Analyzing Distributed Energy – Living Off the Grid in
Emergency Situations
In the aftermath of Hurricane Sandy, people all over the
east coast of the U.S.
are asking themselves what they can do to lessen their reliance on centralized energy
systems for their electricity, heat and transportation needs. As climate change
brings the potential for more intense and frequent extreme weather events, the
desire for alternative energy options is becoming more prevalent. Few experts
doubt that the energy regime of the future will bear little resemblance to our
current system, but what technologies are available and economically viable
today?
CleanEdison explored the practicality of a few of the
leading candidates and found that today’s technology can provide all the
electricity, heat and transportation needs during a power grid failure.
However, continued investment is needed to make these technologies truly
economically viable for mainstream application.
Grid-Tied Emergency Solar Panels with Battery
Backup
Solar proponents have long envisioned the day when
residential solar systems could truly be mini power plants. If the home used
its own electricity when it could, sold excess electricity to the grid when it wanted,
and stood on its own when it needed, installations would spring up across the
nation. Initially, PV systems were installed for many off-grid applications.
However, according to the International Renewable Energy Council (IREC), in the last decade, and especially in the last
several years, grid-connected installations have become the largest sector for
PV installations. Most of these installations are on the customer-side of the
meter, although the last three years have seen an explosion of utility scale
systems. On the other hand, off-grid systems have become such a small section
of the industry that data on them is generally not counted in IREC and EIA
reports.
As impressive as the growth of solar PV installations have
been, grid-tied systems are only as reliable as the grid itself; without a
functioning grid, they produce no energy and the dream of residential energy
independence goes out the window. But large scale disasters, such as Hurricane
Sandy or the Fukishima nuclear disaster in Japan have a way of focusing
attention back on the idea of mixing grid-tied solar PV with battery back-up on
the residential level.
Today, solar installers are willing to provide this type of
system, but there is almost unanimous agreement that it is not worth it. This
is because the cost of current batteries adds about 40 percent to the initial
cost of the system and almost doubles the price over the lifetime of the system.
Furthermore, while the panels themselves will last 25-30 years, most batteries
on the market will only last 5-7 years before needing to be replaced. The
problem is exacerbated by the fact that the 30 percent federal tax credit for
residential renewable energy does not cover storage systems and batteries.
Some companies haven’t given up hope, finding creative ways
to take advantage of incentives that do cover energy storage systems and
combining those with solar installations. The most prominent example of this is
the partnership between Tesla and Solar
City which, according to IDC Energy
Insights, have filed more than 70 installation permits in the Pacific Gas &
Electric territory
of California, most of
which are 5 kw residential projects.
The companies are requesting subsidies from California’s Self-Generation
Incentive Program. To qualify for that program as an energy storage system,
there must be 4 kwh of storage for every kw of generation. That means that each
5 kw system must have 20 kwh of storage. For homeowners, this plan would help
pay for 1/3 of the cost of the system. Customers would save additional costs
through ime-of-use (TOU) utility costs in California, where costs are more expensive
at hours of high-demand and less expensive when there is less demand.
Using maximum power point tracking (MPPT), these systems are
fully automated to charge the battery at night during off-peak times,
discharge, recharge during the solar producing hours and discharge again, all
based on time-of-use power sourcing. All said and done, the plan in California will bring
the dream of mixing cheap grid-connection with security of battery storage for
unexpected blackouts and major disasters for about $6,000 on top of the
installation, around the same as an advanced hard-wired generator would cost.
Of course, all this stands on federal incentives for PV,
state subsidies for energy storage and residential time-of-use utility rates.
Still, given the fact that there was over a $50 billion price tag on Hurricane
Sandy, 60 percent of which was from lost business, supporting this type of
solution should be seriously considered.
Geothermal Ground Source Heat Pumps
Geothermal energy, in the form of a ground source heat pump,
does not produce any electricity and cannot be expected to keep business
running after a super-storm like Hurricane Sandy. But for many of those
affected by the storm, more immediate concerns about their access to space heating
and hot water is the driving factor towards looking into alternatives to their
current system. Around the world, although ambient temperatures change wildly
from day-to-day, the temperature only a few feet below the earth’s surface
remains relatively constant. This stable temperature can be harnessed to
provide heat in the winter and cooling in the summer for less money than other
forms of space heating.
