|The grid will need to be totally redesigned to integrate small generation inputs from PV, wind, biomass and other more sustainable system inputs, the majority of which will need to utilize energy storage to provide reliable energy reduction.|
By Bill vonBrethorst, Planetary Systems
The grid will need to be totally redesigned to integrate small generation inputs from PV, wind, biomass and other more sustainable system inputs, the majority of which will need to utilize energy storage to provide reliable energy reduction. The current grid system essentially precludes effective reductions of greenhouse gasses by these grid tied systems as we will demonstrate, and mandatory energy reductions will be required.
We have been bombarded by press releases and advertising touting advances in Photovoltaic panel efficiencies and the “coming decrease in PV cost” but since 2000, none of this has materialized. The decreased cost of inverter (non-battery) systems was also touted to be a savings, but no real decreased cost per watt in PV has occurred to date. When rebates became available to the end user (mandated by local government) and transferred to the end user by the utility, the taxpayer and ratepayer simply picked up the tab for a portion of the systems cost. Further, no real effective reduction of residential or commercial electrical loads has been realized, including in the state of California which has the highest concentration of residential grid-tied PV systems. The San Francisco Chronicle stated in an article in July, 2006, that the California has a current standard generating capacity of 48,000 megawatts; in just one day in 2006, the state required over 50,000 megawatts. A report submitted by the State of California indicates that, at maximum potential, the State of California might have 1800 megawatts of Renewable inputs from PV in the year 2017, if the current level of funding and installation continues. The obvious shortfall is staggering if greenhouse gasses are to be reduced in any significant way. To-date, according to DOE figures, no actual reduction in coal burning plant output has occurred, thus all reported CO2 offsets have been on paper only, not based in reality. Furthermore, there is currently only one operating CO2 capture power plant in Germany, built at tremendous cost and without any complete and extensive methodology of storing the CO2 captured in a proven safe and efficient manner. To gain perspective here, a brief history of renewables is required.
The original cost to dealers of solar modules was then and is currently around $ 5.00 per watt with an average retail cost of around $7.48 per watt, which limited the market. According to California state data, the average installed PV system costs $ 40,392 for 5.4kw which is an average cost of $ 7.48 per watt (since the inverter is only 5% of the cost). The cost of a battery-based, grid-tied system using standard flooded lead acid batteries and inverters would average $ 25,000 because smaller arrays are possible.
With the emergence of the environmental movement and as Global Warming began to be documented in the late 90’s thru 2000, many inverter manufacturers in conjunction with the PV industry began to implement an inverter which could be connected to the grid without batteries. The theory and rationale was that batteries limited sales, were inefficient, added cost and could not easily be mainstreamed to increase PV sales in the emerging grid-tie market. These inverters were originally low voltage (48vdc) with batteries, but later higher voltage units (250V+) were produced, having deleted the battery storage component. This change was purported to increase system efficiency with the intent to offset higher utility prices by selling back power in excess of load demand. At the same time, state governments, as a part of utility restructuring and de-regulation, began to implement net-metering policies which allowed funds to be credited back to the user for power generated from renewable sources. Due to the higher voltage architecture of the inverter systems, larger strings of PV panels were required due to the voltage requirements of the inverters with higher power requirements which resulted in more PV wattage being installed in systems. Now, PV manufacturers sold more PV panels and made more profit. The profit motive here was significantly more responsible for the integration of these systems than the “green” aspect, specifically for PV manufacturers and for residential consumers faced with high electricity prices. With hindsight, if we now compare this to the real estate meltdown and look at what has happened to our carbon footprint with an economic slowdown, we would see that higher electrical prices were not a contributing component of the economic slowdown and have contributed more to lessening our carbon footprint than all the wind and solar panels deployed to date. Our problem has always been that we never fail to concentrate on short term gain at the expense of long term stability. The real question is, even with high concentrations of wind and PV system input-what will provide utility stability when the sun does not shine and the wind does not blow? What is the fall-back strategy? Where is the base load capability?
As many areas have substantial rebates available and this rebate is based on the kilowatt value of the PV array, more large arrays are being installed. This has resulted in substantial profitability for the PV manufacturers, and high volume of sales for the grid-tie inverter sector. This is evident in the now large selection of PV manufacturers and the growing number of companies offering a non-battery inverter The perception of lowered cost is due exclusively to the rebate available and systems only appear more affordable to consumers, but in reality, the cost of solar modules has actually gone up due to increased demand and a world-wide shortage of silicon, the primary ingredient (see Wall Street Journal-Commodity trading). Meanwhile, the USA has steadily increased its electrical overall load over the past 5 years even though literally thousands of grid-tie systems (without batteries) have been installed along with many megawatts of wind generation, both large and small.
This increase in loads has resulted in an additional 1.3 billions tons of coal being burned by US utilities this year (2007), essentially negating the touted effect of ALL the renewable sources by increasing CO2 emissions, not reducing them. All of the gains in CO2 reduction to date have only been on paper. The most egregious claim is that somehow energy can be “stored” on the grid and that every watt sold back somehow reduces greenhouse gas emissions by utilities. Simple truth in advertising warrants an examination of these claims. Further, as the effects of global warming become more severe, utilities will not be able to guarantee a level of stable electrical services as in the past and this instability will impact the inputs from renewable energy, especially grid tie systems without energy storage.
