Clean Renewable 24/7 Solar Power as cheap as Coal By Tom Beck, Pollution and green house gas emissions can be reduced with the use of renewable power. The problem has been the high cost and intermittency of renewables. There has always been the argument in a trade-off between the environment and the economy. Imagine if these two problems were solved. We may be able to have our cake and eat it too. Based in Saskatchewan Canada, SHEC Energy Corporation has developed a breakthrough technology called Ultra Lite Solar. The technology is based on Concentrating Solar Power (CSP) that uses mirrors to focus sunlight to produce high temperatures hot enough to operate steam turbines as are commonly used in our fossil fuel based power plants today. To make commercial scale CSP plants large enough to power entire cities takes a lot of mirrors and a lot of capital traditionally. About one square mile of land is required to produce 100 mega watts (MW), enough power for about 100,000 homes. The Ultra Lite technology dramatically reduces solar concentrator costs by a fairly large margin of about 80%. Why produce power with Concentrating Solar Power? Photo Voltaic (PV) technology produces electricity with semiconductor material. These have come down in cost over the last several years to the point of being less expensive than traditional CSP. PV’s have a capacity factor of about 17%. That means they typically only put out 17% of its rated capacity per day. They do not produce power at night. CSP without storage has a capacity factor of about 20%. Energy storage is needed to increase the capacity factor for night time power production. Storing the electrons produced by PV panels is expensive, to the extent that it is rarely implemented. You would need batteries or flywheels to store electricity. CSP on the other hand produces heat which is far less expensive to store.
Traditional CSP A typical CSP plant may have enough storage to add 4 to 6 hours of extra production at night. These plants typically don’t have overnight storage since the solar field has to be made larger to accommodate not only daylight production but to produce enough additional energy to store for night time production. This becomes prohibitively expensive. Traditional solar concentrators use a metal super-structure, usually made of aluminum or steel and glass mirrors. The super-structure is complicated as it has to support the mirrors rigidly to conform to the parabolic shape required to focus sunlight. The glass mirrors are also heavy, requiring a strong structure to hold the weight. Ultra Lite Innovation The Ultra Lite Solar innovation greatly simplifies solar concentrator design by using a simplified light weight structure made possible with the use of differential air pressure as a structural component. Instead of using rigid glass mirrors, flexible mirrors are used in the form of a loose film material. This material can be almost any composition such as a polymer, thin glass, or metal and can be as thin as a few thousandths of an inch thick. The contour of the reflective film is shaped with air pressure. Several embodiments of this are possible. The following illustration shows how a partial vacuum shapes a thin film over a framework. The thin walled, light weight framework is further strengthened with air pressure within its structural components. Again air pressure is used as a structural component. This makes possible a dramatic reduction in complexity, materials and costs. It now becomes possible to build much larger solar fields to store enough energy for overnight production and to do so economically.
Levelized Cost of Electricity (LCOE) Often the cost of renewables is measured on the name-plate rating, but this can be misleading. A better method is the LCOE. For example, a solar PV panel rated at 100 watts and having a capacity factor of 17% will produce: 100 Watts X 24 hours X 365 day X 17% = 148,920 watt hours or 148 kWh per year. If this same panel costs $100, then it produces power at a cost of $0.68/kWh in a year. Now compare this to a 100 Watt CSP plant with storage and capacity factor of 80% and assume this plant will cost more - $300 for example. On the surface it appears the PV panel is the cheaper option, but when we take into account the higher capacity factor of 80%, lets see what happens. 100 Watts X 24 hours X 365 days X 80% = 700,800 watt hours or 701 kWh per year. If this same CSP plant costs $300, then it produces power at cost of $0.43/kWr. This is a simplified example for illustration purposes. Actual LCOE calculations take into account longer time frames and many other factors.
The Big Advantage The big advantage to CSP plants are the ability to be base-load plants. This means the reliance on a traditional power plant for backup is no longer required and the cost of duplication of infrastructure is eliminated. CSP plants designed with overnight storage can produce power 100% of the time. On a cloudy day the overnight storage can become depleted. It is possible to build multi-day storage capacity, but this adds to the plant cost. Instead the power plant can use traditional fossil fuels as a backup. The same turbine would work on either fossil fuel or solar energy. The technology can also be retrofitted to some existing power plants with the addition of a solar field. This can become an economical solution to an existing power plant since this infrastructure is already in place.
