Putting it all together:

Energy Star:

Passive solar design:

You might recognize this place:

Thermal mass: e.g. concrete around the elab: holds heat for night time, cools in the daytime

"Renewable" means renewable in your lifetime:

All energy in our world ultimately came from the sun, either long ago (fossil fuels) or now (solar power):

"carbon neutral" means no carbon released into the atmosphere

"carbon capture" is a dream of capturing carbon from fossil fuel sources and compressing it into liquid formations under ground, as CO2 under pressure.

Danger: any seismic activity can make it erupt, and CO2 asphyxiates creatures, including humans

Lake Nyos disaster: https://en.wikipedia.org/wiki/Lake_Nyos_disaster

Biofuels:

Something grown now that removes carbon from the air, then is used as fuel

Can be carbon neutral if it is a natural crop, e.g. Brazilian sugar cane

First biomass ever used: wood-chop it down, burn it

Others: dried manure (still used in lesser developed countries, where wood is scarce, #1 cause of lung cancer in poor women-why?)

Biodiesel is a form of hydrocarbon (C-H) formed by decomposing wood, grass or other cellulose

Bioethanol comes in two forms:

• Bioethanol from sugar (cane, corn) which is a fermentation process
• Cellulosic ethanol is a future technology that breaks down cellulose (grass) into sugars, then fermented.

Ethanol in the US is NOT carbon neutral: we use petroleum based fertilizers and other inputs that actually use more petroleum than they save.

Why do we do it? In what state are the presidential primaries held?

You pay a tax on NON ethanol gas ("E-Free") which goes to the corn farmers, keeping their price high

Two forms: dams and tidal power

Dams: on a river, make a dam, pressurized water shoots over a turbine, makes electricity

Dams are not sustainable, as they fill with silt eventually

They also change the chemistry of the water: cooler water under pressure leaches certain metals from rocks

Some dams open seasonally to enable flooding and nutrient flow in lower areas

Big ones: High Aswan dam-Nile, Three Gorges dam, Yangtze

Recall your solar lab, 6 solar hours per day, about 1000W/m2:

Solar Thermal: radiation from the sun (visible) hits a dark metallic surface (often copper or aluminum, since they conduct heat well). The dark surface transforms visible radiation into thermal (infrared) energy, which is conducted by the copper or aluminum to attached water pipes. To keep the heat energy from radiating away from the panel, the metal is coated with a special paint, and covered with a special glass insulating layer. The glass is the heaviest part!

Two forms of solar thermal: Passive and Active

Active solar:

You've seen this on the cottages, also in Carter dorm (secret room at the back)

Passive solar uses no pump, but a thermosiphon

You've seen these on the roof of the cafeteria, Anna's/PF dorm, and the elab:

Solar PV: radiation from the sun (visible) making electrons move in a special semiconductor material (silicon, made from sand), so photo (light) voltaic (Volts) = PV or photovoltaic. These release direct current (+ and -) energy like a battery. To be used in our electrical system, we use an inverter to change the DC to AC (alternating current). Inverters are large boxes that are usually hot when in use. PV panels are usually made of glass, often with a purple color, which is the semiconductor below.

Uses silicon wafers from the computer industry (no joke)

14% efficient

Cost per kW has dropped in 10 years from $10/Watt to $0.50/Watt (How?)

CST: concentrated solar power

Industrial scale solar heating, uses mirrors (cheaper than PV panels) to heat a material (e.g. salt), then make steam for electrical power (agh! steam again?)

There are several of these around the world, one in Spain, another on the Mojave desert.

Benefit: molten salt can stay hot over night, generating steam when the sun is not out.

Wind energy:

Wind energy: Solar radiation (mainly visible) heats the surface (water or ground) which makes the air in contact with the surface less dense, so it rises into the atmosphere. Wind is the movement of air to replace this rising air. Since air has mass, when is passes over a surface that can move, the kinetic energy of the wind (1/2mv2) can push a wing. Two or more wings working together will rotate a shaft that can be connected to a generator (Direct current, DC) or an alternator (alternating current, AC). Turbines can be horizontal axis (HAWT) or vertical axis (VAWT), which are less popular. Horizontal axis turbines can be leading or trailing, meaning the blades are in front of or behind the tower. Most large turbines are leading, because of the turbulence from the mast.

