solar mountain house


The answer to the problem of global Climate Change is to shift to renewable energy.  While this is a simple thing to state, the implementation is quite involved.   

The recent Paris Accord is a good step in the right direction, although we certainly have a long way to go.   Hopefully, Paris means we can stop making the case for action, and start talking about what that action entails.

The path of transition from fossil fuels to renewables is incredibly complex and in many ways yet unknown.  Even if the cultural resistance to Climate Change vanished tomorrow, we would be hard pressed to make the transition in time to avoid catastrophic changes to our planet.  

It would mean changing from a centralized energy system to what is called distributed generation, which is a semi-decentralized system.    Houses would send electricity into the grid during the day, then draw back off the grid at night.   Wind farms would produce electricity during windy periods, which might not align with peaks in demand.    Instead of power coming from one or two coal-fired electrical plants, it would come from several wind farms positioned around a city.   The average coal plant in the US produces 254 Megawatts of electricity.    To replace this much power with wind, about 500 acres would need to be dedicated to a wind farm.    Wind farms can also be positioned off-shore.  The utility companies will need to learn to manage all these sources, and to match demand with supply when that supply is various and intermittent.

   wind farm with freeway


      The Shift

Both renewable energy and fossil fuel energy sources have their attributes and their limitations. Fossil fuels are light, fast, cheap, portable, and powerful.  FF’s can do things that renewable sources cannot. We have no means, at this point, to get an airplane off the ground using electricity, and even if we could, we have no means of storing enough electrical energy for a flight from one city to another. Cars can run on electricity, and light trucks can run on hybrid systems, but large trucks that haul goods and heavy construction machinery need fossil fuel.   Same goes for ships.

Fire trucks will continue to require petroleum, or conversion to natural gas.   We can not fight fires without fossil fuels.   Garbage trucks are also too heavy to run on electricity.  We could not presently collect our trash without fossil fuels.

Fossil fuels require centralization.   Petroleum, coal and natural gas need to be extracted from the ground, usually in a remote area.      Petroleum and gas need to be refined, then shipped to a central distribution point.   Coal requires little refinement, but the larger the coal plant, the more efficient it is.     Coal fired electrical plants ship their energy long distances because people don’t want them in their back yards, plus the plants require large amounts of water to cool their systems.   6-8% of electrical power is lost in transmission, making the plant less efficient and adding even more CO2 to our atmosphere.

Progress is happening

The Renewable Energy Policy Network reports that in 2013, the world reached 22% of its power capacity via renewable energy.    The biggest additions to capacity were in wind power and solar PV.   China, the United States, and Canada are the three top countries for adding renewable capacity last year.   China actually added more renewable capacity in 2013 than they added fossil fuel or nuclear capacity.

Without some major technological breakthroughs, it will not be possible (nor would it be a good idea) to eliminate fossil fuels completely.   The recent Climate March in New York City, which had over 310,000 participants, stated their goal as achieving 100% renewable capacity by 2050.    This is a good goal to set because the only way to stop global temperature rise is to reduce greenhouse gas emissions to zero.    Achieving this goal would require national and international policy changes by all countries, economic changes, infrastructure improvements (especially, in the U.S., to our grid), cultural expectations, and some important technological advancements– particularly in energy storage.   The use of fossil fuels, however, can be greatly reduced now with the technology we already have.

 Wind Power

 Wind Farm and Milo

Wind is the fastest growing renewable energy source, and it has the potential to produce more electricity than any other renewable source.   In 2010, according to the World Wind Energy Association, wind power generated 430 TWh or about 2.5% of worldwide electricity usage.   Between 2005 and 2010 the average annual growth in new installations was 27.6%.   Wind power market penetration — world wide– is expected to reach 3.35% by 2013 and 8% by 2018.  The United States pioneered wind farms in the 1980’s, primarily in California, and led the world in capacity into the 1990s.   Germany surpassed the U.S. in 1997.   China also has a growing wind capacity, and in 2010 they became the world leader. Wind power generated 4.13% of  the United States’ electrical needs in 2013, according to data from the US Department of Energy, making it the fifth largest electrical source in the country.

Wind farms have a number of inconspicuous benefits.    A wind farm launched in 2014 in Elgin, NE created 17 good paying jobs.    This is a big deal is a town on 645 people.     Farms also generate tax revenue in depressed areas, which makes them big supporters of public education.  Another discrete value of renewables is that they use no water.     

A typical coal plant with a once-through cooling system consumes 0.36 to 1.1 billion gallons of water per year.  A typical coal plant with a wet-recirculating cooling system withdraws less water each cycle, but consumes 1.7 to 4.0 billion gallons per year.   A dry-cooled system still consumes water, but less than the other two.     When water is drawn into a coal power plant, millions of fish eggs, fish larvae, and young fish come along with it.   In addition, millions of adult fish may become trapped against the intake structures.  Many of these fish are injured or die in the process.