Real Plant Economics The National Renewable Energy Laboratory (NREL) of the US Department of Energy (DOE) has created a program called the System Advisor Model (SAM). This sophisticated software program is able to calculate the LCOE of solar power plants based on traditional CSP technology as well as PV technology. This model only assumes an extra several hours of night time storage with a capacity factor (CF) of 40%. We plugged our numbers into the model and modified it to accommodate overnight storage with a capacity factor of 80%. The following table
illustrates the capital cost for; traditional CSP with a 40% CF, Ultra Lite with a 40% CF and Ultra Lite with an 80% CF. The model is based on a 100 MW plant size.
Traditional CSP 40% CF Ultra Lite CSP 40% CF Ultra Lite CSP 80% CF
Total Installed Cost $721,042,832 $352,007,867 $575,625,363
Installed Cost per kW ($/kW) $7,210 $3,520 $5,756
These numbers can be misleading when it comes to the real cost of power produced from these plants, which is why the NREL’s SAM calculates the Levelized Cost of Electricity (LCOE), which is a more meaningful number. The following table illustrates how we compare to traditional CSP. The first row indicates traditional CSP. The second row shows Ultra Lite with a 40% CF to do a direct comparison with traditional CSP. The third row shows Ultra Lite with overnight storage and a CF of 80%
Traditional CSP 40% CF Ultra Lite CSP 40% CF Ultra Lite CSP 80% CF
LCOE (nominal without incentive) 13.20₵ / kWh 6.44₵ / kWh 3.22₵ / kWh
LCOE (real without incentive) 10.45₵ / kWh 5.10₵ / kWh 2.55₵ / kWh
Interestingly enough, the LCOE with an 80% CF for the Ultra Lite plant is much less than for a 40% CF plant. The reason for this is because the solar field cost, which was traditionally the highest cost of a CSP plant, has now become a minor cost in comparison with the balance-ofplant equipment inclusive of the turbine and associated systems. Even though the Ultra Lite plant with a 80% CF has a higher capital cost due to the much larger solar field, it allows the turbine to be more fully utilized, resulting in a lowered LCOE. Again with these being base-load power plants, the real saving are even higher without the need for traditional backup power plants.
Global Deployment The Levelized Cost of Electricity (LCOE) takes into account the sunshine hours in different regions of the world and is referred to as Solar Insolation. The American Southwest could have twice as much Solar Insolation compared to the Northeast. The best economics are realized in areas of the world where better solar conditions prevail. In Europe, there has been discussion on the Desert-Tech project in which the deserts of Northern Africa could deploy CSP plants and the power would be sent to Europe via transmission line.
Space Based Solar Power The natural extension to the Ultra Lite Solar technology is for deployment in space. Space Based Solar Power (SBSP) has been a dream of engineers and scientists for decades, but the cost of deploying large structures in space has made it a non-starter. Launch costs are enormous. Ultra Lite Solar has spun off a company called Planetary Energy Systems with the focus of adapting this technology for space. Very large structures can be compacted into a
launch vehicle and expanded and largely self assembled in space. This could reduce launch costs by about 90% or more. There would still be some assembly required in orbit once system components were deployed. Much of this can be done from the ground using remote-controlled robotic assemblers. This would further reduce the costs of having people in space. The advantage of SBSP it that is can provide power to anywhere on Earth through cloud, rain or snow, 24 hours a day. It then becomes possible for countries to have their own SBSP satellites in orbit, beaming power to their country. The Japanese Space agency has announced their plans to deploy a SBSP platform into orbit by 2030, only 15 years away, the time it take to build and commission one nuclear power plant. The geosynchronous orbit is large with a circumference of 165,000 miles, enough space to power the entire planet many times over.
What’s next? The company has already signed a small contract worth about $16 million in investment that is part of a larger deal for deploying several small projects in the 20 MW range. As the company grows, it hopes to migrate to larger deployments in the 100 to 500 MW range. Even though the SBSP applications take longer to deploy, countries should start planning for them now for deployment in the next decade, as Japan is doing now. The company hopes to enter development agreements with countries interested in securing renewable energy in the near future.
Conclusion Today’s energy mix is largely based on fossil fuels. These are dumping greenhouse gases and pollutants into our atmosphere at an unprecedented rate. Human consumption of power is projected to double to 30 tera watts (TW) by 2050. Conventional sources of energy will not be able to fill this energy gap without burning a lot more coal, and that will have grave environmental consequences. According to the German advisory council of climate change, the world will have no option but to use ever increasing amounts of solar energy. They project that 50% of energy production could come from solar energy by the end of the century. It is hoped that these innovations could provide a significant contribution of renewable energy to this mix. Tom Beck is CEO of SHEC Energy Corporation Contact e-mail:
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