Moving air over airfoils (like an airplane wing) generates lift, turns a generator, makes electricity

Two types:

HAWT: horizontal axis wind turbine: most common, large industrial ones are these

VAWT: vertical axis wind turbine: prototypes have mostly failed on these http://10.14.4.6/public/videos/helix/

Fun fact: we have had several HAWT and VAWT here at the elab, all have failed.

Another fun fact: air is less dense where you are now, so wind turbines are only 92% efficient here

maintenance

noise

sight impact

variability

windy places are often far from users (South Dakota->Denver)

Works at night if windy

Can be industrialized

Mod 40: smart grid and storage

Storage:

Hot water: the cheapest energy storage method is hot water, usually from solar thermal panels, but can also be from PV panels running a traditional electric hot water heater, just like a coffee maker. Insulation is a key aspect to hot water storage, as heat travels from hot to cold through conduction (contact) radiation (radiation) or convection (hot air rising). Most hot water heaters are insulated (conduction), reflective (radiation) and covered (convection).

Batteries: These can be old style lead acid batteries like those in a car or golf cart, or newer lithium batteries like those in electric vehicles or in our IT and student union setups. Batteries only store Direct Current (DC), so they must go through an inverter to supply the grid, which is alternating current (AC). Energy stored in a battery can be as cheap as $100 per kWh stored for lead acid batteries, or up to $500 per kWh for lithium batteries, which charge much faster, last longer, and are much better for the environment than lead acid batteries.

Hydrogen: Passing direct current energy through water splits the water in to its components, Hydrogen and Oxygen. If the Hydrogen is captured and compressed, it can be used to burn for heating, cooking or in vehicles, or if passed through a special Fuel Cell membrane into direct current electricity, just like a battery as well as hot water. This is not as efficient as a battery, but can be used for long term storage.

Electrical Storage:

Batteries for large scale systems are usually either lead acid batteries dating back to around 1800, or lithium batteries from this century:

~1800 lead acid batteries (like in your car)

• lead and sulfuric acid
• environmentally nasty
• 3 year lifespan
• shorter if used more
• only 40% of capacity is usable
• slow discharge and recharge
• about $300 for each kWh stored

Example: our overnight campus use is about 100 kW for 20 hours or 2000 kWh (or 2 mWh). At $300/kWh this would cost us $600,000 and would last 3-5 years at max capacity, but in actuality it would be 2.5 times this because these batteries cannot be discharged all the way, so $1.5M.

~2010 lithium batteries (LiPO, Lithium iron phosphate, etc.)

Used in Prius, Leaf, Tesla and other cars, some homes ("Tesla PowerWall")

• lightweight
• fast discharge and recharge (good for regenerative braking in cars)
• 20 year lifespan at 80% capacity
• greener
• expensive ($>500 per kWh)

Tesla's Power Wall is one example, so is the blue box in the student union and IT office. Kauai island is using these to move that island to complete energy neutrality in the next few years.

The same example above costs more, last longer, and requires fewer batteries. It also discharges faster to maintain our microgrid, and recharges faster when used as backup power for the IT building, protecting our computers from multiple outages we face with HELCO.

Pumped storage hydro:

Water tanks low on campus have a pump and a generator. When we have extra energy, we pump this water uphill to a similar tank where it is stored for use later on. When needed, the system activates the generator, which provides power for the campus. This is green, cheap, renewable, lasts 50 years or more and can be safely integrated into other water systems (e.g. fire suppression) as needed.

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Net neutrality:

We have three ways we can claim neutrality:

1. Net energy neutral: We export the same amount of energy around noon that we use overnight, so as far as the HELCO grid is concerned, we have a net zero energy profile. We still pay for what we use at night, though)
2. Net money neutral: We capture any excess energy during the noon hours when the HELCO meter would be spinning backwards, and use this at night from our batteries or other storage). If we were allowed to sell power to the grid, this would also work.
3. Net carbon neutral: We measure all carbon used on campus, including transportation, heating and other carbon impacts and offset with energy produced via solar thermal, PV, wind or other means (not nuclear, don’t worry). This is the most current global metric used, and relates well to our sustainability misssion.

Each has certain PR and moral aspects, depending on the goals of the organization. Since our business is creating change agents to solve sustainability issues in the future, each of these is important.