Unfortunately, these systems do require a small amount of
electricity, so if the grid is down, you will need a battery-backed solar array
or a small generator. On the other hand, in a major hurricane like Sandy, there is no
concern of damage to the geothermal system, as it is housed entirely
underground. Furthermore, as opposed to furnaces, which run on gas that can be
shut down by the utility or even leak into the flood water caused by
hurricanes, ground source heat pumps use water or other non-toxic liquids to
transfer heat from the ground to the house.
Even when there is not a major disaster that knocks out the
power, geothermal energy is generally a good idea for homeowners (although less
so in high-density areas such as Manhattan).
Geothermal systems represent a savings to homeowners of 30to 70 percent in
heating costs, and 20to 50 percent in the cooling costs of conventional systems.
The systems require little maintenance and the underground pipe of the system
carriers up to a 50-year warranty. Also, the $9,000 price tag is a lot more reasonable
for most people than the $25,000 to buy the equipment for a solar array.
Though geothermal technology doesn’t get the recognition of
the other renewable energy technologies such as solar and wind, it saw high
growth rates this decade as well, although the growth slowed in 2009 due to the
recession.
Electric Vehicle Security and Plug-in Hybrid Vehicles
In addition to the lack of power and heat in many areas
affected by Hurricane Sandy, an ongoing problem has been the lack of available
gasoline. In the New York Metropolitan area, 38 percent of gas stations still
did not have gasoline available 10 days after the storm. This lack of
transportation fuel has caused problems with government and community relief
efforts as well as people’s ability to get back to work, even when the lights
went back on. This is in addition to already sensitive feelings about the price
of gasoline, climate change and the country’s reliance on volatile
international oil markets.
Electric vehicles offer the promise of relieving the
pressure that people face when forced to fill up at the pump, as well as an
alternative for the gasoline shortage that still plagues the east coast. Of
course, these vehicles have drawbacks due to their infancy as an industry. Many
consumers still have “range anxiety” about running out of electricity without anywhere
to charge it. In areas with strong government support such as California,
Oregon and New York, this is becoming less and less of
an issue. Companies have developed and continue to improve the charging times
of public charging stations that work like gas stations for conventional cars
and there has been a steady expansion of these systems to support the growing
number of plug-in hybrid and electric vehicles.
Obviously, these vehicles require a working electrical grid
that might be compromised in the aftermath of storms like Hurricane Sandy. That
is, unless we develop grid-connected solar with battery backup. With this
system, electric vehicles owners could produce enough energy to charge their
vehicles overnight. If this is the plan, homeowners would need a slightly larger
array (an extra three 200 w solar panels should be enough) or will have to
ration electricity use when the grid is down. In either case, for most electric
vehicle/solar PV combinations, you will have around a 14-year payback. While this
might seem like a long time, the payback period for an electric vehicle without
a PV installation is more like 50 years.
Conclusion: Off-Grid Power Solutions Provide Added Security
It is entirely possible with today’s technology to be
independent of the centralized electricity and transportation systems that we
take for granted until they are gone. These solutions do come with high upfront
costs that must be taken into account, but unlike conventional energy
technologies, there are very few on-going costs, so the systems are cheaper in
the long run. Furthermore, in the event of a natural disaster such as Hurricane
Sandy or the Fukishima Nuclear disaster, these distributed energy forms allow
for autonomous energy production and self-reliance.
Government incentives and policies will play an important
role part in the continued development of these technologies. While tax credits
and other direct subsidies are important, a renewed sense of urgency for basic
research into developing energy storage technologies will have the largest
impacts down the road.
For the present, those in states such as California, with subsidies for energy
storage and utilities that offer time-of-use rates, homeowners should be able
to get battery backup for their solar systems for about the same price as a
conventional generator. Having a battery backup system to a solar array opens
the opportunity for further money-saving and disaster resistant systems such as
geothermal heat pumps and electric vehicles. In any case, the threat of more
severe weather events in our future will likely lead towards developing more
independent energy production.
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