I’ve been blogging now for over a year and have covered topics ranging from nano-technology and the future of semiconductors to large scale power generation and transmission. This week marks the 50th anniversary of my company, National Semiconductor. This milestone reminded me of how far we’ve come as a technological race. While writing I’ve often reflected on my past engineering experience to look for examples of how we have improved our way of life. However, in this issue I wanted to take a look forward at one of our civilization’s next big hurdles... our future energy supply.
We are reaching a critical mass where our population will soon exceed 8 billion people - many of whom will be the first generation to use electricity or drive a car. In the midst of our current economic crisis it is hard to imagine global markets surging from the millions of new consumers that will have buying power in the near future due to technology’s reach. As we continue our journey into the 21st century, energy will shape the new economy. It will be driven by the demand for manufacturing, agriculture and transportation. As automobiles begin to shed their gasoline engines for fully electric drives, more electricity will be required to recharge the energy storage onboard these vehicles. A simple shift from burning gasoline to fully electric vehicles will not solve our energy crisis since much of our electricity comes from carbon based fuels such as coal. These shifts will require revolutionary changes to meet the new demands.
As in the beginning of the industrial revolution, there will be change on a scale never before seen. Carbon based fuels have been our energy standard for over 100 years, but are becoming harder to find and reach as well as being responsible for polluting our environment. It is well understood that every day terawatts of power rain down on our planet conveniently provided by our sun. It lights and heats our world as well as drives our weather. However, we currently capture only a tiny fraction of this energy through hydroelectric, wind or solar energy farming.
There are millions of square miles perfect for collecting this free energy, but the technologies are fairly new with some proposed projects reaching incredible scales. For example, in New South Wales, Australia a proposal has been made to build a solar chimney that towers over 3000 feet tall with a heat collector that covers over a square mile. As the air under the collector is heated, it naturally wants to rise due to lower density (like a hot air balloon). As it rushes into the chimney which forms a natural draft, the flowing air will turn huge turbine generators that produce electricity. The energy will then be transferred to the grid and sent to cities where it can be consumed. This is the scale of energy engineering that will become common place by 2060.
Another large scale proposal is to place gigantic solar arrays in deserts around the world. These arrays will either convert solar energy directly into electricity or capture the heat to boil water and turn steam turbines. It has been calculated that a photovoltaic array 100 miles on a side would be capable of providing all of the current energy needs of the United States - and that’s with current conversion efficiencies being under 20% (an incredibly poor efficiency rating).
In practice, placing arrays closer to where the energy is consumed provides great benefit. Combined with "smart grid" technologies, photovoltaic arrays spread over many commercial and residential buildings will be used to gather enough energy to begin reversing the trend of building new large scale carbon based power plants. One of the biggest problems with electrical generation is getting the energy where it needs to be, when it’s needed. The peaks and valleys of electrical demand make power plant operators constantly struggle with keeping the output of the plants balanced with the need. By having local generation spread out over a large population area, peak demands are much easier to manage. It also adds another level of reliability since the local solar generators can form micro-grids allowing them to shed completely from larger grids if necessary without interruption.
Along with solar will be other technologies that can be deployed locally such as wind turbines. Large scale wind farms are a common sight today, but smaller, high efficiency, vertical draft turbine designs will continue to improve and allow almost anyone to harness the wind. As with PV systems, these generation systems will be connected to a smart grid to provide maximum load management.
Many scientists and engineers see an ultimate solution to fusion power in this century. With experiments and even small pilot plants being constructed, the consensus among them is that by 2050 practical fusion plants will be a reality. This is the ultimate replacement for the current infrastructure of carbon fuel or nuclear fission based power plants. But we may find that the fusion reactor we have 93 million miles from earth is all that we need. With PV efficiency improvements and large scale deployment combined with practical storage methods, our technologies may one day be completely driven by the sun.
Think this is far fetched? An average home in the United States consumes around 1000 kilowatt hours per month. Add an electric vehicle, and that may rise to around 1500 kilowatt-hours. So let’s round it up to 2000 kilowatt-hours to completely remove all carbon based fuels such as natural gas and propane. That breaks down to just under 67 kilowatt-hours per day or roughly a continuous 2.8 kilowatt load (roughly the amount of 3 hair dryers running).
Assuming the sun shines 8-10 hours a day, 50% of the days are sunny (even cloudy days produce solar power) and an energy storage efficiency of 50% (laptop batteries are far better than that), a solar PV array would only need to generate around 30 kilowatts while in daylight to meet the entire energy requirement of the home and automobile. Today, even with only 10% efficient PV arrays, 15 kilowatt systems are common and affordable (with tax credits carrying some of the burden). It doesn’t take a large stretch of the imagination to see 30-50 kilowatt systems on every home and business within the next 50 years.
So, while you’re out on a sunny day at the gas station filling up your car and wondering about gasoline futures or wondering what to do to keep your electric bill low enough so you can afford to feed your family, take a look up and realize that all the energy you will ever need is falling on the grass in your back yard - something to think about! Till next time...