Solar Power part 2

learn all about solar powerWhat Solar Power is:

Solar power is electricity made from the sun’s energy that reaches the earth. Fun aside: wind power, fossil fuels and biofuels are all ultimately made from the sun’s energy. But only solar cells directly change the sun’s light into electricity.

How Solar Power is made:

See Solar Power part 1, The basics: light from the sun hits a semiconductor and provides enough energy to make free electrons jump.

How much of our current electricity is produced by solar power:

In 2013, the US used over 8,000 MW hours of solar electricity. That is about 0.2% of the total electricity in the US.

Potential energy supply:

In one year, the entire world uses about 15 terawatts (a 15 followed by 12 zeroes) of electricity. That’s the same amount of sunlight that hits the earth in one hour. In other words, enough sun light hits the earth in one hour to provide electricity for everyone for one year! However, the challenges are collecting this energy, turning it into electricity, and storing it for use when needed (and not just when it’s sunny outside). But there is hope, Germany just reported producing 74% of their energy from renewables, and solar power played a large roll.

Materials and how we get them:

Solar cells are made of silicon crystals and silicon is the most abundant element on earth. However, it is almost always bound to oxygen in a molecule commonly called “sand” or “quartz”. We use electricity to get rid of the oxygen. The silicon is then heated and stretched like taffy. This stretching  draws impurities to one end. The impure end is removed and the remainder is pure enough to make solar cells. The pure silicon is then made into single crystal wafers and other elements are added.

Silicon is very shiny and reflective, which is not useful for collecting light. Titanium dioxide is used to help the silicon absorb more light.  Titanium dioxide is mined throughout the world.

The cells are sealed into rubber, put into an aluminum frame, and covered with a glass or plexiglass protective sheet.

Waste produced and how we deal with it:

Creating silicon wafers for solar cells is quite energy intensive because of the need for purity. A lot of heat and electricity is used in the process, which does produce carbon dioxide. Additionally, the manufacturing process makes industrial sludge and toxic waste, which need to be trucked to waste management sites for cleaning and containment.

Solar power produces no carbon dioxide after the cells have been made. However, the industrial wastes and CO2 produced during manufacture of the solar cells are siginificant. It is important for us to pursue cleaner and better managed outputs, as well as producing cheaper,  more efficient solar cells.


Large scale solar power plants currently produce electricity at the cost of about $0.12-$0.17 per kwh to the customer. The cost of installing solar panels onto the roof of your house is typically about $7-$9 per watt. A 5kW (the typical household consumption) array costs about $30,000. The good news is that it is estimated that solar will cost the same as fossil fuels within the decade. However, we need to act now to start combating our use of fossil fuels.


As I’ve mentioned above, cost and waste are both currently challenges to solar electricity. These challenges will be addressed by making solar cells that can more efficiently turn light into electricity. Currently, solar cells are able to convert about 20% of sunlight into electricity. Nearly 45% efficiency has recently been achieved by researchers in Europe. Being able to mass produce solar cells with that much efficiency will drive down the cost and reduce the number of solar panels needed to produce the amount of electricity that we use, reducing waste as well.

For an introduction on sources of electricity, look here.
For an explanation of how we make electricity, look here.
Clean Coal
Nuclear Energy
Wind Power
Geothermal Electricity
Solar Power part 1

Oh, hey, Building Earth has a facebook page now.  Keep up to date on posts and other interesting green news by liking us!

Solar Power part 1

solar power photovoltaicsBecause the way we create electricity from solar power is completely different from all the other electricity generation I’ve written about, I’m going to break this topic into two parts. Today we’ll cover the science of how we make electricity from sunlight.


Photovoltaics or solar cells, are what we use to change the light from the sun into electricity. Solar cells are made of a semiconductor material, typically silicon. The silicon contains a small amount of phosphorus mixed into the crystal structure. This phosphorus provides free electrons. The light energy from the sun moves these free electrons. And voila, give the free electrons a pathway to move through and you have made electricity.

The trick is to get enough of those free electrons moving and to get them moving further.

Electrons move different distances depending on the energy in light that hits them. Light is composed of various wavelengths which which each have a different amount of energy. We see the wavelengths as different colors, electrons see the wavelengths as different distances to move. With solar power, we want to catch all the wavelengths of light, and we want it all to make the free electrons move. We also want the electrons to move as far as possible because this will produce the highest voltage. Using both low and high energy light is difficult, and so the structure of the semiconductor must be very well designed and controlled. As you might guess, this is a difficult and expensive process. Making even a slight increase in solar power efficiency represents a huge breakthrough in science.

If you’re interested in learning the more detailed science of solar cells, this article is a great place to start.

For an introduction on sources of electricity, look here.
For an explanation of how we make electricity, look here.
Clean Coal
Nuclear Energy
Wind Power
Geothermal Electricity

 Oh, hey, Building Earth has a facebook page now.  Keep up to date on posts and other interesting green news by liking us!

