Green Energy

Renewable Energy on the Farm: Are You Ready?

Don Campbell
Donald Campbell Associates
Northfield, MA

Before I get started with a discussion of the place for various types and scales of renewable energy on a farm, or in any other application I want to give you a two-word lecture. Conservation First!

There, I have done my renewable energy trade colleagues proud, because intelligent conservation practices can save huge amounts of money in certain circumstances, and so can the common, small, individual efforts when taken in aggregate. I will assume that the reader has been working on conservation all along.

Introduction

I grew up in a country area and while we did not farm, I was often on neighbors' farms in the barns and fields. My dad was an electrical engineer and the combination seems to have taken hold. Renewable Energy seemed a no-brainer when I heard about it. When my wife and I had a chance to live off-grid in Northfield, MA, we jumped on it.

Boy, was that an education. I generally learn best by using something and then getting help or the manual when something goes wrong, which usually translates to a dumb move on my part. It took a year or so to get on top of things, but we did. By then I was hooked.

I went onto develop the initiative that became Pioneer Valley PhotoVoltaics, a worker-owned installation business in Greenfield. I became one of the founding members but left when it became clear that I was better at starting the business than growing it. They are now doing well, and I. am working as an independent consultant getting a piece of introducing folks to a renewable future.

Types of renewable energy

By renewable energy we mean sources of energy that, when used, are replaced or renewed in a short, active time frame. It could be that oil is being made under the earth somewhere, but the time frame here is measured in millions of years. Sun, wind, flowing water are perpetually renewed on a daily basis. Biomass, trees, manure, wood chips and switch grass have an annual or longer cycle, but still visible to us in our own lives. (Just think of the work needed to keep the forest from reinvading some garden or patch of pasture!)

In the northeast our indigenous energy sources are pretty much limited to sun, wind, flowing water, and biomass. Coal is present in Pennsylvania, where oil and gas were once major sources of energy. In terms of regionally produced energy in the northeast renewable energy is really all we have to work with as we look ahead. Fortunately there is an active renewable energy community in the region working in solar, wind and micro-hydro applications. There is sophisticated work being done on large-scale biomass in a bid to add value to forest land and help people stay on the land. Many people use wood for heat. In Vermont a 250 cow dairy farm is now making methane from their manure lagoon, running a generator and selling power back to the grid. In this paper I will be concentrating primarily on solar and to a lesser extent wind. Micro-hydro is up and coming so I will have a few comments on that.

Solar

What most people think of as 'solar' refers to two completely different technologies, often referred to as Solar Domestic Hot Water (SDHW) and photovoltaics (PV), which produces electricity. Both of these perform best when oriented less than 15E away from true south. If you do this, please remember that the compass reads magnetic north (and south) that varies from true south geographically and over time. Fortunately no one needs to be surveyor specific. Since your installer will also check, you can safely use a compass to self-evaluate your potential site. All solar has greater output in the bright months.

There are two types of solar collectors used in SDHW presently available. Flat-plate collectors have been used for years and are probably what comes to mind for most people. Evacuated tubes arrived on the scene about 5 years ago. They have been gaining steadily in market share. There is a small difference between the two. The flat plate collectors are like your car in a sunny parking lot with the windows rolled up. Hot! Pipes run through the collector carrying water or propylene glycol, an antifreeze that is actually found in some non-organic foods.

Evacuated tubes are vacuums with a very small amount of water inside and a copper pipe that connects only to the manifold on the top on the top of the tube. In the vacuum, heat is transferred to the copper pipe and in the manifold the fluid picks up the heat.

In the northeast propylene glycol closed loop systems are the norm. This means that whether it gets hot running through the flat plate collectors or through the manifold of the evacuated tube set it will go to a heat exchanger, usually set inside a pre-heat tank, also called a tempering tank. There it heats domestic water that runs to the hot water tank where it is heated to the set temperature if necessary.

These systems can save 60-80% of the energy used "to heat" domestic water. Typically they will cost $6,000-8,000 for a family of four, somewhat more for evacuated tubes. Add about $1,000 per extra person.

Because some of the heat escapes through the glass of flat-plate panels they shed snow, the tubes do not. The tubes perform better in less than full sun so can provide additional heat in the darker months. Should there be any chance of breakage it is cheaper to replace an evacuated tube than drain and replace a flat-plate panel.

A photovoltaic module, or PV, produces electricity. To really get it, you need to have some understanding of power and energy and what a kilowatt (power) is versus a kilowatt-hour (kWh). The kWh is what the utility bills you for. As an example, a typical residence (non-farm) in the northeast uses between 500 and 600 kWh per month and 6000 to 7200 per year. PV makes electricity from sunlight. In our region PV produces about 80% the annual production in the bright half of the year, it is a good match to summer demand, often associated with refrigeration. PV can be roof mounted, pole mounted, or ground mounted.