A common complaint about wind farms is that birds and bats collide with turbines and die.   More birdlife dies by colliding with stationary buildings than moving turbines, according to the WWEA.  Wind farms consume no water, and they kill no fish.

Wind power works best as a centralized source because it requires significant and consistent wind to reach productive levels.   Wind farms are best located in exceptionally windy spots, and away from populated areas where the noise can be a nuisance.     A small turbine can produce useful power  for a home, if zoning and property size allow one to be mounted high enough off the ground, usually 80 feet and preferably 100 feet in the air.

Solar Power

home solar roof

Rooftop solar is the energy source with which this website concerns itself, because solar can be attached to a residential house or any building with an unshaded roof.     A 5 kilowatt array can typically supply half an normal household’s electrical use.    Some houses have too much shade from trees or other buildings to make solar effective, however there are now solar gardens which allow consumers to purchase electricity from a source in their neighborhood, even their block.

Solar panels came onto the market in the 70’s, and the ones that have not been damaged are still producing energy.    Because of reduction in product cost and rise in energy cost, solar can now compete in some markets on a per dollar basis with fossil fuels.   This is a big moment in the solar industry.    Marketing of solar is often centered around how it can pay for itself in ten years.    But what happens when those ten years expire?    Most solar installations have a 25 warranty.  There can be some maintenance costs, but otherwise after 10 years, solar energy is free— NO COST.   Let’s see fossil fuel do that.

Electricity coming from centralized sources loses 6-8% in transmission.  With Minnesota’s goal of 25% of its energy from renewable sources by 2025, a loss of 8% is a big swing.    Transmission loss from rooftop to basement or garage is minimal (less than 1%), and since there is  no carbon emitted in the production, it’s also without significance to Climate Change.

Net metering laws are very important to the solar industry.    Net metering allows the grid to be used for storage, and most of a solar house’s energy is produced during the day while most of it is consumed in the evening.    Depending on area of the country, solar arrays are less productive in the winter than the summer.     Snow cover and low sun angle reduce output.    In Minnesota, a rooftop array will typically make most of it annual production during the warm months and feed energy into the grid, then draw that energy back during the cold months.

There are two main types of solar panels, Photovoltaic (PV) and solar thermal.     PV creates electricity, and solar thermal produces hot water, which can be used for bathing and washing but also to produce energy.    Solar thermal is a very effective water warming system, and it’s especially useful in warmer climates where a large portion of household energy use goes to water heating.     In Hawaii, solar thermal installation is a code requirement in a new house, and a builder must obtain a variance to avoid installing it (typically due to shade problems).

Solar is approaching some big milestones these days.   According to Mike Nobel of, the cost of solar panels has fallen 80% since 2008 and 60% since 2011.     Very soon it will be able to compete dollar for dollar with fossil fuel electricity.    In Germany, on June 9, 2014, when demand for electricity reached its peak that day, 50.6 percent of all the power was supplied by solar energy.    This is the first time that the majority of a country’s electrical needs have been met by solar energy; granted it was only for one hour on one day, and it was a holiday, but it’s still an important threshold in renewable energy development.

As Al Gore points out in the June 2014 issue of Rolling Stone magazine, the cost of electricity from photovoltaic is now equal to or less than the cost of electricity from other sources in at least 79 countries.  By 2020 – as the scale of deployments grows and the costs continue to decline – more than 80 percent of the world’s people will live in regions where solar will be competitive with electricity from other sources.    Gore aptly points out that there “…is a huge difference between “more expensive than” and “cheaper than.   Not unlike the difference between 32 degrees and 33 degrees Fahrenheit. It’s not just a difference of a degree, it’s the difference between a market that’s frozen up and one that’s liquid.”    *



Thrust 4Arlington PlotsSwitchgrassDennis Pennington

Biomass has been successful at reducing emissions, but there is some controversy about how much fossil fuel is used to produce it.    Like ethanol, as a source of energy it is relatively clean.   But its embodied energy (the amount consumed in the creation of the product) can be high, which offsets its value.

In Sweden, the city of Kalmar (population of 60,000) has achieved carbon neutrality by generating all its electricity from biomass, mostly in the form of waste timber and sawdust which they get from surrounding sustainable forests.   The third largest city in Sweden, Malmo, has reduced it carbon emission to under 10 percent by combining biomass with wind and solar energy.    

Biomass can consist of a number of plant and animal products, including waste from a lumber mill, fast growing plants like switchgrass, and even chicken manure and other livestock waste.    The collection and transport of these products usually involves petroleum propelled machines.    Kalmar has tried to counter this problem by requiring that all vehicles on the roads run on Biogas (made from waste wood and some chicken manure).   However, to balance their needs, the residents use ethanol imported from Brazil, which means it travels by ocean freighter.    

Biomass can be burned like coal, which makes its inclusion in a coal fired plant relatively cheap.   Converting a coal plant to biomass is also an option.


