Abating extreme urban heat: Photovoltaic and photosynthetic - - PowerPoint PPT Presentation

Abating extreme urban heat: Photovoltaic and photosynthetic hybridization

ER Rincon (Mexico City University) M Islas-Espinoza (Mexico State U) A de las Heras (IndyRes)

1995 HEAT WAVE

700 Chicagoans dead

Europe 2003: ~70 000 dead Tokyo 2018: ~100 dead + concern over 2020 Olympics

Heat is Top US weather killer

1995 heat wave: July 1-17

0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 55 65 75 85 95 105 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 7 7.5 8 8.5 9 9.5 10 10.5 11 11.5 12 12.5 13 13.5 14 14.5 15 15.5 16 16.5 17

Rainfall

Temperature

Time (half-days)

temp (F) precip (in.) 90 =32.2oC

18.3oC=

Humidity, Temperature, low wind speed Multi-unit housing, top floors, flat roofs 1970s buildings worse: greater mass, poor insulation Over 65, under 5 years old Poverty, living alone Fear of crime: leaving windows closed

Chicago

PV and CSP to replace fossil

In the US

GHG radiative forcing W/m-2 17% of electricity use @ 4-5 COP

<17% @ higher COP

1997 1972

Solution

Max gain, min loss

• f solar irradiance

(in UV, Vis and IR) (Trap and use)

0.00E+00 2.00E-01 4.00E-01 6.00E-01 8.00E-01 1.00E+00 1.20E+00 1.40E+00 1.60E+00 1.80E+00

200 700 1200 1700 2200 2700

W*m-2*nm-1

nm

Irradiance, global tilt (ASTMG173, 37°)

TRAP AND USE

𝐼=∫2_0^24ℎ▒├ 𝐻(𝑢) 𝑒𝑢= Peak H: 20MJ/m2/day 𝐻(𝑢) = 𝐻(𝜇; 𝑢)

𝐽𝑆 𝑉𝑊

𝑒𝜇 =

Goal

Given 𝐻 = ∫ 𝐽(𝜇)

𝐽𝑆 𝑊𝑗𝑡

𝑒𝜇,

• btain A, the part of G absorbed by the hybrid’s

subsystems 𝑗={PV, PS, Pthermal} and transmitted among them: 𝐵 = 𝐵(𝜇)𝑗

𝐽𝑆 𝑊𝑗𝑡

𝑒𝜇

How does it lower the temperature:

Since heat is Q = 𝑛𝑑𝑞 ΔT, temperature changes due to the hybrid’s materials are ∆𝑈 = 𝑛𝑑𝑞 𝑅 The materials’ emissivity is 𝜁𝜇 = 𝛽𝜇 (Kirchhoff’s law) and power lost per m2 is E = 𝜁𝜏𝑈4 (Stefan-Boltzmann’s law)

Conceptually, to decrease surface temperature, energy (Vis and IR) is:  Subtracted from the city by radiation absorption and use  Water cooling enhances PV performance  Water after cooling is further heated up by non-imaging thermal solar concentration  *Thermal energy is stored in heated water (removed from city surface and boundary layer)  Latent heat is released by (PS) transpiration  Remaining solar radiation reflected by PV and PS back to space Then, subtracted energy is used to diminish GHG forcings by replacing thermo- and nuclear electricity for AC through:  CO2 absorption by PS  PV substitution (powering heat pumps and water pumps)  *H2O cooling: cool rainwater can be used to cool walls down. * are alternative mechanisms.

• Fig. 1. Radiative fluxes of the PV-PS-

water hybrid. G is irradiance. 1) PV:

• paque/semi-transparent inlaid in

transparent glass (50:50 area). 41o slope also for snow to slide down. 2) Water cooling under PV. 3) PS leaf area; underground irrigation reduces EV, a loss of water to

• plants. 4) Soil. 5) Concrete. 6a-b) T-

stratified water stores thermal energy for wintertime use; summer inflow to cooler 6b is pumped for spray cooling. 6c) Rooftop soil runoff and infiltration overflow. 7) Temporary rain storage pumped upwards to PV underside. 8) Hose. At the end of the cycle, water heated underneath the PV returns to 6b and so warms 6b up.