Wind

Small wind can be a fabulous addition to a farm energy budget. However, except for high ridges and the coastline, the annual production is not as high as some other areas. Nevertheless, a windmill can produce regular, steady energy. Like PV, there is a seasonality to wind. Fortunately it runs opposite to PV, that is, it produces more in winter as a general rule. Many towns have a hard time accepting the towers and windmills. Before getting into a wind project you should get your ducks in a row and talk to people well before applying for a permit.

Small-scale hydro

Small-scale hydro can be a very inexpensive source of electricity. There are now available small, reliable wheels that allow you to borrow water from a stream, run it through a pipe, turn the wheel, and then put it back into the stream. The problem has been that Conservation Commissions and Planning Boards have little or no experience with this kind of micro-hydro. The result is a lot of meetings to educate your fellow citizens. In Massachusetts, people at the Department of Environmental Protection (DEP) said they knew about this kind of micro-hydro facility and would probably have no problem with it if the Conservation Commission would pass it up for DEP review.

Loads and Phantom Loads

To plan a renewable, energy installation at any site, it is important to know the load the system is required to meet. Load simply means the energy draw. There are two important numbers. The most important is total kWh used in a given period, by month over a year, and annually is usual The other number is important depending on the situation. That is the highest momentary demand.

Speaking of loads, the most important loads to get rid of before sizing a system are phantom 1oads. A phantom load is anything drawing power when not doing anything useful for you. Phantom loads include TVS when they are off (they aren't really and can draw as much power in 22 hours off as 2 hours on), appliance clocks if you don't really use them, transformers for portable radios, cordless phones and the like, these draw power even if plugged in and unattached on the business end. Computers these days should be off when not in use unless you use them for work, then at least they should be off when you are sleeping.

Changing light bulbs to compact fluorescents (CFs) is also a big energy saver. There are more and more shapes and sizes than even a few years ago and the light is much better. I once did a calculation for a restaurant, if they had replaced every light bulb in the dining room with CFs they would have made an 800% return on investment! A friend of mine changed all the most used lights in his home from incandescent to CFs and saved over $20 a month. There are outdoor rated CFs that give plenty of light that would be great in barns.

My guess is that most readers already have done the light bit, but you can sometimes get similar savings if you work at the phantom loads.

Choosing your renewable energy system

If you are serious about renewable system for your home and farm there are some questions you need to answer. Like farming renewable energy system design is site specific. Are you thinking of bringing electricity to a new area? How far away is it? and so on (more later).

The simplest systems are designed to interact with the utility-provided power (the grid). These are called grid-tied systems. Their effect is to reduce the number of kWh you buy through the meter the system is connected to. If you are, not trying to power a remote area of the farm, this is usually the most affordable way to go. However, if the grid goes down, you will lose power. This is a required feature so that, linemen repairing the power lines do not get electrocuted by electricity from your system.

The next category of systems is remote battery systems (PV remote). These can provide AC .or DC power at any site. There is usually less incentive money for these systems and there is more expense in batteries and inverter for the AC. However, how far is remote? You need to consider the extra cost of trenching and permits to come to a fair comparison of costs.

Multimode systems (PV multimode) are those that can switch from grid power to battery power when the grid goes down. This technology is proven. The same switch that keeps power from your system from sending power out into the grid when grid power fails switches, instead to a battery bank. The switch trips in one-half of a cycle (120th of a second). Fast enough for computers to keep working. Because of the battery bank and a more sophisticated inverter these systems are more expensive than simple grid-tied systems.

When more than one kind of renewable energy is providing power to the same load or house the term used is Ahybrid@. An example of this is using wind and PV together so that there is a more even power supply with winter production largely from the wind and summer production largely from the solar.

Applications

In order to get your imagination working, I hope some applications in the real world will give you fodder for thought. I have already mentioned pumping for a stock tank. This pump system can also be used for drip line irrigation, pond aeration, and so on.

We have DC lighting in our barn. Three used golf cart batteries (BV) make a 24 volt system for lights. Two 20 watt PV modules keep the batteries topped off. No rocket science here. It is important to get DC lights rated for the voltage of the system or you will get exploding lights or almost no light at all.. Any application that uses an electric motor might be suitable for a PV direct or PV remote system. The total cost, including labor came to $500.

Where farms have a large power demand for ventilation, refrigeration, or pumping, there is already a generator on site, and it is easy to connect to the grid. The PV grid-tied system is usually best. In this case a barn roof becomes a perfect mounting structure for the PV array and extra money is available if you make the PV be the roof, and not put it on the roof. Since finish work that would be required for a house is not necessary in this case, there can be real savings. Or, if the load is more winter based, the a windmill can be installed with a similar electrical hook-up.

PV can be mounted on single poles or on a structure in a sheltered area for shed roof style. This can provide shade for animals of a sheltered area for farm visitors or customers.

