In January, Scientific American writers unleashed an ambitious plan to halt global warming, eliminate our dependence on petroleum and the substantial trade deficit, boost the economy and create 3 million jobs, and brighten the dismal forecasts for the mid twenty-first century.

The plan is conceptually simple but would be substantial to implement:

• Construct a 30,000 square mile array of solar panels in the Southwest,
• along with concentrated solar power arrays and,
• a massive direct-current power transmission backbone to distribute electricity throughout the country.
• Excess power produced by the photovoltaic arrays would be distributed and stored as compressed air in below-ground caverns.

Development of such a system could provide almost three-quarters of the nation’s electricity by 2050.

If this sounds like fantasy-land, it’s not. The technology is already here, and even if it wasn’t the need for renewable power is very real. Some scientists are calling for an all-out Manhattan-Project-style focus on developing alternative energy sources. One thing is almost certain: if we can’t move beyond coal as our (worldwide) primary energy source, we’re in for a rocky future.

I’ve written several posts lately about plug-in hybrid electric vehicles (PHEVs) and their need for renewable energy charging sources. PHEVs are a stepping stone as the future of transportation heads toward electric vehicles powered either by batteries or hydrogen fuel cells. Solar power would be the ultimate source of clean energy for either type of electric vehicle.

The authors of the Scientific American article think all of this energy can come from solar power. Here are some excerpts:

• Utilizing only 2.5% of the sun’s energy falling onto the 250,000 square miles in the Southwest suitable for constructing solar power plants could match the total power used in the US in 2006.
• With a massive investment in solar power plants and infrastructure, solar could provide 69% of US electricity and 35% of total energy (including transportation) by 2050.
• If wind, biomass, and geothermal power sources were also developed, the US could produce 100% of its electricity and 90% of its transportation energy (in the form of hydrogen) from renewable sources.
• To make this happen, the US would have to invest $10 billion per year for the next 40 years. For comparison, the US is now spending $12 billion per month for military involvement Iraq and Afghanistan, according to Nobel Prize-winning economist Joseph Stiglitz. The entire solar array would cost approximately 15% of the total bill for both of these operations. $420 billion is also less than the tax subsidies paid for the nation’s telecommunications infrastructure in the last 35 years.
• A conversion to renewable energy of this scale would displace 300 coal and 300 natural gas-fired power plants, and eliminate all imported oil. Even better, greenhouse-gas emissions would be reduced to 62% below 2005 levels.

In sum, the potential is there, but it’s going to take some work. As the authors conclude:

The greatest obstacle to implementing a renewable U.S. energy system is not technology or money, however. It is the lack of public awareness that solar power is a practical alternative—and one that can fuel transportation as well. Forward-looking thinkers should try to inspire U.S. citizens, and their political and scientific leaders, about solar power’s incredible potential. Once Americans realize that potential, we believe the desire for energy self-sufficiency and the need to reduce carbon dioxide emissions will prompt them to adopt a national solar plan.

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Read Sustainablog’s take on this article here.

Source: Scientific American (Jan. 2008): A Solar Grand Plan

Photo Credit: GreenOptions

Technology

The American Southwest would be the home of massive amounts of solar power needed for this clean energy conversion. Specifically, two types of solar power would be employed: Photovoltaic (PV) cells and concentrated solar power.

According to the solar grand plan, 30,000 square miles of PV cells would provide 3,000 gigawatts (GW) of energy. The “30,000 square miles” part made me flinch, but already existing solar installations indicate that the land needed for each gigawatt-hour of solar energy in the Southwest is less that the amount of land needed to run a coal plant and mine the fossil fuel for it.

Concentrated solar power would supply about one-fifth of the solar energy in the plan. Concentrated solar power uses long metallic mirrors that focus the sun’s rays onto a pipe filled with fluid. The fluid is heated and runs through a heat exchanger that produces steam that turns a turbine. Nine plants like this already exist in the in U.S.

Storage

The solar grand plan recommends compressed-air energy storage for PV energy: Electricity from the PV plants compresses air and pumps it into empty underground spaces like caverns, abandoned mines, aquifers or depleted natural gas wells. The air can be released on demand to turn a turbine and make electricity, aided by burning small amounts of natural gas. Compressed-air technology has been used in Germany since 1978 and in Alabama since 1991.

To store the concentrated solar power, pipes could be run into a big insulated tank containing molten salt that would retain the heat. At night when the sun isn’t shining, the heat could be extracted to create steam. Of course, the salt doesn’t retain heat indefinitely and so the stored energy would have to be tapped within a day. The first commercial installation with this molten salt storage technology is being built in Spain and has seven hours of storage, so this technology would still have a ways to go.

Transmission

Our existing grid of AC power lines isn’t up to the job of efficiently carrying solar power from the Southwest to consumers around the country (it would lose too much energy over that distance). Rather, the plan proposes a high-voltage, direct-current (HVDC) transmission backbone for the nation.

Studies have shown that an HVDC line loses less energy than AC lines over long distances and are less expensive to build. The lines would end at converter stations, where the power would switch over to AC and then be sent along already-existing regional transmission lines. About 500 miles of HVDC lines already exist in the U.S. and companies are eying them up for their renewable energy projects: Southwest Power Pool of Texas is designing a system of DC and AC transmission for a wind farm in Texas and TransCanada proposed 2,200 miles of HVDC to carry wind power from Montana and Wyoming down to Las Vegas and beyond.

Cost

The cost of this plan is admittedly large, as any major change in the nation’s infrastructure would be. The plan estimates $420 billion in subsidies are needed from 2011 - 2050 to fund the infrastructure and technology advances to make solar power more cost-competitive. Economies of scale and continued efficiency milestones will also help:
A report by the Solar Task Force of the Western Governors’ Association found that concentrated solar power could cost 10 cents per kWh or less by 2015 if four GW of plants were constructed.

The cost would be well worth it. The writers argue:

The infrastructure would displace 300 large coal-fired power plants and 300 more large natural gas plants and all the fuels they consume. The plan would effectively eliminate all imported oil, fundamentally cutting U.S. trade deficits and easing political tension in the Middle East and elsewhere. Because solar technologies are almost pollution-free, the plan would also reduce greenhouse gas emissions from power plants by 1.7 billion tons a year, and another 1.9 billion tons from gasoline vehicles would be displaced by plug-in hybrids refueled by the solar power grid. In 2050 U.S. carbon dioxide emissions would be 62 percent below 2005 levels, putting a major brake on global warming.

The biggest obstacle to the solar grand plan may not be the money or the advances in technology, but rather the political will to get it done. And while I personally appreciate and recognize the need for grand plans to demonstrate how we can get this done, I question whether solar power is really the best technology or if it’s being billed as the silver bullet answer to our energy problems. At the same time, the arguments for efficiency and a modern transmission system are on-target. Whether our clean energy future employs a majority of solar power or is a mix based on the local resources of the region (solar in the South, geothermal in the West, wind in the Midwest, etc.), our obsolete electric grid and advancements in storage capacity will be crucial for expanding other renewable energy systems.

The amount of sunlight the earth receives in 40 minutes is enough to power the globe for a year. With the 250,000 square miles in the U.S. Southwest suitable for solar power plants, a large amount of this resource must be a part of a 21st century system.

Scientific American Magazine