* Grid-tied PV systems are an economical way to reduce electrical billing;
* Grid tied PV systems are a socially responsible way to “Green up” your home; Installing a PV array on your roof to sell back power, taking your rebate and not substantively altering your electrical consumption does not serve the larger purpose or energy conservation because this action does not appreciably alter the lifestyle which created the excess electrical loads. Without thinking about our energy use, we will eventually end up right back where we started, with more load than the existing array can offset.
* A larger the PV array equates to a more affordable the system with rebates;
* Grid-tied PV systems will combat Global Warming and reduce CO2 emissions; By far, the largest misconception regarding grid-tied PV systems is the claim that each kilowatt produced is directly correlated to a corresponding reduction in CO2 output from a utility source. Nothing could be further from the truth and supporting data, which is easily available from the government and private sector, proves this dramatically. According to the US Department of Energy, Renewable sourced inputs still remain at less than 1% of the total aggregate, and overall use of coal by utilities without substantial emissions controls is up. Nearly every state has a permitted new coal fired plant being or one about to be constructed. Coal fired plants simply cannot respond to grid-tie inputs (hundreds of miles away) by reducing fuel consumption. The average coal fired power plant is rated at about 500 megawatts. The fuel and water used are in continuous process and the steam supply is constantly level because they are all base loading plants, with computerized fuel and steam input. Even at best, grid tied PV is marginally available as a power source using grid-tied non-battery technology given the intermittent capability of PV output.
Simply converting PV energy to AC and putting this energy out on the grid may make sense from an accounting standpoint, but PV without storage does not make efficient use of the energy produced. Generally, grid tie systems without batteries consist of a very small (in terms of KVA and electromagnetic mass) inverter which is electrically unable to push great amounts of power back into an “infinite” grid. In the case of grid-tied inverters (without energy storage), these inverters have very little mass, and cannot remain connected to the grid without the main base loading generators being on-line also. Any instability and the grid-tied PV systems all, by design, are off-line, so they cannot help during brown-out conditions.
Main base loading generators are, at this point, mostly coal fired. A constant, computer controlled amount of steam and fuel are required to maintain the turbine output. No variation based on load is ever permitted in the fuel and steam levels. Therefore, no short-term grid input (PV or other) will affect the CO2 emissions of these plants outside of real (24 hour a day) load reduction.
Grid-tied systems with batteries and with virtually the same or smaller PV array can power major loads including refrigeration, fans, washers, dishwashers, lighting and other motor loads from stored energy rather than instantaneous power from the grid or PV. Independently powered using battery based inverters can effectively soak up the load surges, thus these loads are removed from the grid (isolated by the local lower generation and not transferred to the grid).. In addition these systems, using a reduced solar array and advanced lead-acid, sealed AGM (note-3) battery systems can supply as much as 50% of the homes load on a 24hour a day basis. This “flywheel” (a flywheel continues rotating even though the motivation force is removed) effect would have a very significant effect on the grid compared to the few hours daily that a grid tied system without batteries can deliver full power. With the same numbers of grid tied systems with batteries this 24 hour a day load reduction will benefit the utility and the environment since nearly all AGM batteries are completely recyclable. If 100,000 homes were fitted with PV-energy storage systems, instead of non-battery systems, the electrical profile of these homes would be reduced by over 70% as an aggregate. The resulting extra cost of the battery systems, would be more than offset by the reduction in solar modules while giving the same effect, and the overall cost to the consumer would be reduced even further by the same rebates.
1. A mandatory energy standard will need to be established for homes, businesses and energy producers. Although this may be perceived as rationing, it will be necessary. Our survival depends on viewing energy as a valuable commodity and equally valuing the side effects of how we get that energy. No carbon credits, no cap-and-trade, just carbon reduction-you cannot pay for the privilege of polluting.
2. Use of renewable energy inputs should be required with rebates tied to energy conservation and reduction including wind, PV, thermal and all must include an energy storage component. Excessive regulation of home-based RE systems will tend to suppress usage, so reasonable safety regulation is all that is necessary. All incentives need to be tied to a production credit rather than a rebate from the utility for long term incentives such as in Washington State’s production credit law-they pay consumers up to $ 0.26 per kwh produced from the RE source. In order for the energy standard to be viable, cities and rural areas will need to maximize the storage of energy to bring load reductions to a fully realized 24-hour a day minimum and maximum which is predictable and reliable.
3. Emphasis needs to be placed on a mix of energy resources with local control. In some cases this will still be coal, with superior emission controls and with limited carbon sequestration technologies, other areas may require small-scale nuclear plants as are used in France, where the average plant is around 100 megawatts. There can be no distinction between carbon sequestration and nuclear waste, as both will impact all our futures and either will do us great harm if not carefully controlled. Energy will and should cost more; we cannot delude ourselves into constantly looking for cheap energy-it never existed in the first place.
Note-3: AGM, absorbed glass mat batteries have been used for over 40 years in telecommunications and commercial applications and are more efficient, are not affected by environmental conditions and are usually sealed and maintenance free with very long life cycles. In most grid-tie applications, AGM batteries see no cycling whatsoever and in these cases, have unlimited life cycle as with float service application ratings (20+ years). Lead acid batteries, while seeming less efficient, can be recycled and require less exotic and expensive elements such as Lithium or Cobalt, natural resources of which the USA does not have.
Author: Wm. von Brethorst has been a project engineer and designer in the power generation industry for over 25 years with experience in hydro-electric, power plant operation, diesel power generation and renewable energy systems. He has operated Planetary Systems, Inc. since 1994. Home and business operate off-grid in southwestern Montana since 1998, building and selling patented Power Package Systems at our facility with hundreds of operating grid-tie and off-grid systems worldwide employing advanced AGM battery systems.