Electric Avenue

After writing my last post about how we are enrolled in DTE’s Green Currents program, I was curious about what sorts of programs other electric companies were offering in support of renewable energy and energy efficiency.  I found a list of the top 10 electric companies in terms of population served and looked into what each of them had to offer.  I thought I’d share the list here in case anyone out there is interested in putting some of their electricity dollars into renewables as well.

electric companies

1. Pacific Gas and Electric – PG&E offers financial help to customers who want to install their own solar panels and allows you to sell extra electricity back to them.

2. Southern California Edison – SCE provides about 19.9% renewable power across the board.  They also provide rebates for evaporators (alternative to air conditioning), and give cash incentives for installing your own electric generating equipment.

3. Florida Power and Light – FPL has been installing smart meters across Florida since 2010.  Once your house has a smart meter you are able to pay a variable rate for your electricity, allowing you to pay less for off peak use.

4. Commonwealth Edison – ComEd is also installing smart meters for their customers.

5. Consolidated Edison – ConEd provides rebates for upgrading to more energy efficient appliances and has a time of use program that provides variable rates depending on when you use electricity.

6. Georgia Power – GP has Green Energy and Premium Green Energy programs similar to DTE’s Green Currents program.  Their customers pay a bit extra each much to get their electricity from biomass and solar power.  At least 50% of the electricity comes from solar.

7. Dominion Resources – I couldn’t find any renewable energy information on Dominion Resources website.  Does anyone have them as their electric company and know if they offer any programs?

8. Public Service Enterprise Group – PSEG provides loans for customers who want to install solar panels.

9. Energy Future Holdings – TXU has a program called Energy Texas Choice 12 which allows customers to lock in a 12 month flat rate and buy 100% wind power.  They also have a program called Distributed Renewable Generation, where they will buy surplus energy from customers that produce their own electricity.

10. Xcel Energy – Xcel’s offerings vary based on state, but most states have a program called Windsource, which allows to pay extra to buy up to 100% wind power.  In Minnesota they also are looking to start a Solar Gardens program, which will allow groups of customers to go in on solar panel arrays together.

Gas and Electricity in Detroit

Our apartment is in an old building in midtown Detroit. I’m not exactly sure when it was built, but if I had to wager a guess I’d say probably 1920s or before. This guess is based on the fact that my dad’s house was built in the early 1900’s and there are a lot of similarities between our building and his house.

heating an old apartment in Detroit

The building is heated with radiators. I was really excited about living in a building heated by radiators when we first moved in because I tend to feel cold all the time, and radiant heat said to me “This building will be hot all winter long, in fact, you may very wastefully decide to open the windows in the middle of January to bring it back down to a comfortable temperature.” This turned out to be not the case. Our building is chilly all winter long. But, in addition to the radiators, all the units are also equipped with a gas fireplace. This allows us to give our apartment a warm glow on cold winter’s nights.

heating an old apartment in Detroit

Being conscientious about our energy use, we do try to limit our indulgence in the use of the fireplace to nights or weekends when it is quite cold outside.  The chill in our apartment generally isn’t too bad unless the temperature outside drops into the teens or below. We plastic over our windows to keep the drafts at bay. And, since we live on the top floor, we also get to reap the benefits of our lower level neighbors using their fireplaces. When we do use our fireplace we close all the doors to the kitchen, bedroom and bathroom so that we’re only heating up the living room and dining room.

We also try to be pretty conscious of the electricity we’re using as well. Admittedly, Husby is much better about this than I am. But generally, if we’re not using it, it’s off. And in many cases, not just off, but also unplugged. Unplugging our electronics prevents them from drawing phantom loads even while they are off.

Southeast Michigan is supplied its gas and electricity through DTE. DTE offers a program called Green Currents, which Husby and I have opted into. Basically, we pay a little extra per kilowatt-hour to get our energy from renewables rather than from coal and drilled natural gas.*

Currently in Michigan, the Green Currents program gets about 90% of their energy from bio gas, and 10% from wind power. Our energy costs a little bit more than it would if we weren’t a member of the Green Currents program, but spending the extra dollar or so each month helps us tell DTE that it is important to us that they continue to invest in renewable energy solutions, as well as helping to reduce the overall use of fossil fuels in Michigan. It’s one of the ways that Husby and I choose to vote with our dollars.

Bio gas is methane collected from cattle farms and landfills – both naturally occurring as a product of the breaking down of organic material.  When methane is freely released into the atmosphere it is a very potent greenhouse gas, but it is also a very efficient fuel. Methane produces more energy per unit than coal. When it is captured and burned for energy the by-products are carbon dioxide and water. Carbon dioxide is obviously also a greenhouse gas, although it is less potent than methane. So bio gas isn’t a perfect solution to reducing our carbon footprint, but it is a way to use energy from a more potent greenhouse gas and convert it into a less potent greenhouse gas.

*Being a member of the Green Currents program does not necessarily mean that the exact energy that we are using comes from bio gas and wind power, as these energy sources are currently limited by geographical area. It means that for every kw-h of energy that we use, DTE is supplying that much energy in bio gas and wind power to someone who lives in the areas that have access to these sources. It’s a matching program.

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