Where

• (Green) roofs
• Parks
• Neighbors’

gardens (613711 sq ft=57016 m2)

• Urban farms
• Boulevards
• Parking lots
• Walls
• Malls
• Energy

benchmark buildings (≥50,000 sq ft ea

• r ≥4645 m2)

Largest convention center in North America

[VALOR DE X], [VALOR DE Y]

y = 0.3097x R² = 0.8138

100 1000 10000 100000 1000000 100 1000 10000 100000 1000000 10000000

Vegetated area (Log10(sq ft)) Total area (Log10(sq ft))

Chicago green roofs (Aug 2010)

17645367 5469466 Total area Vegetated area, sq ft

2 223 396, 839 593

• r 1639308 and 508130 m2

1.49 USD/W

Native to NE IL.

PV interpersed more acceptable to birds Multi-functional plantations more acceptable in Planting Priority Areas (highly urbanized)

Goodnesses of hybrids

PS contribution

• 1. Absorb photons
• 2. Absorb C-CO2
• 3. Transpire: cooling via latent heat

release

• 4. Cool down PV underside
• 5. Shade (decrease mean T)

• 1. Absorb photons

Photon flux density (PFD, µmol*m-2*s-1)

(from irradiance G)

Photosynthetic PFD (µmol*m-2*s-1)

(PAR=Vis)

4 photons + 2H2O  4 H+ + 4e- + O2

(light dependent phase)

For a 700 nm photon, E(eV)=hc/λ(µm)=1.2398/0.7µm=1.771 eV (1 eV = 1.602(10-19) J)

48 photons + 6CO2 + 12H2O  C6H12O6 + 6O2 + 6H2O

(light (in)dependent phases)

where C6H12O6 is one glucose molecule

48 photons + 6CO2 + 12H2O  C6H12O6 + 6O2 + 6H2O C-CO2/kg standing biomass C-CO2/kg NEP

• 2. Absorb CO2

C6H12O6 : 16.3 kJ/g calorific content Human brain tissue requirement : 5.6 mg glucose/100g per 60 s Mol glucose/mol photons * mol photons*W-1m-2 => mol glucose*W-1m-2 feeds how many human brains for one second?

• 3. Transpiration (loss of water vapor by plants)

Energy use by transpiration is 0=(G+𝑇)−(𝑠G,𝑇−𝑆)±𝐼±𝑚𝐹+𝐵 with G total solar radiation, 𝑇 the IR from soil and buildings, 𝑠G,𝑇 radiation reflected from leaves, 𝑆 radiation reradiated from leaves (‘additive radiation’), 𝐼 sensible heat exchange with the environment by convection and advection, 𝑚𝐹 latent heat lost in transpiration or gained in dew or frost formation, and 𝐵 energy used in metabolic processes (e.g. photosynthesis 2-3% of the total) In addition to transipiration, there is energy used in evaporating dew or rainfall drops (latent heat).

• PV and PS mutually regulate their T
• Water regulates PV and PS T
• PV protects PS underneath from acid rain and keeps PS in High Efficiency

State rather than Photoprotected State UNLIKE OTHER ENERGY SOURCES:

• Produces O2 (whereas combustion decreases O2)
• Produces energy (for living beings and machines)
• CLEANS! (CO2, C- and non-C particles, waste heat)
• Can be carbon-negative
• Keeps CLEAN water inside the city rather than SOILING and evacuating it
• Sustainability accountability can be done at the building level (I clean my act

AND sweep in front of my door)

• Aesthetic value
• Mid-term cost reduction

The hybrid

SAME time PATTERN AS MONTHLY Mauna Loa CO2 ppm

Is this also useful to curb global warming?

PROBABLY SO (space-time dependence):

Thanks! Let’s retrofit locally!

rinconsolar@hotmail.com ICUC10, NYC, Aug 2018