomes higher to absorb the increase in electricity cost at the peak.

Therefore, if it can be said that "electric power generated during the time when electricity is remaining is transferred at the peak time", both consumers and electric power companies are able to realize stable Win- Because it becomes a Win relationship, development of an energy storage medium which can store a large amount of electricity is required.

· Activation of "private power generation"
Even in Japan, a fixed price purchase system that allows electric power companies to purchase energy for solar power generation has been implemented, so the number of cases where households and companies themselves generate electricity by installing solar panels is on the rise. And at present, the energy efficiency of the solar panel is at most 20% at best, so if the efficiency of electricity generation increases with future technological innovation, the life of self-sufficiency of energy without buying electricity from a power company is also realistic I will come. To complete such a self-sufficient eco energy system, the energy storage medium is likely to be a key player.

The lower line graph shows electricity demand, and the parabolic graph shows the amount of electricity generated by major electric power companies such as households and companies. In other words, the orange part of the graph is in a state where it can generate electricity more than electricity demand.


If this surplus electric power can be stored in the next generation type energy storage medium and it can be effectively used later, it will be a big merit.


· Further utilization of clean energy
Besides solar power generation, wind power generation and tidal power generation are also strongly considered as a clean energy creation method that does not use fossil fuels and nuclear reactions. Compared with photovoltaic power generation, wind power generation and tidal power generation itself generate a small amount of electricity, but installation cost of power generation equipment is relatively inexpensive, and unlike solar power generation, stable power generation can be constantly generated regardless of day and night The advantage is worth noting. It is expected that clean energy that was used only in power plants where hydraulic power generation was limited is limited, as the energy storage technology develops, it can be used more effectively.

ByWashington DNR