The Energy Storage Challenge

According to the Energy Information Administration (EIA) 67% of the energy generated in the United States in 2015 was from fossil fuel sources. There are several reasons for this percentage including economic reasons, existing infrastructure reasons, legacy reasons, and an abundance of these resources in our own country.  Another reason why fossil fuels make up such a large portion of our generation is because we have an inherent problem with some of the most well-known renewable resources. For Solar (.6% US energy) and Wind (4.7% of US energy) the problem is storage.

As everyone knows, the sun is only up for a certain number of hours each day. Unfortunately wind tends to also have patterns of high speeds and low speeds.  In America we like our TVs and lights to turn on any time day or night, and we don’t want to be held prisoner to the cycles of the sun.  That’s where storage comes in to play. If we really want these technologies to make up a larger portion of our energy then we have to be able to store the energy when we can collect it.

Recall from my second blog post we can’t create or destroy energy so if we want to store energy we have to convert it into a form that can be stored. One popular method of storing energy these days is in the form of lithium-ion batteries. These batteries are great for storing energy, but it is difficult do to it on an industrial scale. In other words it would be difficult to store enough energy to power a city with our current lithium-ion technology. Tesla is now producing a Lithium-ion battery that could be used for individual use in people’s homes.  This might be one work around for the industrial scale problem.

There have been several other methods proposed that could be used to store energy. Some of them include pumping water up a hill during the day time and using it to power a hydroelectric dam at night time. You can compress huge amounts of air during the day time, and release it across wind turbines at night time. You can also use electricity to separate water into hydrogen and oxygen and later burn the hydrogen to create thermal energy.  The reason that we don’t see more of these technologies being used commercially is that they all have really low efficiencies. Every time we convert energy from one form to another, we lose some energy due to inefficiencies. In the current market, companies are better off just selling the solar power when the sun is shining.

If you have some thoughts on this post or energy storage in general I would love to hear about them in the comments section below.

Photo credit: http://berc.berkeley.edu/wp-content/uploads/2015/02/energy_storage_2013_11-13-1.jpg

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Spinning Our Wheels

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In my first blog post I mentioned that we cannot create energy but we can only change its form into something which is useful for us. Our history of converting forms of energy since the industrial revolution has largely consisted of converting the energy into mechanical energy in the form of a piston engine or a spinning turbine.  The early days of this produced many wonderful machines that burned wood or coal which have stored chemical energy. That chemical energy was released in the form of heat (fire), and that fire was used to boil water. The steam produced from this boiling water has a lot of energy because it can be at high pressures. All of the pressure is used to turn a steam piston engine or a steam turbine (a glorified pin wheel). The spinning steam turbine is mechanical energy that we can put to good use. In those early machines the steam pistons would directly drive other equipment such as the paddle on a steam boat or the gears on a steam engine train.

Later on down the road some clever people discovered another form of energy that we could put to good use, and that was electricity. Electricity is a wonderful form of energy and it is used to power a huge portion of our equipment today.  The people who were converting energy into mechanical energy also realized how great this electricity thing was and they decided to use the mechanical energy from Steam turbines to spin an electrical generator which would convert the energy into electricity.

Today a large majority of the electricity that we use is generated by a mechanical turbine spinning a generator. We have several different sources of energy that we use to spin these turbines, but at the end of the day they are still just a turbine spinning a generator.  A coal power plant spins a turbine/ generator as described above. A nuclear power plant uses chemical energy stored in nuclear material to boil water and spin a turbine/generator. A hydroelectric power plant uses water at a high elevation aka potential energy to spin a turbine/generator. A wind turbine uses the winds kinetic energy to spin a turbine/ generator. I think you see my point, we really haven’t come that far today from where we were a couple hundred years ago.

One approach to thinking of new energy sources for the future is looking for situations that have some potential energy that we can use to spin a turbine/ generator. If you can think of any other potential sources of energy that we can use to spin a generator please leave a comment below.

Photo Credit: http://www.historyinsidepictures.com/siteimages/R9.JPG

 

Renewable Energy is the Future

The future of our planet depends on how much renewable energy we can generate.  Everything that humans do requires some form of energy.  Many years ago that energy only came in the form of work done by the people themselves and when they got creative they started using horses.  Throughout the ages certain geniuses have figured out new ways to harness ever larger quantities of energy.  All of this energy has been generated from multiple energy sources. Of course us mere humans can’t create energy, we can only change its form into something useful.

I’ve been working for a large geothermal company for the last eight years as a mechanical engineer. This experience has taught me the ins and outs of the energy world. I have seen projections of how our energy demand is going to keep increasing into the foreseeable future. There is no one solution to our energy future. It is going to take a combination of energy sources including several existing technologies as well as some new technologies which have not been developed yet. In this blog I will discuss the current state of renewable energy technology, track where these technologies are trending, and explore some cutting edge technologies which are still in their infancy.

To start you all off, I will discuss a form of renewable energy that is near and dear to my heart. GEOTHERMAL. It always shocks me how little if anything at all people actually know about geothermal power. The basics are geo = earth and thermal = heat so geothermal power is literally taking heat out of the center of the earth.  That heat is transported out of the earth by means of either water of steam. Geothermal power plants require two key ingredients. 1. A geological structure which has a lot of water underground, and 2. An area where high temperatures can be found near the surface of the earth.  You can often tell there is a geothermal resource in the area where there are naturally occurring hot springs.

There are two categories of geothermal power plants. First, there are the old school plants that take steam straight out of the ground and send that steam directly through a steam turbine to spin a generator and create electricity. Second, there are some plants that pull hot water out of the ground and through a series of heat exchangers and a process called the Rankine Cycle, the heat is extracted from the earth, and used to boil a secondary fluid which spins a turbine/ generator and creates electricity.

The future of the geothermal industry which will make it much more accessible around the globe is called enhanced geothermal systems (EGS) a.k.a hot dry rock.  In these systems, people will create their own cracks underground, and pump water into the ground which was previously dry. This will create a geothermal system that can be used to generate electricity. It is basically a human made geothermal system and the advantage is that it can be done in significantly more locations than geothermal systems naturally occur.

Photo Credit: http://mkelectrichawaii.com/wp-content/uploads/2014/05/renewable-energy.jpg