Geothermal Plant in Iceland

Geothermal, like wind power and solar, can be both a household power source or centralized.      Iceland has a wealth of geothermal activity and derives a lot of its power from Geothermal plants like the one pictured.

Geothermal Heat Pump

In a home, geothermal is optimally installed when the house is built because it involves burying tubes deep in the ground or under a large area of land.    Below the frostline, ground temperature is a relatively consistent 58 degrees.   Geothermal Heat Pumps move liquid through the buried tubes.   The liquid changes temperature as it travels, and this conversion creates energy.     Installing a geothermal heat pump is an expensive home investment, but there are state and federal incentive programs.    Heat pumps use electricity to move the liquid, but their energy use is minimal compared to a furnace.     Supplementing with solar can make the system completely renewable.

Geothermal can be added to an existing home by digging a well for pipes, as long as the machinery involved can access the property.


Hydro Station

Hydroelectric is one of several forms of hydropower.   Because it is established– and because it has mostly been exhausted (There are no plans in the US for new hydroelectric dams)–  it has been separated here in its own category.

Dams use descending water to turn turbines that generate electricity.   16% of the world’s electricity is created this way, making it presently the most productive renewable source.   The first Hydroelectric generator went online in Niagara Falls in 1881.  Presently, Hydroelectric supplies about 6.4% of America’s total electricity.

Large scale hydroelectric can create a number of serious environmental and social problems.   By blocking rivers and streams, dams cause habitat destruction, prevention of fish passage, and displacement of local communities.  If done right, however, hydropower can have minimal impact on the environment, usually involving a smaller scale generating system.     The Low Impact Hydropower Institute (LIHI) has developed a voluntary certification program for new projects.   Criteria standards are based on the most recent and stringent mitigation measures recommended by state and federal agencies.


hydro wave power

There are a number of experimental hydropower sources being developed today, including using wave power and tidal power to generate electricity.   Hydropower can be very useful in solving the inherent problems with wind and solar power– intermittence and storage.

Wave power has been experimented with for over 100 years, and it is creating new interest now.     It uses a machine called a Wave Energy Converter.   In 2008, the first experimental wave farm was opened in Portugal, at the Agucadoura Wave Park.  

Tidal power is produced through the use of tidal energy generators.    Large underwater turbines are placed in areas with high tidal movements.   They capture the kinetic motion of the ebbing and surging of ocean.  Tidal power has great potential because of the massive size of the oceans.

Hydroelectric generation can also work without dams, in a process known as diversion, or run-of-the-river.  Portions of water from fast-flowing rivers can be diverted through a penstock to a turbine set in the river or off to the side. The generating stations at Niagara Falls are an example of diversion hydropower. Another design uses a traditional water wheel on a floating platform to capture the kinetic force of the moving river.   Unfortunately, this doesn’t produce much power.  The entire Amazon River would produce only 650 MW of power.

Another type of hydropower, though not a true energy source, is pumped storage. In a pumped storage plant, water is moved from a lower reservoir to a higher reservoir during off-peak times, using electricity generated from other types of energy sources (preferably renewable).   When the power is needed, it is released back into the lower reservoir through turbines.   Some power is lost, but pumped storage systems can be up to 80 percent efficient.   There is currently more than 90 GW of pumped storage capacity worldwide, with about one-quarter of that in the United States.  Future increases in pumped storage capacity could result from the integration of hydropower and wind power technologies.   Researchers believe that hydropower may be able to act as a battery for wind power by storing water during high wind periods.

Intermittence and Storage

The big limitation of renewable energy is the problem of intermittence.    No solar energy when the doesn’t shine, and no wind power when it’s calm.   Even hydropower, while not suffering from intermittence, cannot produce energy on demand– just a steady stream of electricity.   A dam can increase or decrease production, but only very slowly.   Much of the problem of intermittence can be averted by solving the problem of storage.

 Battery technology has made good breakthroughs in the past ten years, but the concentration has been on small batteries for devices like phones and pads.    Breakthroughs in large, and even medium sized, electrical storage will greatly enhance the performance of renewable energy, especially wind and solar.    Tesla, the electric auto company, has made some remarkable advancements in a car batteries; doing things the major auto manufacturers believed were impossible.   Hopefully, some of their new technology can translate to renewables.  Elon Musk, Tesla’s CEO, plans a $5 billion battery factory to be built in one of four southwestern states, possibly starting construction this year.   Construction could potentially start this year.  Musk hopes to drive down the cost of its 60 kilowatt-hour battery pack by 30 percent, to about $10,000.  This could make a major impact on the distributed storage industry.  Musk also plans to power much of his plant with solar panels and wind turbines.


Resources for this page include: Union for Concerned Scientists, US Green Building Council, TED talks,, Carl Seville and SK Collaborative (, Powerfully Green (, Jim Logan Architects (, World Wind Energy Association, Rolling Stone magazine, New York Times, Washington Post, US Dept. of Energy,, and Wikipedia.