Energy Recapture Technologies

11720336Kozo Nagata

The solar cell and wind turbine can’t supply a stable power.The demand of electricity is high for daytime and low for nighttime. The demand of electricity is high for summer and low for spring and fall.

What is energy recapture?Currently , many energy are generated. But over 60 % of that energy is thrown away.

So , the method storage these extra energy and pick up the energy when it is needed have gotten attention.

energy recapture = Storage system

Compressed Air Energy StorageGas Turbine (CAES-GT)

①Activate the compressor by using electricity for nighttime ②Store the compressed air in underground space③Pick up for daytime and generate by gas turbine power

Advantage

Disadvantage

Long-life operation

Need underground space that have air tightness and pressure tightness

Sodium-Sulfur-Battery (NaS-Battery)

Secondary battery that repeat charge and discharge by a chemical reaction between sodium and sulfur

Advantage

Disadvantage

Cost-cutting by mass-produced

Need to keep the heat in 300 ℃

Flywheel-Battery

Repeat charge and discharge by fluctuation of speed of rotation of disk that has big inertia moment

Advantage

Disadvantage

High energy density

Expensive material

Pumped Storage Generation

①Pump up a large amount of water by using electricity for nighttime ②Generate electricity by flowing the water for daytime

Nuclear power generation and thermal power generation are difficult to adjust the amount of electricity generated.So they need these large storage generation.

Advantage

Disadvantage

Generate large electricity

Location

Comparison

Scale Storage efficiency

Response speed

Electricity generated

Compressed air Middle 60-75% Slow 8MWh

NaS Battery Small-Middle 75% Rapid 48MWh

Flywheel Battery Small 70-90% Rapid 58kWh

Pumped Storage Large 65-70% Slow 180MWh

What energy recapture technologies would work best in Japan?

How much energy could Japan generate in this way in one year?

Topics

They have different purpose.So it is best to use them as each usages.

180MWh × 365 days × 50 plants = 3285GWh

The number of Pumped Storage generations in Japan

References• http://avalonbreeze.web.fc2.com/32_01_powerstorage.html• http://www.jeea.or.jp/course/contents/09401/• http://criepi.denken.or.jp/jp/kenkikaku/report/download/IpjgrVODy4pl24VDxzwB29G2OJC1

wjsA/report.pdf• http://www.ngk.co.jp/product/nas/about/index.html• http://criepi.denken.or.jp/jp/kenkikaku/report/download/IpjgrVODy4pl24VDxzwB29G2OJC1

wjsA/report.pdf• http://www.enecho.meti.go.jp/info/statistics/denryoku/result-2.htm• http://www.fepc.or.jp/• http://www.geocities.jp/tobosaku/kouza/plice2.html• http://www.jeea.or.jp/course/contents/09401/• http://avalonbreeze.web.fc2.com/32_01_powerstorage.html• http://www.jspf.or.jp/Journal/PDF_JSPF/jspf2004_07/jspf2004_07-572.pdf