Helpful Programs

Net Metering

Net Metering is the law in many states, though it is applied differently state by state. Net metering allows a renewable energy system owner to get full retail credit for energy produced up to the even steven point where no one owes anyone. If you go over the 0 point so the utility owes you for surplus based on the reset cycle, you either won't get paid at all, or at the lowest wholesale value. This is generally considered to help ISO New England manage the grid safely. The limits on this program have to do with size of system on the customer's side of the meter, the reset to zero cycle, and rules for interconnection agreements. In most cases, behind the meter size will only affect very large installations so I won't elaborate here.

The reset cycle can be significant. In Maine there is an annual reset. This means that surplus energy produced is carried over to the next bill. This means that you can essentially bank summer sun for use in the winter. In New Hampshire, the surplus is simply carried forward. There is virtually no difference to a customer in the values involved. In Massachusetts, the reset is monthly. Practically, that means that PV systems are designed to 'touch zero' for the brightest months, June and July. Annual net metering for domestic use would increase the designed size of PV systems in Massachusetts by a factor of about 3.

Money

If you are planning a renewable energy system the good news is that the USDA wants to help. Through their Rural Development Program, there is a program that will pay 25% of the cost of a renewable installation. You must live in a USDA determined rural community. That means those living near cities might not qualify but check first:

The new energy bill gives a 30% tax credit for rural businesses. The same is available for residential but with a $2000 cap. An accelerated depreciation is also allowed for business.

Many states also have tax incentives and incentive programs all of which are unique in structure and value. Installers and designers working in your state should be knowledgeable about these programs and help you determine the real value of any system you purchase.

Energy Audit

In most cases to qualify for funding you will have to have had an energy audit. It is amazing how much that can uncover. Your utility may have a program that does the audit for free and there are other qualified energy auditors around. On one farm I visited that has a retail operation, and hence refrigerators and freezers, the auditor caught one of the freezers operating at a temperature 15 degrees below what it needed to. One change of the thermostat started saving money. We also discussed capturing heat from the compressors for hot water in the kitchen. Once they get the new compressors and that system set up, the savings will mount. Please get your audit early!

Some examples

A few more examples of farms I am working with follow. An organic vegetable will be putting up a BIPV (building integrated PV) awning so their customers will be protected from the elements while they are waiting at their pick up, rain or shine. This received an extra $1.50 per watt from the Renewable Energy Trust in Massachusetts because of the BIPV. For a 3.3 kW system, that amounts to $4,950. Now customers can be shaded and travelers headed north and south in front will see the PV right there. Certainly good education, and we hope, good marketing.

In another situation, a pick-your-own orchard with an event building is looking at PV and wind. In this case, the load profile is difficult to plan for. There is very little demand in spring an early summer until the picking starts in earnest. A windmill on their very open and high location could help a lot meet refrigeration demands through the winter. The late summer and early fall could be met with PV, but enough to help in August through October would be overkill in May and June. One of the ideas the farm has is to really push the use their event barn in the less busy, spring and early summer to boost demand and make a quality PV installation on the perfectly oriented and pitched roof sensible. As a pick-your-own operation, the opportunity for education will probably net some extra incentive money.

Biodiesel

I cannot end this article without mentioning biodiesel. This is a fuel that has some promise in a modest way. I am especially excited about CoopPower's (www.cooppower.com) biodiesel initiative in Greenfield, MA, which should be selling fuel in spring of 2006. This cooperative effort expects to pay patronage refunds to members based on use. The feedstock will be used grease. They have a contract with a company that picks up restaurant grease in New York City. Some people argue that virgin soy oil makes the best biodiesel. The chemists I have spoken to who are knowledgeable say there no difference in the end product. Further, something bugs me about using a virgin feedstock that could be food for people or livestock.

The DPW in Keene, NH uses B20, a 20% mix of biodiesel and petroleum diesel in their fleet. They have had no gelling problems and anecdotally I have been told that there are noticeably fewer sick days because people feel better. The manager reported having severe headaches if he spent more than a short time in the garage before the shift. No more.

As a replacement for home heating oil, biodiesel is a smart choice. The burner does need tweaking, however, so be sure not to get ahead of yourself. You can burn up to B100 (100% biodiesel) in your oil furnace if you get it adjusted correctly. I recommend starting with more available 83 or 85 so the tweaking is minimal. In a year or two, the oil burner technicians and the industry will have caught up.

Closing

In this article I have tried to give you an overview of what is out there as far as renewable energy options for you and your farm. Because of my experience, it is certainly slanted towards solar There are some general principles, however.

! Conserve first !

! Learn how to read your utility bills.

! The right system for you is site specific. The physical opportunity that exists and the demand placed on it by your use will determine the best system. It is not a case of what worked for you neighbor, friend, or colleague will work for you.

! Work with reputable installers who won't try to force you into one or another type of system without explaining why.

! Talk to your town's building and wire inspectors early to get a sense of any obstacles you might have to overcome. The installer will do most of the heavy lifting in this regard, but you can help by asking for input from these folks. Mostly they are curious, but just haven't seen any systems yet.