Renewable energy electric heat
This PV array will not keep you warm.

 

Electric Heat: A Barrier to Renewable Energy

Renewable energy technologies, when integrated within an offgrid diesel-powered microgrid, can reduce pollution and, when done well, generation costs. However, the first, essential step is often neglected: reducing the community’s demand for electricity. This post will focus on the main challenge: electric heat.

Electric heat: a pollution multiplier

In remote communities, electricity is often used for space heating, water heating, cooking and lighting. The lion’s share of electricity use comes from electric heat (baseboard or furnaces) and water heaters, with the highest demand occurring in winter.

Electric heat systems are cheap to install and convenient. However, diesel generators are at best 30% efficient, meaning that only 30% of the energy of diesel combusted becomes electricity. The other 70% are lost through heat up the smokestack and internal friction.Then, the resulting electricity is converted to heat through electric furnaces, baseboards and water heaters. In short, residents use nearly 3 times as much diesel fuel with electric heat as if they were simply burning diesel (or propane) in a high-efficiency furnace within their home. Thus 3 times the expense, and 3 times as much pollution: it is not uncommon for residents of offgrid communities to pay thousands of dollars per year for electricity.

Beyond pollution: electric heat makes renewable energy more difficult

Using electricity for space heat has several negative consequences:

  • Large electricity/diesel bills constrain the community and residents’ ability to finance a better energy system.

Community energy plan, pre-feasibility, feasibility studies are all upfront costs. While there are grants available, it takes time and effort to apply for funding, and a situation where, for example, community leaders have to constantly juggle budgets to make ends meet is not ideal to start thinking about renewable energy.

  • Electricity demand is high in winter, low in summer, high in the early morning and evening, low at midday.

Most renewable energy systems are not able to match this kind of profile, at least not economically. For example, a solar system will produce electricity only during the day, and will produce much more during a long, clear summer day than a short, cloudy winter day. There might not be any electricity produced when people come home around 5-6pm and need to cook dinner, and so on. While hydro or bioenergy systems are generally more flexible, they face the same issue: building them large enough to match electric heat-driven peak demand is rarely economical.

  • Electricity demand is high overall.

While diesel systems are cheap to install but expensive to run (low capital costs, high operating costs), renewable systems are expensive to install and cheap to run (high capital costs, low operating costs). A 200-person remote community will likely need to find several million dollars to shift most of its electricity demand to renewables, and the final price tag is largely driven by total capacity: do you need a 250-kW system or a 500-kW system? A small turnkey solar-battery offgrid system currently costs around $8/W: a 250kW system will cost $2 million, and a $500kW system just under $4 million (some costs are fixed).

Needless to say, it is easier and faster to fund-raise $2 million than $4 million.

So how do you get your community to stay warm without relying on electricity? This will be the topic of my next post.

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